FRONTISPIECE. I, cell of fleshy scale of bulb of onion (Allium Cepd) showing cyto- plasm, nucleus and large central vacuole. Chloroplasts: 2, a parenchyma cell of green fruit of garden pepper (Capsicum annuum) showing cytoplasm, nucleus and chloroplasts; 2a, a chloroplast of a moss (Funaria) showing green granules, assimilation starch grains and protein granules; ab, a cell near the periphery of the pseudo-bulb of the orchid (Phaitis grandifolius) showing cytoplasm and three reserve starch grains formed by leucoplasts, which latter under the influence of light have developed into chloroplasts. Chromoplasts: 3, a parenchyma cell of ripe fruit of Capsicum annuum showing cyto- plasm, nucleus and yellowish-red chromoplasts; 3a, isolated chromoplasts of carrot (Daucus Carota). 4, transverse section of petal of wild pansy (Viola tricolor) showing colored cell-sap in epidermal cells. APPLIED AND ECONOMIC BOTANY FOR STUDENTS IX TECHNICAL AND AGRICULTURAL SCHOOLS, PHARMA- CEUTICAL AND MEDICAL COLLEGES, FOR CHEMISTS, FOOD ANALYSTS AND FOR THOSE ENGAGED IN THE MORPHOLOGICAL AND PHYSIOLOGICAL STUDY OF PLANTS BY HENRY KRAEMER PH.B. (in Chemistry), Pn.M. (in Pharmacy), PH.D. (in Botany) HONORARY MEMBER BRITISH PHARMACEUTICAL CONFERENCE; HONORARY MEMBER CONGRES INTERNATIONAL DE PHARMACIE, BRUXELLES, 1910; CORRE- SPONDING MEMBER SOCIETE DE PHARMACIE DE PARIS; PAST PRESIDENT AMERICAN CONFERENCE OF PHARMACEUTICAL FACULTIES; MEMBER OF THE EXECUTIVE COMMITTEE OF REVISION OF THE PHARMA- COPOEIA OF THE UNITED STATES OF AMERICA, ETC. ILLUSTRA TED With 424 plates, comprising about 2000 figures SECOND EDITION NEW YORK JOHN WILEY & SONS, INC. LONDON: CHAPMAN & HALL, LIMITED Copyright, 1914 BY HENRY KRAEMER Copyright, 1916 BY HENRY KRAEMER All Rights Reserved PRESS OF BRAUNWORTH & CO. 7/2O BOOK MANUFACTURERS BROOKLYN. N. V. PREFACE TO SECOND EDITION. That this work on Applied and Economic Botany has been appre- ciated is shown by the necessity of a new edition in less than two years. It is now fourteen years since the author first undertook to write a book on -Botany, and since then he has endeavored to improve each succeeding work to conform to the suggestions and criticisms which were submitted. The reviews of this new work have been uniformly favorable, and apparently the book has given great satisfaction to teachers, students, and those interested in botany. The only criticism that has been offered is that it is perhaps too comprehensive for the average student. This criticism is really the best recommendation of the value of the book and the service it is rendering those engaged in applied science. The training of the analyst and pharmacist can hardly be too complete, as their work touches the very depths of science, and unless their training has been very broad and thorough, they cannot hope to solve the problems that are presented to them. This book, however, was written not only for use as a text-book, but it was intended to be a hand-book or laboratory manual for the graduate after he has entered practical fields. That this has also been realized to some extent is shown by the attestations of many graduates who have found in it just the information which they needed. In the present second edition, the author has carefully revised the text, making such corrections as were necessary and bringing the work up to date. Among the new matter added is a much needed glossary, and a concise statement concerning the nature and properties of the Vitamines, an important group of recently discovered nitrogenous substances. A word might be said in regard to the glossary, which is replete and will be found to supplement the subject matter. It was not until the preparation of this part of the work was fairly under way that it was found that the defini- tions as given in the average glossary and in some of the best dictionaries were frequently inadequate and vague. It is believed that the inclusion of the glossary in this volume enhances its value, and will be appreciated by teachers, students and analysts generally. It may not be amiss to state here that since the appearance of the first edition of this work, the author has published a supplementary volume entitled "Scientific and Applied Pharmacognosy." In this latter work, de- voted to the consideration of drug, food and economic products, the class- ification has been according to their natural relationship. The character- istics of the families comprising them are considered from an anatomical view point, so that the information given supplements that in the Applied and Economic Botany, where the treatment is essentially that based upon their organography or outer morphology. In fact the volume on Pharmacognosy, in addition to its value to pharmacists and analysts, will be of very great interest to botanists as it is in a large measure a treatise on the comparative anatomy of plants. September, 1916. H. K. PREFACE. THERE are quite a number of books on botany, many of which serve a very excellent purpose. For the most part, however, they are not adapted for the use of students in the applied sciences where the knowledge of botany is to be utilized later in practical work. It is now more than sixty years since Schleiden showed the value of the microscope in the examina- tion of drugs and Schacht demonstrated its usefulness in the study of textile fibers. Since that time quite a number of works have been pub- lished dealing with the microscopy of special technical products, as drugs, foods, fibers, woods, etc., but there have been no text-books which could be employed in the courses on applied and economic botany that would satisfy either the desires of the student or fit the graduate for practical work in commercial life. It is not generally appreciated that there is a depart- ment of applied botany which is distinct from every other phase of botani- cal study ; the point of view and the technique being peculiarly its own and the problems so intricate and important that they should ever be held be- fore the student and command his constant attention. It is almost self- evident that courses in botany which are intended for intellectual culture or scientific discipline are not adapted for technical courses of instruction. In the latter the student has a right to ask for the application of the in- struction which he is receiving and to show an interest in proportion as the instructor is able to demonstrate its value. There are some who consider that a more or less superficial knowledge of botanical principles and micro- scopic technique is sufficient for the student in applied or economic botany. On the contrary, we find that a rather extended knowledge of botany and a very thorough preparation in certain phases of botanical work are absolutely required in order to prepare him to meet and solve the many problems that arise in the commercial world. Many of the commercial problems that are held to be chemical and which are handed to the chem- ist for solution are, as a matter of fact, of a botanical character and can be solved with less expense and less time by the trained botanist. What is really needed is the trained analyst, who, while proficient with chemical methods, is also thoroughly versed in microscopic technique. We have come to a time, if real progress is to be made both in the manufacture of plant materials and in the examination of commercial substances, that it is necessary to bring both chemical and botanical training and knowledge to bear upon the problems involved. Nearly all of the problems upon which one is liable to be consulted in active practice, whether they involve new processes of manufacture or the examination of the finished market material, show at the outset that the analyst must have a very thorough knowledge of the cell constituents and the tissues composing the raw material. It is for this reason that almost one-half of the material of this volume is devoted to the study of v vi PREFACE. cell-contents, forms of cells, and the outer and inner morphology of higher plants. The facts and illustrations here presented cover not only the latest researches on their morphology, origin, and distribution, but also the most recent advances in regard to their chemical nature. A fair amount of this work is original, and the presentation in one volume, it is hoped, will be appreciated in addition also by students of the plant cell as well as the phyto-chemist. In the practical examination of the crude materials of the market we find more or less contamination with fungi, lichens, and other lower plants, and for this reason, as well as for the understanding of the morphology of the higher plants, a more or less succinct treatment of the Principal Groups of Plants is given in Chapter I. Another reason which has prompted the author to lay considerable stress on the knowledge contained in this chap- ter is that if the student will master the technique and will apply himself to this part of the work, he will be better prepared to take up the study of the structures of higher plants. The chapter on Classification of Higher Plants is quite extended and illustrated with a large number of photographs, showing not only many of our interesting wild plants but the principal economic plants that are used as foods, drugs, and for other economic purposes, 'with considerable valuable technical information concerning them. The chapter on Nomen clature has been included in order that the derivations of botanical names might be better understood and their correct spelling facilitated. The chapter on Cultivation of Medicinal Plants, while especially prepared for those interested in the subject, will be found useful to those interested in other industries where the extermination of native plants is calling attention to practical means for their replenishment. The chapter on Microscopic Technique contains methods for the preparation of commercial materials and much information that doubtless will facilitate practical work. The index contains some 6,000 titles, making the information contained in this volume readily accessible. The work is illustrated throughout, and the legends accompanying the illustrations will be found interesting and instructive and in most instances supplement the information given in the text. All of the illustrations which are not reproductions of photographs and drawings made by the author are duly credited. The author acknowledges the valuable services rendered by his associates in the preparation of the text, reading of proof, and prep- aration of the index ; to Professor Wallace Truesdell for assistance in the chapter on Botanical Nomenclature and to Mr. Stewardson Brown for the use of a number of photographs. When larger monographs and authoritative works have been consulted, due credit has been given in the text, so that the present work is a foundation not only of a text-book for students of applied and economic botany but as a reference book for manu- facturers and analysts, i NOVEMBER, 1014. H. K. CONTENTS. CHAPTER I.— PRINCIPAL GROUPS OF PLANTS. PAGE INTRODUCTORY i THALLOPHYTES 6 Schizophytes 7 Schizophyceas (Fission Algae) 8 Schizomycetes (Bacteria) 12 Algae 16 Chlorophyceae (Green Algae) 20 Phaeophyceae (Brown Algae) 28 Rhodophyceae (Red Algae) 31 Diatoms 35 Fungi .' 40 Phycomycetes (Alga-like Fungi) "... 42 Ascomycetes (Including Yeasts) 47 Basidiomycetes 56 Fungi Imperfecti 70 Lichens 71 ARCHEGONIATES 75 Bryophy tes 76 Hepaticae (Liverworts) 80 Musci (Mosses) 84 Pteridophytes 86 Filicales (Ferns) .• 87 Equisetales (Horsetails) 96 Lycopodiales (Club Mosses) 97 SPERMOPHYTES (SEED PLANTS) .' 100 Gymnosperms 101 Angiosperms 119 ORGANIC EVOLUTION 128 CHAPTER II.— CELL-CONTENTS AND FORMS OF CELLS. PROTOPLASMIC CELL-CONTENTS 134 NON-PROTOPLASMIC CELL-CONTENTS 140 FACTORS INFLUENCING GROWTH, INCLUDING FOOD OF PLANTS 246 FORMS OF CELLS 262 Parenchyma 262 Mechanical Tissue 264 Conducting or Mestome Cells 272 Protecting Cells 277 vii viii CONTENTS. CHAPTER III.— OUTER AND INNER MORPHOLOGY OF THE HIGHER PLANTS. INTRODUCTORY 298 I. Outer Morphology of the Root 299 Inner Structure of the Root 309 II. Outer Morphology of the Stem 320 Inner Structure of the Stem 338 III. Outer Morphology of the Leaf 348 Inner Structure of the Leaf 365 IV. Outer Morphology of the Flower 374 Inner Structure (Histology) of the Flower 402 V. Outer Morphology of the Fruit 408 Inner Structure of the Fruit 421 VI. Outer Morphology of the Seed 423 Inner Structure of the Seed , 427 CHAPTER IV.— BOTANICAL NOMENCLATURE 430 CHAPTER V.— CLASSIFICATION OF ANGIOSPERMS YIELDING ECONOMIC PRODUCTS. INTRODUCTORY 463 MONOCOTYLEDONS 463 DICOTYLEDONS 501 Archichlamydeae or Choripetalae 504 Metachlamydeae or Sympetalae 643 CHAPTER VI.— CULTIVATION OF MEDICINAL PLANTS PLANTS GROWN FROM SEEDS 728. PROPAGATION BY CUTTING '. 733 COLLECTING- AND DRYING OF DRUGS 737 RELATIVE VALUE OF DRUGS FROM CULTIVATED AND WILD PLANTS 739 PROGRESS IN THE UNITED STATES 744 CHAPTER VII.— MICROSCOPIC TECHNIQUE AND REAGENTS. MAKING OF SECTIONS 749 PRACTICAL SUGGESTIONS 751 MlCROMETRY OR MICROSCOPIC MEASUREMENT 754 REAGENTS 755 EFFECTS OF IMPORTANT MICRO-CHEMICAL REAGENTS 759 THE MicRO-PoLARiscopE 764 THE SPECTROSCOPE IN MICROSCOPIC ANALYTICAL WORK 764 DARK FIELD ILLUMINATION AND THE ULTRA-MICROSCOPE 765 MICRO-ANALYSIS . . 766 BOTANY INTRODUCTORY THERE are four main lines of botanical work now recognized, — namely, Morphology, Histology, Physiology, and Ecology. MORPHOLOGY treats of the form and structure of plants and the subject is sometimes divided into (i) external morphology or organography and (2) internal morphology or anatomy (histol- ogy)- The former deals with external characters of plant parts and the latter with their minute inner structure. PHYSIOLOGY may be defined as the study which considers life processes and the condi- tions which influence these. ECOLOGY is the study of the adapta- tion of plants and their parts to external conditions. It is impor- tant to bear in mind, however, that these several departments are more or less interdependent, and that one of them cannot be intelligently studied without a consideration of the problems of the others. For instance, as Goebel states, we cannot under- stand the relation of the external forms of organs without refer- ence to their functions. In other words, form and function have a direct relation ; one influences the other. So, too, in the study of ecology we study the influence of external conditions on plants and these, as indicated above, have a direct influence on physiological processes, and thus the study of ecology merges into the study of physiology on the one hand and into morphology on the other. While this book will deal chiefly with the structure of plants and their parts, still it will be necessary occasionally to refer to some of the characters of plants which properly belong to other departments of botanical study. Basis of Plant Structure. — In order to understand the sig- nificance and relation of the various parts of plants it is necessary 2 A TEXT-BOOK OF BOTANY. to know something of their functions and habits of life as well as of their internal structure. It is desirable at this point to give a brief consideration to the cell, as it is the unit of plant structure. If we make a section of a plant and examine it by means of the microscope, the cut surface presents the appearance of a network, indicating that the tissue is made up of small compart- ments or chambers. One of these compartments together with its contents constitutes the structure known as the CELL (see Frontispiece). The cell-contents vary greatly in appearance and composi- tion, but in all active or living cells there is always present the substance known as PROTOPLASM. The protoplasm is the basis of all plant structures whether they belong to the lowest or high- est forms ; for by its aid or from it all parts of the plant are developed. Even the cell-wall is a product of protoplasmic activity. The protoplasmic content of the cell consists of several intimately related but more or less distinct portions, — namely, a somewhat thin, semi-liquid, granular portion known as the CYTOPLASM ; a more or less spherical body embedded in the cytoplasm called the NUCLEUS; and frequently, but not always, certain small bodies which are more or less variable in shape called PLASTIDS, these being also embedded in the cytoplasm (see Frontispiece). The cytoplasm and nucleus are sometimes considered together as a unit, which is known as the PROTOPLAST. . A fuller discussion of the differentiated portions of the protoplasm will be found in Chapter II. The lowest organisms, as the slime molds, do not have an enclosing membrane, but consist of a naked mass of protoplasm. With this exception plants have an outer wall or membrane. They may consist of a single cell, as in the Bacteria, or a chain of cells, as in the filamentous Algae, or a mass of cells, as in the majority of plants, and are accordingly designated as unicellular or multicellular. The cell-wall is composed for the most part of cellulose, but may be modified in various ways. Nomenclature. — The names for describing plants have been derived for the most part from studies of the higher plants, they having exclusively attracted the attention of botanists at first. But with the light which has been thrown on the relationship PRINCIPAL GROUPS OF PLANTS. 3 of the higher and lower groups of plants by the more recent study of the lower forms the older terminology has been somewhat modified. Thus, for example, we speak of the root and shoot, with its leaves, as the vegetative organs of the higher plants, and in describing the corresponding organs (where they exist) in the lower plants, we either apply these terms directly, or indi- rectly by saying that the latter are root-like, stem-like, etc. On the other hand, we now speak of the sexual organs of the higher plants as antheridia and oogonia (or archegonia) instead of classifying them roughly as stamens and pistils, the latter names being retained but with a different signification. Plant Organs. — Depending upon the fact that the plant re- quires nourishment for its growth and development and that it has also to carry on the work of reproduction or propagation, — i.e., the production of new plants, — we distinguish between vegetative or nutritive organs and propagative or reproductive organs. The vegetative organs, such as the root, stem and leaves in higher plants, manufacture the food necessary for the life of the plant, while certain other more or less specialized organs or cells carry on the work of reproduction. In the lower plants, however, the whole structure is much simpler, and in some instances a cell which performs the work of a nutritive cell at one stage may become a reproductive cell at another, or, as in the case of the unicellular Algae, all the various functions of the plant may be carried on by a single celh Generally speaking, there are two principal ways in which plants are multiplied or reproduced: (i) By CELL DIVISION or cell fission, and (2) by the formation of special cells known as SPORES. In cell division (Fig. 85) the nucleus and cytoplasm of a cell divide to form two new cells or -protoplasts, which become distinct by the formation of a wall or cell-plate between the two halves. All growth in plants is dependent upon this method, and in growing parts the cells are said to be in a state of division. Owing to the plasticity of the plant organism, detached portions will often grow and give rise to new plants, as in the case of cut- tings. Growth here as in the parent plant is accompanied by cell division. In some of the lower Algae (Fig. 10) cell division is the only method of propagation, and as only the ordinary vegetative or 4 A TEXT-BOOK OF BOTANY. nutritive cells of the plant are involved in the process it is some- times spoken of as vegetative multiplication. In both lower and higher plants, with the exceptions just noted, reproduction is also carried on by means of spores. FIG. 5. Ulothrix sonata. A, young filament with rhizoid cell (r); B, piece of filament showing escape of swarm spores; C, a swarm spore or zoospore with 4 cilia; D, biciliate gametes escaping from a filament; E; F, G, showing different stages of union of two gametes; H, young zygote or zygospore in which the cilia have been absorbed; J, I -celled plant developed from zygote; K, young plant organizing zoospores. — After Dodel-Port. Depending upon their origin two classes of spores are distin- guished, namely, (a) asexual spores, and (&) sexual spores. In the production of asexual spores the contents of a certain cell called a mother cell or SPORANGIUM break up into a number of new cells sometimes called daughter cells, which escape through the cell-wall. In the lower plants, particularly those growing PRINCIPAL GROUPS OF PLANTS. 5 in water or in moist places, these cells are provided with short thread-like appendages known as cilia, which enable them to move about in the water. They are known as ZOOSPORES or swarm spores (Fig. 5, B, C}, and each individual zoospore is able to produce a new plant. The number of zoospores formed in a sporangium is usually 2 to 8, as in Ulothrix, but the number may be larger. The method of cell formation which gives rise to zoospores is sometimes spoken of as INTERNAL DIVISION from the fact that they arise within the old cell and retain no relation to the old wall as is the case in cell fission. The zoospores are at first naked protoplasts, but later, on coming to rest, may form a wall. Sexual spores, on the other hand, are formed by the union of two cells known as GAMETES. When the gametes are similar the resulting spore is known as a ZYGOSPORE or zygote (Fig. 5, E, F, G), When the gametes are unlike, the spore produced by their union is known as an OOSPORE. In the latter case one of the gametes is larger than the other, is less active, and is spoken of as the female gamete, oosphere, or egg (Figs. 12, 21). The other more active cell is known as the male gamete, antherozoid or sperm (Fig. 51, ///). The cell giving rise to the oosphere is known as the oogonium (Figs. 12, 21), while the one in which the anthero- zoid or sperm originates is called the antheridium (Figs. 12, 21, 22, 51). PLANT GROUPS. Until a comparatively recent time, botanists divided the plant kingdom into two large groups, as follows: The flowering plants, or Phanerogams, meaning " reproductive process evident/' so applied because the reproduction of the plant was readily seen to develop in the flower through the agency of the pistil and stamens. The non-flowering plants, or Cryptogams, meaning " repro- ductive process concealed," so applied to the lower plants like the ferns, mosses, sea-weeds, etc., because in these plants the method of reproduction was not known. Now, however, after a considerable amount of study, it has been learned that a great many of the lower plants have repro- 6 A TEXT-BOOK OF BOTANY. ductive organs which are analogous, even if they are not exactly similar, to those of the flowering plants. Consequently the former classification is no longer applicable, and the following arrange- ment is now generally adopted : Thallophytes ....... ( Fungi Archegoniates ...... ( Bryophytes ( Pteridophytes. Spermophytes ...... (Gymnosperms [ Angiosperms In our study of these groups we shall see that in passing from the Thallophytes through the various groups to the Angio- sperms we pass from very simple forms to those which are quite complex. THALLOPHYTES. General Characteristics. — This group comprises those plants which are simplest in form and structure. They are supposed also to represent more or less primitive types. In these the plant body does not show a differentiation into root, stem, and leaf, as in the higher plants, and is termed a thallus, the word thallus meaning a " mass " of cells. The cells making up a thallus are all alike and are not differentiated for special functions. How- ever, it must not be thought that every Thallophyte is charac- terized in this way. Many of the Thallophytes have cells or groups of cells which become specialized, i.e., set apart for a particular function, as for example the reproductive cells. We see, therefore, that the word Thallophyte is a general term and is applied to many plants which are not thallus-bearing, but which are really closely related to the simpler forms to which the word Thallophyte is strictly applicable. When made up of a mass of cells they may branch in various ways, but the essential structure remains more or less uniform throughout. The Thallophytes vary in size and general appearance from minute, unicellular organisms to those which are filamentous and delicately branched, and even becoming leaf-like structures, attaining a length in some of the marine algae of a thousand feet PRINCIPAL GROUPS OF PLANTS. 7 and even more. Some of these are more or less complicated in structure. The Thallophytes are subdivided into two important groups, as follows : The Algae, plants producing chlorophyll or green cell-contents, and hence capable of manufacturing food from the inorganic substances air and water. The Fungi, plants not producing chlorophyll, and hence not capable of forming their own food, but living upon dead or living matter. Before considering the Algse proper we will consider two groups which are very simple in structure and whose method of reproduction as well as life history is also very simple; namely, the Blue-green Algae and the Bacteria. The Blue-green Algae are ordinarily classified with the Algae, and the Bacteria are very often grouped with the Fungi. Owing to certain resemblances between these two groups it is convenient to arrange them to- gether under the name Schizophytes, or fission plants. SCHIZOPHYTES. Characteristics. — The name Schizophyta means " fission plants," and is applied to this group because the reproduction is chiefly by means of the division of the cells, which may occur either at the middle of the cell and in one direction, in which case a series of connected cells are formed, or in two or three directions, giving rise to spherical aggregates or colonies. They do not usually contain chromatophores, and the coloring sub- stance, when present, is either uniformly distributed throughout the cell or occurs on the external surface of the protoplasmic content. There are two chief groups: the one corresponds to Algae, and, while they do not contain a simple green substance, they are for the most part of a blue-green color, although they may assume various shades of orange, yellow, and brown, even appearing chocolate or purplish-red at times. The second group, correspond- ing to the Fungi, comprises the Bacteria or Schizomycetes, which are distinguished for the most part by being nearly colorless and only occasionally of a reddish or green color. 8 A TEXT-BOOK OF BOTANY. SCHIZOPHYCEyE, OR FISSION ALG.E.— This group of plants, also known as Cyanophyceae or Blue-green Algae (Fig. 6), are generally found in more or less stagnant water and are charac- terized by having associated with the chlorophyll a definite blue- green principle known as phycocyanin. However, many of these Algae contain other pigments in such quantity as to give them dis- tinct colors much like those found in the red and brown Algae, such as Trichodesmium, a filamentous Alga giving the Red Sea its char- acteristic appearance. Some of these live at the highest tempera- ture known to support life ; some developing, as Gloeocapsa, on the sides of the geysers in the Yellowstone Park. These forms have very wide habits, some living, as Stigonema, in symbiosis with fungi ; some, as Nostoc, are endophytic in habit, living in the de- pressions of various plants, and others, as Mastigocoleus, boring into shells. They are found mostly in fresh water, and some, as Uroglena, cause considerable trouble in public water supplies by reason of their breaking down the cell-wall and the liberation of a fetid oily substance. While these plants do not produce true spores, yet they are able to tide themselves over adverse conditions by producing rest- ing bodies through the formation of a thicker membrane and a more concentrated cell-content. In this condition they are able to hold over for several years and then grow when the conditions of temperature, nutrition, etc., are suitable for their germination. As a rule, they grow best in shallow, stagnant water with the rela- tively high temperature of the summer months. When public water supplies are polluted by these blue-green Algae it has been found that the Algae are completely destroyed by the addition of a very small amount of copper sulphate to the reservoir. As small a quantity as one part per million is sufficient to accomplish this result, not only killing the troublesome organisms, but pre- venting their development for some months to come. A few of the common forms will be considered. Gloeocapsa is one of the simplest of the Blue-green Algae (Fig. 6), consisting of spheroidal cells from 0.0035 to 0.005 mm. in diameter, of a yellowish or brownish-yellow color, and usually embedded in groups of two or some multiple of four in an olive- PRINCIPAL GROUPS OF PLANTS. Single cell i nit alter daughter cells re- A mass of celts after numer- tamed in a gelatinous ous divisions, all surrounded mass. Diameter by a mucilaginous envelope. about 4 microns. GLOEOCAPSA. A single colony. Diameter of colonies varying Single cell showing from 40 to 290 microns. spiral chromatophore. Length. 14 to 18 mi- UROGLENA cron' Heterocyst which divides the filament into smaller filaments. Thick-walled resting cells. OSCILLATORIA \Dccay,n8 FIG. 6. Forms of Cyanophyceae or Blue-Green Algae. — Adapted from Engler and Prantl and somewhat modified by Lobeck. io A TEXT-BOOK OF BOTANY. brown gelatinous stratum, this arrangement due to the cell divid- ing in all directions. They occur on moist earth, stones, wharf pilings, and even on window panes of greenhouses, thus being distributed in both fresh- and salt-water regions. They some- times form a kind of crustaceous stratum, and sometimes soft, slimy masses sufficiently abundant that they can be stripped by the handful from dripping, partially shaded rocks. Owing to the variation in color and general habit of the plant a great many species have been described, but up to the present time about 60 have been sharply distinguished. Oscillatoria, formerly known as Oscillaria, is the name applied to a simple filamentous blue-green alga (Fig. 6) that is char- acterized by movement from side to side as in a pendulum, due, as has been suggested, to the movement of spiral masses of proto- plasm extending from cell to cell. These filaments consist of a series of disk-shaped cells like a pile of coins placed side by side, the end cell being rounded off and more or less convex. The con- tents are made up of a finely granular substance differentiated into two areas, a dark central nuclear portion, and a peripheral holding the pigment, which may vary from a bluish-green to dark olive-green or even red sufficiently intense to give the water a red color. The filaments vary from o.ooi to 0.005 nun. in diame- ter, though they may attain a size of 0.050 mm. Oscillatoria is usually found on wet, marshy grounds, in ditches among decayed vegetable matter, on wood subject to hot waste from steam engines, around pumps and cisterns, and in greenhouses. It occurs in fresh and salt water. Lyngbya somewhat resembles Oscillatoria, but does not show any oscillations and the filaments are each provided with a dis- tinct sheath (Fig. 6). It forms late in the summer in large tufts. It is of a bluish-green color, forms long filaments, occurring in the late summer upon Zostera and other Algae. The groups are large and characteristic and have been given the common name Mermaid's Hair. The cells are about 0.030 mm. in diameter. Uroglena is a form which is more or less oval or pear-shaped, about 0.014 to 0.018 mm. in length, and extended into a stalk below, the upper end being provided with two unequal cilia (Fig. 6). The wall secretes a large amount of mucilage. The organisms PRINCIPAL GROUPS OF PLANTS. 11 arrange themselves in a radiating sphere, with the cilia at the periphery. Each cell of the colony contains a more or less spiral, yellowish chromatophore, bearing a reddish spot at one end, a nucleus at the centre, and a few vacuoles. The cells secrete a large quantity of oil, which is of an unpleasant, fish-like odor, and is due either to the decay or breaking up of the cells by mechanical means. This breaking up of the cells is the cause of the disagree- able odor occasionally found in public water supplies. Uroglena is found in New England and has been reported as far west as Indiana, and is probably rather widely distributed in the United States. It seems to thrive best in cold temperatures, usually occurring in greatest numbers when the water is frozen over. It multiplies by cell division, which takes place when the colony becomes rather large. It also produces resting spores which enable the organism to survive conditions which would otherwise exterminate it. A closely related organism, Synura, is responsible for the ripe cucumber odor which was formerly thought to be caused by fresh-water sponges. Nostoc, a form occurring in filaments like a string of pearls, is made up of spherical or elliptical cells, the whole being surrounded by a thick, mucilaginous membrane (Fig. 6). Usually one finds a number of these filaments growing together in a mass which can be seen by the naked eye floating in the water. These masses vary from globular to sub-globular, are irregularly divided or occur in definitely expanded groups. These forms are marked by having two kinds of cells, the one filled with a granular proto- plasmic content, the other being free from protoplasm and some- what larger than the other cells. These latter are fewer in number and are called " heterocysts," which means simply " other cells." At these latter cells the filaments separate, and thus many new colonies are formed. Nostoc is mostly of an olive-green color, but may be dark bluish-green, dark brown, or light yellow or even colorless. It occurs mostly in fresh- water ponds, seldom in brackish water, being found on damp rocks, on mosses and more or less submerged plants, and variously in limestone springs or wet calcareous rocks or on aluminous soil. The colonies vary greatly in size and color, and while some of them may be of microscopic 12 A TEXT-BOOK OF BOTANY. size at one period, later they may be as large as peas or cherries. Owing to their variation in appearance in different seasons various names have been given to the same form by different investigators. They are also associated with lichens. According to systematists, the forms of Nostoc are arranged according to their aquatic or terrestrial habits. SCHIZOMYCETES, OR BACTERIA.— The Bacteria, or Fission Fungi, occupy rather an anomalous position, some writers classifying them with Fungi and some with Algae. They are i- celled plants, microscopic in size, and of various shape. The con- tents consist of protoplasm and a central body in some cases, which is looked upon as a rudimentary nucleus. They are more or less colorless, but sometimes produce a distinct pigment called bacterio- purpurin which is rose-red or violet, and occasionally a chlorophyll- green color substance. They are capable of multiplying by division in one. two, or three directions, and under favorable conditions in- crease very rapidly in number. The wall is more or less albumin- ous in character, in this respect resembling the wall of the animal cell, and is provided with one or more cilia, or flagella, the number and position of which have been used as a basis of classification. Sometimes the walls of the cells become mucilaginous, so that the bacteria hold together, forming a mass known as a zoogloea. Bacteria may form resting spores which arise in two ways. In one case the contents round off and take on a membrane forming a so-called ENDOSPORE ; in the other case the plant body is trans- formed directly into a spore known as an ARTHROSPORE, as in some of the Blue-green Algae. This body is not strictly a spore, but is in the nature of a resting cell (Fig. 7). Two classes of bacteria are frequently distinguished, as follows : Aerobic, or those which require oxygen for their development and conse- quently grow best when they have access to air or oxygen ; and anaerobic, or those whose development is accelerated under re- verse conditions, as in underlying tissues or in the interior of cultures. Occurrence. — Bacteria occur everywhere in nature, and play a most important part in decay and putrefaction, in that they change dead animal and plant tissues back again into simple inor- ganic substances, as carbon dioxide,, hydrogen, water, ammonia, PRINCIPAL GROUPS OF PLANTS. 13 etc. They serve a useful purpose in many technical operations, as in the making of cheese, acetic acid, fermentation of tobacco, curing of vanilla and many vegetable drugs, and in soil nitrification, helping to change ammonia into nitrates — one of the sources of the nitrogen used by plants. Many of them are disease-producing, or pathogenic, and are the cause of a number of infectious dis- eases in man and the lower animals, and plants as well. They are FIG. 7. Bacillus subtilis (hay bacillus), a, Small rod-like organisms such as are found in an infusion of hay, or bouillon; b, zooglcea or mass of bacilli forming the "skin" on the surface of infusions; c, chains of organisms forming spores; d, individual bacilli showing flagella, which are only seen after staining. — After Migula. injurious in two ways : in one case they consume the tissues of the host, as in tuberculosis, and in the other they produce powerful poisonous substances, or toxins, as in diphtheria. Classes of Bacteria. — In order to study Bacteria they are grown upon nutrient media, such as sterile bouillon, potato, milk, etc. They are divided into a number of classes, depending for the most part on the shape of the cell: (i) The Sphserobacteria, or Cocci, are those whose cells are spherical or spheroid, and in 14 A TEXT-BOOK OF BOTANY. which division takes place in one, two, or three directions of space. Very few of this group are provided with cilia. According to the number of cells in a colony they are distinguished as Micrococci, Diplococci, etc. (2) Bacteria proper are elongated, rod-shaped organisms in which division occurs in only one direction, namely, transversely to the long axis, and only after a preliminary elon- gation of the bacterium. The Bacteria are subdivided into two important groups, namely, Bacterium and Bacillus. The Bacilli are motile organisms and produce endospores (Fig. 7), whereas the Bacteria are non-motile and do not usually produce endospores. (3) Spiral bacteria constitute the third principal group and are characterized by the cells being spirally coiled. Division is in only one direction. These bacteria are usually motile, and seldom produce endospores. (4) There is another important group which includes the Sulphur Bacteria, of which the most common one is Beggiatoa. These occur in long threads, and move in an undulating manner much like Oscillaria, one of the Blue-green Algae. They are found in sulphur waters, as in sulphur springs, and contain sulphur granules. Bacteriological Technique. — Principally because of the minuteness in size of micro-organisms a different technique is required in their study from that required in the study of the higher plants. In the first place it is difficult to isolate them so as to be able to study individual forms. Another difficulty is to prevent .contamination after they are isolated. And even though a pure culture is obtained it is difficult on purely morpho- logical grounds to differentiate the various forms, as they are all so much alike. I. While it is comparatively easy to prepare a sterile solution, — that is, one in which all life is absent, — it is very difficult to prevent subsequent contamination under ordinary conditions. Even when a cork- or glass-stoppered bottle for keeping liquids is used it is difficult to prevent the entrance into and development of micro- organisms in the liquids. The use of stoppers consisting of plugs of absorbent cotton was first suggested by Schroeder and von Dusch in 1854. They found that if flasks containing liquids, which under ordinary conditions were likely to decompose, as beef broth, etc., were stoppered with plugs of absorbent cotton PRINCIPAL GROUPS OF PLANTS. 15 and the liquid then boiled for some time it would keep indefinitely. II. It remained for Koch and Pasteur to show what took place in the boiling of the liquid, who at the same time developed the principles of sterilization in bacteriological work. These authors discovered that micro-organisms have two stages of de- velopment, one of which is active and the other resting, the latter being known as the egg or spore condition. They found that the organisms in the active condition were completely destroyed on heating the solution containing them for 30 minutes at 100° C. If this solution was allowed to stand for 24 hours or longer there would be evidences of decomposition, which was due to the fact that the spores representing the resting stage of the organ- isms were unaffected by the first heating and developed into the active stage. As a result of further experiments they found that if the solution were heated on the second day for 30 minutes at a temperature of 100° C. the second growth of organ- isms was destroyed, but it was found that the solution might still undergo decomposition in the course of time, owing to the later development of a few remaining spores. It was, however, found that heating the liquid again on the third day was sufficient to kill all of the spores as well as the organisms in the active stage. By repeating these experiments the authors confirmed their observations and established the process known as discontinuous sterilisation, which simply means that if a solution of a putrescent or fermentative substance is heated on three consecutive days for 30 minutes at a temperature of 100° C., the flask or bottle being stoppered with absorbent cotton, it will keep indefinitely. Instead of using a plug of absorbent cotton the neck of the flask can be drawn out into a narrow tube and directed downwards (see Re- agents). The time required for producing a sterile solution, — that is, one free from micro-organisms or their spores, — can, however, be much reduced by increasing the temperature, or pressure, or both. By use of the autoclave, in which the pressure can be increased from 10 to 20 pounds, sterilization can be accomplished in 30 minutes by using a temperature of 110° C. III. As already indicated, one of the greatest difficulties is to isolate the organisms. In a cubic centimetre of water there 16 A TEXT-BOOK OF BOTANY. may be a million organisms representing various groups of bac- teria. In trying to solve the problem of their separation it occurred to Koch that if he could secure a medium which was solid at the ordinary temperature and liquid at a slightly higher temperature, he could mix a certain quantity of liquid containing micro-organisms with the medium in a sterile condition, and then by solidifying the mixture the organisms would be fixed, and thus from each organism a colony would be developed which could be isolated and further studied. We are indebted to Koch for the use of solid culture media like nutrient gelatin and nutrient agar in the study of these organisms. IV. The application of stains for differentiating the various organisms was introduced by Weigert in 1877. Staining is of use in the determination of the number of flagella of certain organisms, in the study of spores, and the identification of certain pathogenic organisms, which occur in mucus and pus, as tubercle bacilli, etc. Gram's method of staining is of great use in differentiating many pathogenic as well as non-pathogenic organisms, and is of importance in classifying bacteria. Characteristics. — Algae are characterized by their habit of living in water or in moist places. They vary from simple, i -celled microscopic forms to those of great size like the sea-weeds. In the various types, however, the cells show little variation in shape. All the Algae contain more or less of a green coloring matter, even though it may be concealed by other pigments of a blue (as in Schizophyta), brown, or reddish color. The possession of this green cell-content or chlorophyll enables the Algae, in the presence of sunlight, to manufacture food substances from simple materials like carbon dioxide and water. The occurrence of chlorophyll can be readily demonstrated by extracting it with 95 per cent, alcohol. Even in the most delicate of the red Algae it can be shown by placing the fresh material in a strong solution of common salt and afterwards extracting the chlorophyll with alcohol, the other pigments being unaffected. Algae are sometimes grouped as Fresh- Water Algae, includ- PRINCIPAL GROUPS OF PLANTS. 17 ing most of the Green Algae, and the Marine Alga; or Sea-weeds, including most of the brown and red forms. Algae are classified in three natural groups, not only on account of color differences, but because of certain corresponding struct- ural relationships, thus : Chlorophyceae (Green Algae). Phaeophyceae (Brown Algae). Rhodophyceae (Red Algae). Arranging the Algae in this way provides the simplest classi- fication. But m addition to these groups there is another some what isolated group that will be taken up first before the Chloro- phyceae,— namely, the Conjugatse. These are Green Algae con- sisting of either single cells or a chain of cells united into threads and further characterized by dividing always in the one direction so that a filament results. They furthermore do not produce zoos-pores, but produce zygospores as a result of a union of two similar or only slightly different cells. After a period of rest they break from the outer membrane and develop directly into new vegetable cells. To this class the Desmids and Spirogyra belong. The Desmids are unicellular Algae, varying from torpedo- shaped to variously branched forms, occurring even in chains. The protoplast is usually separated at or near the middle, where the nucleus is located, dividing the cell into two symmetrical por- tions (Fig. 8, E). In the protoplast is a more or less complex chromatophore, through the center of which are distributed a number of globular pyrenoids. The latter are distinct structures embedded in the chromatophores of Green Algae and consist of a central protein substance surrounded by a number of starch grains, and, therefore, give a purple reaction with iodine. Owing to the fact that the Desmids are motile they were formerly con- sidered to be members of the animal kingdom. The movement is slow and steady and largely influenced by the light. There is also a circulatory movement frequently observed in the contents of active living material. In addition, there is almost always observ- able at the ends a well-defined spherical vacuole containing numerous small crystals of calcium sulphate which exhibit a dancing movement due to surface tension and is known as molec- i8 A TEXT-BOOK OF BOTANY. ular or Brownian movement. Reproduction is either by simple division or by the union of two Desmids. In the latter case the contents of each flow together into a connecting tube formed by the union of the two Desmids, the resultant mass rounding off to form a zygospore. FIG. 8. Forms of Desmids in longitudinal view and transverse section. A, Mesotaeniutn Braunii; B, Ancylonema Nordenskioldii; C, Penium Digitus; D, Cylin- drocystis crassa; E, Closterium moniliferum; F, Sfirotaenia muscicola; G, Pleurp- taenium Trabecula; H, a Docidium Baculum; H, a' D, dilatatum. — From Willc in Engler and Prantl's "Die Natiirlichen Pflanzenfamilien." Spirogyra. — Another one of the common Green Algae is Spirogyra (Fig. 9), one of the pond-scums, which in the spring forms floating green masses on ponds and shallow water. The plant-body consists of a chain of cylindrical cells forming long threads or filaments. The transverse walls are sometimes pecu- liarly thickened. The chromatophores occur in one or more spiral PRINCIPAL GROUPS OF PLANTS. 19 bands (Fig. 9, //), which extend from one end of the cell to the other. In these bands are embedded protein bodies known as pyrenoids. The nucleus lies in the centre of the cell and is con- nected with the cytoplasmic layer lining the walls of the cell by delicate threads of cytoplasm. Spirogyra may be propagated vegetatively by one or more cells of a filament breaking off and forming new individuals by FIG. 9. II. Spirogyra stictica, showing parts of two filaments with band-like chroma- tophores (chloroplasts), in which are embedded spherical pyrenoids. Nuclei are shown in some of the cells with delicate threads of cytoplasm radiating from them. Two of the cells (a, a) of the adjoining filaments (A. B) are beginning conjugation. I, S. Heeriana, showing different stages of conjugation. In the upper cells, the contents have rounded off previous to the rupture of the adjoining walls of the two filaments. The two middle cells show the contents passing from one cell into the opposite cell. In the lower cell to the right the zygospore is shown. — After De Bary. cell division. The plant is also reproduced by means of zygo- spores, as follows: The cells of two adjoining filaments each send out processes (Fig. 9, //, a, a}, which meet; the end walls are absorbed, forming a tube through which the contents from one cell pass over into the other (Fig. 9, /) ; the contents of the two cells then fuse, after which the mass becomes surrounded by a cellulose wall. The spore thus formed may remain dormant over winter, and the following spring germinate and form a new Spiro- 20 A TEXT-BOOK OF BOTANY. gyra filament or plant. This method of reproduction is known as CONJUGATION, and the zygospore is called a resting spore. It should be explained that certain cells, as well as spores, may lie dormant for a period, as during the winter season or at other times, when the conditions are unfavorable to growth, and then renew their activities, these being known as " resting cells." CHLOROPHYCE.E. — The Chlorophyceae, or Green Algae, are dis- tinguished by usually having a green color, due to chlorophyll, and by having no other pigment. The cells contain one or more nuclei. They are either unicellular or made up of many cells forming fila- ments or flat sheets. They occur either singly as simple cells or in groups representing a single individual or a colony. They are found mostly in fresh or salt water, usually being microscopic in size so as not to be noticed, but often attracting attention when they occur in sufficient quantity to form a scum on the surface. The reproduction is mostly by ciliated cells called zoospores or swarm spores. Reproduction also takes place by the union of the zoospores and through the fertilization of egg cells. The sexual spore resulting from this union of like cells (forming a zygospore) or of unlike cells (forming an oospore) seldom develops immediately, but usually undergoes a resting period be- fore growth is continued Protococcus. — One of the commonest of the Green Algae as well as one of the simplest is Protococcus (Pleurococcus} vul- garis (Fig. 10). It occurs as a green coating, in both winter and summer, on the moist bark of trees, moist ground, and stone walls, and is a component of some . lichens. The plant is i- celled, more or less spherical, and at one stage contains a number of chlorophyll grains which finally unite to form a single plate which lies against the wall and is known as a CHROMATOPHORE. Besides it contains a considerable amount of oil. An allied species (Protococcus viridis) contains the sugar erythrite. The plant usually reproduces by simple division, — that is, one cell or plant divides to form two. The divisions may continue by the production of another cross wall, so that four cells result. Under favorable conditions, division may take place by the formation of still another wall at right angles to the other two. In this way two, four and finally eight individuals arise which adhere PRINCIPAL GROUPS OF PLANTS. 21 more or less to one another, thus forming colonies. The number of individuals in a colony depends upon the number of indi- viduals in the colony when division begins and the extent to which division is carried. Thus if there were four cells in a colony to begin with and division took place in three planes, there would be thirty-two cells in the colony at the end of the period. The development of the green coating on the barks of trees, due to the growth of Protococcus and the protonema of mosses, is usually thought to be more pronounced on the north side. This, however, is a slightly false notion. The fact which determines the position of these plants is the quantity of moisture available. The south and southwest sides of trees in the northern hemisphere are exposed to more light and heat and consequently are apt to be drier, with the result that they are rarely covered with coatings of FIG. 10. Protococcus vulgaris. Different stages of division of the cell. — After Wille. Protococcus and mosses. The under side of slanting trees is a very favorable place, as are also the lower slanting surfaces near the ground of large upright trees, because in these places the water is more likely to be conserved. A careful investigation by Kraemer showed a more abundant growth of green plants on the east and southeast exposure, although the north side of many trees showed good growth also. Volvox occurs widely distributed throughout the United States in ponds and pools of fresh water. It is most abundant in warm weather, but also found in midwinter. It appears as a minute spherical colony about V2 mm. in diameter, made up of numerous cells, the number ranging from several hundred to many thousand (Fig. 11). The cells at the periphery are pro- . vided with cilia, so that the colony rolls slowly through the water. Each cell contains a chloroplastid in which starch granules and often a red pigment spot are present. The asexual reproduc- 22 A TEXT-BOOK OF BOTANY. tion is through the formation of daughter colonies within the mother colony, and these after a time develop motile cells like the parent, which swim about and finally escape. A sexual method of reproduction also occurs in which there is a union of cells within the spheres, the resulting cells after germination forming swarm spores that cling together to form a new colony. Hydrodictyon, or Water Net, is a form often very abundant in sluggish and stagnant waters. It consists of a number of cells forming a net, the meshes of which are usually hexagonal or pentagonal in shape, depending on the number of cells outlining them (Fig. u). The cells are all alike, cylindrical in form, attaining sometimes a length of i cm., and usually contain a number of nuclei. The green chromatophore occurs in a plate at the periphery of the cell and usually contains numerous pyrenoids. The asexual reproduction is by means of zoospores which are formed simultaneously in large numbers, sometimes number- ing many thousands in each cell. These zoospores as formed inside of the mother cell show more or less definite movement and arrange themselves finally to form a new net. The sexual reproduction is characterized by several stages, (i) Some of the zoospores are liberated through a pore in the cell- wall of the mother cell and after swimming around for some time pairs of them unite, forming zygospores. (2) After a resting period each zygospore develops 2 to 5 zoospores, which escape into the water and develop into irregular, sharp-angled cells, called polyhedra, which persist through the winter. (3) When these polyhedra develop, small zoospores are again formed, and these arrange themselves to form a net inside of the polyhedron, which then escapes and increases in size. Vaucheria (Fig. 12) is another common green alga which may also be selected as showing the habits of this group of plants. The plant has a branching thallus and lives in shallow water or on moist earth, being attached to the substratum by means of delicvY? root-like processes sometimes spoken of as rhizoids (Fig. 12, w). In the thin layer of protoplasm lying near the wall are numerous nuclei and small oval chromatophores. PRINCIPAL GROUPS OF PLANTS. OEDOGONIUM. Single Net developing polyhedron. inside of polyhedroi Three stages in sexual reproduction. HYDRODICTYON Mature Colony— Diameter 1 mm. A. Egg cell, before fertilization. B. Oospore. C. Daughter colony ULVA FIG. ii. Forms of Chlorophyceae or Green Algae. — All adapted tr^. '' Prantl except Ulva. Drawn by A. K. Lobeck. and 24 A TEXT-BOOK OF BOTANY. Numerous oil globules are also found in the protoplasm, and cal- cium oxalate crystals may occur in the cell-sap. Vaucheria furnishes an example of a plant whose interior is not segmented by cell-walls. In other words, the cavity within the outer or enclosing membrane is continuous, and such a plant is said to be ccenocytic, — i.e., like a syphon. But it should be borne in mind that the plant contains a great many nuclei, and, as we have seen (page 2), a nucleus with its associated cytoplasm FIG. 12. Vaucheria sessilis. A, sporangium from which the multiciliate zoospore is escaping; B, resting zoospore; C, D, germinating zoospores with growing point (s); E, plant showing root-like organ of attachment (w), spore from which the plant is developing (sp); F, showing in addition two oogonia (og) and an antheridium (h). — After Sachs. constitutes a unit of work. Hence such a plant as Vaucheria is in a certain sense equivalent to a plant having as many uninucleate cells as it has nuclei. It would probably be better to call such a plant multinucleate rather than unicellular. Reproduction by means of asexual spores is brought about as follows (Fig. 12, A) : A cross wall is formed near the end of one of the branches, the end portion constituting a sporangium. The contents, including numerous nuclei, group themselves into one large zoospore, which escapes through an opening in the sporan- PRINCIPAL GROUPS OF PLANTS. 25 gial wall, and after swimming about for a time comes to rest and germinates, giving rise to a new plant (Fig. 12, C, D). This large zoospore is multinucleate and multiciliate, there being two cilia for each nucleus, and by some botanists is considered to be an aggregation of numerous biciliate zoospores. It is also of interest to note that the zoospores of Vaucheria appear to arise by a grouping of the cytoplasm and the nuclei already existing in the sporangium rather than by repeated divisions of a single nucleus. Another method of reproduction in Vaucheria (Fig. 12, F) is that by means of oospores, or spores formed by the union of egg and sperm cells. Two special branches are formed on the thallus as short side shoots. One of these branches, known as the oogonium (Fig. 12, og), is somewhat egg-shaped and sepa- rated from the thallus by means of a cross wall. It contains a great many chromatophores and considerable oil, and has a com- paratively thick wall. The apex is somewhat beaked and con- tains colorless protoplasm. The second branch, which is known as an antheridium (Fig. 12, h), is smaller, somewhat cylindrical and curved towards the oogonium. It is also cut off from the thallus by means of a cross wall. The antheridium contains very little chlorophyll, but a great many sperm cells. These are oval or egg-shaped and have two cilia, one at each end. The sperms escape from the apex of the antheridium and enter an opening at the apex of the oogonium, one of them uniting with the egg cell, which then develops a thick membrane, the resulting oospore being a resting spore. Ulva, or Sea Lettuce, is a common form found all over the world, especially in brackish waters. In its usual form it consists of flat, thin, unbranched fronds which are more or less ovate or orbicular in outline and frequently deeply incised, sometimes be- coming linear or even ribbon-shaped (Fig. n). The fronds con- sist -of two layers of cells, which are either in close contact with each other or else at maturity separate so as to form a tubular frond. It sometimes occurs in large quantities in the shallow water along our coast, and is conspicuously disagreeable by its resemblance in shape to the swollen intestines of some animal. CEdogonium is a filamentous alga occurring usually in simple unbranched filaments and attached by a disk-like cell or hold- 26 A TEXT-BOOK OF BOTANY. fast (Fig. n). It occurs in meadow pools or ponds, frequently in streams attached to rocks near rapids. The cells are somewhat elongated and contain a large, irregular chromatophore with pyrenoids. Most of the cells are vegetative cells, interspersed among which are the cells producing the spores. Zoospores are produced singly in the cells and are provided with cilia at one end. After swimming about for some time they attach themselves at this ciliated end to a substratum and develop into filaments. Two other types of cells are formed, which give rise either to oogonia, the female organ containing a large egg cell, or to antheridia, the male organ containing many sperms. The union of a sperm with an egg cell produces an oospore with a very thick wall, capable of over- wintering and developing again when con- ditions are favorable. THE CHARACE/E, or Stoneworts, is a highly differentiated group that is considered as a distinct class between the Chloro- phyceae and the Phseophyceae. They stand so entirely by them- selves that many authorities do not consider them as even Algae. They consist of jointed stems, from the nodes of which whorls of from 4 to 10 so-called leaves arise, the sexual organs being axil- lary (Fig. 13). In many of the members of this family the cell wall is incrusted with lime salts. Chara occurs in great masses in the bottom of ponds and shallow lakes. It occurs in sufficient quantity in many places so that the body of water has a distinct orange color, due to the immense numbers of antheridia. The plant is of such luxuriant growth that if single individuals are kept in an aquarium or large glass vessel it will greatly multiply during the winter and persist for many years. In ponds where Chara occurs large quantities of lime are deposited, so that in ancient deposits now exposed to view one often finds imbedded 'therein the remains of the spore- fruits. In the long cells or internodes there is a large vacuole and a thin layer of protoplasm containing a central nucleus and a large number of oval or lens-shaped chromatophores. In some forms, especially in Nitella, the inner protoplasmic layer shows a streaming movement. This is very interesting, as a distinct streaming movement does not occur in most plants and is limited to a few water plants, the staminal hairs of Tradescantia, the leaf PRINCIPAL GROUPS OF PLANTS. 27 hairs of Cucurbita and Urtica and the hyphae of Rhizopus, etc. This streaming movement in plants like Characeae, as pointed out by Pfeffer (Physiology of Plants), has in most cases a definite purpose. It is, in any case, always possible that the streaming movement may be an accessory but unavoidable accompaniment of some other form of vital activity. In Chara and Nitella the FIG. 13. Stonewort or Chara. At left showing the habit of the plant with minute reproductive organs on the leaves. At right enlarged view of reproductive organs. A, mature organs showing (a) antheridium, (S) oogonium surmounted at the top by a crown of cells (c); b, stem of plant; ft', ft", whorl of leaves, some of which have been removed, as at ft; B, a young antheridium (a), with young oogonium (SK), together with the adjoining cells of the stem; the whorl of leaves not represented. — A, after Wille; B, after Sachs. streaming endoplasm (inner layer of protoplasm) does not cover more than 2 to 3 mm. per minute. The activity of the streaming is influenced by sunlight, oxygen, acids, chloroform, etc. Two kinds of protoplasmic streaming are reco^ *»z*)• It grows near the surface of the water, attached to rocks, and produces a regularly dichotomously branching thallus. Some of the forms in the upper branches produce air bladders which are spherical or slightly elongated and usually in pairs. The margins of the branches are either entire or somewhat serrate. The tips of older branches become more or less swollen and are termed receptacles. They are dotted over with minute PRINCIPAL GROUPS OF PLANTS. 29 cavities, called conceptacles, and these contain the reproductive organs. These consist of oogonia and antheridia, which may be FIG. 14. Some common marine algae. A, Laminaria, showing portions of three leaf- like thalli and hold-fast; B, dichotomously branching thallus of Fucus; C. Sargassum, or "gulf weed," showing a thallus resembling a leafy branch, with swollen, berry-like air bladders, which act as floats; D, Dasya, a delicate branching filamentous sea-weed, attached to a blade of eel-grass; E, dichotomously branching thallus of Chondrus, or Irish moss; F, leaf -like thallus of Grinnellia; G, densely, but delicately branched thallus of Polysiphonia. A, B, C are Brown Algae and D, E, F, G are Red Alga?. present on the same or on different plants. The egg cells and the sperm cells escape into the sea-water, and after their union an 30 A TEXT-BOOK OF BOTANY. oospore results, which, upon finding a favorable resting place, begins shortly to develop into new Fucus plants. The plant contains both iodine and bromine, chiefly combined with salts of sodium and potassium, and was at one time used in medicine. It also contains a bitter principle and a considerable amount of mucilage. ASCOPHYLLUM, a rock-weed closely related to Fucus, is dis- tinguished from this genus by the fact that the branches are desti- tute of midribs and the spores occur in groups of four instead of eight. The frond is thick and narrow, branching somewhat dichotomously, and at intervals produces large, conspicuous floats, which are broader than the frond. The plants occur from }/$ to 2 metres in length. The fruit is found in lateral branches in winter and spring, and in June the receptacles fall off and are sometimes found in immense quantities, covering the bottom of tide pools. LAMINARIA is one of the common kelps or devil's aprons which inhabit principally the colder seas of high latitudes. They all grow in pools at low-water mark, attached to the rocks'and in deep water, and some attain a very large size. The species vary greatly in outline and habit according to the season and place of growth — whether on an exposed or sheltered coast or partly ex- posed at low tide. It consists of three parts (Fig. 14, A] : a long, leaf-like expansion or blade supported by a more or less cylindrical stalk or stipe, which in turn is attached to the rocks by a hold-fast made up of a cluster of fibrous outgrowths. In general the species may be classed in two groups, one in which the frond is ribbon-like or long in proportion to the breadth and not split up into segments, and the other in which the frond is proportionally broader and fan-shaped and laciniate. To this latter belongs the Laminaria digitata. There are some 25 species, distinguished by the arrangement of root-fibres comprising the hold-fast, the structure of the stipe, whether solid or hollow and whether provided with distinct cavities containing mucilage, the shape, especially of the basal portion of the lamina, and the char- acter of the margin and the position of the fruit. The, growing portion of the lamina is at the base, as in the leaves of the Spermo- phytes. The kelps of the Pacific Ocean are among the largest sea-weeds known, the Giant Kelp, Macrocystis, attaining a length PRINCIPAL GROUPS OF PLANTS. 31 of nearly a thousand feet. Other forms have large floats at the base of the lamina. Reproduction is chiefly by zoospores formed in i -celled sporangia which occur either in dispersed patches or in continuous bands near the centre of the frond. SARGASSUM, or Gulf Weed, grows attached to rocks by means of disk-like hold- fasts (Fig. 14, C). When it is torn from the rocks it is carried into the open ocean by currents such as the Gulf Stream. Sargassum is most highly organized and is represented by a very large number of species. They are found especially in the warmer waters near Australia, Japan and the adjacent coast of Asia, and also in the West Indies and at various parts of the Atlantic Coast near the Gulf Stream, some occurring as far north as Cape Cod. The plants vary from 15 cm. to nearly 2 metres in length, and consist of a stem-like axis which bears leaf-like branches with a distinct midrib, berry-like air sacs on stalks, and reproductive branches or receptacles. RHODOPHYCE/E. — This includes all the Algae which are of a reddish or violet color. They contain chromatophores in which the chlorophyll is masked by other pigments, mostly red, and known as phycoerythrin or rhodophyll. The red Algae are mostly found in salt water, occasionally in fresh and running water. They are usually found growing upon other plants or variously attached to some substratum. They vary from microscopic forms or very delicate filamentous types to large plants. They are usually composed of a number of cells or filaments which are so closely arranged as to resemble the tissues of higher plants. Many of the cells are connected by strands of protoplasm, giving them a rather characteristic appearance. Others have an in- crustation of lime on the wall. They are mostly found in deep waters of the Tropics. Reproduction is almost entirely by sexual or asexual spores. CHONDRUS, or Carragheen or Irish Moss (Figs. 15, 16), is a common rock-weed found at low-water mark, and in this country is common from New York northward, being extensively col- lected at a few points about 15 to 20 miles south of Boston. The plant varies considerably in color, being more or less green when close to the surface of the water and of a deep purplish-red when growing at some depth. It varies from 4 to 15 cm. in length, and A TEXT-BOOK OF BOTANY. is attached to rocks by means of a slender hold- fast. The thallus is dichotomously branching, somewhat flattened, but may be quite linear. The fronds show a mucilaginous modification of the cell- walls. In the upper segments occur small differentiated areas, FIG. 15. Specimen of Chondrus crispus still attached to the rock where it was found growing along the Massachusetts coast. sometimes called sori, of a more or less elliptical outline, which on sectioning are found to be in the nature of sporangia, contain- ing numerous tetraspores (Fig. 16). The spores are discharged through narrow canals extending through the more or less com- pact outer layer of the frond. The article found in commerce has the color removed by being bleached through the action of the sun PRINCIPAL GROUPS OF PLANTS. 33 and dews. It shows, however, all the morphological structure of the growing plant. FIG. 16. Chondrus crispus: A, B, C, D, various forms of thallus; H, hold-fast; F, sporangia; T, transverse section of thallus showing epidermis (E), sporangium with spores (F) ; S, spores separated in glycerin preparation of thallus by pressure on the cover-glass. The spores occur in groups of four (tetraspores) and the tetrad group is about 30^ in diameter. In a closely related genus, Gigartina (Fig. 17), which is found in imported Chondrus, the fruit bodies occur in numerous cylindri- 3 34 A TEXT-BOOK OF BOTANY. cal outgrowths developed on the surface of the fronds. This form is found more abundantly north of Boston than south, but, as Chondrus is collected at Cohasset, Scituate, and other towns south of Boston, it is not seen in commerce in this country. RHODYMENIA, or Irish Dulce, is one of the commonest red sea-weeds in the North Atlantic Ocean, usually growing with Fucus, Laminaria, and other Algae between tide marks and extending into deep water. The fronds are purplish-red, flat, membra- FIG. 17. Gigartina mamillosa, a red sea-weed closely related to Chondrus crispus, showing a dichotomously branching thallus and bearing at the upper part numerous cylin- drical outgrowths in which the fruit bodies (sporangia) are found. — After Kutzing. naceous, 15 to 30 cm. in length, irregularly cleft, palmate or dichotomous, the margin often being marked with numerous small divisions. The sporangia occur in scattered patches im- mersed in the cortical tissues of the frond. It is a common article of commerce and is said to possess anthelmintic properties. AGAR-AGAR is derived from several of the marine Algse grow- ing along the eastern coast of Asia, notably species of Gracilaria, Gelidium, and Gloiopeltis. It is a mucilaginous substance which is extracted from the sea-weeds, and is used extensively as a PRINCIPAL GROUPS OF PLANTS. 35 culture medium in bacteriology and in other work where a nutrient is desired. It occurs commercially in bundles 4 to 6 decimetres in length, consisting of thin, translucent, membraneous, agglutinated pieces, yellowish-white in color. It is usually brittle, but becomes tough when moistened. It is used in medicine in the powdered FIG. 18. Arachnoidiscus Ehrenbergii, a characteristic Diatom found in Agar-agar. — From a photomicrographic negative by J. J. Woodward, Surgeon, U. S. A. form. Under the microscope Agar-agar frequently shows the frustules or siliceous cell walls of diatoms, which are disk-shaped (Fig. 18). It is insoluble in cold water, but dissolves slowly in hot water. Upon boiling i part in 100 parts of water it should yield a stiff jelly upon cooling. Diatoms constitute a large group of unicellular plants, occur- 36 A TEXT-BOOK OF BOTANY. ring in both fresh and salt waters. They form the plankton or floating microscopic life found in oceans and lakes, which is the source of food of small animal forms inhabiting these waters. The mud at the mouths of many rivers, the sediment of ponds, ditches, and even rain troughs may contain great numbers of these minute organisms. They have been found in the polar ice, and have been detected in the dust evolved from volcanoes. One of the distinguishing characters of the group is that the cell wall is incrusted with silica. For this reason they are practically indestructible and form marls and strata in the earth. They occur either singly or grouped in bands or chains. They are very variable in shape, being boat-shaped, ellipsoidal, spherical, or peculiarly curved in some forms. They are either free or attached to a substratum, as stones, water plants, etc!, those which are free having an active movement (Fig. 19). The cell wall of Diatoms practically consists of two halves, one fitting over the other like the lid of a box. These are known as " valves " or " theca." The manner in which the two valves are joined results in the formation of a " girdle " or " pleura." The girdle is provided with a series of pores conecting with canals at either end and in the middle, through which food from without is supplied to the protoplast. The valves are very often beautifully marked by a series of parallel cross lines, dots, cir- cles, or polygons, which are characteristic of the different groups. Some forms are used in testing the definition of objectives, as Pleurosigma angulatum, in which the lines are one-half micron (0.0005 mm.) wide (Fig. 19, A). In the Diatoms the protoplasm lies as a thin layer close to the wall surrounding a large central vacuole. The nucleus is sur- rounded by a relatively dense mass of cytoplasm, and occurs in definite positions according to the species. The chromatophores frequently occur in plates which are typical for certain species. They are sometimes greenish-yellow, the color being generally masked by the presence of a brown substance known as diatomin. They frequently contain pyrenoids, which are sometimes asso- ciated with granules of starch. Reproduction takes place by simple division or fission, the two valves separating and a new valve forming on each half to replace PRINCIPAL GROUPS OF PLANTS. 37 the old one. In each case the valve formed fits into the old one, and hence in the case of the smaller valve the new cell or plant becomes smaller than the parent plant, the walls not being able to expand on account of the siliceous composition. In this wayi the cells of one series gradually becomes smaller and smaller until a certain minimum is reached, when the plant rejuvenates itself F/G. 19. Diatoms: A, Pleurosigma attenuatum as seen from above; B, Pleurosigma baltu'uinas seen from the girdle side; C, D, E, Fragilaria virescens showing colonies attached to an alga in C, a view of a single diatom from above at D, and a chain of diatoms viewed from the girdle side at E; F, G, two views of Navicula viridis; H, I, the formation of auxo- ' spores in Navicula firma, H showing the exit of the protoplasts and the throwing off of the original valves. — A, B, D, after Van Heurck; C, E, after W. Smith; F-I, after Pfitzer. t>y the production of spores (auxospores). These are formed in two ways : In one case the valves separate from each other, the protoplast escapes, grows larger and develops a new wall ; in the other case, of which there are several types, two individuals come together, and envelop themselves in a mucilaginous covering. They then throw off their siliceous walls and the protoplasts unite to form a zygospore, which grows until it is three times the 38 A TEXT-BOOK OF BOTANY. original size, after which it develops a new wall, the larger valve forming first (Fig. 19, H, /). DIATOMACEOUS EARTH, also known commercially as " In- fusorial Earth," or " Kieselguhr " (meaning siliceous marl), occurs in extensive deposits, some of these, as the stratum at Richmond, Va., extending to a depth of 18 feet. These deposits consist of the siliceous walls of the Diatoms, which, owing to their composition, are practically indestructible, and are accumulated in those localities which have favored the growth of the organ- ism. The natural deposit is mined and usually calcined to de- stroy the organic matter, after which it is washed and dried. The article used in pharmacy is further purified by boiling with diluted hydrochloric acid, washing, and calcining. This purified product is known as Terra Silicea Purificata, and occurs in the form of an almost whitish, or light grayish, or light brown powder. It is odorless, insoluble in water and in mineral acids or dilute solutions of the alkalies. Under the microscope mounts made in water or solutions of hydrated chloral show the frustules or siliceous walls of the Diatoms. In the better grades of Diatoma- ceous Earth the entire skeleton with the characteristic markings is present. Material coming from various localities shows a differ- ence in genera of Diatoms. The exact naming of the 'species requires the assistance of specialists. In order to avoid confusion it is necessary to bear in mind that there are two and sometimes even three views which may be obtained of the same Diatom. Diatomaceous Earth consists of about 85 per cent, of SiO2, 10 per cent, of water, and 5 per cent, of clay, iron oxide, magnesia, lime, and organic material. Owing to the fact that Diatomaceous Earth is made up of the hollow shells of Diatoms, it has the property of absorbing by capillarity gases and liquids. For this reason it is used in the preparation of dynamite; the highly ex- plosive nitroglycerin being absorbed by the diatomaceous shells, rendering the product capable of being handled. When calcined, it will absorb its own weight of water. It is used in pharmacy for filtering and as a diluent for powdered extracts, etc. Among the technical uses may be mentioned : polishing of metals and woods, insulating steam pipes and electrical insulators, packing of caustic and inflammable liquids, and the manufacture of glass, paper, and PRINCIPAL GROUPS OF PLANTS. 39 soap. It is also used to some extent in dermatology. In India il has been used as a rubefacient. In Sweden, and among the Chinese and Laplanders, Diatomaceous Earth has been used as an FIG. 20. The Algae are put to various uses by the people who collect them. The illustration is taken from an ornament purchased at the Louisiana Purchase Exposition and was made by the Filipinos from various' kelps having large, bladder-like floats. edible earth under the name of " mountain meal " or " bread- stone." Humboldt also calls attention to the fact (Aspects of Nature) that the practice of eating earth is diffused throughout the torrid zone, among indolent races inhabiting the finest and 40 A TEXT-BOOK OF BOTANY. most fertile parts of the globe. It is a saying even among the most distant of the different tribes living on the Orinoco, when speaking of anything very unclean, that it is " so dirty that the Otomacs eat it." ECONOMIC USES OF ALGJE. — Many of the Algae are of use as food, of which the following may be mentioned: Vaucheria fasti- giata, Griffithsia coralina, Ceramium Loureirii, Chondrus crispus, Gigartina mamillosa, Gelidium cartilagineum, Gelidium crinale (yielding agar-agar), Rhodymenia palmata (yielding dulse), and several species of Gracilaria (which also yield agar-agar). Some of the sea-weeds are used in the production of iodine, as Durvillfca utilis, Ascophyllum nodosum, Fucus vesiculosus (bladder-wrack), Sargassum linifolium, Laminaria saccharina, Laminaria digitata, Alaria esculenia, Rhodymenia palmata, Phyl- lophora membranifolia, Macrocystis pyrifera, and Fastigiaria furcellata. A number oi the Algae are also used in medicine, particularly for phthisis, as Fucus cartilagineus, Stilophora rhisodes and Dictyopteris polypodioides. Alaria esculenta and Laminaria digi- tata are used in the making of bougies and tents used in surgery. Owing to the toughness of some of the Algae on drying, the material is used in the manufacture of various articles, as handles for tools from the thick stem of Lessonia fucescens, fishing lines from Chordaria Hagelliformis (Fig. 20), etc. FUNGI. The Fungi form a large group of plants which do not produce chloroplasts or any bodies having a similar function. They have not the power of carbon dioxide assimilation, — that is, unlike the Algae, they are unable to manufacture food materials, such as carbohydrates (starches, sugars, etc.), from carbon dioxide and water. Hence they are dependent upon previously formed food products, and may derive their food from living plants or ani- mals, when they are known as PARASITES, or from decaying animal or vegetable matter, when they are known as SAPROPHYTES. .The living plant or animal atacked by a fungus is known as the host. Fungi are especially characterized by the habit of arising from spores and of producing thread-like cells the growing point PRINCIPAL GROUPS OF PLANTS. 41 of which is at the apex. These threads are known as HYPH^E (singular hypha). They branch and become interwoven, forming a mass or mat known as the MYCELIUM (Fig. 23). The myce- lium constitutes the plant body proper, and absorbs the food material from the substratum, which it ramifies, often causing decay. The mycelium is frequently not visible, and the presence of the fungus is not recognized until the so-called fruit bodies are developed, as sometimes seen in the case of moldy oranges, mildewed linen, and as illustrated by the common mushroom. The mycelium has a cellulose wall which in some cases is modi- fied to chitin, a nitrogenous substance related to animal cellulose and found in crabs and other lower animals. The protoplasm either occurs in a more or less delicate form lining the hyphae and enclosing large vacuoles, or is comparatively dense enclosing numerous small vacuoles. Many Fungi contain color substances which are dissolved in the cell-sap and are of a quite brilliant hue. One of the most interesting classes of substances produced by Fungi is that of the ferments, including the oxidizing ferment allied to laccase. They contain also amido-substances related to lecithin ; fats ; carbohydrates, as trehalose and mannitol ; organic acids, as oxalic, tartaric, malic, etc. ; and calcium oxalate may be present in some cases. Reproduction in the Fungi is chiefly by means of asexual spores, which arise in two ways. In the one case they are devel- oped in a special cell or sporangium at the end of a mycelial thread and are known as ENDOSPORES. In the other case they arise on special hyphae, or directly from the mycelium, and are known as EXOSPORES or conidia. There are also several modifications of these two types of spores, which may be referred to later. Groups of Fungi. — There are four principal groups of Fungi : 1. Phycomycetes. 2. Basidiomycetes. • 3. Ascomycetes. 4. Fungi Imperfecti. The Phycomycetes, or Algal-like Fungi, are so called because they show a certain relation to the Algae. The Ascomycetes are distinguished by having a sporangium of 42 A TEXT-BOOK OF BOTANY. a definite shape and size, which is called an ASCUS, and which contains a definite number of spores, which is two or some multi- ple thereof. The Basidiomycetes are the most highly developed Fungi, producing large fruit bodies, such as are seen in mushrooms, toad- stools, and puffballs. They are characterized by producing spores (basidiospores) on special hyphae. The spores are usually four in number, and the spore-producing organ is known as a BASIDIUM. The Fungi Imperfecti constitute a group of Fungi which, while having certain natural relationships with the other types already considered, yet do this so imperfectly that they are brought in a class by themselves. The complete life-cycle is not in all cases known, and future studies will probably distribute them among the other principal groups. PHYCOMYCETES : ALGA-FUNGL— The plant body of the Phycomycetes consists of a mycelium which is unsegmented, more or less thread-like and sometimes considerably branched. Reproduction takes place by means of several kinds of spores, and by reason of the production of two kinds of sexual spores they are subdivided into two important groups. These are ( I ) the Oomy- cetes, which produce oospores, and (2) Zygomycetes, which produce zygospores. Saprolegnia. — Probably one of the best representatives of the Oomycetes is the group of water molds known as Saproleg- nia, which are aquatic in their habits and are both parasitic and saprophytic, occurring on living fish, insects, crayfish and decay- ing plants and animals as well. The plant body consists of a mycelium which may be simple or branched, sometimes forming a dense mass (Fig. 21, A). Like the alga Vaucheria, it produces both swarm spores (zoospores) and oospores. The swarm spores (Fig. 21, B, C) are produced in sporangia formed by the pro- duction of a partition wall at the end of a hypha. The sporangia are either cylindrical or spherical, and contain numerous zoospores which have two cilia at one end. These spores are peculiar in that after their escape from the sporangium they swim about, then come to rest and take on a wall, after which resting period they develop two cilia on the side, again move about, and germi- nate when they find a suitable host. PRINCIPAL GROUPS OF PLANTS. 43 The oogonia and antheridia (Fig. 21, D-F) are also formed at the ends of hyphse. The oogonia are usually spherical and the wall contains a number of small pores. The contents, which are at first more or less uniform, later develop egg-cells, of which there may be as many as fifty in a single oogonium. The anthe- ridium is more or less cylindrical and contains a somewhat uni- FIG. 21. Species of Saprolegnia: A, mycelium growing out from and surrounding a dead house-fly in a water culture; B, C, sporangia with biciliate swarm spores; D, a num- ber of oogonia containing oospheres; E, F, oogonia and antheridia, in F the tube of the antheridium having penetrated the oogonium. — A-C, after Thuret; D-F, after De Bary. form mass of protoplasm. The antheridium bends toward the oogonium and comes in contact with it, but apparently does not in all cases penetrate it. Nevertheless the egg-cells develop walls and become resting oospores. In Peronospora, one of the Oomycetes, the antheridium (Fig. 22, n) develops a tube which pierces the wall of the 44 A TEXT-BOOK OF BOTANY. oogonium (Fig. 22, o) ; the contents unite with the egg-cell, after which a heavy membrane develops, forming an oospore, which germinates when it finds a suitable host. The plants belonging to Peronospora as well as related genera are destruc- FIG. 22. A. Cyslopus candidus; B, Peronosfiora calotheca. Mycelia (m) with haustoria penetrating cells (z) of hosts. C, Oospore formation in Peronospora: o, oogonium; n, anthe- ridium. At the left the antheridium is in contact with oogonium; the next stage shows the antheridium penetrating oogonium and discharging its contents; at the right the resulting oospore is shown. — After De Bary. tive to many cultivated plants, constituting mildews or blights, as those occurring on the leaves of hyoscyamus, tobacco, anthe- mis, matricaria, aconite, grape vine, lima bean, potato, etc. The group has received the name " downy mildews " because of the PRINCIPAL GROUPS OF PLANTS. 45 fact that the conidiophores rise to the surface of the leaves where the spores are discharged, forming powdery patches. Black Mold. — A common example of the Zygomycetes is furnished by the " black mold," Mucor Mucedo. The mycelium FIG. 23. B, richly branching mycelium (m) of the mold Phycomyces nitens showing upright hyphae bearing sporangia (g). A, C, D, the common black mold Mucor Mucedo. A, sporangium with columella; C, germination of zygospore (z), with formation of hypha (k), and sporangium (g); D, earliest stages in the development of a zygospore. the hyphal branches (b) showing adjoining ends (a) cut off by cross walls. — After Sachs. of this plant is coenocytic, thread-like, very much branched, and profusely developed, much like that of Phycomyces nitens (Fig. 23, B). This mold is widely distributed, causing trouble in the spoiling of many sugar- and starch-containing substances in the household, including preserves, syrups, fruits, etc. In fact, a 46 A TEXT-BOOK OF BOTANY. number of species of Mucor have the power of inducing alcoholic fermentation in glucose-containing solutions. They are also commonly found in many aqueous solutions of inorganic chemicals as well as organic substances. Asexual spores are formed at the ends of hyphse which rise into the air. The sporangia are spherical and are cut off from the hyphse by means of a transverse wall which projects upward into the sporangium and which is techni- cally known as the columella (Fig. 23, A}. The contents by FIG. 24. Peziza confluens showing stages in the development of ascospores. In the youngest asci (m, r) there is only one' nucleus; this divides into two (s); the division is repeated, so that there are 4 nuclei in (t) and 8 in (n). These surround themselves with protoplasm and a cell-wall (v, w), but the protoplasm of the mother cell or ascus is not entirely used up. — After De Bary. simultaneous division form numerous i -celled spores, which are discharged by the bursting of the sporangium wall and distributed by air-currents or the wind. As the name of the group to which this plant belongs indicates, it also produces zygospores (Fig. 23, £>). These are formed by hyphal branches which ascend from the substratum. The ends of two branches come together, a transverse wall is formed in each branch, the walls in contact are absorbed, the contents unite, and a spore is formed with PRINCIPAL GROUPS OF PLANTS. 47 three membranes, two belonging to the spore proper and the third being formed by the united hyphse. As would be expected, these spores are quite resistant, being able to withstand unfavorable conditions, and germinate (Fig. 23, C) only after a period of rest. ASCOMYCETES. — The Ascomycetes are distinguished for the most part, like the other higher Fungi, in having a septate mycelium, i.e., one cellular in structure, and in producing asci FIG. 25. Species of Saccharomyces (Yeasts). A, 5. cerevisite or beer yeast; B, 5. Pastorianus; C, 5. glomeratus; D, S. Piculatus: a, vegetative cells reproducing by budding; b, formation of ascospores. — After Reesz. (sacs), which latter are formed at the ends of the branches of the mycelia. Two main sub-groups are recognized, the one producing an indefinite number of spores in asci which are not well developed, and known as the HEMIASCI ; the other producing a definite number of spores, which number is characteristic for each species, in a well-developed ascus, and known as the EUASCI. In the latter group the spores arise by successive divisions of the primary nucleus into two, as shown in Peziza confluens (Fig. 24). Yeasts. — The simplest o-f the Ascomycetes is the sub-group known as the Saccharomyces, or Yeasts. The Yeasts do not produce a mycelium, but the plant body consists of a single cell, or a chain of cells, and multiplies by a peculiar process known as "yeast budding" (Fig. 25, a). From either end of the cell a wart-like process develops, which enlarges until about the size 48 A TEXT-BOOK OF BOTANY. of the original cell, from which it is then separated by the forma- tion of a transverse wall. The cells are spherical, ellipsoidal, or egg-shaped, and in some cases somewhat elongated and hypha- like. In the protoplasm are one or more large vacuoles. In certain of the cells, which may be considered to be asci, two to eight spherical or ellipsoidal spores are produced (Fig. 26). There are a number of different species of Yeasts, some of which FIG. 26. Formation of ascospores in a number of different species of Yeasts. I, Sac- charomyces cerevisia; 2, S. Pastorianus; 3, S. intermedius; 4, 5. validus. — After Hansen. are cultivated ; and these latter are of great economic importance on account of their property of inducing alcoholic fermentation. They are also of use in the making of bread, changing the carbo- hydrates in part into carbon dioxide and alcohol, both of which are driven off in the baking. The property of yeast causing the fermentation of a solution PRINCIPAL GROUPS OF PLANTS. 49 of sugar whereby alcohol is formed, was for a long time supposed to be due to the presence of the living yeast cell or to the action of living yeast protoplasm, and hence fermentation brought about by living organisms was distinguished from those fermentative processes where distinct principles such as diastase were involved ; the former being known as " organized "* ferments, while the latter were referred to as " unorganized " ferments. Biichner obtained from freshly expressed yeast a nitrogenous substance capable of changing solutions of cane sugar or glucose into alcohol and carbon dioxide. This principle he termed zymase, and it has all of the properties of an enzyme or ferment and behaves exactly as the living yeast cell in a sugar solution. In the living yeast plant zymase is continually being formed and decomposes the sugar which has diffused into the cell. Yeasts are used in the treatment of certain skin diseases, their action being attributed to a fatty substance, ceridine. Other principles found in yeasts as well as extracts are used in the treatment of cancer. Under the name of Xerase a mixture is marketed consisting of 150 parts of dried beer yeast, 20 parts of dextrose, 125 parts of white clay or aluminum silicate, and 3 parts of a mixture of nutritive salts. It is used in the treatment of putrid wounds, ulcers, etc. The ginger beer plant, which is used in England for making a beverage known as ginger beer, consists of a yeast (Saccharo- myces pyriformis) and a bacteria (Bacterium vermi forme). These two organisms live in a somewhat symbiotic relationship, the yeast changing the sugar into alcohol and the bacteria developing lactic acid (see Technical Mycology, by Lafar). Green and Yellow Mildews. — To the Ascomycetes also be- long the green and yellow Mildews, Penicillium and Aspergillus, so common in the household, the dairy, and the granary. These plants produce profusely branching mycelia which form patches upon or just under the surface of the materials upon which they grow. These areas become soft and spongy and are always white at first. After a time hyphal branches, which are more or less flask-shaped, rise above the substratum, and by a process of division at the end of the branch, or conidiophore, a spore called 4 5o A TEXT-BOOK OF BOTANY. a conidiospore is formed (Fig. 27, A; Fig. 28, A}. The process of division at the end of the conidiophore continues from below until a chain of conidiospores is formed. The conidiophore fre- quently branches, so that a fan-like series or group of conidia or FIG. 27. Penicillium, a green mildew. A, richly branching mycelium with conidio- phores; B, enlarged view of conidiophore showing chains of conidia; C, D, E,F, successive stages in the development of a perithecium; G, H, J, development of asci; K, groups of asci containing from 4 to 8 ascospores; L, ascospores seen from the side and showing char- acteristic markings. — After Brefeld. conidiospores is produced (Fig. 27, B; Fig. 28, A). The conidia are usually some shade of green, but finally they may become more or less brown. They are thin-walled, quite small, and so light that they float freely in the air. If a colony is inhaled it gives PRINCIPAL GROUPS OF PLANTS. 51 the sensation commonly called the "smell of mold." They are cap- able of germinating on almost everything, as old shoes, old paper, as well as on bread and other articles of the household. They may occur on "moldy drugs," and in pharmaceutical preparations, as syrups and infusions. Some of the molds produce citric and ox- alic acids (Amer. Jour. Pharm., 1916, pp. 125 and 337). Aspergillus (Fig. 28) is distinguished from Penicillium (Fig. FIG. 28. Aspergillus, a yellow mildew. A, conidiophore with enlarged, more or less spherical end, from which the fan-like series of chains of conidia arise; B-E, successive stages in the development of perithecium; F, section through a nearly ripe perithecium; G, groups of young asci; H, a ripe ascus with 8 spores. — A, after Kny; B-H, after De Bary. 27) by the fact that the upper end of the hyphal branch or conidio- phore is somewhat enlarged and more or less spherical. In addition to the conidiospores these Fungi sometimes pro-duce in the fall of the year, particularly when grown upon bread, asci fruits (Fig. 27, C-F; Fig. 28, B-E}. In this case two fertile ini- tial hyphae wind themselves around each other, after which they become surrounded with sterile branches which form a kind of 52 A TEXT-BOOK OF BOTANY. loose tissue, more or less cellular in structure, that finally develops into a yellowish leathery wall. This body, which may be regarded as a closed ascocarp, is known as a perithecium (Fig. 27, F ; Fig. 28, F}. As a result of the conjugation of the fertile cells, asci (Fig. 27, G, H, J; Fig. 28, G, //) develop within the perithecium, which are more or less spherical or ellipsoidal and contain from four to eight spores (ascospores) (Fig. 27, K; Fig. 28, H}. After maturity the cellular tissue around the asci dries up and dis- integrates, the walls of the asci dissolve, and the ascospores are liberated from the perithecium by slight pressure. The spores lie over winter and then germinate, producing a mycelium from which conidia first develop and afterwards the perithecia, thus repeating the life history of the plant. Ergot. — Another Ascomycete of special interest is the fungus known as Ergot (Claviceps purpurea). The spores of this fungus germinate on the flowers of certain grasses. The myce- lium penetrates the walls of the ovary, absorbing the nutriment. After a time the mycelium develops on the surface, and from this short conidiophores arise bearing small ovoid conidia (con- idiospores) (Fig. 29, A}. The mycelium secretes a sweet fluid, the so-called honey dew which attracts insects, and thus the conidia are carried to other plants. As the conidia are capable of immediate germination the so-called " ergot, disease " rapidly spreads during the flowering season of the host plants. After the formation of conidia ceases, the mycelium forms a dense mass which is surrounded by a dark layer, and this, if developed upon rye, constitutes the ergot grains (Fig. 29, B) used in medicine, these grains being a number of times larger than the rye grains which they replace. The mycelial tissues connected with the host plant die, and the ergot drops to the ground. At this stage the ergot mass is more or less cellular in structure and is known as the SCLEROTIUM. It is quite resistant and usually remains dormant until the following spring when the grasses are in flower again. The sclerotium then shows signs of renewed activity by the de- velopment of small, reddish, spherical bodies with a fair-sized stalk (Fig. 29, C). Within the periphery of these spherical heads are produced flask-shaped perithecia or ascocarps (Fig. 29, £>) PRINCIPAL GROUPS OF PLANTS. 53 containing numerous cylindrical asci (Fig. 29, £), each of which contains eight spores (Fig. 29, F) ; the latter are i -celled, hya- line, and thread-like (Fig. 29, H). These spores are carried by FiG. 29. Claviceps purpurea. A. mycelium developing conidia; B, an ear of rye with a number of lipe sclerotia replacing grains of rye, and known as ergot; C. sclerotium developing spherical fruit bodies; D, fruit body in longitudinal section showing numerous flask-shaped perithecia at the periphery; E, enlarged perithecium with numerous cylin- drical asci; F, closed ascus with 8 ascospores; G, discharge of ascospores; H, single thread- like ascospore. — A, after Brefeld; B, after Schenck; C-H, after Tulasne. the wind to the flowers of certain of the grasses, as already stated, and the life history or cycle of growth begins again. 54 A TEXT-BOOK OF BOTANY. Chestnut Bark Disease is caused by a fungus parasite known as Diaporthe parasitica Murrill, and is said to very closely re- semble the parasite found in Italy, Endothia radicalis. This fungus has been the cause of very great destruction of chestnut trees in the eastern United States. When any of the spores of this fungus gain entrance into a wound on any part of the tree, thread-like mycelia are developed in the inner layers of the bark, and these spread concentrically until they girdle the trunk or FIG. 30. Large Chestnut tree partly killed by the bark disease. Note branches in the center either killed or bearing dwarfed leaves, and the other larger branches still unaffected.— From photograph by Haven Metcalf. limb, so that if it happens that the trunk is affected the entire tree may die within the year, while if it is the smaller branches which are attacked, only those parts beyond the point of infection are killed, while the remainder of the tree will survive for some years (Fig. 30). . WKen the bark is attacked by the fungus it shows minute, more or less crater-like spots of a yellowish-orange or reddish-brown PRINCIPAL GROUPS OF PLANTS 55 color which are pustules of the fruiting fungus. These pustules produce mostly winter spores (ascospores), although occasionally a long strip of summer spores (conidia) are also produced (Figs. 31 and 32). FIG. 31. Typical appearance of branches of Chestnut tree affected with chestnut blight. At left, bark showing pustules of the parasitic fungus bearing winter spores. At right, the diseased bark showing pustules and form of discharge of summer spores in damp weather. — From photograph by Haven Metcalf. The control of the disease over large districts consists mainly in destroying the affected trees and carefully burning the rubbish. 56 A TEXT-BOOK OF BOTANY. Single trees are treated by removing the affected branches and painting over the cut ends with coal tar to prevent reinfection. For further details on this fungus consult : Murrill, " A New Chestnut Disease," Torreya, Sept., 1906; Farmers' Bulletin 467, U. S. Department of Agriculture ; Metcalf, " Diseases of the Chestnut and Other Trees," Trans. Mass. Hort. Soc., August, FIG. 32. Chestnut-blight disease, which occurs in small yellowish pustules the size of a pin head. A, section of pustule showing perithecia; B, asci with sporidia; a, usual form; b, form rarely found; C, sporidia; D, summer spores. — After Murrill. 1912 ; Farlow, " Fungus of the Chestnut-Tree Blight," Science, May 10, 1912. BASIDIOMYCETES. — The Basidiomycetes are the most highly organized of the Fungi. The mycelium consists of white branch- ing threads and is usually concealed in the substratum. In the cultivation of the edible mushrooms propagation is by means of the mycelium, which is known commercially as " spawn." It is recognized, however, that mushrooms can not be propagated in PRINCIPAL GROUPS OF PLANTS. 57 this way exclusively for more than two or three years. The my- celium is really the plant body, and the part which rises above the surface and is commonly regarded as the toadstool or mushroom (Figs. 33 to 37) is a fruit branch, or spore-producing organ. When these branches first make their appearance they are in the form of small solid bodies known as " buttons " (Fig. 33, l-V}. ». /^> /^ -* FIG. 33. Agaricus campestris, the common edible mushroom, showing at A on tha left mycelium (m) and development of buttons or young mushrooms; I to V, longitudinal sections showing successive stages in development of fruit body; m, mycelium; st, stipe; h, portion between veil (v) and spore-bearing portion (1). The illustration to the right (A, B, C) shows the structure of the hymenium in different degrees of magnification: A, section through portion of pileus showing five of the gills; B, section of a gill somewhat magnified; C, section of gill still more magnified and showing sterile cells or paraphyses (q), and the fertile cells or basidia (s), from each of which arise two basidiospores. — After Sachs. As growth proceeds these bodies differentiate into a stalk-like portion known as the stipe (Fig. 33, st), which is directly con- nected with the mycelium, and an umbrella-like portion borne at the summit of the stalk, called a pileus, which at first is closed down over the stalk, but later expands or opens more or less widely according to the species. On the under surface of the pileus, known as the hymenium, the spores are borne (Fig. 33, A TEXT-BOOK OF BOTANY. FIG. 34. Some common edible mushrooms and a common poisonous one. The fol- lowing are edible: I, Common Field mushroom (Agaricus campestris); 3, Clavaria flava, young plant; 6, Puffball (Lycoperdon cyathiforme); 4, Morel (Morchella esculenta); s, Chanterelle (Cantharellus cibarius); 7, Fairy-ring Fungus (Marasmius oreades). Only one poisonous species is shown, namely, 2, the deadly Agaric (Amanita phalloidcs), — Adapted from Farlow. PRINCIPAL GROUPS OF PLANTS. 59 A, B, C). In some cases the under surface is composed of a series of narrow, radiating, knife-like plates, or gills, as in the common edible mushroom Agaricus. On the surface of the gills the basidia or spore-bearing organs arise. The basidia are sorhewhat swollen terminal cells of the closely arranged hyphae composing the gills, which bear a group of spores on short stalks (Fig. 33, C). Both the basidia and spores (basidio-spores) are of a characteristic size and number for the different species. Several types of Basidiomycetes are usually recognized, de- pending on the manner in which the spores are borne. 1. The Gill Fungi (Agaricaceae), in which the spores are borne on plates or gills which radiate from the stem to the edge of the cap. 2. The Pore Fungi (Polyporaceae), in which the spores are borne in tubes or pits opening by pores rather than on gills. 3. The Coral Fungi (Clavariaceae), in which the Fungi are coral-like or leaf-like, the surface of the cap or its branches being smooth. 4. The Leather Fungi (Thelephoracese), in which the spore- bearing surface is smooth or slightly wrinkled. The texture is usually leathery or papery. 5. The Jelly Fungi (Tremellaceae), in which the fruiting sur- face is smooth and the cap is more or less jelly-like when wet. 6. The Puff Balls (Lycoperdaceas), in which the cap is a closed ball, which breaks open at maturity to release the enclosed spores. 7. The Carrion Fungi or Stink-horn Fungi (Phallaceae) re- semble the puffballs when young, but are ruptured longitudinally, the spores thereby being exposed on the top as a gelatinous mass. Of these seven groups the Gill Fungi are the commonest, and one or two types will be considered, namely, the common edible mushroom and two of the poisonous group, 'Amanita. Edible Fungi. — .Igaricus campestris (common mushroom) (Figs. 33 and 34) is practically the only edible species cultivated in this country. The plant grows wild in open grassy fields dur- ing August and September. It is not found in the mountains to any extent, and is never found in the woods or on trees or fallen trunks. The color of the stipe and the upper surface of the 6o A TEXT-BOOK OF BOTANY. FIG. 35. A decaying tree trunk showing the cause of the death of the tree by the appearance of the several fungi (probably Lepiota Americana). It is not unusual to find trees showing signs of disease and, finally, even -dying, and it is not until the death of the tree that the mature fungus makes its appearance. For some years the mycelium of the fungus has been working its way into the tissues not only of the bark but of the wood, sapping it of its vitality. The fungus finally produces its fruit with spores, the latter being scattered by either the wind or through the agency of birds, are carried to other trees and find entrance into wounds, where they germinate and repeat their destruction. — From a photograph by Troth. PRINCIPAL GROUPS OF PLANTS. 61 pileus varies from whitish to a drab color, but the color of the gills is at first pinkish and then of a brownish-purple, which is an important character, the color being due to the spo'res. The stipe is cylindrical and solid, and a little more than half way up is furnished with a membranous band known as the ring. There are no appendages at the base of the stipe, which appears to rise FIG. 36. Edible Boletus (Boletus edulis), an excellent edible mushroom found in woods and openings in summer and autumn. The cap is 8 to 15 cm. wide, grayish-, yellowish-, or brownish-red, sometimes paler toward the edge, smooth, and more or less convex; flesh whitish or yellowish, or somewhat reddish just beneath the skin; stem white, stout, and often bulbous. — After Atkinson, "Studies of American Fungi." directly out of the ground. Before the pileus is fully expanded a veil extends from its border to the stipe, which when ruptured leaves a portion attached to the stipe, and it is this which consti- tutes the ring. The ring shrinks more or less in older specimens. but usually leaves a mark indicating where it has been formed. Poisonous Fungi. — There are two of the poisonous group of Fungi which are very common and which have some resem- 62 A TEXT-BOOK OF BOTANY. blance to the edible mushroom just described, namely, the fly agaric (Amamta muscaria) (Fig. 38) and the deadly agaric (Amanita phalloides} (Fig. 34) . The fly agaric, while more abun- dant in some localities than the common edible mushroom, is FIG. 37. Pale Lenzites (Lenzites betulina), a non-edible tungus common on trunks and stumps throughout the year. The cap Is whitish, corky, more or less densely hairy, and marked by concentric grooves; the stem is lacking and the gills are whitish, more or. less branched and united. — From monograph on Minnesota Plant Diseases by E. M. Freeman. seldom found in grassy pastures, but more generally in poor soil, especially in groves of coniferous trees. It occurs singly and not in groups. The gills are always white ; the stipe is white, hollow, and provided with a ring at the top, and the base is bulbous, hav- ing f ringy scales at the lower part. The pileus is yellow or orange PRINCIPAL GROUPS OF PLANTS. FIG. 38. Fly Agaric (A manita muscaria), a very deadly mushroom. The cap is bright red or orange, becoming yellow or even whitish in age, roughened with many thick, white angular fragments of the volva; the stem is stout, white, scaly, bulbous, and hollow; volva forming several concentric scaly rings on the bulb; gills free or touching, white or yellowish. This is frequent in woodland, forest, or clearing from June to frost, and is deadly poisonous. —From monograph on Minnesota Mushrooms by Frederic E. Clements. 64 A TEXT-BOOK OF BOTANY. and sometimes reddish; the surface is smooth, with prominent, angular, warty scales, which can be easily scraped off. The deadly agaric (Fig. 34, illus. 2) somewhat resembles the fly agaric and also differs from the common mushroom in not usually growing in pastures. It occurs singly, but not in groups, in woods and borders of fields. The gills and stipe are white, the latter, when young, having a number of mycelial threads running through it. The base is quite bulbous, the upper part of the bulb having a sac-like membrane called the volva. The pileus may vary from any shade of dull yellow to olive, although some- times it is shiny and white. While it does not possess the warty scales found in the fly agaric, it has occasionally a few mem- branous patches. The Toxic Principles in Poisonous Fungi. — The deadly agaric (Amanita phalloides) is the cause of the greatest number of cases of mushroom poisoning. According to Abel and Ford, it contains two toxic principles: (i) Amanita-hemolysin, a blood- laking principle, which is a very sensitive glucoside,- — that is, pre- cipitated by alcohol, destroyed by heating to 70° C. and by the action of digestive ferments; (2) Amanita-toxin, which is soluble in alcohol, is not destroyed by the action of heat or ferments. The latter principle is the important poisonous prin- ciple in mushroom poisoning and is probably the most toxic principle known, 0.4 of a milligramme killing a guinea pig within 24 hours. " The majority of individuals poisoned by the ' deadly amanita ' die, but recovery is not impossible when small amounts of the fungus are eaten, especially if the stomach be very promptly emptied, either naturally or artificially." The fly agaric (Amanita muscaria) owes its toxicity to mus- carine, an alcohol-soluble crystalline substance. It is supposed by Ford that the fly agaric may contain another poisonous constit- uent. In cases of poisoning atropine has been successfully ad- ministered hypodermically in doses of T|¥ to ^ of a grain. It is stated that the A. muscaria, used by the peasants of the Caucasus in the preparation of an intoxicating beverage, is deficient in muscarine. The question as to whether the ordinary edible mushrooms, as distinguished from the poisonous toadstools, may not in cer- PRINCIPAL GROUPS OF PLANTS. 65 tain localities or at certain periods of the year be the cause of fatal intoxication is answered by Ford in the negative. He states '(Science, 30, p. 105, July 23, 1909) that there are no authentic cases of poisoning from the black or brown spored agarics, although old and badly decomposed specimens may cause transient illness. Economic Uses of Fungi. — A large number of the Fungi, particularly of the Basidiomycetes, are used for food. There are, however, only a few of these which enter the market. These are derived chiefly from Agaricus campestris (Figs. 33 and 34) and Agaricus arvensis, although some other species of Agaricus as well as Morchella esculenta (Fig. 34, illus. 4) furnish excellent products and are cultivated to a limited extent. The " truffles " of the market are tuber-like masses formed under ground, which consist of the ascocarps of certain Tuberaceae, one of the sub- groups of the Ascomycetes, and which are used as a condiment and sometimes roasted like potatoes. Tuckahoe or " Indian bread " is also produced under ground and consists apparently of the fungus Pachyma Cocos and the roots of Liquidambar, the tissues of which have been changed into a compound resembling pectic acid by the fungus. Quite a number of Fungi have been used in medicine, as Clainceps pur pur ea (Fig. 29), Polyporus officinalis and other species, and various species of Lycoperdon. A number of species are used in making surgeon's agaric (Fungus chinirgorum) formerly used as a haemostatic, including Lycoper- don Bovista and Polyporus fomentarius. Many of them yield very toxic principles, as ( i ) several species of Amanita which contain several toxic principles; (2) Lactarius piperatus and others which yield highly poisonous resinous principles. Other uses of Fungi have been mentioned under the several groups. USTILAGINE^; and UKEDINE^-:. — There are two groups of Fungi of considerable economic interest which by some writers are classed by themselves, and by others placed with the Basidio- mycetes. These are the Ustilagineae, or Smut Fungi, and the Uredineae, or Rust Fungi. The Smut Fungi are parasitic on higher plants. The myce- lium penetrates the tissues of the host, but does not seem to cause either disease or malformation of the plant. Injury to the 5 66 A TEXT-BOOK OF BOTANY. host results only after the development of resting spores. The mycelia are hyaline, more or less branched, and finally become septate. They send short branches, called haustoria, into the cells of the host, from which they obtain nourishment. Eventu- ally the mycelium becomes much branched, compact and more or less gelatinous through a transformation of the hyphal walls, forming gall-like swellings or blisters on the host. Spores are formed within this gelatinous mass at the ends of the. branches FIG. 39. Corn smut (Ustilago Maydis) showing several gall-like masses of smut full of spores. of the mycelium. At a later stage the smut loses its gelatinous character, the mass breaks up, and the spores are freed and dis- tributed as a dry, dusty powder. The spores (primary conidia) are somewhat spherical or ellipsoidal, and are generally separate, but are sometimes united into a mass forming the so-called " spore balls." These are resting spores and upon germination (Fig. 40) produce a promycelium or basidium which becomes septate and from each cell of which conidia called sporidia arise. The sporidia are formed in succession one after another and the process con- PRINCIPAL GROUPS OF PLANTS. 67 tinues for some time. On germination they bud like yeast, form- ing new conidia, or when nutrition is not abundant they may form a mycelium, which is usually the case when they germinate on a host plant. Corn Smut. — One of the Smut Fungi, namely, Ustilago Maydis, which develops on Indian corn (Fig. 39), is used in medi- FIG. 40. Spores of various Smuts. I, U stilago longissi ma growing on the reed meadow- grass (Panicularia americano); 2, Ustilago Maydis from Indian corn (Zea Mays); 3, Ustilago Oxalidis on the yellow wood-sorrel (Oxalis stricta); 4, Ustilago utriculosa on the Pennsyl- vania persicaria (Polygonum pennsylvanicum). FIG. 4oa. Germination of spores. 5, Ustilago utriculosa, in water, showing promy- celium and sporidia; 6, Doassansia opaca from the broad-leaved arrow-head (Sagittaria latifolia) in water, showing promycelium, sporidia, and secondary sporidia which are falling off; 7, Ustilago Avence from oat (Avena saliva) in horse dung, showing promycelium, and lateral "infection threads" or hyphae; 8, germination of a sporidium of Ustilago Sorghi into an infection thread; 9, small portion of a group of sporidia developed from promycelium of Tolyposporium Eriocauli on potato agar; 10, cross-section of epicotyl of broom-corn infected by Ustilago Sorghi showing mycelium ramifying through parenchyma cells of the cortex. — After Clinton. cine. It forms rather large gall-like masses on all parts of the plant, including the root, stem and leaves, and both staminate and pistillate flowers. The spores (Fig. 40) are at first a dark olive- green, but on maturity are dark brown. They are sub-spherical, have prominent spines, and vary from 8 to 15 microns in diameter. They do not germinate at once, but on keeping them for six 68 A TEXT-BOOK OF BOTANY. months to a year they germinate readily on a culture medium of potato, and retain their power of germination for years Rust Fungi. — The Rust Fungi are parasitic on higher plants FIG. 41. Wheat rust (Puccinia graminis). A, teleutospore or winter spore germinating and giving rise to a promycelium (p) and sporidia (s); B, a few leaves of barberry attacked by sporidia which give rise to the aecidia; C, transverse section through barberry leaf show- ing three cup-like receptacles (aecidia) on the lower surface of the leaf containing per- pendicular rows of conidia (ascidiospores) ; D, germinating ascidiospore on wheat; E, wheat plant attacked by ascidiospores as shown by the elongated blotches on the leaves; F, cross section of leaf of wheat showing on the upper surface the rust spores which are breaking through the epidermal layer (r); G, summer spores (uredospores) ; H, teleutospores or winter spores formed on wheat leaf. — After Dodel-Port. and produce a thread-like branching, cellular mycelium, which develops in the tissues of the host. They differ especially from the other Fungi in producing resting spores known as TELEUTOSPORES. PRINCIPAL GROUPS OF PLANTS. 69 These spores consist of one or more cells surrounded by a thick black wall, and they produce the " black rust " seen on foliage at the end of the season. Wheat Rust. — The most important member of the Rust Fungi is Puccinia, of which there are a large number of species that are destructive to economic plants, as wheat, plum, cherry, red cur- rant, etc. The one whose life history has been best studied is the wheat rust (Puccinia graminis), which requires two different plants to complete its life history, namely, wheat and barberry. The Teleutospores, or "winter spores" (Fig. 41, //), as they are called, because of their carrying the life of the plant over the winter season, consist of two cells. These spores exist on the leaves and stems of wheat over winter, and in the spring they ger- minate (Fig. 41, A). From each cell a mycelium (promycelium or basidium) consisting of two to four cells arises (Fig. 41, A, />), and from the tip of each branch of the promycelium a spore known as a sporidium develops (Fig. 41, A, s). The Sporidia are scattered by the wind, and .when they fall on the barberry leaves (Fig. 41, B) they germinate, producing a dense mass or mycelium which penetrates into the tissues of the host. Sooner or later, just within the under surface of the leaf, there is formed a more or less spherical, dense mass, which grows outward, breaking through the surface, forming a cup-like re- ceptacle known as an aecidium (Fig. 41, C}. The ^cidia, or cluster cups, are orange or yellow and are filled with perpendicular rows or chains of spores which arise from the basidium-like mycelium below. The spores, which have received the name ^Ecidiospores, are somewhat spherical or polyhedral, and contain a reddish-yellow oil. They are scattered by the wind and, falling upon the wheat plant (Fig. 41, £), germinate immediately, form- ing a dense mycelium. At first it produces what is known as a " Summer spore," or Uredospore (Fig. 41, G), giving rise to the reddish-brown spots and stripes on the leaves and stalks of the wheat plant. The Uredospores are i -celled, and are carried by the wind to other wheat plants, thus rapidly spreading the disease. The Uredospores arise in much the same way as the Teleuto- spores (Fig. 41, //), which form brown patches later in the sea- son, and which have been already considered. The Teleutospores 70 A TEXT-BOOK OF BOTANY. last over winter on the old wheat plant, and in the spring begin again the life-cycle of the rust. The plant which results from the germination of a teleutospore gives rise to sporidia, which are carried to the barberry leaves where aecidiospores are pro- duced. The latter are then carried to growing wheat, forming first uredospores and later teleutospores. It should be remembered that these are all asexual spores. In regions where there are no barberry plants to act as host the aecidiospore stage is omitted. THE FUNGI IMPERFECTI. — The miscellaneous fungi included in this group are of importance because of the great damage which they cause to agricultural crops. The potato scab is an especially destructive pest in New England and in Canada. The scab not only develops on the growing tubers in the soil, but can be spread from a few affected potatoes to a whole bin of clean ones if they come in contact with them. Prevention of this disease usually consists in disinfecting the tubers which are used for seed so as not to carry the minute organisms into the soil. A disease affecting the leaves of the potato and thereby destroy- ing the crop is due to a fungus whose spores, settling on the leaves, germinate and penetrate to the interior through the stomata, finally weakening or killing the plant. Some of the other important forms produce a pink mold on apples, scabs on peaches and other fruits, mold on onions and other garden crops. The -blight of ginseng and the blight of cotton, the dry rot of various vegetables and the blotches on many of our common fruits can be traced to the development of these fungi. The study of these forms is a very difficult one, and re- searches are constantly being carried on at the government experi- ment stations, as well as by individual workers. For a description of these forms, as well as many other harmful fungi, consult " Fungous Diseases of Plants," by Duggar. DETECTION OF FUNGUS IN HOST. — Unless special means are employed, it is ofttimes rather difficult to trace the mycelial of the fungus in among the cells of the host plant. Vaughan (Annals of the Missouri Botanical Garden, 1914, p. 241) has used the stain known as " Pianeze Illb " in differentiation of the fungus from the plant substratum. The host tissue stains green and the my- celium a deep pink. This stain, devised by Dr. Pianeze for the PRINCIPAL GROUPS OF PLANTS. 71 study of cancer tissue, is made up as follows: Malachite green, 0.50 Gm. ; acid fuchsin, o.io Gm. ; " Martius gelb," o.oi Grn. ; water distilled, 150.00 c.c. ; alcohol (95 per cent.), 50.00 c.c. For use with plant tissues the procedure is as follows : Wash in water or alcohol, stain in the undiluted mixture 15 to 45 minutes, remove excess stain in water, and decolorize in 95 per cent, alcohol to which a few drops of hydrochloric acid have been added. For per- manent mounts, clear with a carbol-turpentine mixture, remove clearing solution, and mount in balsam. This stain is also valuable for staining spores which have been allowed to germinate on the surfaces of leaves. In such cases the killing and tissue-clearing mixture proposed by Duggar is recommended, viz., consisting of equal parts of glacial acetic acid and alcohol. In the study of the rusts, the best results are obtained by the use of Durand's combination of Delafield's hsema- toxylin and eosin (Phytopathology, 1911, p. 129). LICHENS. General Characters. — The Lichens are a peculiar group of plants in that an individual lichen consists of both an alga called a GONIDIUM and a fungus. These are so intimately associated that they appear to be mutually beneficial, and such a relation is known as SYMBIOSIS (Fig. 42). The Algae which may be thus associated in the Lichens are those members of the Blue and Green Algae which grow in damp places, as Protococcus, Nostoc, Lyngbya, etc. (Fig. 42). The Fungi which occur in this relation belong both to the Ascomycetes and Basidiomycetes, and it is on the characters of the* fruit bodies of these particular Fungi that the main divisions of Lichens are based. The Fungi, however, are not known to exist independently of the Algae with which they are associated ; that is, the mycelia of the fungi will not live for any length of time unless they come in contact with suitable algae. In its development the fungus forms a mycelium which encloses the alga, the growth of which, latter is not hindered. The two organisms then continue to grow simultaneously, forming lichen patches. A section of a lichen shows a differentiation into several parts (Fig. 43) : a more or less compact row of cells on both surfaces forming two epidermal layers ; and an inner portion 72 A TEXT-BOOK OF BOTANY. made up of the hyphal tissue of the fungus in which the alga is em- bedded either in a single layer or throughout the mycelium. The mode of growth and branching is influenced largely by the fungus, although in some cases the alga may exert the most influence. In some cases the lichen consists of a thallus which is irregular in outline, growth taking place at no definite point, and in other cases branches which are more or less regular are formed, growth taking place at the apex. FIG. 42. Lichens showing manner of union of algae or gonidia (g) and hyphse (h) of Fungi. A, Protococcus, showing the manner in which hyphae penetrate the cell and in- fluence cell division; B, Scytonema, an alga surrounded by richly branching hyphae; C, chain of Nostoc showing hypha of fungus penetrating a large cell known as a heterocyst; D, fungal hyphae have penetrated the cells of Gl&ocapsa, a blue-green, unicellular alga; E, Chlorococcum, a reddish or yellowish alga found in Cladonia furcata, the cells of which are surrounded by the short hyphae of the fungus. — A, after Hedlund; B-E, after Bornet. The walls of the hyphae of the fungus comprising Lichens con- sist at first of pure cellulose. In older material the walls undergo more or less modification, being changed in part to starch, mucilage, or fixed oil. There may be also infiltrated among the layers of the wall calcium oxalate, the latter constituent being especially characteristic of the crustaceous Lichens. The most interesting constituents of Lichens are the coloring principles, which are mostly of an acid character and are termed Lichen-acids. They PRINCIPAL GROUPS OF PLANTS. 73 give very striking reactions with solutions of the alkalies and solu- tions containing chlorine. The reaction with iodine solutions is also employed for diagnostic purposes ; some of the Lichens give a blue reaction, while others behave like amylo-dextrin. Groups of Lichens.— According to the manner of growth and the manner of attachment to the substratum, three principal groups of Lichens may be distinguished: namely, (i) Crus- taceous Lichens, where the thallus adheres closely to the stones and barks of trees and practically can not be removed without injury; (2) Foliose Lichens, or those which are more or less flattened, somewhat leaf-like and attached at different points 1(3) Fruticose Lichens, or those which are attached at a particular part of the thallus, and form diffusely branching clumps. To this latter group belong Cetraria islandica or Iceland moss (Fig. 43), which is used in medicine, Usnea barbata and the red-fruiting Cladonias which are so common. Reproduction in the Lichens takes place in several ways. In all of them there is a vegetative mode by means of what are known as SOREDIA. These are small spherical bodies consisting of a group of algal cells, which are surrounded by a mass of hyphse, and which when cut off from the main body are able to grow. Lichens also produce spores of a number of kinds. In the largest group, the one to which Cetraria islandica (Fig. 43) belongs, the spores are found in special spherical receptacles, known as PYC- NIDIA, which are formed on the teeth of the margin of the thallus. The spores arise from the ends of hyphse at the base of the pyc- nidia and are in the nature of conidiospores. To these spores the name PYCNOCONIDIA has been applied. Cetraria also pro- duces, like many other Lichens, disk-like or cup-shaped bodies at various places on the surface of the thallus, which are known as APOTHECIA and which may be regarded as exposed or open asco- carps. The inner surface of the apothecia is lined with a number of asci as well as sterile cells, the former giving rise to ascospores. Economic Uses of Lichens.— A number of the Lichens, are used in medicine, as several species of Cetraria, Pertusaria com- wunis, Physica parietina, Sticta pulmonacea, Evernia furfuracea. Some of those used in medicine are also used as foods on account 74 A TEXT-BOOK OF BOTANY. of the gelatinous carbohydrate lichenin which they contain. Be- sides those given, the following may be mentioned : Cladonia rangiferina (reindeer moss), Lecanora esculenta (supposed to be the manna of the Israelites). The Lichens are, however, chiefly of interest because of the coloring principles which they contain. FIG. 43. Iceland Moss (Cetraria islandica). A-F, various forms of thalli showing apothecia (a); I, cross-section of an apothecium showing the hymenium (h), the hypothe- cium (p), the algal layer (e), the medullary layer (m), and lower or ventral surface (1); K, an ascus with eight ascospores and two paraphyses from the hymenium (h). Roccella tinctoria, Lecanora tartarea, and other species of Leca- nora, yield upon fermentation the dyes orcein and LITMUS, the latter of which finds such general use as an indicator in volu- metric analysis. Cudbear, a purplish-red powder, is prepared by treating the same lichens with ammonia water ; while in the prep- PRINCIPAL GROUPS OF PLANTS. 75 aration of orchil, a purplish-red pasty mass, sulphuric acid and salt are subsequently added. A number of species contain a yel- low coloring principle, as Zeora sulphured, Zeora sordida, Lecidea geographica and Opegrapha epigcea. ARCHEGONIATES. The two main features which distinguish the Archegoniates from the Thallophytes are the structure of the sexual organs and the distinct manner in which the peculiar phases known as alter- nation of generations are shown. The antheridium or male sexual organ is a well differentiated multicellular body which is either sunk in the adjacent tissues of the plant or is provided with a stalk. Within it are organized the sperms of spermatozoids, which are ciliate and swim freely in water. Corresponding to the oogo- nium of the Thallophytes is the ARCHEGONIUM or female sexual organ which gives name to the group. The archegonium is a flask-shaped cellular botly consisting of a basal portion of venter, which contains a single egg, and a neck through which the sperms enter (Figs. 49 and 51). In the life history of this group of plants there are two gen- erations or phases of development. During one stage the arche- gonium and antheridium are developed, and this is known as the sexual generation, and as these organs give rise to gametes or sexual cells it is also spoken of as the GAMETOPHYTE. By the union of the sex cells (sperm and egg) an oospore is formed which germinates at once within the archegonium. That portion of the plant which develops from the oospore gives rise to asexual spores, and hence this phase is called the asexual generation. It is also spoken of as the SPOROPHYTE from the fact that it gives rise to spores. These spores are in the nature of resting spores and do not germinate on the plant as does the oospore. They are distributed and on germination give rise to the gametophyte stage. In some of the Archegoniates these two phases are combined in one plant, as in the Bryophytes, whereas in other members of the group the two phases are represented by two distinct plants ; that is, the gametophyte and sporophyte become independent of each other, as in the Ferns. 76 A TEXT-BOOK OF BOTANY. The following table shows the main divisions and subdivisions of the Archegoniates : Bryophytes. . . . I HePatic« (Liverworts). JMusci (Mosses). Archegoniates Pteridophytes . . , Filicales (Ferns). Equisetales (Horsetails). Lycopodiales (Club Mosses), BRYOPHYTES The structure of the sexual organs in the Liverworts (Fig. 44) and Mosses (Fig. 49) is essentially the same, but the vegetative organs are more or less dissimilar. In the Liverworts the plant FIG. 44. A common moss (Funaria). A, germinating spores: v, vacuole; w, root- hair; s, exospore. B, protonema about three weeks after germination: h, procumbent primary shoot; b, ascending branch of limited growth; K, bud or rudiment of a leaf -bearing axis with root-hair (w). — After Sachs. body or thallus lies more or less close to the substratum or rises somewhat obliquely, whereas in the Mosses the part we designate as the plant is in all cases an upright leafy branch. The moss plant is said to have a radial structure from the fact that the leaves radiate from a central axis, while in the Liverworts the thallus is dorsiventral ; that is, as a result of its habits of growth, it is characterized by having a distinct upper and lower surface. PRINCIPAL GROUPS OF PLANTS. 77 The Life History of this group of plants may probably be best illustrated by following that of a moss plant. Beginning with the germination of an asexual spore which is microscopic in size and which germinates on damp earth, there is produced an FIG. 45. A common moss (Polytrichum gracile). A, showing leafy branches (gameto- phores) two of which bear sporogonia, a detached sporogonium (sporophyte) with sporan- gium from which the calyptra (ca) has been detached. B, longitudinal section through a nearly ripe sporangium showing columella (o), the elongated area of sporogenous tissue (archesporium) on either side, annulus (n), peristome (p), lid or operculum (u); C, trans- verse section of sporangium showing columella in center and dark layer of sporogenous tissue (archesporium); D, ripe sporangium (capsule) showing the escape of spores after detachment of lid; E, ripe spore containing large oil globules; F, ruptured spore showing separated protoplasm and oil globules; G, two germinating spores 14 days after being sown, showing beginning of protonema in which are a number of ellipsoidal chloroplasts. — After Dodel-Port. 78 , A TEXT-BOOK OF BOTANY. alga-like body consisting of branching septate filaments, which is known as the PROTONEMA, or prothallus (Fig. 44). The Proto- nema lies close to the surface of the ground and is more or less inconspicuous except for the green color. From the lower por- tion thread-like processes, or rhizoids consisting of a row of cells, are developed, which penetrate the ground. Sooner or later lateral buds arise from some of the lower cells. Growth continues from an apical cell which divides and gives rise to cells that differentiate into stem and leaves, forming an upright branch, which consti- tutes the structure commonly regarded as the " moss plant " (Fig. 45, A}. The leaf-bearing axis varies considerably in size; in some cases it is but a millimeter high, whereas in some species, as Polytrichum (Fig. 45), it may be several hundred millimeters in height. At the tip of the branch the antheridium (Fig. 49, A) and archegonium (Fig. 49, B) are formed. These organs are developed in among the leaves and certain hairy processes, known as paraphyses ( Fig. 49, />) . They may both occur at the end of one branch (Fig. 49, C) or they may occur on separate branches (Fig. 49, D), when the plants are said to be monoecious, whereas when these organs occur on separate plants (Fig. 49, At B) the plants are called dioecious. In the case of dioecious plants the plant bearing the antheridium is frequently smaller and less com- plex than the one producing the archegonium. As already stated, the archegonium produces the egg-cell or female gamete (egg) and the antheridium, the sperm cell or male gamete (sperm). The sperms in the Bryophytes are more or less filiform and are provided with a pair of cilia at one end. The antheridia, 'owing to the peculiar mucilaginous character of the cells, only open when there is an abundance of moisture, when the sperms are discharged and move about in the water, some being carried to t.he archegonium, which likewise opens only in the presence of moisture. With the transferral of the sperms to the archegonium and the union of one of these with the egg which remains sta- tionary, the work of the gametophyte may be said to be com- pleted. The act of union of the egg and sperm is known as FERTILIZATION, and when this is effected the next phase of the life history begins. The egg after fertilization divides and re-divides within the PRINCIPAL GROUPS OF PLANTS. 79 archegonium, which becomes somewhat extended until finally it is ruptured. The dividing cells differentiate into a stalk and a spore case or sporangium which is borne at the summit, the whole structure being known as the SPOROGONIUM (Fig. 45). The base of the stalk is embedded in the apex of the moss plant, and is known as the foot, it being in the nature of a hausto- rium or nourishing organ. As the sporogonium develops and rises upward it carries with it the ruptured archegonium which forms a kind of covering over the top, called the calyptra (Fig. 45, ca). At first the sporangium is more or less uniform, but eventually differentiates into two kinds of tissues, the one being sterile and the other fertile (producing spores), which latter is known as the ARCHESPORIUM (Fig. 45, B, C). The fertile tissue in both the Liverworts and Mosses is variously disposed; some- times it forms a single area and is dome shaped, spherical, or in the form of a half sphere. In other cases it is separated into two areas by sterile tissue. The sterile tissue which extends up into the dome-shaped archesporium, or which in other cases separates the fertile tissue into two parts, is known as the columella (Fig. 45, B, C). The sporangium in the mosses is capsule-like and the spores are distributed in three ways : ( I ) In some cases the capsule does not open, but when it decays the spores are liberated. (2) In other cases the capsule dehisces longitudinally in dry weather, and thus the spores are freed. (3) There is a third method in which the capsule is provided with a lid or operculum which comes off and permits the spores to escape, this being the most common method for the escape of the spores (Fig. 45, D). In the latter instance the mouth of the capsule is usually marked by one or two series of cells, constituting the PERISTOME, which are teeth-like and characteristic for some of the groups of mosses. These teeth bend inward or outward, according to the degree of moisture, and assist in regu- lating the dispersal of the spores. In the sphagnum mosses there is no peristome, but, owing to unequal tension of the lid and capsule on drying, the lid is thrown off, and the spores are sometimes discharged with considerable force and sent to quite a distance (as much as 10 centimeters), in this way insuring their dispersal. The spores (Fig. 45, £) vary in diameter from 10 to 20 80 A TEXT-BOOK OF BOTANY. microns, being sometimes larger. They occur in groups of four in a mother-cell, and the spore-group is known as a tetrad, which is characteristic for the Bryophytes and the higher groups of plants. The spores therefore vary in shape from spherical tetra- hedrons to more or less spherical bodies, depending upon the degree of separation. The contents are rich in protoplasm and oil (Fig. 45, F). The wall consists of two layers, the outer of which is either yellowish or brown and is usually finely sculptured. At the time of germination the outer wall is thrown off, and the protonema develops (Fig. 45, G). The spores may germinate almost immediately, or only after a considerable period. These spores are asexual and each one is capable of giving rise to a new plant. With the formation and dispersal of the spores the work of this generation terminates, and this phase is called the sporophyte or asexual generation, from the fact that it produces spores. Having thus followed the stages of development in the life history of a moss, we see that it is composed of the following parts: (i) The alga-like protonema; (2) the leafy branch which gives rise to an oospore (sexual spore), and (3) the sporogonium which produces asexual spores. The leafy branch is sometimes spoken of as the gametophore (gamete-bearer), and it and the protonema together constitute the gametophyte or sexual gen- eration, while the sporogonium represents the sporophyte or asexual generation. The protonema sooner or later dies off in most plants, but in other cases it persists, forming a conspicuous portion of the gametophyte. HEPATIC^. General Structure. — The Hepaticae or Liverworts (Fig. 46) are usually found in moist situations. The protonema formed on germination of a spore is filiform, and the plant body which develops from it consists of a flat, dichotomously-b ranching thallus, or it may in some of the higher forms differentiate into a leafy branch, as in the leafy liverworts. The thallus, owing to its position, has an upper and an under surface which are some- what different, as in Marchantia (Fig. 46), hence it is said to be PRINCIPAL GROUPS OF PLANTS. 81 DORSIVENTRAL. From the lower colorless surface unicellular rhizoids arise (Fig. 47, h). The upper surface consists of several layers of cells containing chlorophyll which give the green color to the plant. Vegetative propagation may ensue by the lower portion of a branch dying and the upper portion continuing as an inde- pendent plant. Or special shoots, known as GEMM.E, may arise FIG. 46. Dichotomously branching thallus of the common liverwort (Mafchantia polymorpha) showing near some of the margins the cup-like depressions in which gemmae are borne (c), and several archegoniophores (a). either on the margin of the thallus or in peculiar cupules, which, when detached by rain or other means, are capable of growing and producing a new plant. In addition the thallus body produces both antheridia and arch- egonia (Fig. 46) which may arise on special stalks above the sur- face. After fertilization of the egg-cell, which completes the work of the sexual generation of gametophyte, the sporophyte develops, 6 82 A TEXT-BOOK OF BOTANY. producing a sporogonium consisting of a short stalk which is embedded in the tissues of the gametophyte, and a capsule (spor- angium). The latter at maturity dehisces or splits and sets free the spores, which are assisted in their ejection by spirally banded cells called " elaters " (Fig. 48, C-F). The spores on germination give rise to a protonema which then develops a thallus bearing the sexual organs. As in the mosses, the sporogonium represents the asexual generation known as the sporophyte. Liverwort Groups. — There are three important groups of FIG. 47. Transverse section through the thallus of Marchantia polymorpha. A, middle portion with scales (b) and rhizoids (h) on the under side; B, margin of the thallus more highly magnified, showing colorless reticulately thickened parenchyma (p), epidermis of the upper side (o), cells containing chlorophyll (chl), air pore (sp), lower epidermis (u). —After Goebel. Liverworts: (i) The MARCHANTIA Group (Fig. 46), in which the thallus is differentiated into several layers and so somewhat thickened. Another character is the diversity in form of the sexual organs, which range from those which are quite simple to those which are highly differentiated. In Riccia the sexual organs are embedded on the dorsal (upper) side of the thalluc, while in Marchantia they are borne upon special shoots, one, which has a disk at the apex that bears the antheridia, known as the antheridio- phore, and another whose summit consists of a number of radiate PRINCIPAL GROUPS OF PLANTS. divisions and bears the archegonia (Fig. 46) on the lower sur- face, known as the archegoniophore ; these being borne on separate plants. In Riccia, the simplest of the Liverworts, the sporangium is enclosed by the thallus and the spores are not liberated until the decay of the plant. (2) The JUNGERMANIA Group, known as " Leafy Liver- worts " or " scale mosses," includes those forms which are more FIG. 48. Anthoceros gracilis, one of the liverworts. A, thallus with 4 sporogonia; B, a ripe elongated sporogonium, dehiscing longitudinally and showing two valves between which is the slender columella; C, D, E, F, various forms of elaters; G. spores. — After Schitfner. or less moss-like and develop stems and small leaves. The sporo- gonium has a long stafk and the capsule is 4-valved, i.e., separates into four longitudinal sections at maturity. (3) In the ANTHOCEROS Group (Fig. 48) the gametophyte is thallus-like and very simple in structure, the sexual organs being embedded in the thallus. The sporogonium is characterized by a bulbous foot and an elongated, 2-valved capsule. Like the thallus, 84 A TEXT-BOOK OF BOTANY. it develops chlorophyll and possesses stomata resembling those found in certain groups of mosses and higher plants. MUSCI. In the Mosses the archegonia always form the end of the axis of a shoot, whether this be a main one or a lateral one. As has already been stated (p. 78), the sexual organs are surrounded by leaves or leaf-like structures, known as perichxtia or peri- chastal leaves, and by hair-like structures or paraphyses, both of which are considered to act as protective organs. Sometimes the groups of sexual organs together with the protective organs are spoken of as the " moss flower." As already stated, the Mosses are both monoecious (Fig. 49, C, D) and dioecious (Fig. 49, A, B), hence a moss flower may contain only one of the sexual organs or it may contain both. Mosses are also characterized by an abundant vegetative propagation. Xew branches are developed from the old. " Almost every living cell of a moss can grow out into protonema, and many produce gemmae of the most different kinds." Entire shoots provided with reserve material are cut off and form new plants. In this way moss carpets are frequently formed in the woods, or masses in bogs. Moss Groups. — There are two general classes of mosses : ( i ) SPHAGNUM forms are those which produce leaves without nerves, and in which the sporogonium does not possess a long stalk or seta. What appears to be the stalk is the prolongation of the gametophyte stem which is known as the pseudodium or " false stalk." These forms are characteristic of wet places. Some of the group, as Sphagnum proper, form " sphagnum bogs." New plants develop on top of the old, which latter gradually die and finally pass into sphagnum peat, which forms thick masses and finds' use as a fuel. (2) The TRUE MOSSES are especially distin- guished by the differentiated character of the sporogonium, which not only produces a stalk but also the peristome (Fig. 45, />), which when present is of great importance in distinguishing the different species. Economic Uses of Bryophytes. — The investigations on the chemistry of the Liverworts and Mosses have not been very numerous. The constituents which have been found are in the PRINCIPAL GROUPS OF PLANTS. 85 nature of tannin, resins, ethereal oils, glucosides, alkaloids, color- ing compounds, and organic acids like citric, oxalic, tartaric, and aconitic. In the mosses starch and silicon salts are found in addition. Several species of Marchantia and Jungennannia are FIG. 40. Longitudinal sections through tips of leafy branches of mosses. A, show- ing antheridia (a, b) in different stages of development and paraphyses or cell-threads (c), the apical cell of which is spherical and contains chlorophyll, and leaves (d, e); B, show- ing archegonia (a) and leaves (b); C, section of Bryum showing both archegonia, and an- theridia, paraphyses, and leaves; D, section of Phascum showing archegonia (ar), antheridia (an), thread-like paraphyses (p), and leaves.(b). — A, and B, after Sachs; C, after Limpricht; D, after Hofmeister. used in medicine. Of the mosses the following have been found to have medicinal properties : Sphagnum cuspidatum, Grimmia pulvinata, Funaria hygroinetrica, Fontinalis antipyretica, and sev- eral species of Polytrichum and Hypnum. 86 A TEXT-BOOK OF BOTANY. PTERIDOPHYTES. The Pteridophytes were formerly known as the VASCULAR CRYPTOGAMS. Like the Bryophytes, these plants show a distinct alternation of generations ; i.e., the gametophyte or sexual genera- tion alternates with the sporophyte or asexual generation. Their relation is, however, somewhat changed. In the Bryophytes the gametophyte is the most conspicuous and is looked upon as con- stituting the plant proper, whereas in the Pteridophytes the gametophyte is rather insignificant in size, while the sporophyte constitutes the generation or phase which is ordinarily regarded as the plant. In the higher members of the Pteridophytes the sporophyte is entirely detached from the gametophyte and is able to lead an independent existence. This group also shows a dis- tinct advance in structure. There is a differentiation into root, stem, and leaves, and the development of a system of conducting tissue known as the VASCULAR SYSTEM. The Pteridophytes include three principal groups, namely, ( I ) Filicales or Ferns, (2) Equisetales or Scouring Rushes, and (3) Lycopodiales or Club Mosses, which differ considerably in general appearance and general morphological characters. With the exception of the sperms in the Club Mosses, which are biciliate and somewhat resemble those in the Bryophytes, the sperms in the Pteridophytes are spirally coiled and multiciliate, and according to the number of cilia of the sperms some writers divide the Pteridophytes into two classes, namely, biciliate and pluriciliate (Figs. 51, C; 62, F). Some of the Pteridophytes, as Selaginella (Fig. 60), are dis- tinguished by the fact that they produce two kinds of asexual spores, which are known respectively as MICROSPORES (Fig. 60, F) and MEGASPORES (Fig. 60, E). The two kinds of spores are formed in separate sporangia, which organs may occur on the same plant or on different plants.. The sporangia have the cor- responding names, microsporangia (Fig. 60, B, i') and megaspor- angia (Fig. 60, B,g}. This differentiation in sporangia and spores also leads to a differentiation in the resulting gametophytes, the microspores giving rise to gametophytes which produce antheridia, and hence called male gametophytes ; and the megaspores to PRINCIPAL GROUPS OF PLANTS. 87 gametophytes which give rise to archegonia, and hence called female gametophytes. When a plant produces both microspores and megaspores it is said to be HETEROSPOROUS, as in Selaginella (Figs. 60, 62, and 63) ; while one that produces but one kind of sporangium and one kind of asexual spores is said to be ISOSPOROUS. In this connection attention should be called to the fact that the spores from a single sporangium of an isosporous plant may give rise to male and female gametophytes, which shows that a certain degree of differentiation in the spores has already taken place. The causes leading to the differentiation of the spores seem to be B FIG. 50. Male fern [Dryopteris (Aspidium or Nephrodium) Filix-mas], A, prothallus of garpetophyte as seen from the under (ventral) side showing archegonia (ar), antheridia (an), and rhizoids (rh); B, prothallus showing young plant (sporophyte) which has devel- oped from an oospore and is still connected with the gametophyte, roots (w), and the first leaf (b).— After Schenck. connected with nutrition, those nuclei which are in more favorable positions giving rise to larger and better nourished spores which eventually lead to the formation of the megaspores, and those which are less favorably placed leading to the microspores. The subject of heterospory is one of great interest, and when it is pointed out that all of the higher plants are heterosporous the subject has even more interest. FILICALES. General Characters. — On germination the asexual spore in the Filicales or Ferns gives rise to a thallus-like body known as A TEXT-BOOK OF BOTANY. the prothallus which is frequently dorsiventral and in a number of cases somewhat heart-shaped, but varies considerably in out- line, being sometimes 'more or. less tuberous. The prothallus is frequently but a few millimeters in diameter, and the cells usually contain chloroplasts. On the under or ventral surface rhizoids are usually present (Fig. 50, r]i). The sexual organs usually arise on the lower surface (Fig. 50), but they may develop on the upper or dorsal surface or even laterally. A single prothallus gives rise to both kinds of organs, unless stunted in its growth, when it produces antheridia only. K A FIG. 51. A, B, development of archegonia of a fern (Pteris) showing the neck (h), the neck-canal cells (k), and oosphere (e). — After Strasburger. C, development of antheridium in the Venus-hair fern (Adiantum Capillus-Veneris): prothallus (p), antheridium (a), sperm (s), sperm mother cell with starch grains (b); I, immature state of antheridium, II, sperms developed, and III, discharge of sperm mother cells and escape of coiled and pluriciliate sperms. — After Sachs. The antheridia either develop upon or are sunk in the tissues of the prothallus. The archegonia (Fig. 51) are not flask-shaped as in the Bryophytes. The venter containing the oosphere or egg- cell (Fig. 51, e) is embedded in the thallus, the structure being surmounted by a few-celled neck (Fig. 51, h). The inner cells of the neck are known as canal cells (Fig. 51, k), and these at the time of ripening of the egg swell and exit through the opening of the archegonium, through which then the sperms enter, one of which unites with the egg, thus effecting fertilization. The fer- tilized egg or oospore takes on a cellulose membrane. PRINCIPAL GROUPS OF PLANTS. 89 The oospore which is held in the venter of the archegonium is not a resting- spore, but germinates immediately and early differen- tiates into the several organs ( Fig. 52 ) . These arise independently and include a stem-bud (Fig. 52, s) ; a first leaf or cotyledon (Fig. 52, b), so called because it does not arise out of the .stem as the later leaves do; a first or primary root (Fig. 52, w) ; and a foot or haustorial organ (Fig. 52, /) whereby it obtains nutri- ment from the prothallus (Fig. 52, pr}. This latter organ is, how- ever, only a temporary provision, for as soon as the root grows out and penetrates the soil, it dies off and the sporophyte thus becomes independent. The stems are frequently more or less con- FIG. 52. The brake fern (Pteris) . A, differentiation of cells in germinating oospores; B, later, stage showing development of embryo: pr, prothallus; f, foot embedded in the archegonium (aw); w, root; s, young stem; b, young leaf. — A, after Kienitz Gerloff; B, after Hofmeister. densed and lie prostrate in the soil, developing roots from the under surface and leaves from the sides and upper surfaces. The leaves which constitute the conspicuous part of the ordinary ferns consist of a stalk and lamina or blade on which are borne the spor- angia (Figs. 53 to 55). The sporangia usually occur on the under surface of the leaf in groups or clusters known as SORI (Fig. 53, A). The sori are of characteristic shape and in certain species are covered by a plate called the INDUSIUM (Fig. 53, 5) which rises from the epidermis. In some species the entire leaf becomes a spore-bearing organ, and is then known as a SPORO- PHYLL (Figs. 54, 55), to distinguish it from the foliage leaves. The sporangia develop a row of cells around the margin consti- A TEXT-BOOK OF BOTANY. tuting what is known as the ANNULUS (Fig. 53, n). The form of the annulus determines the manner of dehiscence of the sporangia, which occurs on drying. The spores are ejected with consider- FIG. 53. Male fern [Dryopteris (Aspidium or Nepkrodium) Filix-mas]. A, portion of leaflet showing a number of more or less reniform sori near the mid-vein; B. transverse section through a ripe sorus showing clusters of stalked sporanpia, which are covered by the indusium (i), an outgrowth of the leaflet; C, a closed but ripe sporangium showing the annulus or ring (n), and the irregular-shaped spores within; D, showing the manner of opening of the mature sporangium and the dispersal of the spores; E, two spores much magnified. — After Dodel-Port. able force (Fig. 53, D). They (Fig. 53, E; Fig. 57) are either bilateral or tetrahedral and require a short period to elapse before they germinate. They retain their vitality for a long time, except those which are green, i.e., contain chlorophyll. The spores are PRINCIPAL GROUPS OF PLANTS. 91 greenish or yellowish in color, variously sculptured, and vary from 0.025 mm. to 0.158 mm. in diameter. Fern Groups. — There are a number of distinct groups of FIG. 54. Several Osmundas. I, the royal fern (O. regalis) showing fertile tip of branch and sterile bipinnate leaflets below; 2, Clayton's fern (O. Claytoniana) showing three pairs of fertile leaflets in the middle and a number of sterile leaflets above and below; 3, cinnamon fern (O. cinnamomea) showing a fertile leaf (sporophyll) to the left and a sterile leaf (foliage leaf) to the right. ferns which vary considerably in appearance. ( i ) In the Tropics as well as in greenhouses TREE FERNS, characterized by an over- ground stem, occur. The leaves arise at the summit of the stem or trunk and form a crown. 92 A TEXT-BOOK OF BOTANY. (2) The TRUE FERNS include by far the largest number of species which inhabit temperate regions. These vary consider- ably in size, ranging from quite diminutive plants 5 to 12 cm. high, as the slender Cliff Brake (Pellaa atropurpurea and the variety FIG. 55. Different types of Ferns and fern allies, i, fertile and sterile leaves of slender cliff brake (Pellcea Stelleri); 2, ebony spleen-wort (Asplenium platyne uron) ; 3, rhizome with two leaves of the common polypody (Polypodium vulgare); 4, maiden-hair spleen- wort (Asplenium trichomanes) ; 5, ternate grape-fern (Botrychium ternatum), showing the tripinnate sterile leaf on the left and the upright sporophyll on the right; 6, walking fern (Cftmptosorus rhizophyllus) showing a new plant developing from the tip of one of the leaves; 7, fertile and young sterile leaves of ostrich fern (Onoclea Struthiopteris) . PRINCIPAL GROUPS OF PLANTS. 93 cristata} and maiden hair spleenwort (Asplenium Trichowianes}, to plants several feet high, as in the several species of Osmunda (Fig. 54), ostrich fern (Fig. 55), etc. This group is chiefly --E B FIG. 56. A, transverse section of stipe of Dryopteris marginalis: E, epidermis; H, hypodermis of collenchymatous cells; P, parenchyma containing starch; V, fibrovascular bundle; S, sieve; T, tracheae; N, endodermis surrounding each bundle. B, transverse sec- tion of stipe of Osmunda Claytoniana: H, hypodermis of lignified sclerenchymatous fibres; N, endodermis surrounding a large central fibrovascular bundle; Tn, tannin cells. characterized by the underground or prostrate stems, known as rhizomes, the part of the plant that is seen above ground being the leaf. 94 A TEXT-BOOK OF BOTANY. (3) There is also a group of ferns known as WATER FERNS which are aquatic in habit; that is, they live in marshy- places or float on water. As representatives of this group may be men- tioned Marsila, from whose slender rhizome that is buried in the FIG. 57. Some fern spores. A, B, C, different views of the bilateral spores of the common polypody (Poly podium vulgare), showing outer wall (ep), middle wall (ex), inner wall (end) and line of dehiscence (dl) ; D, a tetrahedral spore of the royal fern (Osmunda regalis); E, F, spores of Ceratopteris thalictroides seen in two views. — A-D, after Sadebeck; E-F, after Kny. muddy bottom of streams arise the clover-like leaves that float on the water (Fig. 59) ; and Salvinia (Fig. 58), which is a small floating plant that develops two kinds of leaves, one which float on the surface of the water and are more or less oblong^ and PIG. 58. A water fern (Salvinia natans). A, a plant seen from side and showing floating leaves at top attached to the horizontal stem, root-like finely divided leaves beneath, and a cluster of globose sporocarps; B, a view from above showing especially the character of the upper leaves; C, young plant developing from a megaspore (msp). — A and B, after Bischoff ; C, after Pringsheim. another which are filiform, branching, root-like, and submerged. The water ferns are further distinguished by the production of megaspores and microspores. (4) The ADDER'S TONGUE FAMILY, to which Ophioglossum PRINCIPAL GROUPS OF PLANTS. 95 and Botrychium belong, develops a subterranean prothallus which is destitute of chlorophyll. The prothallus is in some cases tube- FIG. 59. Marsilea quadrifolia (from Bantam Lake, Conn.), a submersed or emersed aquatic plant belonging to the Marsileaceae, a family of the Ptetidophytes. Of the forty different species, only two or three are found in the United States. It produces long, slender rhizomes, which are buried in the muddy bottoms of shallow lakes or streams and from which arise the leaflets which float on the surface. The leaves are on long, slender petioles and 4-foliate. the leaflets being mostly triangular-obovate. In Marsilea quadrifolia, a European form growing in Connecticut and Massachusetts and frequently cultivated, the leaves are nearly glabrous, while in M. vestita, a form found in shallow ditches in the Southern States, the leaflets are usually hairy. This character is quite marked in the spor- ocarps of the two plants. — After a photograph by Henry Troth. 96 A TEXT-BOOK OF BOTANY. rous, and the sporophyte produces two kinds of leaves, namely, foliage leaves, and fertile leaves or those which bear the sporangia. The sporangia occur on lateral branches of the sporophyll and open at maturity by means of a horizontal slit. Ferns Used in Medicine and as Foods. — Many of the ferns contain tannin, a brownish coloring principle, and in addition an anthelmintic principle. They may also contain ethereal oils, starch, coumarin, aconitic acid, and other principles. A large number have been used in medicine, of which the following may be mentioned: Dryopteris (Aspidium or Nephrodium} maryinalis and D. Filix-mas, yielding the official Aspidium. A number of other species of Aspidium, as well as species of Adiantum, As- plenium and Polypodium, are also used in various parts of the world. The rhizomes of some of the ferns contain cpnsiderable starch and are used to some extent as foods, as, Pteris esculenta of China; Pteridium aquilianum var. lanuginosum of the Canary Islands ; Aspidium varium and Asplenium bulbosum of Cochin China. Polypodium vulgare contains a substance related to glycyr- rhizin. Adiantum pedatum and Polypodium Phymatodes are said to contain coumarin, the latter plant being used in perfumery. EQUISETALES. The Horsetails, or scouring rushes (Equisetums] , are peren- nial plants containing a large amount of silica in their tissues. Like in the ferns, the more or less branching, creeping rhizome persists from year to year, sending out each year new shoots. As in. some of the ferns, it develops two distinct kinds of leaf-shoots, a fertile and a sterile one, each of which is distinctly jointed. The scale-like leaves are arranged in circles about the joints or nodes, the work of photosynthesis being carried on by the green stems. The fertile branch develops at the apex a group of sporophylls known as a cone or strobilus. The archesporium, or initial spore- producing zone, is unilocular. In Equisetum, the only representa- tive of the group, the spores are spherical and each is furnished with two spiral bands or elaters which assist in its dispersal. Some of the Equisetums contain aconitic acid and are used in medi- cine. Common scouring rush (Equisetum hyemale) is used for PRINCIPAL GROUPS OF PLANTS. 9? polishing woods, and Equisetum arvense is used for scouring tinware. LYCOPODIALES. The Lycopodiales, or Club Mosses (Fig. 66), are perennial moss-like plants, with more or less erect or creeping and branching stems, on which are borne numerous small simple leaves. The sporangia arise either at the base of the upper surface of the leaves or occur in terminal cones. They have short stalks, are uni- locular and 2-valved. The asexual spores are of one kind in Lycopodium and in the form of spherical tetrahedrons, resulting from the manner in which division has taken place (see Vol. II). In Selaginella (Fig. 60) two kinds of asexual spores are produced, that is, both microspores and megaspores, which in turn give rise to male and female prothalli respectively. The microspore develops a male gametophyte (Fig. 62) which remains entirely within the spore, and consists of a few-celled prothallus and a number of mother cells which produce sperms that eventually escape by the breaking of the wall. The megaspore frequently begins to develop the gametophyte (Fig. 63) while still within the sporangium. The prothallus con- sists of a number of cells and partly protrudes through the rup- tured spore wall. On the upper part of the prothallus or nutri- tive layer a few archegonia are borne. It should be stated that sometimes the archegonia are developed very early on the pro- thallus tissue, but usually they are developed after the spores have escaped from the sporangium. After fertilization of the egg a multicellular embryo develops which shows the following parts (Fig. 61) : (i) An elongated cell or row of cells which extends into the tissues of the prothallus for the purpose of obtaining nutriment; (2) a root; and (3) a stem bearing at its tip two leaves, or cotyledons. One of the . specially notable characters of the plants of the Selaginella group is, as we have seen, the great reduction in size of the gametophyte, which in the case of the microspore does not enlarge beyond the wall of the spore, and in the case of the megaspore only partly protrudes beyond its wall. Isoetes. — This is a genus of aquatic or marsh plants known 7 98 A TEXT-BOOK OF BOTANY. as quillworts. The plants produce a number of filiform roots which .penetrate the mud, and a compact tuft of rush-like leaves. The plants are heterosporous, as in Selaginella. The sporangia FIG. 60. Selaginella helvetica. A, sporophyte consisting of leafy branches giving rise to microsporangia (i), megasporangia (g), and rhizoids (r); B, longitudinal section of portion of branch showing a megasporangium (g) with 3 megaspores in view, a microspor- angium (i) containing microspores; C, a young microsporangium showing free mother cells before formation of tetrads; D, tetrahedral division of spore mother cell; E, ripe megaspore; F, four microspores of tetrad separated; G, microsporophyll seen from above showing ripe microsporangium. — After Dodel-Port. are borne in the axils of the leaves, the outer leaves bearing the megasporangia and the inner leaves the microsporangia. The gametophytes consist of but a few cells. While the group is het- PRINCIPAL GROUPS OF PLANTS. 99 erosporous and the gametophytes resemble those in Selaginella, the sperms are multiciliate and coiled as in the Ferns. Distribution and Uses of Lycopodiales. — A number of the Lycopodiums are common on rocks, damp woods, sandy bogs, and illustrations of several of these are shown in Fig. 66. Some tropical species are used in medicine; the spores of Lycopodium clavatum, on account of their fixed oil, are used as a dusting powder, and for burning in the production of flash lights (see Vol. II). The Selaginellas, of which there are several native species, are commonly used for decorative purposes. Some species II FIG. 61. Longitudinal section of young embryo of a Selaginella before separation from the prothallus: et, suspensor; w, root; f, foot; hi, cotyledons; hg, ligules or bud scales. —After Pfeffer. are, however, also used in medicine, and it is interesting to note that the spores of one species (Selaginella selaginoides) are used like those of Lycopodium. While the Pteridophytes do not form a very conspicuous por- tion of the flora at the present time and yield but few products of use to man, it may be pointed out that in former ages they formed the dominant vegetation of the earth. Many of the ancestral forms of this group attained the size of trees and made up the forest vegetation during the Devonian and Carboniferous Ages, the latter being sometimes spoken of as the age of Pterido- phytes. It is also called the Coal Age from the fact that the coal 100 A TEXT-BOOK OF BOTANY. measures were chiefly laid down during this period. By some it is thought that the deposits of coal of this age were probably princi- pally formed from the remains of certain marsh plants including two extinct groups of huge, tree-like club mosses (Lepidodendron and Sigillaria) and the Calamites, representatives of the scouring rushes. SPERMOPHYTES. The Spermophytes, or Seed Plants, constitute the third of the great divisions into which plants are divided. The plants belong- FIG. 62. Successive stages in the germination of the microspores of a Selaginella: p and w, cells of the prothallus; s, cells giving rise to sperms. A, B, D, views of spores from the side; C, view from the back; in E. the cells surrounding the sperm mother cell are dis- organized; F, two biciliate sperms. — After Belajeff. ing to this division not only form the most conspicuous feature of the flora because of their size and general distribution, but also because of the fact that they produce flowers make a large num- ber of them especially attractive. The plants of this group are also of great importance from an economic point of view. They fur- nish a large part of the food of man and other animals, as well as materials for clothing, shelter, fuel, and divers other purposes. In this group of plants there are the highest differentiation of tis- sues and the most complicated structure. The one character which especially distinguishes them from the lower groups of plants is that of the production of seeds. PRINCIPAL GROUPS OF PLANTS, 101 The plants have for the most part well-differentiated stems and leaves, and represent the sporophyte or asexual generation. The sporophyte produces sporophylls which are of two kinds, namely, megasporophylls and microsporophylls. The megasporo- phylls bear small ellipsoidal bodies known as ovules, which develop into seeds. The megasporangium is not separate and distinct in the spermophytes as it is in Selaginella, but is embedded within an ovule and corresponds to that part of the ovule known as the nucellus. The nucellus encloses the embryo-sac, which is regarded as a megaspore (Figs. 70, 71, and 81). Each megasporangium (nucellus) therefore contains but a single megaspore, whereas in Selaginella the megasporangia contain from i to 8 megaspores. The microsporophyll bears microsporangia (pollen sacs) which contain microspores (pollen grains). The female gametophyte in the Spermophytes is still more limited in its development than even in the highest Pteridophytes (as Selaginella and Isoetes) and remains wholly within the megaspore or embryo-sac. As a result of fertilization of the egg-cell an embryo is produced which consists of root, stem, and one or more cotyledons and which with the integuments covering it constitutes the seed. Spermophytes embrace two well-defined groups, namely, (i) Gymnosperms, or naked-seeded plants, and (2) Angiosperms, or enclosed-seeded plants. GYMNOSPERMS. In the Gymnosperms the ovules, each of which contains a megasporangium (nucellus), are borne on an open sporophyll (carpel), and thus are exposed, as are also the seeds developed from them. In the Angiosperms the ovules are borne within closed sporophylls, and are thus protected or covered until the seeds, which develop from them, mature. The Gymnosperms represent an ancient group of plants and were more numerous during the Triassic period than now. They are mostly shrubs and trees, and do not shed their leaves period- ically as the Angiosperms do, and hence are known as " ever- greens." As in some of the Pteridophytes (Lycopodium, Equi- setum), the sporophylls occur in groups forming cones or strobiles (Fig. 72). They not only differ in external appearance from the 102 A TEXT-BOOK OF BOTANY. Angiosperms but also in the anatomical structure of the stem, which is without large conducting vessels. In order to understand the relation of the Gymnosperms to the Pteridophytes on the one hand and to the Angiosperms on the other, it will be necessary to consider briefly the life history of a representative group, such as the Coniferae. General Characters. — The seed consists essentially of three parts, namely, a woody or leathery seed-coat, a nutritive layer rich in oil known as the endosperm, and a straight embryo. The latter is a more or less differentiated plantlet, consisting of a stem FIG. 63. The female gametophyte of a Selaginella; prothallus (pr) projecting through the ruptured wall (spm) of the megaspore; ar, sterile archegonium; embi, embz, two embryos embedded in the tissue of the prothallus; et, et, suspensors. — After Pfeffer. with a varying number of cotyledons or first leaves (2 to 16), and a small root which is attached to a suspensor, as is the embryo in Selaginella (Fig. 63). When the embryo begins its develop- ment into the plant it uses up the nourishment with which it is surrounded in the endosperm, and as it increases in size the seed- coat is split. The root then protrudes and the cotyledons, to some of which the seed-coat is still attached, are carried upward by the stem through the surface of the soil, when the seed-coat is cast off and the plant begins an independent existence. The first root is the primary or tap root, and from this are sent out numerous branches known as secondary roots, constituting a well-developed PRINCIPAL GROUPS OF PLANTS. 103 root system which serves the double purpose of absorbing nutri- ment from the substratum or soil and holding or fixing the plant in its upright position. The embryonal stem grows vertically upwards, continuing its growth indefinitely. Lateral branches arise at more or less regular intervals which extend from near the ground to the apex, the younger branches continually succeeding FIG. 64. Bird's Nest Moss (Selaginella lepidophylla) . A, the plant growing in a moist situation or upon the addition of water; B, the habit of the plant under dry conditions, it unrolling and becoming as (A) upon the addition of water. This plant is also known as Resurrection plant and Rose of Jericho, the latter name is more correctly applied to Anastatica hierochuntica, a cruciferous plant of the East Mediterranean and Egypt, the stems on drying becoming folded together and the whole plant being scattered by the wind. The Bird's Nest Moss grows in Mexico and western Texas, and in the rolled-up condition (B) is found occasionally in commerce and is used as a table decoration. It has the advan- tage that even though it dries out, it may be renewed many times. — After Hieronymus in Engler and Prantl. the older ones from the ground upward, thus giving the trees a cone-like outline. The leaves arise on the branches and are of two kinds, primary leaves which are more or less scale-like and deciduous, and secondary leaves which are true foliage leaves, and are usually quite simple in structure. The leaves vary in form but are usually narrow and somewhat thickened, giving them a needle-like appearance. 104 A TEXT-BOOK OF BOTANY. In addition, sporophylls (spore-bearing leaves) are formed at the ends of the young shoots or in the axils of more mature ones FIG. 65. A piece of slate from the coal formation in Shenandoah, Pennsylvania, showing a fossil fern which is probably a species of Neuropteris. (Fig. 69). These are compactly arranged, forming cones or stro- bili which are always of two kinds and borne on different twigs of the same plant or on different plants. The staminate cones PRINCIPAL GROUPS OF PLANTS. 105 consisting of microsporophylls (stamens) are more or less elon- gated and cylindrical or ovoid (Fig. 69, A). The carpellate cones consisting of megasporophylls (carpels) have a shorter longitudinal axis, and the cones vary considerably in the different groups (Fig. 72). The Microsporophylls (Fig. 69) are usually of a yellowish- brown color, and consist of a slender stalk and a lamina which bears the microsporangia (pollen sacs) on the lower or dorsal surface (Fig. 69, B, C). In this they show a resemblance to io6 A TEXT-BOOK OF BOTANY. FIG. 67. White Pine, also called Weymouth Pine, (Pinus Strobus).— From a photograph by Mr. C. J. Hibbard in " Minnesota Trees and Shrubs." PRINCIPAL GROUPS OF PLANTS. 107 ferns where the sori are borne on the under surface of the leaves. The microsporangia vary in number from 2 to 15, and are pro- tected in various ways, either being sunk in the tissues of the sporo- phyll, as in Pinus and Abies, or they are, as in Juniperus and Thuja, provided with a covering resembling the indusium of the sori of the ferns. The walls are variously thickened and on drying, s.w FIG. 68. Pinus rejtexa. Transverse section of a portion from the inner face of the spring wood showing a schizogenous resin duct or passage with the central canal (C) and the thin-walled and resinous epithelium (ep); with parenchyma tracheids (t). the spring wood (Sp. W.) and the summer wood (S. W.). — After Penhallow. The Conifera? represent the most ancient group in which resin passages or reservoirs are found. While \hese passages show certain important variations in structure and origin, and while even in certain genera of the group, as in the genus Pinus, they exhibit consider- able variation in detail, yet in this genus they are all of the same structural type as in Pinus reflexa, the white pine of the high mountainous regions of New Mexico and Arizona. The. epithelial tissues are thin-walled and readily broken in making sections except in the hard pines as the Loblolly pine (P. Tceda), where the cells often become strongly resinous. (See Penhallow's "Manual of the North American Gymnosperms.") owing to unequal tension, the sacs are ruptured longitudinally and the spores scattered. The microspores are very numerous, sometimes forming powdery deposits. They are either i -celled or 3-celled. In the latter case two lateral cells act as wings for the dispersal of the spores by the wind (Fig. 69, D). io8 A TEXT-BOOK OF BOTANY. The Megasporophylls consist of sessile carpels (leaves) on which are borne one or two naked ovules containing the sporangia (nuclei). In certain groups, as in the pines, balsams, etc., a scale is formed at the base of the carpel which bears the ovules, and this scale is called the seminiferous scale. The ovules con- sist of several parts (Figs. 70 and 71) : a stalk ; an integument or wall which has an opening at the apex known as the micropyle ; a nucellus (megasporangium), being that portion next within the FIG. 69. A, longitudinal section of cone composed of microsporophylls, of one of the pines; B, longitudinal section of microsporophyll showing microsporangium (pollen sac); C, the same in transverse section showing both microsporangia; D, winged microspore (pollen grain), with a two-celled male gametophyte, the upper cell being the generative cell, the remaining nucleated cell giving rise to the pollen tube. — After Schimper. integument ; and embedded within the nucellus a portion known as the megaspore or embryo-sac. Gametophytes. — The development of the gametophytes from the asexual spores, namely, the microspore or pollen grain, and the megaspore or embryo-sac, is as follows : The nucleus of the megaspore divides repeatedly (Fig. 71), cell walls are formed, and a multicellular structure known as the ENDOSPERM is pro- duced. This structure constitutes the prothallus of the female PRINCIPAL GROUPS OF PLANTS. 109 gametophyte (Fig. 70, E; Fig. 71). In the upper portion of the prothallus (that is, at the micropylar end), three to five archegonia are formed (Fig. 70, a; Fig. 71), which are separated from one another by cells of the endosperm or prothallus, which are rich in protoplasm. The structure of the archegonium is much like that nc FIG. 70. Longitudinal section of an ovule of a spruce (Picea): i, integument; nc, nucellus (megasporangium) ; e, embryo-sac (megaspore) which has developed the female gametophyte consisting of endosperm (e), two archegonia (a), which show the neck (c), and the egg (n); p, germinating pollen grains (microspores) with pollen tubes (t) which have penetrated the nucellus (nc) and reached the neck cells of the archegonia. — After Schimper. of the preceding group, consisting of a venter which contains the egg, and a short neck composed of 4 to 8 cells. The male gametophyte begins to develop while the pollen is still in the sporangium. At this stage it consists of a generative cell and a wall-cell, which constitute the antheridium, the cells of the prothallus being usually suppressed (Fig. 69, D). In addition to the extreme minuteness of the gametophytes no A TEXT-BOOK OF BOTANY. we have also to note the character of the male gamete or sperm. With the exception of the Cycads and Ginkgo, motile sperms are FIG. 71. Development of garnetophyte and embryo in one of the Coniferse. e, em- bryo-sac (megaspore) ; .a, archegonium; h, neck of archegonium; i, integument; p, pollen tube; n, nucellus; f, wing of seed; g, fibrovascular tissue; kz, canal cells of archegonium; ka, beginning of embryo; k, nuclei; ws, tip of root; wh, root-cap; c, cotyledons; v, point of growth of stem; s, suspensor. I, early stages of embryo-sac (e); II, young archegonium (a) after development of neck cells (h), cell lumen (1); III, section of ovule with portion of attached seminiferous scale (f) showing entrance of pollen tube; IV, embryo-sac with two developed archegonia; V, archegonium after fertilization, there being four nuclei at the lower part, only two of which are seen; VI, further development of embryo; VII, VIII, IX, X, showing develop- ment of large tortuous suspensor, to which is attached the young embryo (ka); XI, XII, mature embryo. — After Strasburger. PRINCIPAL GROUPS OF PLANTS. in not found in the Gymnosperms, but these are represented by two male nuclei which are transferred directly to the archegonium from the male gametophyte, formed through germination of the microspore (pollen grain). It may be recalled that in the Pteri- dophytes the motile sperms are discharged from the antheridium and carried by the agency of water to the archegonium, but in the Gymnosperms water is no longer a medium of transferral. The microspores themselves are carried to the ovules usually through the agency of wind, after which they germinate, developing a tube which carries the male nuclei directly to the archegonium without their ever having been free. The transferral of the microspores or pollen grains to the ovule is known as pollination. After pollination the wall-cell de- velops a tube, the pollen tube, and the generative cell gives rise to two male nuclei, which, with the remaining protoplasmic con- tents of the antheridium, are carried by the pollen tube to the micropyle, which it enters, penetrating the tissue of the nucellus (Fig. 70, £)• On reaching the neck of an archegonium the pollen tube pushes its way down into the venter, where it discharges one of the sperm nuclei, which unites with the egg, forming an oospore. Cessation in growth does not yet take place and the oospore develops into the embryo already described. The develop- ing embryo obtains its nourishment by means of a suspensor (Fig. 71, s), which also places the embryo in a favorable position. There being several archegonia in an ovule (Figs. 70, 71), a corresponding number of embryos may be formed, but rarely more than one survives. While the embryo is developing, the other tissues of the megaspore are likewise undergoing changes leading to the maturity of the seed. The carpels and seminifer- ous scales also continue to grow, and they usually become more or less woody, forming the characteristic cones of the pines (Fig. 72), but may coalesce and become fleshy, producing the berry-like fruits of Juniper (Fig. 75). The seed on germination gives rise to the sporophyte (tree). Groups of Gymnosperms.— There are several important groups of Gymnosperms: (i) The Cycads or Fern Palms, which are characteristic of tropical and sub-tropical countries. The trunk does not branch as in the ordinary evergreens, and 112 A TEXT-BOOK OF BOTANY. FIG. 72. Cones of some of the Coniferae. A, branch of Spruce Pine (Pinus echinata) with two cones; B, from Pitch Pine (Picea exeelsa); C, from Great Sugar Pine (Pinus Lam~ bertiana); D, from Black Spruce (Picea mariana); E, from the California Silver Fir (Abies magnified); F, from Loblolly or Frankincense Pine (Pinus Tada); G, branch of Pitch or Torch Pine (Pinus rigida). PRINCIPAL GROUPS OF PLANTS. 113 the leaves form a crown at the summit of the stem or trunk. An important character of some of the Cycads is the production of multiciliate sperms, as in the ferns, Equisetiim and Isoetes. (2) The Ginkgonaceae (to which belongs the Ginkgo or Maidenhair Tree, which is extensively cultivated in China and Japan and is found wild in China. It is very widely cultivated in this country, owing to its ornamental foliage ; the staminate tree is preferable, as the seeds of the pistillate tree have a very offensive odor. The triangular shaped leaves occur in fascicles and the seeds are berry-like. (3) The Coniferae is by far the most important group and consists of two families, the Taxaceae and the Pinaceae. To the Taxaceae belongs Taxus, or yew, a low tree bearing flat, linear leaves and a seed which is exposed and surrounded by the scarlet, fleshy, aril-like disk or scale. To the Pinaceae belong most of our important Gymnosperms. Pinus (Pine) is the most important genus (Figs. 67, 73, and 74). It is characterized by having needle-like leaves arranged 2 to 5 in a fascicle. The cone of the pine is usually woody, and upon becoming dry splits open so as to release the winged seeds. Perhaps the most valuable member of this genus is'the white pine (Fig. 67) which is found throughout the northern half of the United States east of the Mississippi River. Its timber is light brown or reddish, soft and fine-grained, but not very strong. It is used extensively in rough building construction. Finns palustris, or long-leaved pine, is one of the most valuable members of this group. It is the chief source of the terebinthinous products of this country, and its wood contributes no small part to the lumber industry. The long-leaved pine is tall, straight, has a thin-scaled bark and a very hard, resinous wood. The stem separates near the summit into several diverging branches, giving the tree a flattened top. The leaves are in threes, rarely in fours, from 10 to 15 inches long, and the cones are 6 to 10 inches long, the scales being armed with short recurved spines. Other pines yielding turpentine are Pinus Tceda, loblolly pine ; Pinus hetero- phylla, Cuban or swamp pine ; Pinus echinata, short-leaved yellow pine. Tsuga canadensis (Hemlock) is a common tree of eastern North America (Fig. 73). It attains a large size, and the delicate 8 114 A TEXT-BOOK OF BOTAXV. FIG. 73. Leaves and cones of Balsam Fir (Abies balsamea). Larch (Larix laricina), Douglas Fir or Douglas Spruce (Pseudotsuga taxifolia), White Pine (Pinus Strobus), Hem. lock (Tsuga canadensis) , Spruce (Picea mariana), and Jack Pine (Pinus Banksiana). — From. "Minnesota Trees and .Shrubs." PRINCIPAL GROUPS OF PLANTS. 115 spray of its branches gives it a delicate beauty. Although its lum- ber is not very strong nor durable, it is extensively used. The bark is also used to an enormous extent in the manufacture of heavy leather. In recent years many tanneries have been built in the hemlock districts so as to be near the supply of bark. For the finer grades of leather the hemlock bark is mixed with that of I monTana FIG. 74. Cross-sections of leaves of six different species of Pirius, showing in the diagrams the variation in the shapes of the cross-sections, with the distribution of the oi' reservoirs, and beneath each an enlarged view of the epidermal layer and underlying tissues. — From "Minnesota Trees and Shrubs." the oak, in order to avoid the reddish color produced by the former. Another important genus is Juniperus. The red cedar (/. vir- giniana, also called Sabina virginiana} or savin is a tree producing valuable fine-grained soft and durable wood which is used exten- sively in making chests, pails, posts, etc. It is interesting to note that this tree, which is frequently planted to form windbreaks, develops the fungus Gymnosporangium in the form of cedar apples, which in the aecidial stage produce the leaf rust of apple. A TEXT-BOOK OF BOTANY. The berries of the common juniper (/. communis) are sweet and fleshy and are used medicinally as a diuretic and also in the manufacture of gin. FIG. 75. A branch of Red Cedar (Juniperus virginiana) with numerous berry-like cones. PRINCIPAL GROUPS OF PLANTS. 117 Economic Uses of the Coniferae. — From an economic point of view the Coniferge are by far the most important group of plants thus far considered. In fact, they may be ranked first in the production of valuable timber. Of those yielding timber the following species may be mentioned : White pine (Pinus Strobus) ; long-leaved, yellow, or Georgia pine (Pinus palustris Mill) ; spruce pine (Pinus echinata) ; the Redwood of Upper California (Sequoia sempervirens) ; pitch pine of New Mexico (Pinus pon- derosa) ; the Scotch fir, the common pine of Europe (Pinus sylves- tris). Some of the woods are adapted for special purposes: as that of Pinus Celubra of the high mountains of Europe and Northern Siberia, which is excellent for wood-carving ; red cedar (Juniperus virginiana} (Fig. 75) used in the making of cigar boxes and lead pencils; balsam fir (Abies balsamea) used in the manufacture of wood pulp. By reason of the oleoresinous constituents the woods of some of the Coniferae are among the most durable known. A few years ago Jeffrey examined a specimen of Sequoia Penhallowii which was obtained from auriferous gravels of the Miocene in the Sierra Nevada Mountains and found it to be in a very perfect state of preservation. Penhallow (loc. cit.) considers this to be the most ancient record of an uninfiltrated and unaltered wood. Coleman, in 1898, found in the Pleistocene clays of the Don Valley a specimen of red cedar (Juniperus virginiana) which not only possessed all of the external characteristics of this species but when sawed emitted the aromatic odor of the bark. In the Pleistocene deposits of the western United States and Canada are found more or less unaltered specimens of various species of Juniperus, Pseudotsuga, Picea, and Larix. Some of the pines yield edible seeds which have been used by the Indians of Western America ; as the edible or " nut pine " of California and New Mexico (Pinus edulis) ; Pinus monophylla, discovered by Colonel Fremont in Northern California ; Pinus Jeffreyi of Northern California ; and Pinus Pinea of Europe, the seeds of the latter being used like almonds and known as " pig- none." The seeds of Pinus Lambertiana (Fig. 72, C) of Califor- nia are baked before being used as a food. This latter species is also known as the sugar pine, as it yields a manna-like product. n8 A TEXT-BOOK OF BOTANY. A manna is also yielded by Cedrus Libani and Larix decidua. The latter is known as " Briancon Manna," and contains melizitose. The bark of some species furnishes valuable tanning material, as that of the hemlock spruce (Tsuga canadensis). Thuii FIG. 76. Fruiting twig of common Juniper (Juniperus communis), of Red Cedar or Savin (Juniperus virginiana), and young twig of White Cedar or Arbor Vitae (Thuja occiden- talis). — From "Minnesota Trees and Shrubs," The Coni ferae yield large quantities of volatile oils, resins, and allied products which are used both in medicine and the arts. A number of them yield turpentine (see Vol. II)- Larix decidua of the Alps and Carpathian mountains yields Venice turpentine. Abies balsamea is the source of Canada turpentine or balsam of PRINCIPAL GROUPS OF PLANTS. 119 fir; Pseudotsuga mucronata or Douglass Spruce (Red fir) is prob- ably the source of a balsam resembling Canada turpentine and which is known commercially as Oregon balsam. Picea mariana or black spruce yields spruce gum, largely used in the manufacture of chewing gum, and is also the source of spruce beer. Picea excelsa or Norway spruce yields Burgundy pitch. Abies alba, white fir or silver fir yields the Strasburg turpentine. Canada pitch is the resinous exudation from the common hemlock ( Tsuga canadensis). Sandarac is yielded by Callitris quadrivalvis found growing in Northwestern Africa. Volatile oils are yielded by a number of the Coniferae, of which the following may be mentioned : Juniperus Sabina yielding oil of savin ; Juniperus communis yielding oil of juniper, both of which are used in medi- FIG. 77. Microscopical view of fragments of wood found in the coal deposits of upper Silesia, Prussia. — After Link, from article by Potonie on the origin of coal and petroleum in Ber. d. d. pharm. Ges., 1907, p. 181. cine. The remains of Coniferae (Picea, etc.) are often found as fossils, as the fossil resin amber, which is used in the arts, and on distillation yields a volatile oil having medicinal properties. ANGIOSPERMS, General Characters. — They constitute the most conspicuous portion of the flora, embrace the greatest variety of forms, and are the most highly organized members of the plant kingdom. They vary in size from diminutive plants like the windflower to the giant oak which shelters it. They may accom- plish their life work in a few months, as the common stramonium, or they may persist for several hundred years, as the trees of our primitive forests. They may inhabit dry desert regions, as the Cacti and Chenopodiaceae, or they may live wholly in water, as the water lilies. In short, they show the greatest adaptability I2O A TEXT-BOOK OF BOTANY. to their surroundings. But no matter how diversified they may seem in form and structure, they agree in this with possibly one exception, namely, mignonette, that the seeds are produced in a closed carpel. This has been considered, as already indicated, to be the chief difference between the Gymnosperms and Angio- sperms. The two groups are further distinguished by several other important characters : ( I ) The carpel or carpels (megasporophyll) is developed into an organ commonly known as a pistil (Fig. 78). This organ consists of three parts, namely, ovary, style, and stigma, the ovary enclosing the ovules. (2) In the Angiosperms the megaspore (embryo-sac) develops a gametophyte which does FIG. 78. A, longitudinal section through orange flower (Citrus Aurantium) showing stalk (PE); sepals (s); petals (p); stamen with filament (F) and anther (A); compound pistil (composed of united carpels) with stigma (T), style (Y) and superior ovary (O) with ovules; disk or nectary (D). B, longitudinal section of a bud of clove (Caryophyllus) showing inferior ovary (O), style (Y), stamens (F), petals (P), sepals (S), nectary (D). not give rise to archegonia, but the egg arises directly from the megaspore nucleus by a series of divisions. (3) The Micro- sporophyll (stamen) differs considerably in structure and appear- ance from that of the Gymnosperms. The stamen may be defined as a leaf which bears sporangia (spore cases). It usually con- sists of the following differential parts: filament and anther, the latter consisting of pollen sacs (microsporangia) in which the pollen grains (microspores) are developed (Figs. 78, 79, and 80). (4) In a large number of cases in the Angiosperms there is developed in addition to the sporophylls or sporangial leaves (stamens and pistils) another series of leaves known as floral leaves (Fig. 78). The latter usually are of two kinds, known as sepals and petals. PRINCIPAL GROUPS OF PLANTS. 121 The Development of the Two Generations, namely, the sporophyte and gametophyte, is much the same in the Angio- sperms as in the Gymnosperms ; that is, the sporophyte consti- tutes the plant body and what is commonly considered to be the plant. The gametophytes are still more reduced than was the case in the Gymnosperms, the male gametophyte consisting of but two cells. Beginning with the germination of the seed, we may outline the life history of the plant as was done under Gymnosperms. The seeds in the two groups are much alike, with the exception that in the Angiosperms they usually have two integuments. Within the Angiosperms two classes of embryos are distinguished, which give rise to the most important division of this group of plants. In the one case a single cotyledon is formed at the apex of the stem, and all plants having an embryo of this kind are known as MONOCOTYLEDONS, that is, plants having one seed leaf. In the other case two cotyledons arise laterally on the stem and opposite each other, and those plants having an embryo of this type are grouped together as DICOTYLEDONS, or plants having two seed leaves. In the monocotyledons the cotyledon is limited to one, but in the dicotyledons the seed leaves are not limited in number and there may sometimes be three or more. The sporophyte which develops from the germinating seed consists of the essential parts already given, i.e., root, stem, and leaves. The leaves are of four kinds: (i) Foliage leaves, (2) scale leaves or bud scales, (3) floral leaves, which in some cases are wanting, and (4) sporangial leaves or sporophylls. Inasmuch as the latter give rise to the gametophytes (male and female) the development of the sporangia in each will be considered in detail. The Microsporangia (pollen sacs) arise by the division of certain cells under the epidermis of the anther (Fig. 79). This process of division continues until four regions of fertile tissue (sporangia) are produced (Fig. 79, D). The sporangia are directly surrounded by a continuous layer of cells which consti- tutes the tapetum or tapetal cells (Fig. 79, t), these being in the nature of secretion cells and containing considerable oil. The tapetum is in turn surrounded by a layer of cells which are peculiarly thickened and which on drying assist in the opening 122 A TEXT-BOOK OF BOTANY. of the anther and the discharge of the pollen, and this layer is called the endothecium (Fig. 79, end). There is still a third or external layer of cells, which constitutes the exothecium (Fig. 79, ex). These four sporangial regions may remain more or less distinct and separate at maturity, or the two on either side may c. FIG. ?g. Development of pollen sacs (microsporangia) in several of the Angiosperms: A, showing beginning of archesporium (a), an outer sterile layer (b), position of connective (con); B, later stage showing development of fibrovascular tissue (gf); C, longitudinal section of archesporium; D, E, F, successive later stages showing in addition pollen mother cells (sm) and tapetum layer (t). G, H, diagrammatic sections of mature pollen sacs show- ing pollen mother cells (pm), tapetum (t), endothecium (end), exothecium (ex), and in H longitudinal dehiscence with formation of what appears to be a unilocular pollen sac on either side of the connective. — A-F, after Warming; G-H, after Baillon and Luerssen. coalesce. This latter usually occurs at maturity, when dehiscence takes place, forming apparently a single pollen sac on either side of the connective or axis (Fig. 79, H). The Microspores (pollen grains) are developed somewhat differently in Monocotyledons and Dicotyledons. In most mono- PRINCIPAL GROUPS OF PLANTS. 123 cotyledons the nucleus of each cell (pollen mother cell) making up the archesporium divides into two nuclei, each of which takes on a wall of cellulose. Each of these (daughter cells) in turn divides, giving rise to four pollen grains. In dicotyledons (Fig. 80) the nucleus of a mother cell divides into four nuclei before the walls are formed which separate the nuclei, thus giving rise to the tetrad group of spores to which attention has already been called (Fig. 60, Z)) under Bryophytes. The wall of each spore is divided into two layers, an inner layer consisting of cellulose known as the intine, which gives rise to the pollen tube on germi- nation of the spore; and an outer layer somewhat different in FIG. 80. Development of pollen grains (microspores) of garlic (Allium narcissi florum): a, pollen mother cell with nucleus; b, the same with homogeneous nucleus and a thicker wall; c-e, changes in nucleus prior to division; f, formation of spindle with nuclear masses in the center from which nuclear threads extend to the poles of the spindle; g, division of nuclear substance and receding of it from the center of the cell; h-i, further stages in the organization of the nuclear substance at the poles; k, formation of a wall between two daughter cells; 1, beginning of division of one daughter cell; m-n, final divisions resulting in the formation of a tetrad (group of 4 cells). — After Strasburger. composition and variously sculptured, known as the exine. When the spores are mature the original walls of the cells of the arche- sporium dissolve and the ripe pollen grains are set free, forming a yellowish powdery mass filling the pollen sac. In some cases the spores of the tetrads hang together, or even the whole mass of pollen tetrads may be more or less agglutinated, as in the orchids and milkweeds, these masses being known as pollinia. Male Gametophyte. — Before the dispersal of the pollen grains or microspores, certain changes leading to the development of the gametophyte have taken place (Fig. 81). The spore, as we have seen, is unicellular. This divides into two cells : one, which is relatively small, known as the mother cell of the antheridium (Fig. 81, v), and another, which, composed of the remaining 124 A TEXT-BOOK OF BOTANY. nucleus with the surrounding cell-contents, constitutes the tube- or wall-cell of the antheridium. Development of Ovule and Megasporangium (nucellus). — The ovule at first develops as a small protuberance on the inner surface of the ovary, after which it differentiates into (a) a stalk or funiculus by which it is attached to the ovary, the tissue to which it is attached being called the placenta; and (&) an upper portion which becomes the ovule proper. The differentiation of the tissues is in a general way as follows : ( i ) The cells beneath the epidermis in the apical portion of the ovule go to make up the megasporangium (nucellus) ; (2) the peripheral cells from below the nucellus give rise to the integuments ; and (3) while the integu- ments are developing the archesporium or mother cell of the FIG. 81. Development of male gametophyte in an Angiosperm. I, pollen grain (microspore) which has divided into the mother or generative cell (v) and a larger tube-cell with nucleus (sk); II, appearance of pollen on treatment with osmic acid showing the .separation of the generative celi (v) from the wall of the pollen grain; o.at the right giving a view of the generative cell with the nucleus embedded in the hyaline protoplasm; III, showing the development of the tube-cell into the pollen tube which contains the two male cells (nuclei) or gametes formed by the generative cell. — After Elfving. embryo-sac (megaspore) is being formed within the nucellus near the apex. Female Gametophyte. — The archesporium divides into two cells, the lower one of which repeatedly divides, finally giving rise to the embryo-sac which is sunk in the tissues of the nucellus. The nucleus of the embryo-sac divides and redivides until 8 cells are produced (Figs. 82 and 83), which are separated into the fol- lowing groups: (i) Three of the cells form a group lying at the apex, the lower cell of the group being the egg or egg-cell, the other two cells being known as synergids or helping cells. (2) At the opposite end of the sac are three cells, known as antipodal cells, which usually develop a wall of cellulose and do not seem to have any special function. (3) Near the centre of the sac are the two remaining nuclei, which unite to form a single nucleus, from PRINCIPAL GROUPS OF PLANTS. 125 nr. FIG. 82. Development of embryo-sac or mepaspore in an Angiosperm. la, longi- tudinal section through a young ovule. Ib, longitudinal section through a rudimentary ovule before the formation of the integument, showing mother cell of the embryo-sac (mega- spore) (em) and primary tapetal cell (t). II, later stage showing the two cells into which the mother cell has divided, the nuclei of which are in the act of dividing. Ill, mother- cell of the embryo-sac divided into four cells (sporogenous mass of cells) ; the lowest of these cells (e) displaces the rest and becomes the embryo-sac in IV. IV, pek, is the primary nucleus of the embryo-sac. V, two daughter cells resulting from the division of the nucleus of the embryo-sac. VI, VII, show egg apparatus composed of two synergids (s) and the oosphere (o), and antipodal cells (g). VIII, longitudinal section through a mature ovule with the inner integument (ii), the outer integument (ai), the nucellus (n), the vascular bundle (gf) entering the funiculus (f), and secondary nucleus in the embryo-sac (sek). — After Strasburger. 126 A TEXT-BOOK OF BOTANY. which after fertilization the endosperm is derived. The embryo- sac, as it is organized at this stage, constitutes what is regarded as the female gametophyte (Fig. 82). The undifferentiated embryo-sac constitutes the megaspore, which latter, after germina- tion or differentiation into egg-cell and other cells, constitutes the gametophyte. It is thus seen that in the female gametophyte of the Angiosperm archegonia are apparently not formed. The gametophyte, then, consists of the cell group containing the egg and the remaining portion of the embryo-sac, which latter may be compared to a prothallus. This comparison is not difficult to understand if we bear in mind the structure of the gametophyte in the Gymnosperms, and particularly if we recall the structure in Selaginella and other higher Pteridophytes. Fertilization. — While in the Gymnosperms the pollen grains are usually provided with wings so as to bring about their trans- ferral to the carpel by the agency of the wind, in the Angiosperms, on the other hand, the grains are not provided with wings, but are adapted to the transferral by insects. Pollination, however, may be also effected by the wind, as is the case with many of our forest trees. After the deposition of the pollen grain on the stigma, the tube-cell begins to form a tubular process (pollen tube) which carries the male nuclei to the egg-cell (Fig. 83, i). It pierces the tissue of the stigma (Fig. 83, /i) and traverses the style (Fig. 83, g] until it reaches the micropyle of the ovule, which it enters (Fig. 83, m), then reaching the nucellus it penetrates this, enter- ing the embryo-sac. The tip of the tube breaks and one of the generative nuclei which has been carried downward unites with the egg, after which a wall is formed, giving rise to an oospore. The oospore develops at once into the embryo or plantlet as seen in the seed, this stage being followed by a period of rest. In fact, the young plant may lie dormant in the seed for years. Development of Seed. — The steps in the development of the mature seed occur in the following order (Fig. 84). The oospore divides into two parts, an upper portion which gives rise to the embryo, and a lower portion which by transverse segmentation gives rise to a short suspensor (Fig. 84, v} which practically serves the same purpose as in the Gymnosperms (page in). The em- bryonal cell develops the embryo, which consists of: (l)a root por- PRINCIPAL GROUPS OF PLANTS. 127 tion which is connected with the suspensor (Fig. 84, w) ; (2) one or two cotyledons (Fig. 84, c) which are attached to the stem ; (3) a little bud at the apex of the stem which is known as the plumule. While the embryo is developing, the nucleus of the embryo- sac, either after fusing with the prothallial cell of the pollen grain, or in the absence of such union, begins active division, forming, FIG. 83. Diagrammatic representation of fertilization in an Angiosperm. d, floral leaves; stamen consisting of filament (c) and anthers (a,b), one of which (b) has dehisced, exhibiting numerous pollen grains; e, nectar-secreting bodies; pistil consisting of ovary (f), style (g), and stigma (h). On the latter pollen grains (i) are germinating, the tube (1) of one of them has penetrated the tissues of the stigma and style, and entered the foramen (m), or opening of the ovule. The ovule consists of several parts: raphe (n), outer integument (p), inner integument (q), chalaza (o), nucellus (s), embryo-sac or megaspore (t) with egg-cell (z), synergids (v), antipodal cells (u), and the nucleus in the center which gives rise to the endosperm. — After Sachs. a highly nutritive tissue rich in starch, oil, or proteins, known as the endosperm (see chapter on Seed). Simultaneously with the development of the endosperm the nucellus may give rise to a nutritive layer called the perisperm, or the tissues of the nucellus may be modified and form, with the altered integuments or coats of the ovule, the seed-coat. Inasmuch as the Angiosperms furnish by far the larger pro- portion of plants and plant products used in medicine, it is desir- 128 A TEXT-BOOK OF BOTANY. able to give particular attention to the morphology of this group, as also to the distinguishing characters of a number of the impor- tant families. Economic Importance. — As indicating the great usefulness to mankind of the products obtained from the Angiosperms it will be sufficient to merely mention that all of our garden vegetables as FIG. 84.- Development of embryo in the shepherd's purse (Capsella Burso-pastoris). I -VI, various stages of development: Vb, apex of the root seen from below, i, i, 2, 2, the first divisions of the apical cell of the pro-embryo (suspensor); h, h, cells from which the primary root and root-cap are derived; v, the pro-embryo; c, cotyledons; s, apex of the axis; w.root. — After Hanstein. well as the great crops of cereals like wheat, corn, rye, etc. ; edible fruits and seeds ; textile products, such as cotton, flax, etc. ; medic- inal products ; timbers of various kinds, as oak, mahogany, walnut, chestnut, cherry, etc., are furnished by this great group of plants. EVOLUTION. Contrary to a popular opinion, the idea of evolution is almost as old as the human race. From the time when man began to think about the things around him he could not help but see that PRINCIPAL GROUPS OF PLANTS. 129 nothing was permanent, and he could not help but wonder how both the inorganic and the organic world came to be as he found them. The fact is, then, that for years the thinking element of the human race has had a fairly clear conception of the idea of evolu- tion ; all they lacked was the proof. Nothing is more decidedly FIG. 84A. Hypothetical tree of relationship and descent of the leading groups of plants. -—After Ganong. wrong than the belief that Darwin first conceived the theory of evolution. His renown only lies in the fact that he was one of the first to suggest an explanation, and probably also because his explanation came at a most opportune time and was worked up in such a masterly way. 130 A TEXT-BOOK OF BOTANY. The theory of evolution has as its basis the idea that the existing species of plants and animals are the descendants of earlier forms. It holds that there is an unbroken line of descent from the beginning of life on the earth, but that during the long ages the successive descendants gradually changed in appearance from their ancestors until we find the forms of the present day. Nearly all branches of biological science give evidence in support of the theory of evolution. Embryology, for instance, has shown that in its development the individual during its life, begin- ning with the fertilization of the egg-cell, passes through a series of stages which are thought to represent the same series of stages through which the whole race before it passed. The develop- ment of the individual (i.e., ontogeny) represents in a very brief space of time the evolution of the race (i.e., phylogeny). In other words, " ontogeny epitomizes phylogeny." Another branch of science which is bringing forth new evi- dence is the branch called paleontology. This subject has to do with the study of fossil remains and with the time they existed on the earth in the living state. It has been found that fossils from the different series of formations that make up the earth's outer crust represent a regular advancement from the very simplest types to those which are most complicated, right up to the most recent forms. In not a single instance has a highly developed form been found in a layer of rocks representing an early stage in the earth's history. Every scientist of the present time, probably without exception, believes in the theory of evolution, but there is a great diversity of opinion as to how it should be explained. This diversity of thought, instead of disproving the idea of evolution, is making its truth more generally felt. The problem, then, which is confront- ing the scientist is not to prove that evolution is a truth, but to explain it; to show how new forms may arise from old ones, — that is, to account for the origin of species. Among the many explanations the following have become most conspicuous : ENVIRONMENT. — It was naturally thought at first that the natural conditions under which organic life developed must have a certain effect upon the individual, thereby bringing about a cer- tain modification which would be transmitted in successively PRINCIPAL GROUPS OF PLANTS. 131 greater degree to those progeny living under the same conditions, and so gradually give rise to a different species. This, of course, assumes that any change induced by environment would be trans- mitted to the offspring, to be retained so long as the environment remained constant, an assumption which .is probably not far from the truth. While it is admitted that changes in the environ- ment may cause direct responses, yet it is doubtful whether they are definite or permanent enough to produce new forms. Near the end of the eighteenth century this explanation was supported by Erasmus Darwin of England, St. Hilaire of France, and Goethe of Germany. USE AND DISUSE. — There is very little difference between this explanation and the preceding one. Lamarck proposed, in the early part of the nineteenth century, that the use or disuse of organs would so modify them that the acquired differences would be inherited by the offspring. But, here again, the proof depends upon the transmission of acquired characters, and this is now almost disproved. NATURAL SELECTION. — In 1859 Darwin published his " Origin of Species by Means of Natural Selection," and this single event revolutionized science. In this book Darwin arranged an enor- mous mass of facts gained through many travels, incessant obser- vation, and prolonged experiments. He built up an argument in such a convincing way as to immediately attract the attention of the world, not only of scientists but of laymen. The theory of natural selection has for its basis the idea that great competition is continually taking place between individuals of the same species and between the individuals of various species. This struggle for existence results in the " survival of the fittest " and the destruc- tion of the unfit. The idea that two plants or animals from the same parent might vary slightly, suggested the belief that the one which was better equipped for the struggle for existence would survive and so transmit its desirable characteristics to its offspring, and that the unfortunate one would not survive and its undesirable characteristics would thus be lost to the race. The objections to the theory of natural selection are of various kinds, but the most serious is probably the fact that it is hard to conceive how a very slight difference in character can be of advan- 1 32 A TEXT-BOOK OF BOTANY. tage in a life and death struggle. Necessarily when natural selec- tion first begins to operate on two individuals the differences must be only slight and hardly sufficient to give one of them such a vital advantage over the other. MUTATION. — This explanation was offered in 1901 by Hugo de Vries of Holland. The word mutation means a change. In this sense it means a sudden change and has to do with the fact that among the offspring of a certain individual may be found one or more individuals markedly differing from the parent, so much so as to be regarded in a few instances as a distinct species. Moreover, these mutants, as they are called, continue to breed true, thereby giving rise to what might very well be called a new species. In the study of mutation many experiments have been conducted by scientists and breeders. MENDEL'S LAW. — In intimate relationship with the subject of evolution is the question of heredity. In the middle of the last century there lived an Austrian monk, Mendel by name, who ex- perimented with the cultivation of peas and other plants in the monastery garden. , In his studies he discovered a certain law underlying the transmission of characters in reproduction. This law, which for many years lay hidden from the scientific world, was recently brought to light and now forms the basis of most of the recent breeding experiments and is of profound value in the study of heredity. In the simplest case it is as follows: If two different species, A and B, are crossed, the result is a hybrid (AB) which combines certain characters of both parents. When this hybrid propagates, the progeny splits up into three sets : one resembling the hybrid parent (AB) ; and the other two sets re- sembling the parent forms (A and B) that entered into the hybrid. Mendel's law is a statement of the mathematical ratio expressed by these three groups of forms derived from a " splitting" hybrid. This means that in a series of generations initiated by a hybrid, ap- proximately one-half of the individuals of each generation will represent the hybrid mixture, one-fourth of the individuals will represent one of the pure forms that entered into the hybrid, and the remaining fourth will represent the other pure form. Of course, the 1:2:1 ratio holds only when the one unit-character is involved, and does not apply to the hybrids as a whole, as differ- ent characteristics are generally inherited independently of others. PRINCIPAL GROUPS OF PLANTS. 133 It should be understood that the use of hybrids in such experi- mental work is simply a device to secure easy recognition of the contributions of each parent to the progeny. For example, if red and yellow races of corn are crossed, it is very simple to recognize the color contribution of each parent to the hybrid progeny, when it would be impossible to separate the contribution of two yellow parents. The inference is, that what is true of hybrids is true of forms produced in the ordinary way, so that laws of heredity obtained from a study of hybrids may be regarded as laws of heredity in general. In the working out of Mendel's law it has been observed that, while one-fourth of the progeny are like one parent, the remaining three-fourths will all show the characteristics of the other parent, although only one of the remaining three-fourths will breed true. That is to say that the hybrids, which make up half of the progeny, look like one of the parents, but all do not breed true to that parent. In this case the character of the true pure-strain parent which marks the hybrids is said to be a dominant character, while the character of the other pure-strain parent is said to be a recessive character, because in the hybrids its presence can not be observed and can be discovered only by breeding the hybrids. It is only by experiment and breeding that dominant and recessive characters can be determined. For instance, in the culture of peas the character of being tall has been found to be dominant over the character of being dwarf. This means that all the hybrids will be tall, although one-fourth of their progeny will be dwarf. Again in the pea, the character of having a round seed is found to be dominant over that of having a wrinkled seed. In .wheat the character of being beardless is dominant over that of being bearded, and again the character of being susceptible to rust is dominant over that of being immune to rust. The infinite number of characters which complicates the study of hybrids and the fact that in breeding it is sometimes the dom- inant and sometimes the recessive character which is the desirable one to maintain suggest at a glance the breadth and difficulty of the problem. CHAPTER II. CELL-CONTENTS AND FORMS OF CELLS. A TYPICAL living cell may be said to consist of a wall and a protoplast (a unit of protoplasm), although it is often customary to refer to the protoplast alone as constituting the cell. This is in view of the fact that the protoplasm which makes up the sub- stance of the protoplast is the living substance of the plant. Besides the protoplasm other substances are also found in the cell, hence in a general way the cell may be said to be composed of a wall and contents (cell-contents). The wall, as well as the cell-contents, consists of a number of substances, and, as the cell- contents are of primary importance in the development of the plant, their nature and composition will be considered first. Cell-contents. — With the distinction already made the cell- contents may be grouped into two classes: (i) Protoplasmic, or those in which the life-processes of the plant, or cell, are mani- fested; and (2) non-protoplasmic, or those which are the direct or indirect products of the protoplast. The first class includes the protoplasm with its various differentiated parts, and the second, the various carbohydrates (starches and sugars), calcium oxalate, aleurone, tannin, oil, and a number of other substances. PROTOPLASMIC CELL-CONTENTS. Protoplasm. — Protoplasm occurs as a more or less semi- fluid, slimy, granular, or foam-like substance, which lies close to the walls of the cell as a relatively thin layer and surrounding a large central cavity or vacuole filled with cell-sap, or it may be distributed in the form of threads or bands forming a kind of net- work enclosing smaller vacuoles. Protoplasm consists of two comparatively well differentiated portions: (i) Certain more or less distinct bodies which appear to have particular functions and to which a great deal of study has been given, as the nucleus and plastids; and (2) a less dense portion which may be looked upon 134 CELL-CONTENTS AND FORMS OF CELLS. 135 as the ground substance of the protoplast and which is now com- monly referred to as the CYTOPLASM (see Frontispiece). These differentiated bodies and the cytoplasm are intimately associated and interdependent. The nucleus and cytoplasm are present in all living cells, and it is through their special activities that cell FIG. 85. Successive stages in nuclear and cell division, n, nucleolus; c, centrospheres s, chromosomes; sp, spindle fibers; A, B, C, division of chromosomes, i, cell with nucleus containing nucleolus (n), and two centrospheres (c); 2, showing separation of nucleus into distinct chromosomes (s) and the centrospheres at either pole of the nucleus; 3, forma- tion of spindle fibers (sp); 4, longitudinal division of chromosomes; 5, division of the cen- trospheres; 6, 7, 8, further stages in the development of the daughter nuclei; 9, formation of cell-wall which is completed in 10 giving rise to two new cells. — After Strasburger. division takes place. When, in addition, plastids are present, con- structive metabolism takes place, whereby complex substances are formed from simpler ones. Besides the nucleus and plastids other protoplasmic structures are sometimes found embedded in the cytoplasm.. These are the CENTROSPHERES (Fig. 85, c) , small spherical bodies that are 136 A TEXT-BOOK OF BOTANY. associated with the nucleus and appear to be concerned in cell division. There are, in fact, quite a number of minute bodies in the cytoplasm which may be always present or only under certain conditions, and which are grouped under the general name of MICROSOMES Or MICROSOMATA. Chemically protoplasm is an extremely complex substance, but does not appear to have a definite molecular structure of its own, being composed in large measure of proteins, a class of organic compounds which always contain nitrogen, and frequently phos- phorus and sulphur. The molecule of the proteins is large and more or less unstable, and hence subject to rapid changes and a variety of combinations, and it is to these interactions that the vital activities of the plant are attributed. Nucleus. — The nucleus consists of (i) a ground substance in which is embedded (2) a network composed of threads con- taining a granular material known as CHROMATIN, and (3) gen- erally one or more spherical bodies called NUCLEOLES, the whole being enclosed by (4) a delicate membrane (Fig. 85). The chro- matin threads are readily stained by some of the aniline dyes, and are mainly composed of nucleins (proteins) rich in phosphorus, which by some writers are supposed to be essential constituents of the nucleus and necessary to the life of the protoplast. Chroma- tin is constant in the nucleus, and prior to cell division the threads become organized into bodies of a definite number and shape known as CHROMOSOMES (Fig. 85, s). Plastids. — The plastids or chromatophores form a group of differentiated protoplasmic bodies found in the cytoplasm (Front- ispiece) and are associated with it in the building up of complex organic compounds, as starch, oil, and proteins. The term chro- matophore means color-bearer, but applies also to those plastids which may be colorless at one stage and pigmented at another. Hence we may speak of colorless chromatophores. According to the position of the cells in which these bodies occur and the functions they perform, they vary in color — three distinct kinds being recognized, (i) In the egg-cell and in the cells of roots, rhizomes, and seeds the plastids are colorless and are called LEUCO- PLASTIDS. (2) When they occur in cells which are more or less exposed to light and produce the green pigment called chloro- CELL-CONTENTS AND FORMS OF CELLS. 137 phyll, they are known as CHLOROPLASTIDS or chloroplasts. (3) In other cases, independently of the position of the cells as to light or darkness, the plastids develop a yellowish or orange-colored principle, which may be termed chromophyll, and are known as CHROMOPLASTIDS. Chloroplastids are found in all plants except Fungi and non-chlorophyllous flowering plants, and chromoplas- tids in all plants except Fungi. Plastids vary in form from more or less spherical to polygonal or irregular-shaped bodies, and they increase in number by simple fission. They suffer decom- position much more readily than the nucleus, and are found in dried material in a more or less altered condition. Leucoplastids. — The chief function of the leucoplastids is that of building up reserve starches or those stored by the plant for food, and they may be best studied in the common potato tuber, rhizome of iris, and the overground tubers of Phaius (Fig. 2, b). The reserve starches are formed by the leucoplastids from sugar and other soluble carbohydrates. The chloroplastids occur in all the green parts of plants (see Frontispiece). They vary from 3 to n ^ in diameter and are more or less spherical or lenticular in shape, except in the Algae, where they are large and in the shape of bands or disks (Figs, 8 and 9) , and generally spoken of as chromatophores. Chlo- Toplastids are found in greater abundance in the cells .near the upper surface of the leaf than upon the under surface, the pro- portion being about five to one. These grains, upon close exam- ination, are found to consist of (i) a colorless stroma, or liquid, in which are embedded (2) green granules; (3) colorless .gran- ules; (4) protein masses; (5) starch grains; and (6) a mem- brane which surrounds the whole. The green granules are looked upon as the photosynthetic bodies ; the colorless grains are sup- posed to assist in the storing of starch or in the production of amylase, the conditions for these processes being directly opposite, i.e., when photosynthesis is active, starch is stored, and when this process is not going on, as at night, amylase is produced and the starch is dissolved. The protein grains may be in the nature of a reserve material of the plastid and probably are also formed in connection with photosynthetic products. While the protoplasm has been termed by Huxley " The phys- 138 A TEXT-BOOK OF BOTANY. ical basis of life," the chloroplastid has been spoken of as the mill which supplies the world with its food, for it is by the process of photosynthesis that the energy of the sun is converted into vital energy, and starch and other products formed, which become not only the source of food for the plant itself, but also the source of the food-supply of the animals which feed upon plants. In other words, horse-power is derived from the energy of the sun which is stored in the starch grains of the chloroplastids. Chromoplastids. — In many cases, as in roots, like those of carrot, or flowers and fruits, which are yellowish or orange- colored, there is present a corresponding yellow pigment, and to this class of pigments the name chromophyll may be applied. Some of these pigments, as the carotin in carrot, have been iso- lated in a crystalline condition (see Frontispiece, also Fig. 86). Chromoplastids usually contain, as first pointed out by Schim- per and Meyer, protein substances in the form of crystal-like bodies ; starch-grains may also be present. The Chromoplastids are very variable in shape and in other ways are markedly differ- ent from the chloroplastids. They are more unstable than the chloroplastids, and are formed in underground parts of the plant, as in roots, as well as in parts exposed to the light, as in the flower. Their formation frequently follows that of the chloroplastids, as in the ripening of certain yellow fruits, such as apples, oranges, persimmons, etc. The PLASTID PIGMENTS are distinguished from all other color- substances in the plant by the fact that they are insoluble in water and soluble in ether, chloroform, and similar solvents. In fact, they are but little affected by ihe usual chemical reagents under ordinary conditions. Apart from the difference in color, the yellow pigment (chro- mophyll) is distinguished from the green (chlorophyll) by the fact that the latter is said to contain nitrogen, and also by their difference in behavior when examined spectroscopically, chloro- phyll giving several distinct bands in the yellow and orange por- tion of the spectrum, which are wanting in the spectrum of the yellow principle. CYTOLOGY, or the science of. cell formation and cell life. Dur- ing recent years considerable attention has been given by botanists CELL-CONTENTS AND FORMS OF CELLS. 139 FIG. 86. Various forms of Chromoplastids: A, from the fruit of Bryonia dioica; B, the fruit of the European mountain ash (Pyrus aucuparia) ; C, the petals of nasturtium (TropCBolum. majus) ; D, petals of Iris Pseudacorus; E, petals of Tulipa Gesneriana; F, the root of carrot (Daucus Carota). — After Dippel in "Das Mikroskop." 140 A TEXT-BOOK OF BOTANY. to the studies of the protoplasmic structures of the cell, especially the nucleus ; the reason for this being that all of the vital phe- nomena of which living organisms are capable have their origin in these substances. The nucleus is regarded as a controlling center of cell activity, for upon it all growth and development of the cell depend, and it is the agent for the transmission of specific qualities from one generation to another. Furthermore, cytolo- gists look upon the chromatin material of the nucleus as being the agent for the transmission of individual characters to offspring. The reason for this is that in the male generative cell it is prac- tically only the nucleus which fuses with the egg-cell, no other substances entering into the union. The centrosomes are usually apparent during the process of nuclear division and by some are regarded as the controlling organ of cell division, hence they are known as the dynamic centers of the cell. The functions of the plastids and cytoplasms are largely, if not entirely, connected with the synthesis, transportation, and dissociation of metabolic substances. NON-PROTOPLASMIC CELL-CONTENTS. The non-protoplasmic constituents of plants may be said to differ from the protoplasmic cell-contents in two important partic- ulars, namely, structure and function. For convenience in con- sidering them here, they may be grouped as follows: (1) Those of definite form including (a) those which are colloidal or crystalloidal, as starch and inulin; (b) those which are crystalline, as the sugars, alkaloids, glucosides, calcium oxa- late; (c) composite bodies, as aleurone grains, which are made up of a number of different substances. (2) Those of more or less indefinite form, including tannin, gums and mucilages, fixed and volatile oils, resins, gum-resins, oleo-resins, balsams, caoutchouc, and also silica and calcium car- bonate. I. SUBSTANCES DEFINITE IN FORM. COLLOIDAL OR CRYSTALLOIDAL. Starch is the first visible product of photosynthesis, although it is probable that simpler intermediate products are first formed. This substance is formed in the chloroplastid (see Frontispiece) and is known as ASSIMILATION STARCH. Starch grains are CELL-CONTENTS AND FORMS OF CELLS. 141 c ss?!^ u ,fe$\ «• xw\ r grvuvj r LU ivf LUC ucrcwpmcnv ui After Dippel in "Das Mikroskop." usually found in the interior of the chloroplastid, but may attain such a size that they burst through the boundary wall of the plastid, which latter in the final stage of the growth of the starch grain forms a crescent-shaped disk attached to one end of the 142 A TEXT-BOOK OF BOTANY. grain, as in Pellionia. Starch is changed into soluble carbohy- drates by the aid of ferments and probably other substances, and in this form is transported to those portions of the plant requiring food. The starch in the medullary rays and in other cells of the FIG. 88. A, potato starch grains showing the excentral and circular point of origin of growth, and lamellae; B, maranta starch grains showing fissured point of origin of growth, and distinct lamellae ; C, wheat starch grains showing indistinct point of origin of growth, and lamelte; D, corn starch grains, which are more or less polygonal in outline and have a 3- to s-angled point of origin of growth. wood and bark of plants is distinguished by being in the form of rather small and nearly spherical grains. In rhizomes, tubers, bulbs, and seeds the grains are, as a rule, quite large, and possess CELL-CONTENTS AND FORMS OF CELLS. 143 more or less distinct characteristics for the plant in which they are found. Starch of this kind is usually spoken of as RESERVE STARCH (Fig. 87). Occurrence of Starch. — Starch is found in most of the algae and many of the mosses, as well as in the ferns and higher plants. The amount of starch present in the tissues of plants varies. In the grains of rice as much as 84.41 per cent, has been found. This constituent also varies in amount according to the season of the year. Rosenberg has observed that in certain perennial plants there is an increase in the amount of starch during the winter months, whereas in other plants it decreases or may entirely disappear during this period. In the latter case, from six weeks 0* howing peculiar horseshoe-like fissure UCVUUIU UCctlvCU VUUWU gllUIUI Ui. glUgCI 1 lll^Uillc longitudinal fissures; E, compound starch grai to two months in the spring are required for its re- formation, and about an equal period is consumed in the fall in effecting its solution. Structure and Composition of Starch Grains. — The formula which is generally accepted for starch is (C6H10O5)n, this being recognized by Pfeffer, Tollens, and Mylius. It is supposed that the molecule of starch is quite complex, it being composed of dif- ferent single groups of C6H10O3 or multiples of the same. While this formula may be accepted in a general way, still it has been shown that there are at least two substances which enter into the composition of the starch grain, and more recent studies tend to show that it is in the nature of a sphero-crystalloid, resembling inulin in some respects. Starch grains have an interesting struc- 144 A TEXT-BOOK OF BOTANY. ture. They vary in shape from ovoid or spherical to polygonal, and have a more or less distinct marking known as the " hilnm," " nucleus," or the POINT OF ORIGIN OF GROWTH. The substances of which the grains are composed are arranged in concentric layers or lamellae which are more or less characteristic and which sometimes become more distinct on the application of certain reagents (Fig. 90). The point of origin of growth and alternate lamellae are stained by the use of gentian violet and other aniline dyes, which may be taken to indicate that these layers contain a colloidal substance somewhat resembling a mucilage, while the FIG. 90. Successive stages in the swelling and disintegration of starch grains in the presence of water on the application of heat (6o°-7o° C.),or certain chemicals. Potato starch i-io; wheat starch 11-22. alternating layers are stained with dilute iodine solutions and are probably composed of soluble starch, this latter corresponding to the a-amylose of Arthur Meyer or the granulose described by Nageli. The peripheral layer of the grain appears to be a distinct membrane. It is quite elastic, more or less porous, and takes up stains readily. While starch grains usually occur singly, they are not infre- quently found in groups of J;wo, three, or four grains, when they are spoken of as two-, three-, or four-compound. In some of the CELL-CONTENTS AND FORMS OF CELLS. 145 cereals, as rice and oat, they are loo-compound or more. The individuals in compound grains are in some cases easily separated from one another. This occurs frequently in microscopical prep- arations, and is especially noticeable in the commercial starches. The various commercial starches belong to the class of reserve starches and may be distinguished by the following characteristics : 1 i ) The shape of the grain, which may be spherical, ellipsoidal, ovoid, polygonal, or of some other characteristic form (Figs. 88 and 89). (2) The size of the grain, which varies from i to 2 /x to about 100 fi in diameter. (3) The position of the point of origin of growth, which may be central (Fig. 88, C, D) or excentral (Fig. 88, A, B). In some cases there are apparently two points of origin of growth in a single grain, and it is then spoken of as " half-compound," as occa- sionally found in potato. (4) The shape of the point of origin of growth, which may be spherical, as in potato (Fig. 88, A) ; cross-shaped, as in maranta (Fig. 88, B) ; a three- or five-angled fissure or cleft, as in corn (Fig. 88, D), or indistinct or wanting, as in wheat (Fig. 88, C). (5) The convergence of the lamellae, which may be either toward the broad end of the grain, as in maranta (Fig. 88, B), or toward the narrow end, as in potato (Fig. 88, A). In most grains the lamellae are indistinct or wanting, as in wheat and corn (Fig. 88, C,D). (6) Behavior toward dilute iodine solutions, the color pro- duced varying from a deep blue in most starches to a red or yellowish-red, as in the amylodextrin grains of mace. (7) The temperature (45°-77° C.) at which the " kleister " or paste is formed, and its consistency. (8) The appearance as viewed by polarized light, the distinct- ness of the cross, as well as the degree of color produced, varying considerably as Nichol's prism is revolved (Fig. 91). (9) Behavior toward various reagents, as chromic acid, cal- cium nitrate, chlor-zinc-iodide, diastase, and various aniline stains, showing peculiarities of both structure and composition (Fig. 90). General Properties of Starch. — If starch is triturated with 10 146 A TEXT-BOOK OF BOTANY. water and the mixture filtered, the filtrate does not give a reaction with iodine solution ; if, on the other hand, the starch is previously triturated with sand and then with water, the filtrate becomes blue • « * .> " FIG. 91. Larger grains of various starches as viewed through the micropolariscope when mounted in oil: A, potato (70-80 M); B, wheat (30-40 M); C, ginger (30-50 M); D, galangal (45-55 /n); E, calumba (40-60 M); F, zedoary (50-75 ft); G, maranta (35-50 /t); H, colchicum (10-20 n); I, corn (20-25 /*); J, cassava (20-35^ ); K, orris root (30-35 /n). on the addition of iodine solution. It appears that in the latter operation the wall of the grain is broken and the soluble starch present in the grain is liberated. CELL-CONTENTS AND FORMS OF CELLS. 147 If dry starch and iodine are triturated together no color or, at the most, a faint blue color is produced ; whereas, if a little water is added and the trituration repeated, a deep blue color is immediately produced. The blue color of starch solution and iodine disappears on the application of heat, but slowly returns on cooling the solution, but not with the same degree of intensity, part of the iodine being volatilized. When starch is heated with glycerin it dissolves, and if alco- hol is added to the solution, a granular precipitate is formed which is soluble in water, the solution giving a blue reaction with iodine. When starch is heated with an excess of water at 100° C. for even several weeks, dextrinization of the starch does not take place ; i.e., the solution still gives a blue color with iodine. If, how- ever, a mineral acid be added, it is quickly dextrinized, turning violet-red, reddish, and yellowish with iodine ; finally, maltose and dextrose are produced, these giving no reaction with iodine, but reducing Fehling's solution. The ferments and other chemi- cals have a similar effect OH starch. When dry starch is heated at about 50° C. from 15 to 30 min- utes the lamellae and crystalloidal structure become better defined and the polarizing effects produced by the grains also become more pronounced. When starch is mounted in a fixed oil, as almond, the polarizing effects are more pronounced than when it is mounted in water, but the inner structure is not usually apparent, unless the starch has been previously heated. (For literature on the starch grain see Kraemer, Bot. Gazette, Vol. XXXIV, Nov., 1902 ; Ibid., Vol. XL, Oct., 1905 ; also Eighth In- ternational Congress of Applied Chemistry, Vol. 17, p. 31.) BOTANICAL DISTRIBUTION OF STARCH. — This constituent is commonly present as a reserve material in a large number of plants. The sources of the commercial starches are constantly being extended. The commercial starches are chiefly obtained from one or more genera of the Gramineas, Marantaceae, Eu- phorbiaceae, and Solanaceae. The following is a list of the fami- lies yielding one or more economic products which contain starch: Cycadaceae, Gramineae, Araceae, Liliaceae, Amaryllida- ceae, Iridaceae, Musaceae, Zingiberaceae, Cannaceae, Marantaceae, 148 A TEXT-BOOK OF BOTANY. Orchidaceae, Piperaceae, Fagacese, Aristolochiaceae, Polygonaceae, Phytolaccaceae, Nymphaeaceae, Ranunculaceae, Menispermaceae, Myristicaceae, Lauraceae, Papaveraceae, Cruciferas, Rosaceae, Legu- minosae, Gcraniaceae, Rutaceae, Simarubaceae, Euphorbiaceae, Celastraceae, Sapindaceae, Rhamnaceae, Malvaceae, Thymelseaceae, Punicaceae, Myrtacese, Umbelli ferae, Loganiaceae, Apocynaceae, Convolvulaceae, Solanaceae, Scrophulariaceae, Gesneraceae, Rubia- ceae, Caprifoliaceae, Valerianaceae, and Cucurbitaceae. PERCENTAGE OF STARCH IN PLANTS. — The amount of starch in economic plants, especially those used for food, is very high, being, on an average, much greater than that of any other con- stituent except water. The percentage of starch, calculated on dry material, in a number of foods and spices is here given : Bar- ley, 53.45 to 72.90; cardamom seed, 18.66 to 40.53; carrot, 0.87 to 0.92; chestnut, 37.31 to 47.93; chinquapin, 44.45; cinnamon, 10.44 to 65.72 ; cloves, 9.41 to 51.03 ; cocoa (cacao), 3.83 to 48.73 ; corn, 36.72 to 77.54; ginger, 46.16 to 62.53; lentils, 45-37; ma.ce, 26.77 to 56.11 ; millet, 56.70 to 74.40; nutmeg, 17.19 to 40.12; oak acorns, 32.64; oats, 42.64 to 63.50; onion, n.oo to 29.39; peas, 50.02 to 57.59; pepper, 28.15 to 64.92; pimenta, 16.56 to 59.28; potatoes (sweet), 8 to 78.59; potatoes (white), 25.00 to 75.00; rice, 74.80 to 84.41 ; rye, 51.15 to 74.08; wheat, 53.66 to 76.51. . MANUFACTURE OF STARCH. — In the preparation of commer- cial starches the object is to break the cells and separate the starch grains, freeing the product from the other constituents of the cell as much as possible. The preparation of potato starch is exceedingly simple, as all that is necessary is to reduce the tubers to a fine pulp, the starch grains being separated from the tissues by means of a sieve. The water containing the starch is removed to tanks, the separation of the starch being facilitated by the addition of alum or sulphuric acid which coagulates the dissolved protein substances. The starch is washed and dried over porous bricks by exposure to air. It is then thoroughly dried in a hot chamber, reduced to a powder, and sifted. One hundred pounds of potatoes yield about 15 pounds of dry starch. It is said that diseased tubers produce as good a quality of starch as the sound tubers. In the preparation of the cereal starches the gluten interferes CELL-CONTENTS AND FORMS OF CELLS. 149 with their ready separation. The process is therefore modified by either allowing the cereals to ferment, whereby the gluten is rendered soluble and easily removed, or the flour is made into a dough which is kneaded over running water, whereby the starch grains are separated. The starch is subsequently purified by washing and settling. It is dried by gentle heat and assumes the columnar structure as seen in the more or less irregular particles in the commercial product. One hundred pounds of wheat yield from 55 to 59 pounds of starch, the fermentation process giving a larger amount. In the preparation of corn starch, a weak solution of sodium hydrate is usually employed to facilitate the separation of the starch. Sulphurous acid is also used. One hundred pounds of corn yield 50 pounds of starch. Rice starch is prepared by either an alkaline process or by an acid process similar to that used in the manufacture of corn starch, hydrochloric acid being employed instead of sulphurous acid. Rice yields a greater percentage of starch than any of the other raw materials, 100 pounds of the grain giving 70 per cent, of starch. Starch is used as a food and for various other industrial pur- poses. The principal nutritive starches are sago, tapioca, and corn. Maranta, or arrowroot starch, is largely employed in the preparation of infant foods. Much of the dextrin of commerce is prepared by the action of dilute acids upon potato starch. Starch for laundry purposes is prepared from wheat. Rice starch is largely used as a dusting-powder. Cassava starch has consider- able advantages over the other starches in the making of nitro- compounds, and is employed in the preparation of smokeless powders. PYRENOIDS. — In the chromatophores of a number of algae a distinct body is observed. It is more or less of a lenticular shape, stained a dark purple on the addition of iodine, and is known as a Pyrenoid. It is not definitely known whether it is a true cell organ having a function similar to the plastids in manufacturing starch or whether it is merely a mass of complex reserve substances. It can be differentiated readily into two distinct portions: an inner, somewhat highly refracting and 150 A TEXT-BOOK OF BOTANY. consisting of protein matter, and an outer layer, consisting of a number of starch grains. The studies of Baubier tend to show that the pyrenoid is perfectly differentiated and independent of the chromatophore, and that the starch is formed from a leuco- plastid which surrounds a phyto-globulin or crystalloid at the center. This would quite agree with the studies of Timberlake, who observed the complete conversion of the pyrenoid into starch. That the substances of the pyrenoid are in the nature of reserve food materials, is apparent from the fact that the pyrenoid entirely disappears in Hydrodictyon prior to spore formation, and that it is afterward formed anew in the young cells, thus behaving very much like a leucoplastid. Attention should also be directed to the fact that in some of the unicellular and filamentous algae the pyrenoid divides during the division of the cell, thus behaving like other protoplasmic organs. INULIN appears to be an isomer of starch and occurs in solution in the cell-sap of parenchyma cells of stems and roots, being also found in the medullary rays. It exists in greatest amounts during the early fall and spring, being changed at other times to levulose. In the Monocotyledons it is found in the Amaryllidacese, Liliaceae, etc. In the Dicotyledons it is characteristic of the Compositae, but also occurs in the following: Asclepiadaceae, Bignoniaceae, Cactaceas, Campanulaceae, Capri foliaceae, Compositae, Cruciferse, Droseraceae, Euphorbiaceae, Geraniaceae, Labiatae, Leguminosae, Lythraceae, Magnoliaceae, Menispermaceae, Moraceae, Nepenth- acese, Passifloraceae, Ranunculaceae, Rubiaceae, Rutaceae, Salicaceae, Santalaceae, Theaceae, Thymelaeaceae, Urticaceae, Valerianaceae, Verbenaceae, Violaceae, etc. According to Dragendorff, there are two forms of inulin ; one of which is amorphous and easily soluble in water, and another which is crystalline and difficultly soluble in water. The latter is probably, however, a modification of the former, and it is not unlikely that the various principles known as pseudoinulin, inu- lenin, helianthenin, and synantherin are all modifications of inulin. In examining fresh material (Fig. 92) the sections should be mounted in as little water as is necessary to enclose the section. If inulin is present it shows in the form of colorless, highly refracting globules. The latter are usually relatively small and tend to unite, forming one or more large globules. Upon increas- CELL-CONTENTS AND FORMS OF CELLS. 151 ing the amount of water they dissolve and are diffused among the other constituents. If fresh sections are mounted directly in alcohol, or if to the original aqueous mount strong alcohol is added, the inulin separates in the form of rod-like or needle-like crystals, which strongly polarize light. If the plant material is preserved for some days in 70 per cent, alcohol, the inulin separates in the form of sphere-crystals which adhere to the walls of the cell. This aggregate consists of concentric layers of radially arranged, needle-shaped crystals, the structure of which is more apparent upon the addition of either nitric acid or a solution of hydrated chloral. The crystal mass is insoluble in glycerin and sparingly soluble in cold water. It is soluble in warm water, warm solu- tions of glycerin and water, acetic acid, mineral acids, chlor- zinc-iodide, and ammoniacal solution of cupric oxide. With solu- tions of the alkalies it dissolves with a lemon yellow color, and with acetic acid the crystals dissolve, forming a greenish colored solution which soon fades. Tunmann (Ber. d. d. pharm. Ges., 1910, p. 577) has sug- gested the use of a solution of pyrogallol as a distinctive re- agent for the microscopic study of inulin. The solution con- sists of o.ioo Gm. Pyrogallol, alcohol 5 c.c., and 5 c.c. of hydro- chloric acid. Upon carefully heating sections treated with this reagent the cells containing inulin are colored a violet red. A simi- lar solution made with resorcin in place of pyrogallol colors inulin a cinnabar red. In taraxacum, inula, pyrethrum, and other drugs inulin occurs in the form of an amorphous mass having a more or less angular outline. The masses are highly refracting and probably consist of aggregates of small crystals similar in appearance to those of mannit found in commercial manna. HESPERIDIN. — Although not a carbohydrate, hesperidin is of wide occurrence and separates in the form of sphere-crystals re- sembling inulin. It is a glucoside (C22H,,6O12J, and it would appear, from the studies of Tunmann (Schweis. Woch. f. Chem. u. Pharm., 1909, p. 794), that, like inulin, there are several forms of it. Hesperidin, like inulin, occurs in living cells in the form of a more or less viscous fluid. Upon the addition of water, alcohol, glycerin, or solutions of hydrated chloral it separates in 152 A TEXT-BOOK OF BOTANY. the form of yellowish sphere-crystals. If the fresh plant material is placed in alcohol the crystals separate in the form of large needles, often forming branching tufts. When examined by means of the micropolariscope, they polarize light more or less strongly, depending upon how the crystals were prepared. Upon quickly drying the plant material in which it occurs, hesperidin separates in the form of irregular, slightly yellowish clumps, re- sembling those of inulin found in the composite drugs of com- merce. If the material is slowly dried, the crystals are decom- posed. Crystals of hesperidin have been found in Citrus fruits ; FIG. 92. Sphero-crystals 'of inulin. A, parenchyma cells of the root of chicory (Cicho- rium Intybus) treated with alcohol: a, numerous small globules shortly after the addition of alcohol; b, a somewhat later stage, showing the fusion of many of the small globules of inulin; c, crystal formation in the globules after the alcohol has acted upon the cells for 24 hours. B, sphero-crystals resembling starch grains formed in the tubers of Dahlia vari- abilis in alcoholic material: in b, the section has been treated with nitric acid, the crystal aggregate showing a trichiten structure. — After Dippel in "Das Mikroskop." the fruit of Cocculus laurifolius; the leaves of Buchu, and Pilo- carpus ; species of Mentha, Hyssopus, Teucritim, Satureia, Tilia ; Conium maculatum; Scrophularia nodosa, and stamen hairs of the flowers of Verbascum. The crystals are found especially in the epidermal cells of bracts. The crystals in the hairs of the flowers of Verbascum are usually referred to as a sugar, but, according to the studies of Tunmann, are in the nature of a hesperidin. CELL-CONTENTS AND FORMS OF CELLS. 153 If sections are mounted in a small quantity of water and the latter replaced with dilute glycerin, followed by concentrated glycerin, then there separates in the cells a number of yellowish globules which are highly refractive (Fig. 93) ; these globules tend to unite in the center and very soon crystallize. The sphero- FIG. 93. Hesperidin. A, B, formation of sphero-crystals in the epidermal cells of the foliage leaves of Linden upon the addition of glycerin; in A the hesperidin occurs in highly refracting globules, which in B have united in a large central globule in which a crystal- aggregate has formed. C, crystals in stamen hair of the flower-bud of Verbascum. D, crystals in the cells of the upper epidermis of Hyssopus officinalis. E, cells of the upper epidermis of the foliage leaves of the Linden. — -After Tunmann. crystal consists of radiating needles, the aggregate frequently being marked by concentric lamellae, the whole being surrounded by a more or less mucilaginous wall (Fig. 93). As there are other substances in the cell the sphere-aggregate may contain some of these in the interstices. If the crystals are formed slowly and in the cold they are apt to be of a yellowish, or even dark yellow, color, whereas if heat is employed and the crystallization 154 A TEXT-BOOK OF BOTANY. is more rapid they are nearly colorless and dissolve readily. The crystals of hesperidin are insoluble in water, alcohol, glycerin, ether, chloroform, solutions of hydrated chloral, dilute sulphuric acid and dilute or concentrated hydrochloric acid and nitric acid. They are sparingly soluble in ammonia water and hot acetic acid. Upon the addition of either dilute or concentrated solutions of potassium hydroxide or sodium hydroxide, hesperidin dissolves, forming a yellowish solution. With concentrated sulphuric acid it gives a deep yellowish solution, which upon warming becomes a reddish-brown. Sometimes hesperidin, as in the stamen hairs of Verbascum, is colored with concentrated sulphuric acid only a light yellow. GLYCOGEN is a carbohydrate allied to amylo-dextrin and occurs commonly as a reserve food material in the fungi and some of the Cyanophycecc. It usually occurs in the form of a more or less amorphous mass in the hyphue of the fungi, but occasionally is found in definite granules resembling starch. It is supposed to arise in plastid bodies resembling leucoplastids, but its general formation is controlled by the protoplasm. In yeast it is found in large quantities, sometimes nearly filling the entire cell. CRYSTALLINE SUBSTANCES. The sugars constitute a group of crystalline principles of wide distribution. They occur in the cell-sap, from which by evaporation or on treatment with alcohol they may be crystallized out. There are chemically two main groups: monosaccharoses (formerly termed glucoses) and disaccharoses (formerly the saccharoses). Under the former are included the simple sugars containing two or more atoms of carbon and known as biose (C2H4O2), etc. Among the pentoses (C5H10O5) are rhamnose, a component of certain glucosides ; f ucose, found in fucus and other brown algae, and chinovite, occurring in certain Cinchona barks. The most important subdivision of the monosaccharoses comprises the hexoses (C6H12O6), which include glucose and fructose, and are widely distributed ; d-mannose, found in the manna of Fraxinus Ornus and obtained by hydrolyzing cellulose, especially the reserve cellulose in the seeds of the vegetable ivory. Of the disaccharoses (C^r^Ou) cane-sugar is the most im- CELL-CONTENTS AND FORMS OF CELLS. 155 portant. In this group are also included maltose, formed by the action of diastase on starch and by the action of ferments on glycogen ; trehalose or mycose, found in the Oriental Trehala, ergot, Boletus edulis, and other fungi ; melibiose, occurring in Australian manna and in the molasses of sugar manufacture; touranose, found in Venetian turpentine (obtained from Larix europcea] and in Persian manna ; and agavose, occurring in the stalks of Agave americana. Of the numerous sugars the following are likely to be met with in the microscopical study of drugs and economic products : Dextrose (grape-sugar or dextro glucose) is found in sweet fruits, the nectaries of the flowers, and stems and leaves of various plants. It crystallizes in needles and varies in amount from I to 2 per cent, (in peaches), to 30 per cent, in certain varieties of grapes. It also occurs in combination with other principles, form- ing the glucosides. Levulose (fructose, fruit-sugar, or levo-glucose) is associated with dextrose, occurring in some instances even in larger quanti- ties than the latter. Sucrose (saccharose or cane-sugar ) is found rather widely distributed, as in the stems of corn, sorghum and the sugar-cane; in roots, as the sugar-beet ; in the sap of certain trees, as sugar- maple and some of the palms ; in the nectaries and sap of certain flowers, as fuchsia, caryophyllus, and some of the Cactaceae ; in seeds, as almond and chestnut, and in various fruits, as figs, mel- ons, apples, cherries. In some plants, as in sugar-cane, the yield is as high as 20 per cent. It crystallizes in monoclinic prisms or pyramids, and forms insoluble compounds with calcium and strontium. Maltose is found in the germinating grains of cereals (see Malt) ; it forms colorless, needle-shaped crystals resembling those of dextrose, and forms compounds with calcium, strontium, barium and acetic acid. Trehalose occurs in some fungi, as ergot and Amanita mus- caria — the latter containing as much as 10 per cent, in the dried plant. Mannitol occurs in the form of needles or prisms and is found in the manna of Fraxinus Ornus to the extent of 90 per cent. It A TEXT-BOOK OF BOTANY. is also found in some of the Umbelli ferae, as Apium graveolens, some of the Fungi and sea-weeds, and is rather widely distributed (Fig. 94). Dulcitol, which is closely related to mannitol, is found in Enonymus europccus and in most of the plants of the Scroph- ulariacese. PERCENTAGE OF SUGAR IN PLANTS. — No analysis is necessary to indicate that most fruits contain quite a large percentage of sugar. The following figures show the amount of sugar in some of the more common fruits, the per cent, being calculated on FIG. 94. Orthorhombic crystals of Mannitol (Mannit) obtained from aqueous solutions: A, large crystals; B, feathery aggregates of needles. dry material: Apple, 33.16 to 87.73; apricot, 7.58 to 86.21; banana, 6.20 to 21. go; blackberry, 32.67 to 40.17; cantaloupe, 0.27 to 11.98; cherry, 29.97 to 85.86; currant, 33.76 to 75.49; fig, 10.00 to 29.90; gooseberry, 47.33 to 79.82; grape, including raisin, 67.82 to 83.00; huckleberry, 12.60 to 46.87; orange, 36.48 to 66.91 ; peach, 6.69 to 74.07; plum, 15.25 to 78.70; prune, 32.04 to 69.46; pumpkin, 0.15 to 11.98; and raspberry, 14.93 to 47.50. The following percentage of sugars is present in some of the cereals, common vegetables, etc. : Asparagus, 0.45 to 3.47 ; barley, 5.82 to 8.73; beet (garden), 4.20 to 31.45; beet (sugar), 3.55 to 89.61 ; buckwheat, 1.42 to 1.67; carrot, 3.62 to 15.30; cauliflower, 1.22 to 7.40; chestnut, 5.22 to 8.52; cocoa (cacao), 2.77; coffee, 0.20 to 14.50; corn, 0.96 to 6.77; cucumber, 0.72 to 1.51; CELL-CONTENTS AND FORMS OF CELLS. 157 lentils, 2.75; maple sap, 2 to 4; oats, 0.51 to 5.27; onions, 0.44 to 14.02; rye, 0.39 to 9.46; sorghum juice, 8.60 to 14.70; sugar- cane juice, 16.00 to 18.10; spinach, 0.06 to 6.66; turnip (Swedish), 5.05 to 9.67; sweet potato, 0.32 to 8.42; tomato, 2.53 to 3.86; vanilla, 7.07 to 9.10; wheat, 0.58 to 5.12. HONEY-DEW is a pathological sugar formed as a result of the stings of insects (Aphides and Coccidese) on the leaves of certain trees. There are a number of trees the leaves of which, during the summer time, are covered with a thin layer of sugar solution. Among these may be mentioned the linden, tulip poplar, and chestnut. Honey-dew may also be formed, according to Bonnier, without the assistance of aphides, and may be seen oozing out of the stomata. It may be formed in such quantities that it may drip from trees, as in the so-called rain trees of the Tropics (see Pfeffer, " Physiology of Plants "). THE ORIGIN AND FORMATION OF CARBOHYDRATES. — The first visible product of photosynthesis is starch, and this is sometimes called photosynthetic starch. Investigations during recent years seem to indicate that grape-sugar or dextrose is the basal photo- synthate, and that from this starch is later formed in the plastid. This sugar is called photosynthetic grape-sugar to distinguish it from the grape-sugar found in the cell-sap of the grape, raisins, figs, etc. There is no question but that in the plastids starch is readily formed from glucose, and, vice versa, that the starch in the plastids is readily changed through the agency of the ferment, amylase, into grape-sugar. There are four factors necessary for the formation of a photo- synthetic carbohydrate (starch or glucose) by the chloroplastids : (i) Light; and in this condition it is the energy of the red and blue rays of sunlight which are necessary to bring about the synthesis. (2) Carbon dioxide. This compound must be present in about the normal proportions that we find it in the air, namely, 3 parts in 10,000. (3) Water is essential, and this is always pres- ent in living cells. It is by the dissociation of the CO2 and H2O and rearrangement of the atoms that carbohydrates are formed, being either starch (C6H10O5) or glucose (C6H12O6), with oxy- gen as a by-product. These interactions may be shown by the following equations : 158 A TEXT-BOOK OF BOTANY. (Starch) 6CO2 + 6H2O = C6H12O6 + 6O2. (Glucose) (4) Certain mineral substances must be present, although, appar- ently, they take no part in the photosynthetic reaction. Bokorny has shown that compounds of potassium are essential to bring about the reactions above given. Some form of iron has always been considered necessary for the development of the green pigment or chlorophyll in the chloro- plastid. While this element may seem to be necessary in water culture, it is not always essential, particularly if plants are grown under control conditions in sand. The development of chlorophyll also requires the presence of oxygen. The activity of the chloro- phyll apparatus is further influenced by other factors, viz., the maintenance of a proper temperature. It is self-evident that there is a minimum and maximum temperature at which photosynthesis is scarcely perceptible, and that there is an optimum temperature during which the activity of the chloroplastid is at its height. The latter varies with different plants, depending on the climate to which they are either indigenous or naturalized. In the Tropics the optimum temperature is somewhat higher, while in the Arctic regions it is much lower. In temperate climates the optimum varies between 20° C. (68° F.) to 30° C. (86° F.). From the facts just given it would appear that considerable is known in regard to the conditions and the substances which are concerned in the formation of photosynthetic products. On the other hand, we know practically nothing of the successive steps in the formation of either starch or glucose in the plant. Numerous experiments have been conducted and a number of hypotheses have been advanced. According to von Baeyer, the first step in the process of photosynthesis is a reduction in the CO2, formalde- hyde being formed, and this is then polymerized into a carbohy- drate, which is finally changed into dextrose. This may be repre- sented by the following equations : CO2 + H2O— >-HCHO + O2 xHCHO=(CH2O)x 6(CHaO)=C6H1206 CELL-CONTEN'TS AND FORMS OF CELLS. 159 There are a number of other views which have been advanced. Erlenmeyer, for instance, has suggested that instead of formalde- hyde being first formed, formic acid is the first product of photo- synthesis, hydrogen peroxide being liberated ; both of these then are decomposed, formaldehyde being formed according to the following equations : CO2 + H2O = HCOOH + H2O2 HCOOH + H2O2 = HCOH + H2O + O2 By the further condensation of formaldehyde as in the hy- pothesis of von Baeyer, dextrose is formed. On the other hand, Brown and Morris consider that the first carbohydrate formed is, in reality, cane-sugar, and that from this, then, dextro&e and the other carbohydrates are formed. Some very interesting experiments were conducted by Berthe- lot (Compt. rend., 1898, 1900, etc.), who obtained both formic acid and formaldehyde while working with a mixture of carbon dioxide and hydrogen. Later he obtained a synthetic carbohy- drate, which on warming had an odor of caramel. Furthermore, when using an excess of carbon monoxide with hydrogen, Berthe- lot obtained a substance closely related to oxy-cellulose. Lob (Ber. d. d. pharm. Ges., 1907, p. 117) concludes that from formal- dehyde, glycolic-aldehyde (xCHO.CH2OH) is formed; this is then followed by the formation of glyceric-aldehyde (CH2OH.CH- OH.COH), which is finally polymerized into a hexose as glucose, or even a higher carbohydrate. THE ALKALOIDS include a group of organic bases which possess remarkable toxicological properties. They are compounds of car- bon, hydrogen, and nitrogen ; oxygen is also usually present, except in the liquid or volatile alkaloids, in which it is wanting. They are usually combined with some organic acid, as malic acid or tannic acid. In many cases the alkaloids are combined with acids that are peculiar to the genus, — e.g., aconitic acid in Aconitum, meconic acid in Papaver, etc. They are found in a large number of plants, especially among the Dicotyledons, and are rather char- acteristic for certain families, as those of the genera Strychnos, Cinchona, Erythroxylon, Papaver, etc. When present, alkaloids may be found in any part of the plant, but usually they are most abundant in certain definite regions, as roots, rhizomes, fruits, 160 A TEXT-BOOK OF BOTANY. seeds, or leaves. Furthermore, the amount is greatest at certain stages of development, as in the fully ripe seeds, more or less immature fruits, during the resting periods of roots and rhizomes, and in leaves when photosynthetic processes are most active. They occur in greatest amount in those cells which ^re in a poten- tial rather than an active condition, being associated with starch, fixed oils, aleurone grains, and other reserve products in the roots, rhizomes, and seeds. They are found in fruits in greatest amount during the development of the seed, but after the maturing of the latter they slowly disappear, as in the opium poppy and conium. The alkaloids probably arise in the protoplasm, although they may also be formed from the decomposition of protein substances. The fact that asparagine, a weak base, is usually present when the proteins are being formed from the protoplasmic substances and is also present when the proteins are being used in the growth of the plant, as during the germination of seed, would seem to indicate that both views are more or less tenable. The studies of Lotsy on Cinchona showed that alkaloids are formed in con- nection with photosynthetic processes and that they are subse- quently stored for the use of the plant. On the other hand, it is rather interesting to note that when cinchona trees are grown in the hot-house they do not produce any quinine, and, again, it is said that the conium growing in Scotland does not contain any coniine. From these observations we must conclude that alkaloids are produced only under certain conditions, and that they are not essential metabolic substances. The fact that the presence of alkaloids may be demonstrated in the thick-walled cells of the endosperm in nux vomica has led some investigators to conclude that they may arise in the cell-wall. The occurrence of alkaloids at this point is due to their imbibition by the wall, just as other soluble cell contents are absorbed, especially upon the death of the cell. MICROCHEMISTRY OF ALKALOIDS. — The alkaloids occur in rather large quantities in a number of plants. Seldom do we find them in the form of crystals in the plant cell. Crystals of the alkaloid Piperine are not infrequently observed in the oil secre- tion cells of the endosperm of Piper nigrum (Fig. 94, A). The CELL-CONTENTS AND FORMS OF CELLS. 161 alkaloids form crystallizable salts and, in many instances, definite double compounds. Nevertheless, not a great amount of progress has been made in their detection and localization, either in the living plant or in economic products. The reason for this is that other substances, as calcium oxalate, may interfere with the reactions forming crystals with the reagents, so that nothing definite can be deduced. Then again, when an alkaloid is charac- terized by certain color reactions, especially if a rose or violet color is formed, it may be due to the reaction of the reagent with carbohydrates or protein substance. For this reason practically a Fio. 94A. Crystals of Piperine: A, cells of endosperm showing a single oil cell (b) in which crystals of pipeline have separated; (a) starch bearing parenchyma. B, piperine crystals separated from sections which have been first treated with alcohol, and to the oily globules remaining after evaporating the alcohol, a drop of distilled water has been added. In from fifteen to thirty minutes there separate needles, short rods and aggregates of piperine. — After Molisch's work on Histochemie. there are only a few instances where satisfactory results are obtained in the study of alkaloids in plant tissues. These, for the most part, have been obtained in connection with the dried mate- rials of commerce. As it is very important that thes-e studies should be carried further, a few illustrations may be given. . Hydrastis contains two alkaloids in considerable quantities which form definite salts with nitric and sulphuric acids. Fur- thermore, this plant does not contain calcium oxalate, so that the crystals formed upon the addition of mineral acids could not be of either the nitrate or sulphate of calcium, and if in other respects they corresponded to the sulphates and nitrates of the alkaloids peculiar to hydrastis, then the crystals must be salts of the alka- loids. If sections of the fresh rhizome of hydrastis or the moist- ii 1 62 A TEXT-BOOK OF BOTANY. ened drug are mounted directly in sulphuric acid, there separate very soon small acicular or rod-shaped crystals of berberine and hydrastine (Fig. 95). This is one of the most satisfactory of microchemical tests of the alkaloids that is known, and Leuff has shown that they can be readily determined even in the endosperm cells in the seeds of hydrastis (Pharm. Post, 1913, p. 977). Caffeine is an alkaloid which is rather widely distributed, and its presence can be easily determined, in dried material as coffee seeds, in several ways. ( i ) It may be sublimed, the long, \ B FIG. 95. Alkaloids in Hydrastis: A, prismatic crystals which separate after a time on treatment of sections of the rhizome of hydrastis or its powder with sulphuric acid; B. the separation of needle-shaped crystals of the sulphates of the alkaloids in the paren- chyma cells of hydrastis upon treatment with sulphuric acid. silky needles of caffeine being deposited upon a watch crystal or a microscopic slide. (2) Similar crystals may separate from aqueous or hydro-alcoholic mounts of the material. (3) The most satisfactory method for the detection of caffeine is to form a double salt with gold chloride, the crystals of which are very characteristic (Fig. 96). The test may be applied to coffee seeds, cola nuts, tea leaves, guarana, etc., as follows : Sections are placed in strong hydrochloric acid and slightly heated ; then one or two drops of a solution of gold chloride are added and the sections pushed to one side, allowing the liquid to evaporate. Near the CELL-CONTENTS AND FORMS OF CELLS. 163 edge of the residue branching groups of needles of caffeine gold chloride separate. Cocaine is another alkaloid which forms char- acteristic crystals, and the double salt of the chloride with palladous chloride is very characteristic (Fig. 97). The crystals of the latter may be prepared in the same manner as caffeine, except that to the sections of coca leaves or the powdered material a smaller quantity of hydrochloric acid is added. FIG. 96. Caffeine gold chloride; crystals formed on the addition of a solution of gold chloride to a dilute aqueous solution of caffeine. PROPERTIES OF ALKALOIDS. — In the microchemical study of the cell-contents it is important to bear in mind that the alkaloids possess certain characteristic properties and give definite reactions with the so-called " alkaloidal reagents." The alkaloids occur in combinations with acids forming salts which are mostly soluble in water or in alcohol, and consequently may be extracted by means of these solvents. From the latter well-characterized crystals may be easily formed. The free alkaloid may be separated from solutions of their salts in water by the addition of alkalies, but it is usually important that the solutions of the latter be not in excess, as otherwise the separated alkaloids may dissolve. With 164 A TEXT-BOOK OF BOTANY. few exceptions, as Berberine and Sanguinarine, they form mostly colorless crystals. Among the alkaloidal reagents giving charac- teristic precipitates the following may be mentioned. Phospho- molybdic acid (Sonnenschein's Reagent) gives with nearly all of the alkaloids a yellow, insoluble amorphous precipitate. Potas- Fic. 97. Cccaine: A, monoclinic crystals cf cocaine; B, orthorhombic crystals of co- caine hydrochloride ; C, monoclinic crystals of cocaine hydrochloride and palladous chloride; D, skeleton aggregates of cocaine hydrochloride and palladous chloride. sium mercuric iodide (Mayer's Reagent) precipitates many of the alkaloids in even dilute solutions, the precipitates being usually yellowish-white and more or less rlocculent. Wagner's Reagent, or iodine dissolved in a solution of potassium iodide, is another reagent that precipitates nearly all the alkaloids. The precipi- tates are of a reddish or reddish-brown color, and are more readily formed in acidulated solutions. From alcoholic solutions CELL-CONTENTS AND FORMS OF CELLS. 165 crystalline double compounds may be formed. Picric acid forms characteristic crystals with a number of the alkaloids. Wormley's Reagent, or a solution of bromine in hydrochloric acid, gives definite microscopic crystals with some of the alkaloids, as atro- pine, hyoscyamine, and veratrine. Auric chloride and platinic chloride both form characteristic double salts with a number of the alkaloids. There are a number of other reagents which are used in the study of the localization of alkaloids in plants. Most of these depend upon certain color reactions. While it is true that the alkaloids give rather striking colors with certain reagents, yet, as a rule, they are of little value except when the alkaloids are in a pure condition. This same objection holds, but with some- what less force, to the employment of the alkaloidal reagents just mentioned. FAMILIES YIELDING ALKALOIDS. — It is very difficult to deter- mine from the literature of the analyses as to how widely distrib- uted alkaloids are in plants. Time and again principles, which give definite reactions with certain alkaloidal reagents, are subse- quently shown to be other than alkaloids. In enumerating the families in which alkaloids occur we do not mean to say that they are lacking in the families not mentioned here. Alkaloids are seldom found in the Cryptogams, being confined, with few exceptions, to the poisonous fungi, as Amanita of the Agaricacse. Among the Monocotyledons they are found in the Palmse and the Liliaceae. They are more widely distributed in the Dicoty- ledons, occurring in the following families : Piperacese, Chenopo- diacese, Ranunculaceae, Berberidaceae, Menispermaceae, Lauraceae, Papaveraceae, Leguminosse, Erythroxylaceae, Rutaceae, Aquifolia- cese, Sapindacese, Sterculiaceae, Punicaceae, Umbelli ferae, Logania- ceae, Apocynaceae, Solanaceae, Rubiaceae, and Lobeliaceae. THE AMOUNT OF ALKALOIDS in plants varies under different climatic conditions and is also very much influenced by culti- vation (see chapter on "Cultivation of Medicinal Plants"). For these reasons there is a wide range in the alkaloidal content of drug products, and, as the alkaloids are among the most poisonous constituents known, the various pharmacopoeias have set alkaloidal standards. At the International Conference for the Unification of Pharmacopceial Formulae for Potent Medicaments held in Brus- 166 A TEXT-BOOK OF BOTANY. sels in 1902 a protocol was prepared designating the strength of the various galenicals. Unfortunately, a standard for the alka- loidal content of drugs was not also established, and consequently in the several pharmacopoeias there is still some variation in drug standards. For percentage of alkaloids in different drugs and their variation, consult Volume II, treating of Pharmacognosy. CHEMICAL CLASSIFICATION OF ALKALOIDS. — The chemical study of the alkaloids shows that each plant contains not one but a number of alkaloids, cinchona bark and the opium poppy yield- ing not less than twenty different alkaloids. As their chemical constitution is not well known, it is customary even for the chemist to group them into certain natural classes, as the alkaloids of conium, tobacco alkaloids, the cinchona alkaloids, opium alka- loids, etc. They may also be grouped into certain fundamental groups, according to their nuclear structure derived from their probable constitution. While the natural classification may be more convenient, it will be replaced by a classification based on chemical constitution when our knowledge of this class of sub- stances is extended. From studies thus far made the following groups of alkaloids may be recognized : PYRIDINE GROUP. — Alkaloids derived from pyridine (C5H5N) are found in Conium maculatum, Piper nigrum, and other species of Piper, Trigonella Fccnum grcccum, Areca Catechu, Beta vul- garis, Nicotiana Tabacum, Pilocarpus Jaborandi and other species of Pilocarpus, Lupinus, Laburnum, and other genera of the Leguminoscc. This group includes the liquid or volatile alkaloids. PYRROLIDINE GROUP. — Derivatives of Pyrrolidine (C4H8NH) occur in Atropa, Hyoscyamus, Datura, Scopolia and other genera of the Solanacece, Erythroxylon Coca, and Punica Granatum. QUINOLINE GROUP. — Alkaloids with a Quinoline nucleus (C9H7N) are obtained from cinchona bark and nux vomica. ISOQUINOLINE GROUP. — Isoquinoline is isomeric with quino- line ; alkaloids with this nucleus are found in the opium poppy, Hydrastis canadensis, Berberis vulgaris, Menispermum canadense and quite a number of genera in the closely related families of Ranunculacecc, as well as in some other plants. PHENANTHRENE GROUP. — Morphine and codeine, closely re- CELL-CONTENTS AND FORMS OF CELLS. 167 lated alkaloids in opium, probably contain the Phenanthrene nucleus (C14H10). PURINE GROUP. — Caffeine, the characteristic alkaloid of coffee, tea, and guarana, as well as theobromine associated with caffeine in cacao and kolanut, are derivatives of Purine (C5H4N). AMINO-ACID GROUP. — Asparagine, or the monamide of aspartic acid, is very widely distributed throughout the plant kingdom. Consult J. W. Bruhl, " Die Pflanzen-Alkaloide " ; A. Pictet, " The Vegetable Alkaloids," translation by H. C. Biddle ; O. A Oesterle, " Grundriss der Pharmakochemie." ASPARAGINE (C4H8N2 + H2O) (/?-asparagine, the monamide of aspartic acid) is an amido compound which is most widely distrib- uted throughout the vegetable kingdom. It is found not only in reserve organs as the tubers of the potato and dahlia, the roots of althaea, belladonna, etc., and the seeds of the chestnut tree, but it also occurs in young shoots as of asparagus and in peas, beans, and other members of the Leguminosse. Asparagine has also been detected in some of the fungi as the Agaricineae and cer- tain of the Myxomycetes. Unlike certain derivatives of urea, it is a plastic product playing a very important role in plant metabolism. On account of its crystalline character and solubility in water, it is classed among the translocatory substances, appearing not only when proteins are being utilized by the plant, but when they are being formed. The crystals of asparagine are formed rather easily from the expressed juices of young shoots, and may be obtained even in sections upon mounting them in glycerin. The crystals vary in length from 0.3 mm. to 15 mm. (Fig. 98). Asparagine occurs in two forms, one of which is Isevo-rotatory and the other dextro-rotatory; the former is the one usually present in plants. At 17.5 ° C., i part of asparagine is soluble in 47 parts of distilled water; at 98° C., I part is soluble in 1.9 parts of distilled water. THE GLUCOSIDES or Glycosides are a class of plant substances which under the influence of ferments split up into a number of substances, one of which is always glucose (dextrose) or an analo- gous compound. Van Rijn has proposed the class name Glykoside for all substances of this group, restricting the name glucoside to those which yield glucose on hydrolysis. The glucosides are i68 A TEXT-BOOK OF BOTANY. always associated in the plant cell with the special ferments which are capable of decomposing them. There are other sub- stances which have the property of breaking up the glycosides, viz., dilute acids and alkalies. Of the mineral acids, dilute sulphuric acid and dilute hydrochloric acid are the most effective. They do not, however, always produce the same results on the same glucoside, as sometimes one acid works better than the other. Some glucosides are hydrolyzed by the use of strong FIG. 98. Microphotograph of the rhombic prisms of Asparagine (amido-succinamic acid), which is rather widely distributed in the vegetable kingdom. From aqueous solution the smaller crystals are combinations of base and prism (a) ; one or both of the acute angles may be truncated on the faces of the brachydome (b) ; in the larger crystals (c) the brachy- dome is more developed and is either equidimensional or elongated on the a -axis. organic acids, as oxalic acid and citric acid. In view of the fact that most glucosides require the presence of water in addition to the presence of the ferment to produce an interaction, they are looked upon as ether or ester derivatives. This view is strengthened by a careful study of the glucosides which have been prepared synthetically, but it is not known in what manner the glucoside is united with the other compounds making up the natural glucosides. CELL-CONTENTS AND FORMS OF CELLS. 169 DISTRIBUTION OF GLUCOSIDES. — This class of substances has only been isolated in the Dicotyledons, being present in the Pina- ceae, Gramineae, Liliaceae, Iridaceae, Salicaceae, Fagaceae, Moraceae, Urticaceae, Proteaceae, Santalaceae, Polygonaceae, Caryophyllaceae, Ranunculaceae, Magnoliaceae, Calycanthaceae, Anonaceae, Moni- miaceae, Cruciferae, Saxifragaceae, Rosaceae, Leguminosae, Tropaeo- laceae, Linaceae, Rutaceae, Simarubaceae, Polygalaceae, Anacar- diaceae, Corynocarpaceae, Aquifoliaceae, Celastraceae, Hippocas- tanaceae, Sapindaceae, Rhamnaceae, Vitaceae, Tiliaceae, Malvaceae, Theaceae, Dipterocarpacese, Cistaccae, Caricaceae, Datiscaceae, Thymelaeaceae, Lythraceae, Punicaceae, Combretaceae, Myrtaceae, Araliaceae, Ericaceae, Primulaceae, Sapotaceae, Oleaceae, Logania- ceae, Gentianaceae, Apocynaceae, Asclepiadaceae, Convolvulaceae, Hydrophyllacese, Boraginaceae, Verbenaceae, Labiatae, Solanaceae, Scrophulariaceae, Bignoniaceae, Orobanchaceae, Globulariaceae, Rubiaceae, Caprifoliaceae, Cucurbitaceae, and Compositae. CHEMICAL CLASSIFICATION. — The natural glucosides may be grouped either according to the nature of the sugar formed on hydrolysis or their probable organic derivatives. Most glucosides yield either dextrose or rhamnose. (i) Of the dextrose-gluco- sides the following may be mentioned : ^sculin, amygdalin, arbu- tin, coniferin, fraxin, gaultherin, gossypetin, gynocardin, indican, iridin, linamarin, phloridzin, populin, prulaurasin, ruberithrinic acid, salicin, sambunigrin, saponarin, serotin, sinalbin, sinigrin, and syringin. (2) Of the rhamnose-glucosides the following may be mentioned : Baptisin, datiscin, f rangulin, fustin, glycyphyllin, and quercitrin. (3) There are a few glucosides which yield peculiar sugars, as apiin, which on hydrolysis gives apiose and dextrose ; barbaloin forms d-arabinose ; convolvulin yields rho- deose and dextrose ; digitalin forms digitalose and dextrose ; digitonin forms galactose and dextrose; digitoxin yields digi- toxose; gentiin yields xylose and dextrose; hesperidin forms rhamnose and dextrose, which are also formed from naringin and rutin ; robinin forms galactose and rhamnose ; strophanthin yields rhamnose and mannose ; vicianin forms arabinose and dextrose ; and xanthorhamnin yields galactose and rhamnose. Rosenthaler (Pharm. Zentralh., 1907, p. 94) has attempted to group the glucosides, according to the constitution of the non- 170 A TEXT-BOOK OF BOTANY. sugar substance formed on the hydrolysis of the glucoside. He has given the non-sugar substances the class name of '' Aglykone," and groups the glucosides accordingly into the following three classes: I. Glucosides without Nitrogen Aglykones. II. Gluco- sides with Nitrogen Aglykones. III. Glucosides with Nitrogen and Sulphur Aglykones. Class I is further subdivided as its members yield aliphatic, aromatic, or other derivatives ; each .of these again is further subdivided into a number of subgroups. Among the aliphatic aglykones are included the glucosides jalapin and convolvulin. The glucosides with aromatic aglykones are subdivided as follows: (A) Those yielding benzol derivatives and include arbutin, salicin, populin, gaultherin, etc. (5) Deriva- tives containing the styrol nucleus include coniferin, daphnin, aes- culin, scopolin, fraxin, naringin, and hesperidin. (C) Derivatives containing anthracene in their constitution, as f rangulin, morindin, and the glucosides of emodin, rhein, etc. (D) Glucosides which are derivatives of flavon include apiin, fustin, quercitrin, rutin, xanthorrhannin. II. The glucosides with Nitrogen Aglykones include a number of cyanogenetic glucosides, of which amygdalin is the representative. III. The glucosides with Nitrogen and Sulphur Aglykones include sinigrin and sinalbin found in the genus Sinapis and other genera of the Cruciferae. (Consult J. J. L. van Rijn, " Die Glykoside"; O. A. Oesterle, " Grundriss der Pharmakochemie.") PROPERTIES OF THE GLUCOSIDES. — Like the alkaloids, some of the glucosides are highly toxic. Among those that possess a high degree of toxicity may be mentioned convallamarin, digitalin, scil- lain, strophanthin, sapotoxin, etc. They are soluble in water, alcohol, ethyl acetate, and chloroform, and insoluble in ether. The aqueous solutions are neutral or but faintly acid. Glucosides may be separated from solutions of salts of the alkaloids owing to the fact that they are soluble in chloroform and some other of the immiscible solvents, providing the solution is slightly acid. Most of the glucosides form well-developed crystals and may be studied with a petrographical microscope (Fig. 99). There is no special class of reagents, as with the alkaloids, used in their detection ; on the other hand, some of them give strikingly distinct color reactions whereby they may be detected in the CELL-CONTENTS AND FORMS OF CELLS. 171 tissues of the plant. With very few exceptions, however, the color reactions are not satisfactory. MICRO-CHEMISTRY OF GLUCOSIDES. — Although the glucosides upon extraction from the plant tissues form well-defined crystals (Fig. 99), they have not been identified as such in the plant. A few have been identified by giving distinct color reactions with certain reagents. The glucoside strophanthin can be detected in the seeds of Strophanthus hispidus. This glucoside is colored a brilliant green with sulphuric acid and is confined to the cells of the endosperm. The test is carried out as follows : Sections are mounted first in water and then transferred to a drop of sulphuric acid contained on the same slide, when the cells con- taining stropharithin are colored a bright green. Saponin is an- other glucoside which, it is stated, may be readily detected in plant cells, giving a reddish color reaction with sulphuric acid. Lafon's reagent also may be applied for the detection of saponin ; this consists in the use of two solutions: (a) equal volumes of alcohol and sulphuric acid; (&) a very dilute solution of ferric chloride. The sections are placed in solutions (a) and then a drop of solution (b) is added. Cells containing saponin are col- ored red, changing to violet, becoming brownish-blue, or brown upon the addition of ferric chloride. Coniferin, the glucoside found in the cells of pine and other Coniferous trees, is colored red with sulphuric acid ; it also gives a characteristic reaction on treatment of the section first with phenol, followed by sulphuric acid or hydrochloric acid, it becoming a deep blue almost instantly. THE SAPONINS are a group of glucosides which possess the common property of forming a froth on shaking their aqueous solutions, and are present in the " soap-plants," which have been widely used as detergents. The saponins also dissolve the red blood-corpuscles, and for this reason are considered to be toxic substances. They have been found in the cell-sap of a large number of plants, occurring in parenchyma cells and medullary rays of roots and stems, the secretion cells and secretion reser- voirs of leaves, and all parts of fruits and seeds. A large number of principles have been isolated from different plants, some of these being given distinct names, but the majority of them are homologous substances having the general formula CnH2n_8O10, 172 A TEXT-BOOK OF BOTANY. On account of some of the saponin-containing plants being added to beverages and used as emulsifying agents, the toxicity of a number of the saponins has been studied, those which are highly poisonous being known as sapotoxins. The following are some of the plants which contain sapotoxin: Quillaja Saponaria (9 per cent.), Agrostemma Githago (6.5 per cent.), Saponaria officinalis (4 to 5 per cent.), and Polygala Senega (2.5 per cent.). Saponins have been found in more than a hundred different plants, including one or more genera of the following families: Liliaceae, Dioscoreaceae, Araceae, Chenopodiaceae, Phytolaccaceae, Caryophyllacese, Berberidaceae, Magnoliaceae, Ranunculaceae, Bixaceae, Theaceae, Rutaceae, Zygophyllaceae, Meliaceae, Simaru- baceae, Sapindaceae, Hippocastanaceae, Melianthaceae, Polygalaceae, Pittosporaceae, Rhamnacese, Saxifragaceae, Passifloraceae, Big- noniaceae, Myrtacese, Rosaceae, Leguminosae, Primulaceae, Sapo- taceae, Oleaceae, Solanaceae, Scrophulariaceae, Rubiaceae, and Compositae. Gluco-alkaloids represent a class of compounds intermediate between the alkaloids and glucosides, possessing characteristics of each. To this class belong achilleine, found in various species of Achillea, and also solanine, found in a number of species of Solanum. FUNCTIONS OF ALKALOIDS AND GLUCOSIDES. — In the growth of the plant there must not only be an adaptation to the external conditions and provision made to protect the plant against tem- pests, drought, excessive light, extreme temperatures, etc., but the plant must protect itself from diseases as well as from the depredations of animals. As a rule, plants, particularly of the tropics, depend on their own power to repair any injury to which they may be subjected. Nevertheless, there are many plants which produce poisonous substances, and these are usually sup- posed to have the function of protecting them from various dis- eases, as well as attack by herbivorous animals. Many of the alkaloids and glucosides are apparently aplastic substances, — i.e., are formed either occasionally or continually as unavoidable by- products of metabolism, or are produced for special purposes. Some of these principles, as asparagine, an alkaloid, and hesperi- FIG. 99. Salicin. Orthorhombic crystals from alcoholic solution. FIG. 100. Cocaine hydrochloride. Aggregates from aqueous solution. CRYSTALS IN POLARIZED LIGHT (Crossed nicols). CELL-CONTENTS AND FORMS OF CELLS. 173 din, a glucoside, are not only products of constructive metabolism, *but are entirely reassimilated. SUBLIMABLE PRINCIPLES. — Quite a number of plant principles are capable of being sublimed. Not only is this true when they are in the pure state, but also when they are associated with other compounds in the plant cell. This fact is of very great interest in the examination of commercial articles and also in the study of the localization and distribution of plant constituents. The method of procedure is very simple, and. a small quantity of material only is necessary, usually from 0.020 to 0.050 Gm. being required. In the study of leaves a fragment about 10 square millimeters is sufficient. The material is dried, either cut up or more or less comminuted and placed in a small watch crystal, the latter being covered either with a slide or another watch crystal for the deposi- tion of the sublimate. The watch crystal containing the material is carefully heated either on a sand bath or on a bath containing sulphuric acid (Figs. 101 to 104). Rosenthaler (Ber. d. d. pharm. Ges., 1911, p. 338) has sug- gested in the examination of powdered drugs a specially con- structed apparatus. A small quantity of the powder is intro- duced by means of a long funnel into a suitable tube, so that nene of it comes into contact with the side walls. The powder should be covered with a layer of asbestos to prevent any of it being carried up mechanically. The tube is closed with a rubber stopper having two holes, one of which carries a doubly bent tube leading to a small vessel acting as a receiver, the other carrying a tube con- nected with an air-pump. The air is exhausted and the tube con- taining the drug is heated in a bath of sulphuric acid or paraffin. A sublimate will form in the upper part of the tube containing the material, and distillation products will pass into the tube acting as a receiver and can be tested with various solvents and reagents. Plants containing thein, vanillin, and coumarin may be examined by direct sublimation in a watch crystal. Substances which yield tarry distillate, as cinchona, hydrastis, piper, etc., probably are better examined using the apparatus described by Rosenthaler. Tunmann (Ber. d. d. pharm. Ges., 1911, p. 312) examined a number of plants of the Ericaceae and found, by the microsublima- 174 A TEXT-BOOK OF BOTANY. tion method, that they contained arbutin. The latter is a rather widely distributed glucoside in this family and yields upon treat- ment with solutions of emulsin or hydrochloric acid the sublimable principle hydrochinon. The latter forms prisms and plates and may be further examined with acetone solution, dilute solutions of . V \> V V l'« '/ ' ' ^ <=>—>««= -'»y^K^ ! / / fisstV^ii/X <*' --=^^/^^.. -Ml- FIG. 101. Alkaloids of hydrastis obtained by microsublimation. The method fol- lowed by Tunmann is to mix from o.oio to 0.050 Gm. of powdered hydrastis with a drop of water upon a glass slide and heat to a temperature of 80° to 95° C. The sublimate consists )f a number of radiating particles in which different types of crystals very soon separate (A). The microsublimate may be further treated with alcohol and a solution of potassium iodide, when crystals of hydrastine (B) and needle-shaped crystals of berberine (C) form. — After Tunmann in Gene & Co.'s Handelsbericht, 1912. ferric chloride and ammonia water. Arbutin occurs in the leaves of Arctostaphylos Uva-ursi, Vaccinium Myrtillus, Kalmia angustifolia, and Pyrola rotundi folia. Rosenthaler obtained definite crystals in the microsublimation or pyro-analysis of the following drugs : cinchona, uva-ursi, f ran- CELL-CONTENTS AND FORMS OF CELLS. 175 gula, rhamnus purshianus, rheum, hydrastis, opium, cubeba, piper, anisum, senna, radix scammoniae, chrysarobinum, rheum rhaponti- FIG. 102. Microsublimate crystals of alkaloids in hydrastis: A, White crystals of hydrastine formed upon the addition of chloroform to the sublimate. B, Type crystals obtained on the microsublimation of pure hydrastine hydrochloride. C, Type crystals obtained on the microsublimation of pure hydrastinine hydrochloride. D, Crystals of hydrastine formed upon the addition of water to the amorphous and crystalline sublimate obtained in the heating of powdered hydrastis. E, Resublimed crystals of hydrastin ibtained from the chloroformic solution of the microsublimate. — After Tunmann in Gehe Hi Co.'s Handelsbericht, 1912. cum, jalapa, coca, stramonium, kamala, cousso, aurantii fructus cortex, guarana, cacao, kola, cantharides, podophyllum, radix canaigre, and kava-kava. (Consult Figs. 101 to 104.) A TEXT-BOOK OF BOTANY. The drugs thus far studied may to some extent be grouped according to the sublimable constituents which give characteristic reactions. I. Thein- or caffeine-containing drugs, as coffee, tea, cacao, and guarana. 2. Arbutin-containing drugs or those yielding hydrochinon, as uva-ursi and other Ericaceae. 3. Drugs yielding oxymethylanthraquinone and giving a distinct purple color with solutions of the alkalies, as rhamnus purshianus, frangula, rheum, senna, etc. FIG. 103. Alkaloids of ipecac obtained by sublimation as follows: 0.050 Gm. of the powdered drus; is mixed with 2 drops of water on a glass slide and heated; the third dis- tillate at a temperature of 100° to 115° C. gives colorless or yellowish, highly refractive globules (A) in which crystals of emetin separate. B, Short, rod-shaped crystals of the double •alts formed on the addition of gold chloride to the globules of the oily distillate. C, Oily globules of the distillate uniting and in which, upon the addition of potassium bismuth iodide, small spherites arise. D, Crystals of the alkaloids formed on treating small sections of ipecac or o.ooi Gm. of the powder with an aqueous solution of picric acid acidified with hydrochloric acid. E, Crystals formed at edge of cover glass. — After Tunmann in Gehe & Co.'s Handelsbericht, 1912. Cell-sap Colors. — The majority of the other color-substances found in the higher plants besides the green and yellow principles previously mentioned occur in solution in the cell-sap, and may be in the nature of secondary substances derived from the plastid pigments, or they may be produced directly by the protoplasm. Upon making sections of the tissues containing cell-sap color- substances, not infrequently strikingly contrasting colors are observed in contiguous cells; as in the petals of the poppy and CELL-CONTENTS AND FORMS OF CELLS. 177 petals of certain lilies, where we find some cells of a deep purple color, others of a deep red, and still others of intermediate shades. These substances are easily extracted with water or dilute alco- hol and are all more or less affected by certain chemicals (many of which occur naturally in the plant), such as citric acid, oxalic acid, salts of calcium, iron, aluminum, etc. FIG. 104. Microcrystals formed in Kava-kava, the root of Piper methysticum: A, crystals of methysticin obtained on treatment of sections of the root or the powder with alcohol, the crystals being long rods, of p. light yellow color, attaining a length of 0.160 mm. and becoming violet red on the addition of sulphuric acid. B, Crystals of methysticinic acid obtained upon heating a small quantity of the powder with one or two drops of a solution of potassium hydroxide, then adding dilute alcohol and allowing the slide to stand for 24 hours. Crystals of methysticin can also be obtained upon sublimation, providing the powder has been acted on previously with dilute sulphuric acid, emulsin, or saliva. — After Tunmann in Gehe & Co.'s Handelsbericht, 1912. A number of plant pigments of this class are used as indi- cators in volumetric chemical analysis, their use in this connection being dependent upon their sensitiveness to acids and alkalies. The fact that they respond to iron salts, — that is, give a blue or green reaction with these salts, — would indicate that they are associated with tannin or that they are tannin-like compounds, as has been supposed by some writers, but they behave very differ- 12 1 78 A TEXT-BOOK OF BOTANY. ently from tannin toward other reagents, such as organic acids, alkalies, lime water, and solution of alum. An examination of the color-substances of a large number of plants shows that the flower color-substances are distributed in all parts of the plant. For example, the flower color-substance of the rose occurs in the leaves and prickles as well as in the petals. The color-substance in the root of the radish closely corre- sponds to that in the flowers, while the one in the grains of black Mexican corn corresponds to that in corn silk. The cell-sap color-substances are usually found in greatest amount at the tips of the branches, this being well marked in the foliage of the rose, and may be said to be rather characteristic of spring foliage. Not infrequently in the purple beech the young leaves will be of a distinct purplish-red color and almost entirely free from chlorophyll, suggesting a correspondence in position and color to a flower. Color in Autumn Leaves. — The coloring matters in both spring and autumn leaves closely resemble the cell-sap color- substances of flowers, although it is the spring leaves which give the most satisfactory results when examined. The fact that in the autumn leaves there is little or none of the plastid pigment present would point to the conclusion that the color-substances occurring in these leaves are in the nature of by-products and of no further use to the plant. Of course, in the case of autumn leaves, we know that these products cannot be further utilized by the plant, and for this reason we are justified in regarding them as waste products. So-called White Colors. — The so-called white colors in plants do not properly belong to either class, but may be said to be appearances due rather to the absence of color, and depending upon the reflection of light from transparent cells separated by relatively large intercellular spaces containing air. In other words, the effect produced by these cells may be likened to that produced by the globules in an emulsion. The white appearance is most pronounced in the pith cells of certain stems, where on the death of the cells the size of the intercellular spaces is increased and the colorless bodies in the cells as well as the walls reflect the light like snow crystals. CELL-CONTENTS AND FORMS OF CELLS. 179 CHEMISTRY OF PLANT COLOR PRINCIPLES. — The substances giving colors in plants may be divided into two classes: I. Sub- stances having a specific color, as chlorophyll in leaves, chromo- phyll in flowers and fruits, and anthocyanin, the cell-sap color in flowers. 2. Substances which, while they themselves are color- less and known as leuco-compounds, yet form color derivatives. Some of these are more or less readily oxidized, forming charac- teristic color-substances, as brazilin. Again, some occur as gluco- sides which through the action of ferments yield color-substances, as quercitrin, which yields the yellow pigment quercetin. All of the researches which have been made seem to indicate that the color in plants is due to a basic substance or nucleus, and that the variation in color is due to the nature and arrangement of certain groups and side chains. For example, benzo-quinhydrone is green in color, while thymo-quinhydrone is of a purplish color (Pharm. Review, 1908, p. 330). Again, the hydroxybenzoquinones vary in color with the number of hydroxy groups, hydroxybenzo- quinone being of a light yellow, di-hydroxybenzoquinone is of a dark yellow, tri-hydroxybenzoquinone is of a black color, and tetra-hydroxybenzoquinone is of a bluish-black color. In the artificial dyes there are a number of so-called chromo- phores or chromophorous groups (radicals) characteristic of the various classes. In plant color-substances, on the other hand, we find the carbonyl group (C = O), the imido group (NH), and C = C group. The introduction of the chromophorous radical gives a basic compound which is more or less colored and known as a chromogen. The intensity of the color varies on the intro- duction of certain salt-producing groups or auxochromes. In the case of plant pigments, the most important of these is the hydroxyl group, and, as we have just seen, the intensity of color varies according to the number of these groups. According to their constitution, plant color principles may be arranged into six different classes: i. Phenol derivatives, includ- ing orcin, the coloring principle in many lichens, that forms color- less prisms which become red ; and thymo-quinone found in Monarda (Kremers, in Pharm. Rev., 1908, p. 329). 2. Naphtha- lene derivatives, including juglon, which forms garnet-colored needles. 3. Anthracene derivatives, including alizarin, the color- 180 A TEXT-BOOK OF BOTANY. ing principle in madder root. 4. Pyrone derivatives, of which there are several, as gentisein, maclurin, catechin, and rottlerin. being xanthone derivatives ; quercetin, rhannetin, and fisetin, which are flovone derivatives ; and hsematoxylin and brasilin, being chro- mene derivatives. 5. Isoquinoline, of which berberine is an ex- ample. 6. Benz-pyrrol derivatives; in this group is indigotin or indigo blue, the coloring principle in Indigofera tinctoria. ORIGIN AND FORMATION OF ANTHOCYANIN. — At the present time it is very difficult to determine the nature of the chemical processes which underlie the formation of anthocyanin, or the pigment dissolved in the cell-sap and giving the blue, purplish, and reddish color to flowers, fruits, etc. A great many observations have been made on the distribution of anthocyanin, the nature of the constituents with which it is associated in the plant cell, and their relation to various metabolic processes. In order to determine the Mendelian factors for color it is necessary that we have a definite knowledge concerning the nature and formation of this pigment. Of the numerous theories which have been proposed concerning the formation of anthocyanin, that proposed by Muriel Wheldale (Jour. Genetics, 1911, p. 134) seems the most plausible and is as follows: (1) The soluble pigments of flowering plants, collectively termed anthocyanin, are oxidation products of colorless chromo- gens of an aromatic nature, which are present in the living tissues in combination with sugar as glucosides. (2) The process of formation of the glucoside from chromo- gen and sugar is of the nature of a reversible enzyme action : Chromogen + sugar •*~^ glucoside + water. (3) The chromogen can only be oxidized to anthocyanin after liberation from the glucoside, and the process of oxidation is carried out by one or more oxidizing enzymes : Chromogen + oxygen = anthocyanin. (4) From (2) and (3) we may deduce that the amount of free chromogen, and hence the quantity of pigment formed at any time in a tissue, is inversely proportional to the concentration of the sugar and directly proportional to the concentration of glucoside in that tissue. (5) The local formation of anthocyanin, which is character- CELL-CONTENTS AND FORMS OF CELLS. 181 istic of the normal plant, is due to local variation in concentration of either the free sugars or the glucosides in the tissues in which the pigment appears. The abnormal formation of pigment tinder altered conditions is due to differences in the concentration of these same substances due to changes in metabolism brought about by these conditions. (6) On the above hypothesis the formation of anthocyanin is brought into line with that of other pigments produced after the death of the plant, as, for example, indigo and the post-mortem or respiration pigments, so termed by Palladin. FUNCTION OF PLANT COLORS. — A great many theories have been advanced as to the nature and uses of color-substances by the plant. With the exception of chlorophyll present in the chloro- plastid and its relation to photosynthetic processes little is known concerning the other pigments. Without attempting to discuss the various theories which have been proposed concerning their uses, the following facts should be borne in mind : 1. The occurrence of chromoplastids in a reserve organ, as in the tuberous root of carrot, and the similar occurrence of chromo- plastids and of reserve starch in the petals of the buttercup, lead to the inference that the petal of the buttercup, like the root of the carrot, has the function of storing nutrient material. In each case cells containing chromoplastids rich in nitrogenous substances are associated with cells containing reserve materials. 2. The distribution of the so-called flower color-substances in other parts of the plant than the flower shows them to be in the nature of metabolic substances, and that the part which they play in attracting insects to flowers is incidental rather than funda- mental. (The fact that certain colored flowers as in spruce are pollinated by the wind would tend to confirm this view.) 3. Unorganized or cell-sap color-substances are distributed usually in largest amount at the termini of the branches, as in flowers and terminal leaves, or in roots, or in both tops and roots. Their occurrence in those portions of the plant which are young and growing points to the conclusion that they are not to be disre- garded in the study of metabolic processes. Goebel likewise holds to this view. He says that it is " very probable^ that the 182 A TEXT-BOOK OF BOTANY. feature of color which so often appears when the propagative organs are being brought forth has some connection with definite metabolic processes, although up till now we cannot recognize what these are." ARTIFICIAL COLORING OF FLOWERS. — Ever since the time of Magnol (1709) there has been considerable interest in the subject of coloring white flowers. A number of aniline dyes can be used, but those belonging chiefly to the azo and rosaniline coloring matters, especially the acid dyes or those used for dyeing wool, give the best result. These dyes are readily soluble in water, and the solutions are made up of a strength of I part of dye to 1,000 parts of water. The effects are best seen in white flowers and are produced by allowing the flower-stalks to remain in the solu- tions from one to two hours, when they are placed in water. With some flowers, as the cultivated anemones, the effects are noticeable in from ten to fifteen minutes. Some flowers will take up the dyes better than others. White flowers may be changed to yellow, orange, blue, green, purplish-red or magenta, crimson, purple, salmon-pink or gray by the use of the following dyes: 1. Yellow flowers are produced by the .use of the dye known commercially as '' Acid Yellow A. T.," which is chemically the sodium salt of disulpho-diphenylazin-dioxytartaric acid. 2. Orange-colored flowers may be produced by the use of the dye " Orange G. G.," which is the sodium salt of benzene-azo-/?- naphthol-disulphonic acid. 3. Blue flowers may be produced by the use of the dye " Cyanol F. F.," which is the sodium salt of meta-oxy-diethyl- diamido-phenyl-ditolyl-carbinol-disulphonic acid. 4. Green flowers may be produced by the use of equal parts of the dyes " Acid Yellow A. T.," and " Cyanol F. F." 5. Purplish-red flowers are produced by the use of the dye " Acid Magenta," which is the sodium salt of the trisulphonic acid of rosaniline. 6. Crimson flowers may be produced by the use of equal parts of the dyes " Acid Yellow A. T." and " Acid Magenta." 7. Purple flowers may be produced by the use of equal parts of " Cyanol F. F." and " Acid Magenta." CELL-CONTENTS AND FORMS OF CELLS. 183 8. Salmon-pink flowers may be produced by the use of the dye " Brilliant Croceine M. O. O.," which is the sodium salt of ben- zene-azo-benzene-azo-/3-naphthol-disulphonic acid. 9. Gray flowers may be produced by the use of the dye " Naph- thol Black B.," which is the sodium salt of disulpho-/?-naphtha- lene-azo- a-naphthalene-azo-/2-naphthol-disulphonic acid. Calcium oxalate is found in many of the higher plants, and in the algae and fungi as well ; while in the mosses, ferns, grasses, and sedges it is seldom found. It occurs in plants in crystals of either the monoclinic or tetragonal system. The crystals dissolve in any of the mineral acids without effervescence, and their identity is usually confirmed by the use of dilute hydrochloric acid. The crystals of the monoclinic system are rather widely distributed, while those of the tetragonal system are less frequent in their occurrence. • The crystals belonging to the monoclinic system (Fig. 105) may be subdivided according to their prevalent forms into a num- ber of sub-groups. I. SOLITARY CRYSTALS. — These are usually in the form of rhombohedra, sometimes in twin crystals of variable size (Fig. 108). They are very widely distributed, occurring in a number of modifications in the same plant, and are often very characteristic in the identification of economic products. The crystals of this group are sometimes mistaken for silica, owing to the fact that in some instances the lumen of the cell is completely filled by the crystal, and, the inner wall having the contour of the crystal, it is impossible to determine whether the crystal is affected by the use of hydro- chloric acid. It should be stated in this connection that silica never occurs as a cell-content in sharp, angular crystals, but either in more or less ellipsoidal or irregular hollow masses, or in some- what solid, irregularly branching forms (Fig. 109). II. COLUMNAR CRYSTALS or " styloids," being elongated prisms of the monoclinic system (Fig. 107, C), and when typical recall the crystals of gypsum. They also occur in twin-forms, some- times replacing raphides, and occasionally show a number of transition forms. Solitary crystals in the form of rhombohedra or styloids occur in a number of drugs, as follows: Acer spicatum, calumba, carda- 184 A TEXT-BOOK OF BOTANY. A D FIG. 105. Monoclinic crystals of calcium oxalate: A, a to f, crystals from the paren- chyma of the bark of the horse-chestnut (/Esculus Hippocastanum); B, a to c, from the pith of Periploca graca; C, a to e, from the parenchyma in the region of the fibrovascular bundles in Musa sinensis; D, a to c, from the petioles of the pinnate leaves of Cycas revoluta; E, a to c, crystals from the bark of the guaiac tree; F, a single crystal from Citrus Auran- tinm; G. a to c. rectangular crystals from a Brazilian Bignonia. — After Dippel in "Das Mikroskop. CELL-CONTEXTS AND FORMS OF CELLS. 185 momum, coca, eucalyptus, frangula, gelsemium, granatum, hama- melis, hyoscyamus, Jamaica quassia, krameria, pimenta, Prunus serotitta, quercus, quillaja, rhamnus purshianus, senna, uva-ursi, vanilla, viburnum prunifolium, and Xanthoxylum. III. ROSETTE AGGREGATES of calcium oxalate consist of numer- ous small prisms and pyramids, or hemihedral crystals more or less regularly arranged around a central axis, and have the appear- FIG. 106. Tetragonal crystals of calcium oxalate: A, a to f, crystals from the leaves of the onion (Allium Cepa) ; B, a to g, crystals from the stem of Trades- cantia viridis. — After Dippel in "Das Mikroskop." ance of a rosette or star (Fig. 107, A). The development of these aggregates may be readily observed in the stem of Datura Stramonium. Crystals of this class are more widely distributed than any of the others, and are characteristic of a number of drugs. Clustered crystals in the form of rosette aggregates occur in numerous drugs, as follows: Althaea, anisum, buchu, calendula, cannabis indica, carum, caryophyllus, castanea, chimaphila, conium, coriandrum, cusso, eriodictyon, euonymus, foeniculum, frangula,, galla, geranium, gossypii «ortex, granatum, humulus, jalapa, pilo- i86 A TEXT-BOOK OF BOTANY. carpus, pimenta, rheum, rumex, senna, stillingia, stramonii folia,, viburnum opulus, and viburnum prunifolium. IV. RAPHIDES are groups of needle-shaped crystals, especially prevalent in Monocotyledons (Fig. 107, B). They have been mis- FIG. 107. Forms of calcium oxalate crystals: A, transverse section of rheum show- ing rosette aggregates of calcium oxalate in three of the cells and starch grains in some of the others; B, longitudinal section of scilla showing raphides; C, longitudinal section of quillaja showing large monoclinic prisms of calcium oxalate and also some starch grains; D, transverse section of belladonna root showing one cell filled with sphenoidal micro-crys- tals, the remaining cells containing starch. taken by several observers for calcium phosphate. Calcium phos- phate, however, occurs in plants either in solution or in com- bination with protein substance. The cells containing raphides are long, thin-walled and contain, sooner or later, a mucilage, CELL-CONTENTS AND FORMS OF CELLS. 187 which arises from the cell-sap, is stained by corallin, and behaves with reagents much like cherry-gum. The cells are either isolated or occur in groups placed end to end, as in Veratrum viride. Raphides are found in relatively few drugs, as follows : Cinnamomum, convallaria, cypripedium, ipecacuanha, phytolacca, sarsaparilla, scilla, vanilla, and veratrum viride. V. CRYSTAL FIBERS. — In quite a number of drugs a single monoclinic prism or a rosette aggregate occurs in each of the parenchyma cells adjoining the sclerenchymatous fibers, and to this single longitudinal row of superimposed cells the name crystal FIG. 108. A, transverse section of hyoscyamus leaf showing monoclinic prisms of calcium oxalate, also a twin-crystal; B, longitudinal section of glycyrrhiza showing a crystal fiber, i.e., a row of superimposed cells, each containing a polygonal monoclinic prism of calcium oxalate, the crystal filling the cell. Adjoining the crystal fiber is a group of bast fibers on one side and some cells containing starch on the other. fiber has been applied (Fig. 108, B). Crystal fibers are typical of the following drugs: Aspidosperma, frangula, glycyrrhiza, hasmatoxylon, harnamelis, Prunus seroiina, quercus alba, quil- laja, rhamnus purshianus, and uva-ursi. VI. MICRO-CRYSTALS are exceedingly small (about 0.2 to IOM in diameter), apparently deltoid or arrow-shaped, and so numerous as to entirely fill the parenchyma cells in which they occur, giving the cells a grayish-black appearance which readily distinguishes them from other plant cells (Fig. 107, D}. It has been sup- posed that they are tetrahedrons, but they are probably sphenoids 1 88 A TEXT-BOOK OF BOTANY. in the monoclinic system, inasmuch as monoclinic prisms occur in neighboring cells in the same plant or drug, as in stramonium, quassia, etc. Because they are so small and in many instances not clearly defined they have been termed by the Germans " crystal- FIG. 109. Various forms of Silica found in plants. Long rods and spindle-shaped masses (A) and star-shaped fragments (B) found respectively in the thalloid structure made up of roots and shoots and in the leaves of Tristicha hypnoides, a small, moss-like plant (Podostemaceae) growing on rocks, etc., in running water, especially in waterfalls. C, a longitudinal section of the petiole of Caryota urens, a palm of Eastern Asia, showing grape-like clusters of silica completely filling the cells. D, hat-shaped fragments of silica occurring on the edge of the leaves of Cusparia macrophylla. a rutaceous tree growing near Rio Janeiro; in a, b, c, side views of the masses, whereas in d the surface view shows a struc- ture resembling that of sphere-crystals, E and F, siliceous fragments from the leaves of an orchid, Oncidium lencochilum, growing in Guatemala; in E is shown a base fiber with siliceous masses somewhat resembling the crystal-fibers of calcium oxalate, and in F the isolated siliceous masses are seen. — A and B, after Cario; C and D, after Rosanoff; E and F, after Pfitzer. — From Dippel in "Das Mikroskop." sand" (Kristallsand). The typical tetrahedral form was recog- nized by the French and termed " sable tetraedrique." Sphenoidal micro-crystals are found in the following drugs: Belladonnae folia, belladonnae radix, cinchona, dulcamara, phyto- lacca, quassia, Solatium carolinense, and tabacum. CELL-CONTENTS AND FORMS OF CELLS. 189 VII. MEMBRANE CRYSTALS. — There are several forms of crystals which may be included in this group. The so-called Rosanoff crystals consist of rosette aggregates attached to inward- protruding walls of the plant cell. These, however, do not concern us so much as the large monoclinic crystals which have a mem- brane surrounding them. The crystal first appears in the cell-sap, and then numerous oil globules appear in the protoplasm around it; later some of the walls of the cell thicken and grow around the crystal, which they finally completely envelop, as in Moraceae. Crystals of the orthorhombic system may occur either as soli- tary crystals or rosette aggregates, or in the form of acicular crystals and probably micro-crystals, being usually much smaller than the single crystals of the monoclinic system. Solereder, in his work on " Systematic Anatomy of the Dicoty- ledons/' states that the systematic value of the study of the forms of crystals varies considerably. While in some instances a certain form of crystal is characteristic of an entire order, yet in other cases it serves to distinguish only genera or species. In practical work in the identification of economic products the study of the forms of crystals is very important. A few instances may be mentioned. In Jamaica quassia calcium oxalate occurs in the form of 4- to 6-sided rhombohedral crystals, whereas in Surinam quassia the crystals are few or entirely wanting. In Levant scammony root occur numerous monoclinic prisms of calcium oxa- late, whereas in the Mexican root the crystals are chiefly in the form of rosette aggregates. In the bark of Viburnum Opulus the' calcium oxalate occurs almost entirely in the form of rosette aggre- gates, whereas in the bark of Acer spicatum solitary rhombo- hedral crystals are prevalent. In the identification of many drugs the presence or absence of calcium oxalate crystals and the study of the prevalent forms is very important (Fig. no). Owing to the importance of the study of calcium oxalate an enumeration of the families in which calcium oxalate occurs is given. I. Crystals of calcium oxalate, either in the form of solitary rhombohedra or clustered aggregates, are found in the following families: Aceracese, Ampelidacese (also raphides), Anacardiaceae, Apocynacese, Araliacese, Asclepiadacese, Berberidaceae, Bignonia- 190 A TEXT-BOOK OF BOTANY. A B •a/ FIG. no. A few illustrations showing the practical value of the study of calcium oxalate: A, digitalis, without any calcium oxalate; B, hyoscyamus in which monoclinic prisms predominate; C, belladonna, characterized chiefly by sphenoidal micro-crystals as well as occasional prisms; D, stramonium, having rosette aggregates in addition to prisms which are found in the petioles and stems and sphenoidal micro-crystals, which are abundant in the root. — a, upper epidermis; b, lower epidermis; c, non-glandular hairs (which in stra- monium art tuberculate) ; d, glandular hairs; e, calcium oxalate crystals; f, fragments of xylem showing tracheae with bordered pores (s), reticulate markings (r), simple pores (p), spiral thickening (1), and wood fibers (w); g, bast fibers, which, together with wood fibers, are wanting in digitalis. CELL-CONTENTS AND FORMS OF CELLS. 191 ceae (also in the form of octahedra and small acicular crystals), Bixaceae, Bruniaceae, Burseraceae, Buxaceae (also styloids and micro-crystals), Cactaceae, Canellaceae, Capparidaceae, Caprifolia- ceae, Caryophyllaceae, Casuarinaceae, Celastraceae, Combretaceae, Convolvulaceae (also small acicular crystals), Cornaceae (also micro-crystals), Ebenacese, Ericaceae, Euphorbiaceae, Fagaceae, Geraniaceae (also raphides), Guttiferae, Hamamelidaceae, Hippo- castanaceae, Hypericaceae, Juglandaceae, Lecythidaceae, Linaceae, Loganiaceae, Loranthaceae, Lythraceae, Magnoliaceae, Malpighia- ceae, Malvaceae, Meliaceae, Menispermaceae (also small acicular crystals), Moraceae, Myricaceae, Myrsinaceae, Myrtaceae, Oleaceae, Passifloraceae, Pittosporaceae (also columnar crystals), Platana- ceae, Plumbaginaceae, Podostemaceae, Polygalaceae, Polygonaceae, Portulacaceae (also micro-crystals), Rhamnaceae, Rhizophoraceae, Rosaceae, Rubiaceae (also raphides, micro-crystals, rhombohedra, and small acicular crystals), Rutaceae (also styloids and raphides), Salicaceae, Santalaceae, Sapindaceae, Sapotaceae (also micro-crys- tals), Saxifragaceae, Simarubaceae, Solanaceae (also micro-crys- tals), Staphyleaceae, Sterculiaceae, Theaceae (also raphides and styloids), Thymelaeaceae (also micro-crystals), Tiliaceae, Ulmaceae, Umbelliferae, Urticaceae, Vaccinaceae, Verbenaceae (also small prisms and acicular crystals), Violaceae, and Zygophyllaceae. Solitary rhombohedra are found in a relatively few families and are characteristic of the following: Connaraceae, Crassulaceae, Cucurbitaceae, and Leguminosae. II. Crystals in the tetragonal system occurring in the form of small octahedra or prisms, as twin-crystals, and in the form of short rods or needles are found in the following families : Acera- ceae, Apocynaceae, Araliaceae, Aristolochiaceae, Begoniaceae, Big- noniaceae, Boraginaceae, Cactaceae, Caesalpinaceae, Calycanthaceae, Campanulaceae, Canellaceae, Capparidaceae, Chenipodiaceae, Com- positae, Convolvulaceae, Gentianaceae, Gesneraceae, Guttiferae, Lau- raceae, Loganiaceae, Magnoliaceae, Melastomaceae, Menispermaceae, Moraceae, Myristicaceae, Monimiaceae, Oleacese, Papilionaceae, Phytolaccaceae, Piperaceae, Polemoniaceae, Ranunculaceae, Rubia- ceae, Saxifragaceae, Scrophulariaceae, Simarubaceae, Solanaceae, Sterculiaceae, Styracaeeae, and Zygophyllaceae. 192 A TEXT-BOOK OF BOTANY. III. Rosette aggregates or clustered crystals sometimes accom- panying other forms are found in the following families : Acantha- ceae, Begoniaceae, Boraginacese, Calyceraces, Campanulacese, Can- dolleaceae, Chenopodiaceae, Chloranthaceae, Elatinaceae, Empetra- cese, Gentianaceae, Gesneracese, Hydrophyllaceae, Labiatae, Loasa- ceae, Magnoliaceae, Melastomaceae, Melianthaceae, Myristicaceae, Nepenthaceae, Nymphaeaceae, Onagraceae, Papaveraceae, Phytolac- caceae, Piperaceae, Polemoniaceae, Ranunculaceae, Sarraceniaceae, and Turneraceae. IV. Sphaerites (sphere-crystals), or rosette aggregates com- posed of very small needles, have been observed in certain plants of the following families: Aceraceae, Asclepiadaceae, Berberidaceae, Cactaceae, Combretaceae, Crassulaceae, Empetraceae, Euphorbiaceae, Geraniaceae, Melastomaceae, Papilionaceae, Phytolaccaceae, Rosa- ceae, and Solanaceae. V. Raphides are sometimes associated with other forms of crystals, as micro-crystals, rosette aggregates, rhombohedra, and styloids. They are widely distributed among the Monocotyledons and occur in the following Dicotyledons : Geraniaceae, Gesneraceae, Melianthaceae, Phytolaccaceae, Rubiaceae, Rutaceae, Saxifragaceae, Theaceae, Urticaceae, and Zygophyllaceae. PLANT PROTEINS. T^e proteins are nitrogenous compounds, most of which con- tain sulphur and some of which contain phosphorus. Their con- stitution or the molecular structure of their molecules has not been determined, but they are very large, and are built up of amino- acids, the simplest of which is glycocoll (amino-acetic acid). Apart from the protoplasm found in living cells, the propor- tion of proteins in plants is relatively small, except in seeds, where they serve as nutriment during the germinating period, being made available by the action of proteolytic enzymes. Most of the plant proteins are GLOBULINS, and collectively have been termed phyto- globulins. (i) The globulins are insoluble in pure water and in dilute acids, but are soluble in dilute solutions of sodium chloride ( i to 20 per cent.), afnmonium chloride, sodium sulphate and dilute solution of potassium hydrate, from which solutions they may be precipitated by dilution, dialysis, of acidification with CO2 CELL 2I-59 to 32-945 soja beans, 24.38 to 49.10; string beans, 13.06 to 20.19; and Vicia faba, 21.00 to 36.10. Miscellaneous Seeds. — Beechnut, about 25 ; cacao, 7.32 to 15.94; cocoanut, 7.75 to 10.90; chestnut, 5.15 to 15.75; hazel-nut, 16.23 to 21.22; flaxseed, 18.49 to 33.80; mustard, 15.50 to 39.66; coffee, 17.11 to 25.09; rape-seed, 15.18 to 28.13; ricinus, 16.35 to 22.28; sunflower-seed, 5.67 to 33.89 ; sweet almond, 17.50 to 26.62. Common Vegetables. — Asparagus, 15.12 to 33.52; sugar beets, 3.11 to 23.02; garden beets, 4.19 to 29.27; carrots, 3.79 to 16.64; cauliflower, 17.23 to 37.75 ; celery, 8.44 to 25.19 ; cucumber, 21.38 to 26.06; garlic, 1.17 to 13.50; parsnips, 6.38 to 13.50; potatoes, 2.21 to 17.59; sweet potatoes, 1.70 to 19.61; radish, 13.00 to 22.13; spinach, 27.50 to 45.33; and turnips, 4.01 to 21.00. Fruits. — Apples, 0.22 to 1.32; apricots, 0.13 to 1.79; bananas, 3.37 to 7-75; cherries, 0.97 to 4.75; cucumber, 21.38 to 26.06; currants, o.n to 1.44; figs, 0.90 to 2.58; gooseberries, .21 to .94; grapes, 0.22 to 1.20; lemons, 0.49 to 2.90; musk melon, 4.69 to 22.23; oranges, 4.83 to 2.24; peaches, 0.23 to 1.67; pears, 0.19 to 200 A TEXT-BOOK OF BOTANY. 0.56; plums, 0.27 to 0.99; prunes, 0.59 to 0.69; pumpkin, 30.31 to 36.25; raspberries, 0.18 to 1.47; strawberries, 0.35 to 1.05. Spices. — Anise, 16.31 to 18.15; capsicum, 11.20 to 16.81 ; cardamom, 5.50 to 14.77; caraway, 19.43 to 20.25; cloves, 4.73 to 7.06; cinnamon, i.oi to 8.00; coriander, 10.94 t° 12.03; curcuma, 9.18 to 12.56; dill, 6.75 to 21.56; fennel, 16.28 to 17.19; ginger, 3.27 to 10.83 > mace, 4.55 to 7.80 ; mustard, 15.50 to 39.66; nutmeg, 5.16 to 7.12; pepper, 15.18; paprika, 10.9 to 27.16. Miscellaneous. — Agaricus campestris, 20.63 to 62.94 ; sea- weeds, 5.56 to 39.25. CALCIUM CARBONATE occurs occasionally in the form of a cell- content, being present in tracheae or vessels and tracheids of the heart wood, as well as in the medullary rays and pith cells of certain plants. In this form it is rather characteristic of one or more genera in the following families : Aceraceae, Anonacese, Cornacese, Cupuliferae, Rosaceae, Salicaceae, Sapotaceae, Urti- caceae, and Zygophyllaceae. When present it almost completely fills the cells, and may be overlooked or referred to as resin unless its identity is proved by the use of certain reagents. Like the other carbonates, it dissolves with effervescence on the addition of hydrochloric acid, nitric acid, acetic acid, etc., and in this way may be detected. Calcium carbonate is present in special structures known as Cystoliths. The latter are protuberances of the cell wall into the cell, and consist of a stalk and a body (Fig. 113). The stalk consists of a simple core of cellulose on which more or less silica is deposited. The upper or body portion consists of a more or less irregular spherical or ellipsoidal deposit of calcium carbonate. These are found in the parenchyma cells in roots and barks and the subepidermal cells of leaves. They are also found in epidermal cells, as in the short hairs of Cannabis sativa. Cystoliths occur in certain genera of the Acanthaceae, Borraginaceae, Cucurbi- taceae, Gesneraceae, Oleaceae, Ulmaceae, Moraceae, and Urticaceae. Cystoliths occur in a number of modifications, and, while they are usually simple, yet in some of the Acanthaceae and Urticaceae branched cystoliths occur. In some of the genera of the Cucur- bitaceae 2- to 4-adjoning cells may have cystoliths, and hence are known as " double, cystoliths," The cystoliths found in hairs, as CELL-CONTENTS AND FORMS OF CELLS. 201 in Cannabis sativa, do not usually have a stalk, and are known as " hair cystoliths." The latter are, furthermore, variously modi- fied, and may have incrustations of either calcium carbonate or silica or a mixture of both of these substances. In the Begoniacese occurs a certain form of structure resembling a cystolith, but it is uncalcified, and consists of a mucilaginous substance which is ' ==;^=::^F=^/f:==^^::^^^ FIG. 1 13. Cystolith. A cross section of a portion of the leaf ftf Ficus elastica showing cells of the upper epidermis (e), cells of the hypodermal layer (h), among which is a large cell containing a cystolith (c); palisade cells (ch). — After Sachs. sometimes more or less impregnated with resin. These are known as " cystotyles." The protuberances found on the walls of certain epidermal cells and in the subsidiary cells of hairs may be either calcined or silicified, and occur in the families containing true cystoliths and also some genera of the following: Com- positse, Campanulacese, Oleaceae, Leguminosae, Hydrophyllacese, 202 A TEXT-BOOK OF BOTANY. Scrophulariaceae, Polemoniaceae, Verbenaceae, Euphorbiaceae, and Urticaceae. SILICA is seldom found as a cell-content, and when present never occurs as a crystalline deposit, being usually in the form of amorphous masses, termed "silica-bodies" (Fig. 109). The latter arise either in the cell-sap or the silica is deposited on the cdll-wall, ultimately filling the lumen of the cell. In the palms the silica-bodies resemble stalkless cystoliths (Fig. 109, C). They may also occur in the form of long rods, being more or less fusi- form or rectangular, or in the form of discs showing a more or less sphero-crystalline structure, or in other special forms (Fig. 109). Silica-bodies have been found in the Palmae, Orchidaceae, Podoste- maceae, and Rutaceae. Silica is insoluble in any of the ordinary solvents, being dissolved only by hydrofluoric acid. On incinerating the tissues it is not destroyed. The presence of silica may be deter- mined readily upon heating sections with sulphuric acid or any reagent that destroys organic matter. •Silica usually occurs as an incrustation in the cell-wall, being found in epidermal cells, spinose hairs, and even the palisade and mesophyll cells of quite a number of plants. Siliceous walls are rather characteristic of the genera of the following families: Acanthaceae, Aristolochiacese, Bignoniaceae, Borraginaceae, Burseraceas, Calycanthaceae, Campanulaceae, Chloranthaceae, Combretaceae, Compositae, Cucurbitaceae, Dilleniaceae, Euphor- biaceae, Gesneraceae, Goodeniaceas, Hydrophyllaceae, Leguminosae, Loranthaceae, Magnoliaceae, Melastomaceae, Menispermaceae, Oleaceae, Piperaceae, Proteaceae, Rosaceae, Rubiaceae, Santalaceae, Saxifragaceae, Urticaceae, and Verbenaceae. TANNINS AND TANNIDES. — There is a group of water-soluble principles that occur in the cell-sap, especially of parenchyma cells, of a large number of plants. They are derivatives of phenol and phenol acids, and give either dark blue or green precipitates with solutions of ferric chloride. They were formerly designated as tannins and distinguished according to the plants from which they were obtained ; thus we had chestnut tannin, oak tannin, etc. Recent studies on the constitution of these substances show that there are two principal groups of tannins, (i) being in the nature of glucosides and (2) the other not yielding any dextrose on CELL-CONTENTS AND FORMS OF CELLS. 203 hydrolysis with acids. Both of these groups may be subdivided into two classes, namely, (A) those which probably are deriva- tives of protocatechuic acid and (B) those which are derivatives of gallic acid. A class name has been given to include these subgroups, namely, " tannides " or " tannoids." The first sub- group (A) would then include the protocatechuic-tannides or -tannoids, and the second (5) would comprise the gallic-tannides or -tannoids. In working out a system of classification of this kind Kunz-Krause (Swheis. Woch. f. Chem. u. Phann., 1898, p. 424) has arranged all of the possible tannides or tannoids and has given the formulae for a number which have not yet been found in nature. CHEMICAL PROPERTIES OF TANNINS. — The tannins are amor- phous substances and do not form crystalline salts. They are soluble in water, alcohol, ethyl acetate, or a mixture of alcohol and ether. They are almost insoluble in anhydrous ether, chloro- form, and the other immiscible solvents. The solutions give dis- tinct color reactions or precipitates with ferric chloride, stannous chloride, and acetates of copper and lead. They form soluble compounds with iodine and prevent the latter from giving the characteristic blue reaction with starch. Solutions of tannin give insoluble precipitates with cinchonine and other organic bases. Tannins are, furthermore, especially in alkaline solutions, powerful reducing agents, their resulting products being of a dark red or yellowish-red color. Upon treatment of tannins with dilute acids, or fusing with the alkali hydroxides, or heating alone, several classes of products are formed. i. When heated in a sealed tube at 100° C. solutions of tannin in a i per cent, solution of hydrochloric acid yield either crystal- lizable acids, or phlobaphenes, or insoluble red substances. (A) The following glucosidal tannins yield crystallizable acids : The tannin from nut-galls, divi-divi (fruit of Ccusalpinia coriaria), myrobalans (fruit of Terminalia Chebula}, rind of pomegranate fruit, and coffee. (B) Phlobaphene is a reddish, or brownish-red, amorphous substance formed from the tannin of willow bark. It is insoluble in water but soluble in alcohol, dilute solutions of the alkalies and alkali carbonates, and solutions of borax. (C) 204 A TEXT-BOOK OF BOTANY. Quite a number of tannins yield a reddish, amorphous substance which precipitates out of the acid solution and is insoluble in water, alcohol, and solutions of the alkalies. Derivatives of this kind are obtained from the tannin of kino, krameria, etc. 2. When tannins are fused with potassium or sodium hydrox- ide several classes of products are formed, depending on the con- stitution of the tannin. (A) Protocatechuic acid is formed not only on the fusion of certain tannins, but may be prepared from other plant substances, as vanillin, asafcetida, myrrh, etc. Usually other substances are formed in the interaction, these being either acetic acid or phloroglucinol. In this class are in- cluded the most of the tannins, which on heating with dilute acids yield either phlobaphenes or insoluble red substances. (£) Pyrogallol, which is commercially prepared by the dry distillation of gallic acid, is also formed from the glucosidal tannins which yield crystallizable acids in acid solutions. 3. Upon carefully heating tannins to a temperature of 190° to 200° C. they are decomposed and yield two distinct classes of derivatives, being either (A) pyrocatechol (a diatomic phenol) or (B) pyrogallol (a triatomic phenol). Both of these substances are crystalline and may be sublimed unchanged. They are, furthermore, both soluble in water, alcohol, and ether, and are distinguished by giving very characteristic reactions with certain reagents. Solutions of pyrocatechol are colored dark green with ferric-alum and greenish with copper sulphate -f- ammonium hydrate, or concentrated sulphuric acid. Pyrogallol is colored bluish-black with ferric-alum, becoming green and finally brown ; brownish with copper sulphate -(- ammonium hydrate, or sul- phuric acid, and becoming violet with lime water, rapidly chang- ing to brown. Pyrocatechol is formed from those tannins which produce protocatechuic acids on fusion with potassium hydroxide and phlobaphenes or insoluble red substances on treatment with acids. Pyrogallol is formed on heating those tannins which also yield pyrogallol on fusion with potassium hydroxide and yield either gallic acid or ellagic acid on hydrolysis with acids. MICROCHEMISTRY OF TANNINS. — Tannin ocurs as a constituent cf the cell-sap, and the cells containing it may be determined by use of dilute solutions of methylene blue, as proposed by Pfeffer, CELL-CONTENTS AND FORMS OF CELLS. 205 which colors the cell-sap blue, afterward precipitating the tannin. This reagent has the advantage that when used in very dilute solution ( i part methylene blue to 500,000 of water) it does not injure the protoplasm of the living cells, so that the cut end of a twig may be placed in the solution for i to 24 hours and sections examined from time to time. Another reagent that is very satisfactory in the examination of living material is a solution of ammonium carbonate, which causes a precipitation of the tannin in the cells in the form of very small globules or rods. This solu- tion may be used either directly upon sections or by placing freshly cut stems in dilute solutions (i part ammonium carbonate and 200 parts water). Ammonium carbonate does not precipitate gallic acid and therefore may be advantageously used in the study of the development of tannin and related substances, as in galls. The following reagents also give distinct reactions for tannin. Copper acetate in concentrated aqueous solutions is one of the very best reagents for the localization of tannin cells. It is em- ployed by allowing the leaves or twigs to remain in the solution for some days, when the tannin forms a reddish-brown precipitate in the cells. Ferric chloride and ferric acetate also precipitate tannin. Moeller has suggested the use of a solution of iron chloride in anhydrous ether, the cut pieces of the stems and leaves being placed directly in this reagent. Potassium bichromate and chromic acid in dilute solutions give yellowish-brown or blackish- brown precipitate with tannin. DISTRIBUTION OF TANNIN. — There are very few plants in which tannin does not occur in some of the parts or at least in cer- tain cells during some period in their development. This is fre- quently noted in making sections of plant material with a razor ; the liberated cell-sap is colored a dark blue. It is found in the form of highly refracting globules in the Zygnemaceae and other Algae. It occurs in relatively large amounts in some of the ferns, and, with the exception of the Monocotyledons, is widely distributed in the Spermophytes. As tannin is widely used in the making of leather and as a mordant in dyeing, etc., it is extracted from various plants and is an article of commerce. The following are some of the important tannin-yielding plants : The bark of hemlock (Tsuga canadensis, Fam. Pinaceae) yields nearly 14 per cent, of 206 A TEXT-BOOK OF BOTANY. tannin; the bark of several species of Pinus (Fam. Pinacess) growing in southern Europe yields 7 to 10 per cent, of tannin; the barks of the white spruce (Picea canadensis} of Canada, of the larch (Larix laricina) of northern and northwestern part of United States and Canada, and of the fir (Abies balsamea) yield similar amounts of tannin as the barks of hemlock and pine. The wood of chestnut (Castanea dentata, Fam. Fagaceae) yields 8 to 10 per cent, of tannin ; the bark of several species of Salix (Fam. Salicaceae) growing in northern Europe yields 3 to 12 per cent, of tannin ; the bark of chestnut oak, white oak, red oak, etc. (Fagaceae), yields 12 to 15 per cent, of tannin; the scaly in- volucres or acorri-cups (under the name of " Valonia ") of several species of Quercus growing in southern Europe and Levant yield 25 to 35 per cent, of tannin ; the fruit of Terminalia Chebula (under the name of " Myrobalans ") yields 35 to 40 per cent, of tannin ; the stems and leaves of several species of Rhus (Anacardiaceae) yield 1 6 to 24 per cent, of tannin; the fruit of Ccesalpinia coriaria (Fam. Leguminosae) (under the name of " divi-divi ") yields 30 to 50 per cent, of tannin; the wood and the bark of several species of Schinopsis (Fam. Apocynaceae) growing in South America yield from 15 to 23 per cent, of tannin, which is usually found in commerce in the form of an extract known as " Quebracho Extract " ; the bark of the common horse- chestnut (^sculus Hippocastanum, Fam. Sapindaceae) yields considerable tannin, and is employed in Italy ; the bark of Myrica Nagi (Fam. Myricaceae) contains n to 14 per cent, of tannin; the bark of Malpighia glabra (Malpighiaceae) (under the name of " Nance bark ") is used in Mexico and yields about 26 per cent, of tannin ; the bark of Stryphnodendron polyphyllum ( Fam. Leguminosae) yields about 30 per cent, tannin. The tannin of a number of other plants has been investigated, some of these being used in medicine, as granatum, catechu, kino, krameria, tor- mentilla, gambir, etc. (see Vol. II). GALLS. — There are a number of excrescences, found upon the leaves and twigs of a number of plants, termed galls. These result from injuries caused chiefly by insects, and are therefore in the nature of pathological products. Galls which are formed on trees which in themselves contain considerable tannin usually CELL-CONTENTS AND FORMS OF CELLS. 207 yield very large amounts of tannin. Nut-galls formed on certain species of oak yield 65 per cent, of tannin. The Japanese galls and Chinese galls formed on the leaf stalks and young branches of some species of Rhus contain about 70 per cent, of tannin. The galls found occasionally on sumach (Rhus glabra), a shrub abundant in North America, yield over 60 per cent, of tannic acid. The tannins obtained from excrescences of this character were at one time called " pathological tannins," to distinguish them from the tannins formed naturally in the living plant, and which were called " physiological tannins." In the light of the studies on the several tannins this terminology is no longer accepted. INCLUSION CELLS AND TANNIN IDIOBLASTS. — In a number of plants occur special cells which vary considerably in form and con- tents, but are distinguished by giving reactions for tannin. In- clusion cells were first described by Fliickiger in the fruit of Ceratonia Siliqua. These occur in the form of long tubes, which are easily separated from the pulp, and the yellowish contents are colored blue with solutions of ferrous sulphate or ferric chloride. Recently Hanausek has contributed several papers on the distribution of inclusion cells in a number of different plants. In the leaves of Pistacia Lentiscus he found (Ber. d. d. Bot. Ges., 1914, p. 117) that the upper row of palisade cells and the loose mesophyll cells (Fig. 114, A) contain numerous somewhat elongated, transversely striated bodies, which completely fill the cells. These are colored dark green or blackish with ferric chloride and a pale violet with a solution of potassium hydrate. The contents dissolve on heating, changing to a brownish color. They are also partly soluble in concentrated sulphuric acid, and with solutions of vanillin + hydrochloric acid the contents are colored red. They are not completely soluble in hot solutions of potassium hydroxide, there always remaining a small, colorless portion. The inclusions in the date (Fig. 114, B) and tamarind resemble those found in the fruit of St. John's Bread (Ceratonia) and leaves of Pistacia. Inclusions have been found in the seed coat of Pimenta and one or more fruits in the following families : Anonaceae, Anacardiaceae, Ebenaceae, Elaeagnaceae, Leguminosae, Palmse, Rhamnaceae, and Rosaceae. 208 A TEXT-BOOK OF BOTANY. TANNIN IDIOBLASTS were first observed by Zopf in a number of genera of the Fumariaceae (Fig. 115). These are somewhat analogous to and resemble the latex or pigment cells in the Papa- veraceae. They develop in the meristematic cells of certain tissue systems and remain constant throughout the life of the plant. The FIG. 114. Inclusion Cells: A, section of leaf 01 Pistacia Lentiscus showing numerous Inclusion cells (in) in the upper palisade layer and cells of mesophyll; calcium oxalate (kr); palisade layers (pa) ; loose mesophyll (m) ; fibrovascular bundle (i); upper epidermis (ep) ; granules of fatty substance (i); lower epidermis (ep); stoma (sp). B, Inclusion cells or tubes (k, 1, m) in the fruit of the date palm; k, showing a homogeneous amorphous content> 1 and m, separation of irregular inclusion masses in form of projections from the wall. — After Hanausek. cells vary in shape, composition of wall, and color of contents. They may be either short, isolated cells or occur in chains ; or they may become elongated, resembling fibers. The walls may be composed of cellulose or contain a certain amount of lignin or suberin. Some of the cells may contain a nucleus. The cell-sap CELL-CONTENTS AND FORMS OF CELLS. 209 A D FIG. 115. Idioblasts containing tannin and anthocyanin: A-D, idioblasts in primary cortex of root of Corydalis ochroleuca, showing a short, thin-walled cell with reddish sap (A, t), and a long fiber with yellowish content. (A, e); three short, thick-walled idioblasts (B) with a reddish cell-sap; a short fiber with yellowish contents (C) and transverse sections, through an idioblast (D), showing the thick, porous walls. E, a portion of an idioblast, with thick, porous walls, from the pith of Fumaria muralis. F to H, idioblasts in Parnassia Palustris; F, portion of epidermis of leaf showing 5 idioblasts (t) with colorless but highly refracting tannin content; G, portion of epidermal layer of corolla tube with reddish an- thocyanin idioblasts (t) ; H, portion of epidermal layer at the base of corolla tube with very long idioblasts (t) containing a red-colored cell-sap. — After W. Zopf, "Uber die Gerbstoff- und Anthocyan-Behalter der Fumariaceen und einiger anderen Pflanzen," in Bibliotheca Botanica. 14 210 A TEXT-BOOK OF BOTANY. may be either colorless or of an intensely yellow or bright red color, giving a distinct reaction for tannin. The cell-sap is soluble in water and in alcohol and gives an acid reaction. In the yellow idioblasts upon treatment with nitric acid it is colored orange-red, changing to reddish-brown ; with concentrated sulphuric acid it becomes orange-red and finally of a rose-red or crimson color; with solutions of the alkalies it becomes greenish, and it is precipitated with solutions of potassium bichromate, ferric acetate, or ferrous sulphate, the precipitates resembling those found with tannin. Zopf found that the tannin idioblasts may possess either a colorless content or, in addition, have a yellow coloring prin- ciple (yellow anthocyanin) or a red pigment (red anthocyanin). He considers that the yellow pigment is derived from a colorless chromogen and that the red pigment may be formed from either a colorless chromogen or from yellow anthocyanin. Further- more, he concludes that there is a relationship in the Fumariaceae between the anthocyanin and tannin, as the two constituents are always found in the same cell. It is rather interesting to note that chloroplasts may be found in the idioblasts, and that sugar is also a constituent in the idioblasts, occurring in the young roots and stems of Diclytra spectabilis. Tannin idioblasts are found in the palisade tissues of leaves or in the parenchyma cells of roots and stems of some of the genera in the Geraniacese, Celastraceae, Rhamnaceae, Legumi- nosae, Solanaceae, Rubiaceae, Scrophulariaceae, Polygonaceae, Aristolochiaceae, Piperaceae, Euphorbiaceae and Moraceae. THE FIXED OILS, FATS, AND WAXES include a group of sub- stances whiclj are widely distributed in plants, occurring especially abundant in seeds, fruits, and barks. They are distinguished by the fact that in their chemical constitution they possess radicals of the fatty acids. In the diatoms, Vaucheria, and some of the other lower plants fixed oils arise in the chromatophores in place of starch, thus being the first visible product of photosynthesis. Fixed oils usually occur in reserve cells as in seeds and the parenchyma and medullary ray cells of roots and rhizomes. They are either found in the vacuoles of the protoplasm or are formed in the cell-wall, and usually are liberated in the form of globules upon healing the sections or treating them with solutions of CELL-CONTENTS AND FORMS OF CELLS. 211 hydrated chloral or sulphuric acid. The fixed oils remain liquid at ordinary temperatures, whereas the fats tend to solidify, and are occasionally found in the form of crystals in plant cells (Fig. 116). Both of these classes are fatty acid-esters of glycerin, whereas the waxes are combinations of fatty acids and FIG. 116. Crystals of fixed oils: A, section of seed of the oil palm (Elais guineensis) treated with an alcoholic solution of iodine' and very dilute sulphuric acid, showing stone cells (sc); cells with homogeneous brown content (sa); cells with yellowish granular content (sa'); and cells of endosperm (en) having porous walls (x), and containing phytoglobulins (crystalloids) (P, p), associated with needle aggregates of the fatty acids. B, cross section of a cotyledon of cacao, heated in a solution of potassium hydroxide, showing the epidermal layer (ep) with hair (d), phytoglobulin (crystalloids) (al) and aggregates of fatty acids (f). C. a few cells of the cotyledons of ripe cacao seeds mounted in glycerin, showing separation of sphero -crystals of fatty acids in the oil and starch-bearing cells of endosperm. — After Hanausck. some alcohol other than glycerol (glycerin). According to this distinction some waxes as myrtle wax, obtained from the berries of Myrica cerifera, are classed among the fats, it being a mixed glyceride of palmitic and lauric acids. The fatty acids which enter into the constitution of the fixed oils and fats belong to more than one series of hydrocarbons. 212 A TEXT-BOOK OF BOTANY. The following acids are present in the vegetable oils and fat. Normal caproic acid (C6H12O2), Caprylic acid (C8H16O2), and Capric acid (C10H20O2) are found in cocoa-nut oil, expressed from the seeds of the cocoa-nut (Cocos nucifera}, and in palm- nut oil, obtained from the oily sarcocarp of the drupes of the palm, Elcris guineensis. LAURIC ACID (C12H24O2) occurs in laurel-nut, obtained from the seeds of Calophyllum Inophyllum (Fam. Guttiferae), a plant growing in the East Indies and Cochin China. It is also found in cocoa-nut oil and certain other vegetable oils. MYRISTIC ACID (C14H28O2) is found in certain vegetable fats, especially in nutmeg and mace. This oil forms crystalline salts with both potassium and barium. PALMITIC ACID (C16H32O2) occurs combined with glycerol in a large number of vegetable oils, especially in palm-nut oil, and Japan wax. The latter is obtained from fruits of Rhus vernicifera and R. chinensis. It is also found in myrtle wax, which occurs as an incrustation on the fruits of the wax myrtle (Myrica cerifera} and bayberry (M. carolinensis) . This acid is not very readily soluble in petroleum ether. A crystalline silver salt is obtained by adding an alcoholic solution of silver nitrate to an alcoholic solution of ammonium palmitate. STEARIC ACID (C18H30O2) occurs as a glyceride in cacao butter obtained from chocolate seeds, and in " Shea butter " obtained from the seeds of Butyrospennum Parkii, a tree growing in Upper Guinea and in the region of the Nile. ARACHIDIC ACID (C20H40O2) occurs combined with glycerol in peanut oil and other vegetable fats. The acid is soluble in boiling alcohol, ether chloroform, benzene, and petroleum ether. It forms crystalline salts of copper and silver. BEHENIC ACID (C22H44O2) occurs as a glyceride in "oil of Ben " expressed from the seeds of Moringa pterygosperwia, a plant of the East and West Indies. This oil is used for the preparation of cosmetics, by perfumers for extracting odorous substances, and as a lubricating oil for clocks. LIGNOCERIC ACID (C24H4SO2) occurs as a glyceride in peanut oil, and is distinguished from arachidic acid in being slightly soluble in cold alcohol. CELL-CONTENTS AND FORMS OF CELLS. 213 TIGLIC ACID (C3H8O4) occurs as a glyceride in croton oil, and is soluble in water. HYPOG^IC ACID (C16H30O.,) occurs combined with glycerol in peanut oil and in corn oil. It is soluble in cold alcohol and crystallizes in needles. LYCOPODIC ACID occurs, as a glyceride, in lycopodium spores, and is related to hypogseic acid. OLEIC ACID (C18H34O2) occurs as a glyceride in many vege- table oils. The glyceride of oleic acid occurs, as a rule, in larger quantities in most fixed oils than any other glyceride, being present in olive oil to the extent of 90 per cent. It is also found in a large number of seeds, principally in cotton seed, hazel-nut, peanut, sesame, walnut, corn, tea seed, almond, and the kernels of apricot, peach, and plum. These oils are generally grouped to- gether and known as the " olive oil group." The sodium and barium salts of oleic acid are crystalline. RAPIC ACID (C18H34O2) and ERUCIC ACID (C22H42O2) occur combined with glycerol in the oil obtained from rape or colza seed and in other Cruciferous seeds. LINOLEIC ACID (C18H32O2) is the principal acid of the gly- cerides forming the *' linseed oil group " or " drying oils." The acid which is best known is that obtained from flaxseed or linseed, the oil of which contains from 80 to 85 per cent, of linoleic acid or its isomers. Linoleic acid is also present in the fixed oil occurring in the seeds of the following plants: Hemp, walnut, pine (Pinus sylvestris) , fir (Abies balsamea), poppy, saffiower, sunflower, and seeds of a number of species of Aleurites. The seeds of Aleurites moluccana yield the "• candle nut oil " of the South Sea Islands, and the seeds of A. cor data yield the " tung oil " (Chinese wood oil or Japanese wood oil) of China and Japan. RICINOLEIC ACID (C18H34O3) occurs as a glyceride in castor oil, and is the principal constituent of this oil. It is also present in the seeds of other Euphorbiaceous plants, being found in croton, curcas, etc., and is also found in grape seed. Ricinoleic acid is soluble in alcohol and ether and is insoluble in petroleum ether. It forms crystalline salts with barium, calcium, and lead. JAPANIC ACID (C22H42O4) is the only dibasic acid occurring 2i4 A TEXT-BOOK OF BOTANY. in natural fats, and is found in Japan wax. The crystals, formed from the solutions in alcohol or chloroform, are heavier than water. CHAULMOOGRIC ACID (Ci8H32O.,) occurs as a glyceride in chaulmoogra oil, being obtained from the seeds of Taraktogenos Kurzli and other plants of the Bixaceae. It has the composition of linoleic acid, but a study of its constitution shows that it is in the nature of a cyclic compound. The following alcohols occur as esters in vegetable waxes: Ceryl alcohol (C26H54O), combined with palmitic acid, is the principal constituent in opium wax. Ceryl alcohol is also present in carnauba wax, which is obtained from the leaves of the Car- nauba-palm (Copernicia cerifera). Carnauba wax also contains myricyl or melissyl alcohol (C30H62O), the latter being either free or combined as an ester of cerotic acid. PHYTOSTEROL, a compound isomeric with cholesterol (C27H46O), is found in the oils derived from a number of seeds. It is unsaponifiable, and is found in the extracted oils to the extent of about i per cent. Phytosterol crystallizes in the monoclinic system (Fig. 117), whereas cholesterol, which occurs in most ani- mal oils and fats, forms triclinic plates resembling rhombic prisms (Bomer, Zeits. f. Unter. d. Nahr- u. Genussmittel, 1898, p. 42). LECITHIN belongs to a group of fatty substances containing nitrogen and phosphorus, and in which the latter is present as glycerophosphoric acid. They are sometimes grouped together in a special class, known as " phosphatides," and are characterized by containing one or more molecules of phosphoric acid, an alcohol (as glycerin), one or more fatty acid radicals (as stearic or oleic acid), and one or more nitrogenous bodies (such as choline and allied substances). Lecithin occurs in seeds, buds, and young shoots. In barley, wheat, and rye it occurs to the extent of 0.6 per cent. ; in peas, 1.2 per cent. ; lupine seeds, 2 per cent. ; mushrooms, 0.9 per cent. ; dry yeast, 2 per cent. (For amount in other plants see Amer. Jour. Pharm., 1914, p. 169.) According to Stoklasa, the phosphoric acid of plants occurs in the form of organic com- pounds, of which lecithin is an important example. It is formed in those organs and under those conditions where photosynthesis is possible. It is even thought that lecithin may be a product CELL-CONTENTS AND FORMS OF CELLS. 215 of assimilation in the chloroplastid. The fact that fungi con- tain it shows that lecithin may be formed from protoplasm itself. It is one of the most interesting compounds which has been isolated from plants, and no doubt plays an important role in the life of the cell. Lecithin is a yellow, viscous, waxy substance soluble in oils r^ / / 1 V / -* / a/ b c FIG. 117. Phytosterol allowed to crystallize very slowly from strong alcoholic solu- tions, the crystals being recrystallized until the melting-point is constant. I, crystal forms with parallel extinction C D. II, crystals with parallel extinction B C. Ill, crystals with parallel extinction along the long axis. IV, common crystal forms of phytosterol. Phytosterol is a constituent of most vegetable oils and is most abundant in peas, lentils, and other Leguminous seeds. The presence of vegetable oils is detected in animal oils by a study of the forms of crystals, those of phytosterol crystallizing in the monoclinic system, whereas cholesterol forms crystals which belong to the triclinic system. — After A. Bomer, in Zei'/s. /. Unter. d. Nahr.- u. Genussmittel, 1898, p. 45. and warm alcohol. In solutions of ether or chloroform it is pre- cipitated upon the addition of acetone. In contact with water, it separates in the form of spiral threads or loops, giving rise to the " myelin forms " of Kirchow and Beneke. When examined | under the microscope a smear of lecithin, to which a drop of water or a sugar solution has been added, sends out a number of '2i6 A TEXT-BOOK OF BOTANY. rounded projections which gradually elongate and become more and more abundant and intricate. If this process be allowed to take place in a test-tube or other vessel that can be shaken, the water becomes turbid through the dispersion of the delicate microscopic myelin protrusions, and in course of time a uniform emulsion of the lecithin in water is obtained, which consists of fine swollen particles. This is a colloidal solution that can be filtered without change. It is not coagulated by heat, nor precipitated by salts of monobasic or tribasic metals. WAX. — The epidermal layer of the plant shows a number of modifications. It usually consists of an inner layer of cellulose and an outer covering of cutin. While some of the lamellae be- neath the cutin may be modified to mucilage or oil, the surface of the cutin layer may have deposited upon it a coating of wax. Frequently the wax is in such small quantities that it is not ob- served until the sections are heated to a temperature of 90° to 100° C, when the wax separates in the form of oily globules. According to De Bary, there are four principal forms of wax- coatings. i. It occurs in the form of minute rods or needles, such as are found constituting the bloom of fruits as the grape and plum, and the stems and leaves of Eucalyptus Globulus, Ricinus com- munis, etc. 2. The most common form is a simple, granular coating consisting of isolated grains which may lie together as a single layer. These are found in the fruits of some of the Cruciferse, Iris pallida, etc. 3. The coating may consist of minute rods which may be more or less bent or curled, standing perpendicularly on the cuticle, as in the sugar cane, canna, banana plant, etc. 4. The wax incrustation may occur in the form of membrane-like layers, varying from thin scales, as in Taxus baccata, Portulaca oleracea, and various cacti, to thick layers showing a striation and stratification similar to that found in thick-walled cells, as in the fruit of Myrica, leaves of the wax palm (Ceroxylon andicolum). According to Wiesner, the deposit of wax is often crystalline, appearing in four-sided prisms. (Con- sult A. deBary, " Comparative Anatomy of the Organs of Vegetation.") PHYSIOLOGY OF FATS. — It is stated that in the photosynthetic CELL-CONTENTS AND FORMS OF CELLS. 217 processes of some of the lower plants, as Vaucheria, Diatoms, etc., fixed oils rather than starch are formed in the chromatophores. It is well known that in the cells of the bark of a number of plants fixed oils are stored in place of carbohydrates. These facts show that there is a very intimate relationship between the fixed oils and other metabolic substances. Fixed oils constitute the reserve materials in seeds, spores, pollen grains, and are even present in the tubers of certain plants as Cyperus esculentus. The storing of fixed oils instead of starch may be of some advantage to plants, in that there is a greater supply of energy contained in them than is present in the same quantity of any of the carbohydrates. Again, as the specific gravity of the fixed oils is less than that of the carbo- hydrates, this is an advantage in those spores or seeds which are disseminated by the wind and require to be as light as possible. The fixed oils are more or less intimately associated with the protoplasm occurring in vacuoles of the same in fruits and seeds. The waxes which are secreted in the epidermal -cells of leaves and green stems, and also found as a covering of many fruits, serve to protect the underlying cells from loss, or excess of moisture, from the attack of disease-producing micro-organisms, and also prevent the interactions caused by some of their enzymes. The resistance of certain micro-organisms, as the tubercle-bacilli, is supposed to be due to some extent to the fatty substances in which their bodies are enclosed or with which they are impregnated. " It is held by some that the fats, or, more correctly, the lecithin and phospholipines, are essential to the cohesion and physical constitution of the protoplasm, so that any interference with the physical state of these substances arrests the vital functions. The cement which binds the organized matter together is loosened by the solution in it of foreign substances, and it is the loosening of the protoplasmic cement that makes it possible for the normal processes of life to be carried on. " Attempts to form a concrete conception of the physical rela- tionship in the structural organization of cells between fats on the one hand and the other constituents of living matter on the other have not been successful. Some have spoken of ' lipoid mem- branes ' as if the living cell itself were enclosed in a fatty envelope and accessible only to such substances as can permeate this envelope 218 A TEXT-BOOK OF BOTANY. through chemical affinities with the fatty material of which it is composed. Others are inclined to think of protoplasm as an emulsion of proteins and ' lipoids.' Loeb and v. Knaff Lenz find that sea-urchin eggs are liable to undergo cytolysis under the action of any process, chemical or physical, that causes the cell fats to become more fluid." (Consult J. B. Leathes, "The Fats.") Mucilages and Gums. — By the terms mucilages and gums are meant those substances which are soluble in water, or swell very perceptibly in it, and which, upon the addition of alcohol, are precipitated in the form of a more or less amorphous or granular mass. Mucilage originates in the plant as a cell-content, or as a modification of the wall. In the former case it arises as a product of the protoplasm, or it may be a disorganization product of some of the carbohydrates. When it arises through modification of the wall it is spoken of as " membrane mucilage," and owes its origin to several causes : either to a secondary thickening of or an addition to the cell wall, or a metamorphosis of it, at least in part. In the latter case it may arise either as a disorganization product of the primary wall, or of the subsequent lamellae making up the walls of the cells of the medullary rays, parenchyma, and other tissues, as in Astragalus gunimifer (Fig. 118), or it may arise as an intercellular substance. The following is a classification of some plants, based upon the origin of the mucilage: I. Mucilage in the form of a cell-content is of infrequent occurrence in plants. It is usually present in the cells containing raphides, especially in the Monocotyledons. Its origin and de- velopment may be easily followed in the tubers of a number of Orchids, especially those yielding salep. The mucilage arises very early in the development of the cells surrounding the crystal- groups, and continues to be formed as the crystals grow in size, the protoplasm and nucleus being reduced to a very thin layer which lie next to the cell-wall. The mucilage of salep is colored yellowish with iodine and sulphuric acid, or a yellowish-red or rose-red with aqueous eosin solution, and a carmine-red with an aqueous solution of Congo red. The cells containing mucilage are easily differentiated from the surrounding cells by the use of CELL-CONTENTS AND FORMS OF CELLS. 219 alcoholic solutions of Congo red, methylene blue, etc., which dis- tinctly color the mucilage in them. Cell-content mucilages are also found in the fleshy scales of the onion, the rhizome of Agropyron repens, the fleshy leaves of Aloe and other succulent plants. It ms mat FIG. 118. Cross section through pith (m) and the inner portion of the wood (Ib) of Astragalus gummifer, showing successive stages in the modification of the walls in the formation of gum tragacanth (o, I, 2, 3, 4). Some of the tracheae (c) contain globular masses of gum. — After Tschirch. probably also occurs in this form in the Cyanophyceae and in some of the red algae, as Laminaria, although -in the latter it is formed chiefly as a modification of a cell-wall and the intercellular substance. In Dicotyledons the mucilage which is present is 22O A TEXT-BOOK OF BOTANY. usually formed as a modification of the cell-wall, and, according to Solereder, it seems to occur in the contents of the cell in only the following families : CEnotheracese, Rubiacese, and Yitacese, in FIG. 119. Cell-wall mucilage. A, transverse section of seed-coat of flaxseed treated with water, showing the swelling of the mucilaginous layer situated beneath the cutin; B, section of Althaea root showing three large mucilage-cells; C, transverse section of elm bark showing four large mucilage-cells. all of which the mucilage receptacles can be interpreted as being incompletely differentiated raphide-sacs, — i.e., without raphides. II. Cell-membrane mucilage, — i.e., mucilage formed as a CELL-CONTENTS AND FORMS OF CELLS. 221 result of a metamorphosis of the cell-wall, — is of frequent occur- rence, being found in all parts of the plant, including the endo- sperm cells of seeds, parenchyma cells and medullary ray cells of roots and stems, and epidermal cells of leaves, stems, fruits, and seeds. Cell-membrane mucilage is also found in some of the mucilaginous marine algae, as chondrus laminaria, etc., although in the latter case the mucilage is often spoken of as being derived from the intercellular substance, being a modification of the FIG. 1 20. A, B, C, successive stages in the development of the mucilage hairs or glands on the lobes of the leaves of Viola tricolor; D, young secretion hair showing some of the cells with large nuclei and several vacuoles; E, mature hair; F, gland showing mucilaginous layer beneath the cutin and the protrusion of a portion of the mucilage through the broken wall; G, portion of leaf on the upper part of the lobes of which occur the mucilage gla'nds. primary wall. It may also occur as a result of a decomposition of the secondary lamellae. Four different forms of mucilage are recognized, i. Mucilage cells, or distinct cells resembling more or less the surrounding cells, except that they contain mucilage, occur in the tissues of leaves, petals, fruits, seeds, and the parenchyma cells of pith and primary cortex of a number of plants. In this group may also be included the gelatinized cells of the integumental tissues 222 A TEXT-BOOK OF BOTANY. (epidermis and hypodermis), as these in many cases may be mistaken, as in the Violaceae, for distinct cells, although only the inner walls of the epidermal cells are gelatinized. 2. Mucilage cavities arise from the simultaneous gelatinization in the walls of a group of cells. These are found in the cells of the pith, cortex, and petioles in a number of plants of the Malvaceae, Sterculiaceae, Simarubaceae, etc. 3. Mucilage canals are large cavities formed either (A) as a result of the enlargement of the intercellular spaces between the cells, the primary lamellae being modified to mucilage; or (5) are formed by the disintegration or breaking down of a number of cells, the walls of which become gelatinized. In the former case they are spoken of as " schizog- enous canals," and in the latter as " lysigenous canals." The latter are the more common form and occur in the pith and primary cortex of a number of plants belonging to the Guttiferae, Malvaceae, Sterculiaceae, Oleaceae, Rhamnaceae, Vitaceae, Legumi- nosae, Rosaceae, Cactaceae, Piperaceae, Moraceae, and Urticaceae. 4. Glandular hairs (Druzenzotten} . In this form (Fig.. 118) they are found in the lobes of the leaves and calyces of Viola tricolor, Coffea arabica, and of Prunus atrium. CHEMICAL CLASSIFICATION OF MUCILAGE. — Mucilages may be distinguished, according to their behavior with special reagents, as cellulose-mucilages or pectose-mucilages. The former are colored blue by chlor-zinc-iodide, and are soluble in ammoniacal solution of cupric oxide. To this class belong the mucilages of the tuber of salep and the seeds of cydonium. The pectose- mucilages are distinguished by the fact that they are dissolved on being heated with solutions containing from 35 to 65 per cent, cane sugar. They are also stained intensely with solutions of saffranin, methylene blue, or ruthenium red. Mucilage is formed in large quantities in certain trees, and the exudation which is collected forms the so-called gums of com- merce. As these are largely used for a variety of technical pur- poses, their chemical properties have been studied, so that four distinct classes of gums are recognized. i. Gums containing arabin or arabic acid. In this group are included gum arabic, obtained from Acacia Senegal and other species of Acacia ; Feronia gum, obtained from Feronij, elephan- CELL-CONTENTS AND FORMS OF CELLS 223 turn (Fam. Rutacese), and Anacardium gum, obtained from Anacardmm occidentale. 2. Gums consisting of mixtures of arabin and cerasin (cerasic acid). To this group belong the exudations formed on a number of trees of the Rosaceae, as cherry, almond, apricot, and plum. 3. Gums containing bassorin. Tragacanth is the typical gum 1) FIG. 121. Citrus vulgaris. Longitudinal section of a young fresh fruit showing a lysis- enous oil canal or duct. Se, oil; Zs, cell sap; PI, cells in which the walls have been dis- solved; f, thin-walled cells; D, thick-walled cells; K, nucleus; Chr, chromoplasts; o, crystals of calcium oxalate; e, epidermis. — After Meyer. of this class. Included in this group are a few other gums which find some commercial use, as cocoa-palm gum, obtained from the bark of the cocoa-nut palm; chagual gum, obtained from Puya coarctata (Fam. Bromeliaceae), and Moringa gum, obtained from Moringa pterygosperma (Fam. Moringaceae). 4. Gums containing mixtures of cerasin and bassorin. The East Indian gum, obtained from Cochlospermum Gossypium 224 A TEXT-BOOK OF BOTANY. FIG. 122. Development of schizogenous oleo-resin canals in Brauneria pallida. A, intercellular space (o) between four parenchyma cells, being the seat of the early formation of the canal and indicated by a yellowish oily content. B, intercellular oleo-resin canal with five surrounding parenchymatous cells (p). C, later stage of canal showing separation of small oily globules in the intercellular substance. D and E, the intercellular substance showing an almost protoplasmic-like structure, some of the lining cells being developed as papillae and suggesting that they might be in the nature of secretion cells, although it is now considered that the oils and resins of this character are formed from a resinogenous layer in the wall. F, longitudinal section showing the elongated secretory canal between the rows of cortical parenchyma. CELL-CONTENTS AND FORMS OF CELLS 225 (Fam. Cochlospermaceae), has been used as a substitute and adulterant of tragacanth. VOLATILE OILS AND RESINS. — These and related products, known as gum-resins and balsams,* are found in a very large number of plants. Like the mucilages, they originate either as a metamorphosis of the cell-wall or as a. direct product of the protoplasm. The former is of more frequent occurrence, and the B FIG. 123. Development of a lysigenous secretory canal in the leaves of Dictamnus albus (Fam. Rutaceae). The development begins partly in the cells of the epidermal layer and partly in the underlying parenchyma (A). The outer cells divide, forming the secretion cells (c), while the inner give rise to the reservoir (B). The innermost cells then multiply by repeated division in all directions, giving rise to a large number of cells containing globules of oil (C). Later the thin walls are absorbed and the oily globules fuse together, forming a single large globule (D). — After Rauter. * The volatile oils are not infrequently associated with other sub- stances of the plant cell in varying proportions, as resin, gums, cinnamic and benzoic acids. Those products which consist chiefly of oil and resin are known as OLEO-RESINS, and include turpentine and copaiba ; those consisting chiefly of gum and resin and containing but little volatile oil are known as GUM-RESINS, and include ammoniac, asafoetida, galbanum, and myrrh ; oleo-resins associated with aromatic acids are known as BALSAMS, as balsam of Tolu, balsam of Peru, storax, and benzoin, which latter is usually termed a balsamic resin. 15 226 A TEXT-BOOK OF BOTANY. layer of the wall in which the decomposition takes place has been termed by Tschirch a resinogenous layer. The cells or receptacles which contain oils, resins, gum-resins, and balsams are usually referred to as " secretory cells " or " secretory receptacles." The latter term is used by Solereder to include all cells, cell fusions, cavities or canals which are filled with secretions. Usually no attempt has been made to determine whether the secretion is a volatile oil or a resin, or a gum-resin or a balsam, as the appearance of the secretion is always either in the form of globules or more or less rounded masses. Secretory receptacles may arise in three different ways, (i) As a modi- fication of the intercellular substance and an enlargement of the intercellular areas, giving rise to schizogenous receptacles (Fig. 122). (2) As a result of a disintegration of a group of cells and a decomposition of the wall substance, forming lysigenous receptacles (Fig.- 123). (3) They may have at the outset a schizogenous origin, but later the surrounding cells in addition break down, so that the receptacle is more properly designated as being schizo-lysigenous. In certain plants, as in the bark of Sassafras and Cinnamon, there is a more or less even distribu- tion of cells in the cortex, containing volatile oil, on the one hand, and mucilage, on the other. Indeed, it is supposed that the cells giving rise to mucilage may under different conditions develop volatile oil. In a general way it may be said that the secretory receptacles resemble those containing mucilage, both as to the manner in which they originate in a plant and the physical char- acters of the secretion. Indeed, they may be closely related to the mucilages in that they may contain a large proportion of gum, or the proportion of oleo-resin and gum may be reversed. In the examination of technical products, and especially in taxonomic work, it is very important to note not only the chemical character of the secretions but also the fact whether the cells are isolated or whether they form canals, or whether the secretory receptacle is only a cavity. The following facts may be given in reference to the four principal types of secretory receptacles: i. Secretory cells are distinct cells which may be quite dis- tinct from, or may show more or less resemblance to, their neighboring cells, except that they contain oil or resin. They CELL-CONTENTS AND FORMS OF CELLS. 227 vary in length and outline, being either spherical, ellipsoidal, sac- shaped (Fam. Bixaceae), or branched (Fam. Meliaceae). The contents may be in the form of distinct globules adhering to the wall (or in dried material may be in the form of amorphous masses), varying in color from colorless to yellowish or even dark brown. In the secretory cells of certain plants of the Lauraceae, Magnoliaceae, Canellaceae, Aristolochiaceae, and Piperaceae the secretory contents are enveloped by a thin-walled sheath, con- nected with the cell-wall by means of a stalk. The internal glandu- lar hairs occurring in the rhizome of Dryopteris and in Pogoste- mon Patchouli may be included among secretory cells, although they project into the intercellular area rather than into the cells. The cell-wall of the secretory cells not infrequently gives a dis- tinct reaction for suberin. Elongated secretory cells or sacs, resembling tannin-idioblasts, and with diverse contents varying from resin to latex-like sub- stances or tannin-like masses, are distributed in the cells of the pith, bast, and pericycle of the stem and occasionally in the larger veins of the leaves of some of the genera of the following families : Anacardiacese, Berberidaceae, Capri foliaceae, Compositae, Crassu- laceae, Euphorbiaceae, Lecythidaceae, Leguminosae (very widely distributed and with diverse contents), Menispermaceae, Monimi- aceae, Myristicaceae, Passifloriaceae, Polygonaceae, Rosaceae, and Rubiaceae. Solereder also states that similar elongated sacs with brownish contents are observed in the epidermal cells and occasionally in the upper layers of mesophyll of one or more of the genera in the following families : Crassulaceae, Euphorbiaceae, Geraniaceae, Moraceae, Saxifragacese, and Violaceae. 2. Secretory cavities are either spherical or ellipsoidal in shape and the contents vary from oily or resinous to gum-like or tannin- like masses. The mode of development of the cavities, as to whether schizogenous, etc., is usually not considered, as this fact is not easily determined in the mature tissues. When occurring in leaves the cavities give rise to transparent dots or glandular punctate areas. They are also found in the pith and primary cortex of quite a number of plants. There are a number of special forms of secretory cavities, the 228 A TEXT-BOOK OF BOTANY. latter in some cases being lined by a papillose epithelium or a form of bracket-cells, etc. They are found in the following fami- lies : Araliacese, Bixaceae, Caesalpinaceae, Composite, Connaraceae (with sphaero-crystalline contents), Euphorbiaceae (with bracket- epithelium), Geraniacese (with sphsero-crystalline contents), Guttiferae, Leguminosse (intramural glands with a papillose epi- thelium or bracket-epithelium), Lythracese, Malpighiaceae, Mal- vaceae, Meliaceae, Menispermaceae, Myrtaceae, Oleacese, Passi- floriaceae, Piperaceae, Podostemaceae, Polygalaceae, Polygonaceae (secretory cavities sometimes formed from four epidermal cells), Primulaceae (occasionally with red crystalline contents), Pro- teaceae (intramural glands), Rhamnaceae (with a papillose epi- thelium), Rosaceae, Rubiaceae, Rutaceae, Simarubaceae, Styracaceae, and Theaceae. 3. Secretory canals differ from secretory cavities in that they are more or less elongated receptacles and often referred to as oil-ducts or oil-tubes. Like the secretory canals, they originate variously and have diverse contents. They may occur in a number of different portions of a plant, but their distribution is quite characteristic of certain genera or even of families. Secre- tory canals have been observed in the following families: Ana- cardiaceae, Araliaceae, Burseracese, Cactaceae, Caesalpinaceae, Celastraceae, Compositae, Gesneraceae, Gutti ferae, Hamamelidaceae, Leguminosae, Pittosporaceae, Podostemaceae, Rhamnaceae, Ruta- ceae, Simarubaceae, Theaceae, and Umbelliferae. (Consult Sole- reder's " Systematic Anatomy of the Dicotyledons.") 4. Glandular hairs. Volatile oils and resins arise in the glandular hairs formed on the surface of stems, leaves, and various parts of the flower in the Labiatae, Compositae, and other families. In these hairs a volatile oil separates in the form of large, oily globules which lie between the cuticle and the outer wall of the underlying cells (Fig. 124). The origin of this secre- tion has been variously ascribed to the protoplasmic content of the cell or to a modification of the cell-wall. In the former case it is said to arise as a metabolic substance in the protoplasm, and is later diffused into the glandular area between the outer cellulose wall and cuticle. While this manner of formation of the oily secretion would seem reasonable, yet the studies by Tschirch CELL-CONTENTS AND FORMS OF CELLS. 229 and Tunmann would seem to show that the secretion in the glandular hair arises in a subcutaneous layer of the wall, which has been termed a " resinogenous layer." Even De Bary, with char- acteristic caution, has stated that the secretion found in the walls of glandular hairs originates in the wall even though the ma- terials for its formation must a'rise in the protoplasm of the cells. In the study of glandular hairs the method of Tunmann may be followed (Ber. d. d. pharm. Gesellsch., 1908, p. 513). Fresh, or even dried, material may be used. Surface sections are made FIG. 124. A glandular hair from the young leaves of Lavandula vera seen in different stages in the course of three days, showing that the underlying cells remain of the same size and structure, but that there is a gradual increase in the glandular area or resinogenous layer. — After Tunmann. and examined in aqueous solutions containing 10, 20, 30, or 40 per cent, of hydrated chloral. The 10 per cent, solution is used first, then the 20 per cent., etc. The proper solution renders the hair transparent, dissolves the resin, and, if the cover-glass is moved sidewise, the cuticle bursts, showing the resinogenous layer. Tunmann distinguishes three different types of glandu- lar hairs, depending upon the character of this resinog- enous layer, (i) In which by this treatment there separate small rod-like crystals resembling bacteria, as in Fig. 125, A, B, C. (2) A second type is given in which vacuoles occur consisting of A TEXT-BOOK OF BOTANY. FIG. 125. Several terms of glandular hairs: I. In which the resinogenous layer (rsg) separates in the form of small rods, as the leaves of violets (A), Fraxinus (B), and Alnus (C). 2. The resinogenous layer separating in the form of vacuoles in the hairs of Salvia (D) and Hyssopus (E), observed in the dried material treated with dilute solutions of hydrated chloral. 3. A lattice-like or cellular resinogenous layer occurring in the hairs of Rhodo- dendron (F) and Azalea (G). — After Tunmann. CELL-CONTENTS AND FORMS OF CELLS. 231 a fine net- work, as in Fig. 125, D, E. (3) A third type in which the secretion is in the form of neither rods nor vacuoles but a somewhat cellular structure, termed by Tunmann a lattice-work. In the walls of the glandular hairs other substances are some- times present, as resins, gums, etc. Hanstein originally pro- posed the use of a mixture of aniline dyes to distinguish resin, gum, and protoplasm (Bot. Zeit., 1868, p. 754), but later studies have shown that these dyes are limited in differential diagnosis of many of these substances. The cells of the glandular hairs may contain, in addition to protoplasm, protein bodies, chloro- phyll grains, starch, fixed oil, tannin, calcium oxalate, reducing sugars, and other special substances, which are colored yellowish- red with solutions of the alkalies or sulphuric acid. MlCROCHEMISTRY OF THE VOLATILE OlLS AND RESINS. — They are readily soluble in alcohol, .ether, chloroform, benzene, acetic ether, carbon disulphide, petroleum ether, etc. They are also quite soluble in glacial acetic acid and in aqueous solutions of hydrated chloral. Some of them are soluble in dilute alcohol. They may be liberated on the heating of sections for about ten minutes in a drying oven to a temperature between 100° and 130° C. Like the fixed oils, they are colored brownish or brownish-black with osmic acid and are intensely colored with alkannin and cyanin. The volatile oils are also colored a carmine red with very dilute solutions of fuchsin. Cells containing resins and terpenes are colored green by the use of aqueous solutions of copper acetate, the freshly cut twigs or leaves being allowed to remain in the solution for a few days. VOLATILE OILS. — The odors which are characteristic of very many plants are due chiefly to a group of principles known as volatile oils. They are, for the most part, mixtures of terpenes and camphors, and are obtained from the plant by distillation with steam, the oil rising to the surface of the distillate, being only slightly soluble in water. Volatile oils are readily soluble in alcohol, ether, chloroform, and in the fixed oils. Some of them show a tendency to absorb oxygen, and are converted into resinous substances. They are widely distributed and are char- acteristic of certain families, viz. : Pinacese, Cruciferse, Labiatae, Lauracese, Myrtaceae, Rutacese, and Umbelliferae. 232 A TEXT-BOOK OF BOTANY. With the exception of the seeds, in which they are seldom found, volatile oils occur in nearly all parts of the plant. They are formed either as a direct result of the activities of the pro- toplasm or by reason of changes in some of the constituents of the cell-wall. In a few instances the volatile oil is formed from a mother substance, being in the nature of a glucoside, and in this form occurs in the seeds of the almond and mustard. BOTANICAL CLASSIFICATION. — The composition of volatile oils is in many cases very complex ; seldom do they consist of only one substance, as in turpentine oil. Usually they consist of a number of chemical compounds, the most complex being American peppermint oil, from which no less than seventeen different, well-characterized chemical compounds have been isolated. As the volatile oils are of considerable economic value, they have been rather extensively studied. It remains for botanists to apply this knowledge to the study of the living plant. The physiologist will find the study of the origin, transportation, and localization of volatile oils in different parts of the same plant of very great interest. Such studies will throw considerable light upon the entire question of origin and transformation of the different plant constituents. In many cases, even the constitution of the constituents in volatile oils has been ascertained, so that on a sound scientific basis, hypotheses may be developed con- cerning the complex changes which are possible in the substances derived from the protoplasm. Again, the distillation products obtained in the study of volatile oil show that the living plant may contain such simple compounds as formic alcohol, formalde- hyde, formic acid, hydrocyanic acid, etc. Volatile oils which have been carefully studied are obtained from plants of the following families: Poly pod iaceae, Pinacese, Pandanaceae, Gramineae, Palmae, Araceae, Liliaceae, Iridaceae, Zingi- beraceae, Piperaceae, Salicaceae, Myricaceae, Juglandaceae, Betu- laceae, Moraceae, Aristolochiaceae, Chenopodiaceae, Ranunculaceae, Magnoliaceae, Anonaceae, Myristicaceae, Monimiaceae, Lauraceae, Cruci ferae, Resedaceae, Hamamelidacese, Rosaceae, Leguminosae, Geraniaceae, Tropaeolaceae, Erythroxylaceae, Zygophyllaceae. Rutaceae, Burseraceae, Meliaceae, Polygalaceae, Euphorbiaceae, Anacardiaceae, Vitaceae, Tiliaqege, Malvaceae, Theaceae, Diptero- CELL-CONTENTS AND FORMS OF CELLS. 233 carpaceae, Cistaceae, Turneraceae, Lythraceae, Myrtacese, Aralia- ceae, Umbelliferae, Ericaceae, Primulaceae, Convolvulacese, Ver- benaceae, Labiatae, Solanaceae, Capri foliaceae, Valerianaceae, and Compositae. COMPOSITION OF VOLATILE OILS. — The volatile oils are usu- ally of a very complex composition ; it will be found, however, that they owe their principal characteristics to one or more definite compounds. The following classes of compounds have been derived from the volatile oils. TERPENES, hydrocarbons of the formula C10H16, are found in the volatile oils of the Pinaceae, Rutaceae, etc. The terpene pinene makes up practically the entire bulk of turpentine oil. The terpene limonene is found in the oil of lemon to the extent of 90 per cent. It is not, however, the characteristic constituent in this oil, the odor of lemon being due to an aldehyde, citral. SESQUITERPENES, hydrocarbons of the formula C15H24, have been isolated from a number of oils, the best known representa- tive of this class being cadinene, occurring in the oils of cubeb, patchouli, savin, etc. ALCOHOLS belonging to the aliphatic and aromatic series occur in a number of oils combined as esters with the fatty acids. Both methyl alcohol and ethyl alcohol are found in the aqueous dis- tillates in the preparation of certain oils. This occurrence is usually explained as being due to the decomposition of other sub- stances. Methyl alcohol is thought to be derived from the de- composition of cellulose, while ethyl alcohol is considered to be a product of the fermentation of carbohydrates. That ethyl alcohol may be derived in this manner is probable from the obser- vations of Maze, who obtained alcohol from germinating seeds. Esters of methyl alcohol, especially methyl salicylate, are widely distributed. Among other alcohols, the following may be men- tioned : Linalool constitutes the bulk of lignaloe oil ; geraniol, a diolefinic alcohol makes up the bulk of rose oil ; benzyl alcohol, is an ester, occurs in the oils of jasmine, tuberose, ylang-ylang, etc. ; cinnamic alcohol, as an ester, occurs in cassia oil, storax, and Peru balsam ; menthol (peppermint camphor), a secondary alcohol, is found in peppermint oil; borneol (camphyl alcohol) occurs 234 A TEXT-BOOK OF BOTANY. in the oils of valerian and serpentaria, the acetate of this alcohol being found in many oils of the Pinaceae. ALDEHYDES. — The simplest of the aliphatic aldehydes, for- maldehyde, has been found in apopin oil, the latter being derived from an unknown plant growing in Japan. Acetaldehyde is com- monly present in the distillates of seeds. Citral is found in lemon oil, giving it its characteristic odor. It is also found in the oils distilled from the leaves and twigs of the lemon tree, sweet orange tree, sassafras, etc. Benzaldehyde is formed upon the hydrolysis of amygdalin. KETONES. — Of the aliphatic ketones, acetone has been ob- served, together with hydrocyanic acid, in the distillation of a number of leaf oils. Carvone occurs in the oil of caraway^ Pulegone occurs in large amounts in European pennyroyal oil and the oils of other members of the Labiatae. Japanese or laurel camphor is obtained by the distillation of the wood of Cinnamomum Camphora. Irone, a cyclic ketone, occurs in orris root. PHENOLS AND PHENOL ETHERS are found in a number of volatile oils. Thymol constitutes the larger part of the oil of ajowan (Ptychotis coptica). Carvacol is a constituent in many Labiate oils. Anethol is the principal constituent of the oils of Pimpinella Anisum and Illicium verum and is an important constituent in the oil of fennel. Eugenol occurs in the oils of the Myrtacea and Lauracecc. Apiol is a constituent of the fruit of parsley, and safrol is the principal constituent of sassafras oil. ACIDS. — Quite a number of acids are obtained as a by-product in the aqueous distillation of volatile oils. Among these may be mentioned formic acid, acetic acid, isovaleric acid, benzoic acid, cinnamic acid, salicylic acid, etc. ESTERS give the fragrance to most volatile oils. Some oils consist almost entirely of esters, as wintergreen oil and birch oil, which contain methyl salicylate. The latter is probably one of the most widely distributed of the esters. Linalyl acetate is the characteristic constituent of bergamot and lavender oils. Geranyl acetate is found in the oils of lemon grass, neroli, CELL-CONTENTS AND FORMS OF CELLS. 235 coriander, etc. Esters of benzoic and cinnamic acids are found in storax, Tolu balsam, and Peru balsam. Bornyl isovalerate occurs in valerian oil. LACTONES. — The odoriferous principle known as coumarin is widely distributed in the plant kingdom. It occurs in some of the ferns, grasses, tonka bean, " Waklmeister " (Asperula odorata), etc. It apparently is formed as the result of the action of a ferment, as it is detected only after the drying of the plant. Alantolactone is the principal constituent of the oil of Inula Helenium. NITROGEN AND SULPHUR COMPOUNDS occur frequently in the aqueous distillates of plants yielding volatile oils. Hydrocyanic acid is readily detected by means of Prussian blue, and occurs in the distillates not only of cyanogenetic plants but in a "large num- ber of others as well. The mustard oils 'are esters of isothio- cyanic acid and are characterized by their penetrating odors. Allyl mustard oil is obtained from the seeds of Sinapis nigra and a few other plants of the Cruci ferae. (Consult " The Volatile Oils," Gildemeister and Hoffman, translation by Edward Kremers ; also " Semiannual Reports," by Schimmel & Co.) FORMATION OF VOLATILE OILS. — The chemical study of odorous principles shows that they vary considerably in their* composition. Not much is known regarding the formation of volatile oils. Charabot and Herbert have suggested that the esters may originate in the cells containing chloroplastids. They suggest that under the influence of an enzyme of reversible activity the esters are formed from the acids and alcohols present in the plant cell, and that they continue to form until the flowering period. They are then diffused to other parts of the plant, notably the inflorescence. While some of the oils are indirect products connected with photosynthesis, others arise through the decom- position of a mother substance, as the glucosides, and still others originate as a metamorphosis of the cell-wall. PHYSIOLOGICAL ROLE OF OILS. — It is usually considered that volatile oils occurring in receptacles near the surface of the plant, as in fruits like the orange, serve to prevent the entrance of animal and vegetable parasites, and thus prevent disease. Again, the oils which are found in glandular hairs covering the leaves 236 A TEXT-BOOK OF BOTANY. and stems of many plants are supposed to be useful in preventing depredations by animals. The odorous principles which occur in many flowers are supposed to exert a directive influence upon insects and thus assist in the work of cross-pollination. While biologists usually consider the volatile oils as serving ecological uses yet those investigators, who study the perfume-yielding con- stituents very closely, are inclined to consider them as being in the nature of food materials that are used after the fertilization of the flower and during the development of fruit and seeds. RESINS, GUM-RESINS AND BALSAMS. — A large number of this class of plant products are found in commerce and used in medi- cine and in the arts. A few of these occur as normal products FIG. 126. Menthol: A, individual crystals obtained by sublimation; B, the commonly occurring aggregates of very fine needles. in living plants, as the gum-resins of the Umbelliferse, the gum- resin euphorbium, and the resins of mastiche and sandarac. Most of the others arise as a result of wounds in plants and are in the nature of pathological products, as benzoin, styrax, Tolu balsam, Peru balsam, etc. Until recently not much was known except in a general way regarding the composition of resins. Largely through the researches of Tschirch and his students the nature and the constitution of the important constituents in a number of the resins have been worked out. As a result of these studies seven principal groups of resins are recognized. i. Tannol Resins, — These are esters of aromatic phenols and CELL-CONTENTS AND FORMS OF CELLS. 237 Behave toward iron salts and some other reagents like tannin. They are found in relatively large amounts in a number of the resins and balsams, and occur in rather widely separated families, as follows : Peru balsam and Tolu balsam obtained from certain members of the Leguminosae, styrax from the Hamamelidaceae, benzoin from the Styracaceae, aloe from the Liliaceae, dragon's blood from the Palmae, and the resins from the Umbelliferae, in- cluding ammoniac, galbanum, asafretida, etc. 2. Resene Resins. — These are mostly colorless, indifferent substances occurring in resins and are not only insoluble in potassium hydroxide but exceedingly resistant to it, and are not capable of acetylization. To this group belong the resinous exudations of the Burseraceae, including myrrh, olibanum, and elemi ; also of the Anacardiacese, including mastic ; and of the Dipterocarpaceae, including gurjun balsam and dammar. 3. Resinolic Acid Resins. — These are oxy-acids containing either or both hydroxyl and carboxyl groups. They form color- less crystals and are either free or combined with alcohol in the form of esters. They have an acid reaction and are soluble in solutions of sodium hydroxide, and with difficulty form com- pounds with acetyl chloride. Acids belonging to this group have been obtained from a number of the resinous exudations of the Coniferae, including sandarac, Canada turpentine, and Strass- burg turpentine. It is also obtained from a number of resins which are in the nature of pathological products, as larch turpen- tine, Jura turpentine, and French turpentine. The abietic acid in colophony and the succinoabietic acid found in the fossil resin known as amber, also belong to this class of acids. Furthermore, resinolic acids are found in the fungus Polyporus officinalis, and in some of the exudations of the Leguminosae, including the oleo- resin known as copaiba and the recent-fossil resin, Zanzibar- copal. 4. Resinol Resins. — Resinols are aromatic alcohols which usually form colorless crystals and occur either free or in the form of esters. The principal constituents of guaiac resin belong to this class, namely, guaiaconresinol (guaiaconic acid), guaiacresinol (guaiacic acid), and guaiacinresinol (guaiacinic acid). Resinols are also found in small quantities in other resins. 238 A TEXT-BOOK OF BOTANY. 5. Fatty-resins. — The resins of this class differ from the others heretofore considered in that they are derivatives of some of the fatty acids. To this group belongs the resinous exudation known as " stick-lac," occurring on a number of trees growing in the East Indies, being caused by the punctures of a hemipterous in- sect, Coccus lacca. 6. Pigment Resins. — In this group are included those exuda- tions in which the resins are combined with a chromogenic deriva- tive. These have been studied but very little, and the best repre- sentative of this class is gamboge, which is used in medicine as well as for coloring in art. 7. Glucosidal Resins. — This group includes, as the name would imply, those resins which are in the nature of glucosides and yield on hydrolysis glucose as well as some other derivative. The resins found in jalap, scammony, and other plants of the Convolvulaceae belong to this group. (Consult A. Tschirch, " Die Harze und die Harzbehalter.") ORIGIN OF RESINS. — It was at one time considered that the resins were derivatives of tannin. Now that Tschirch has shown that there is a class of resinous substances that give reactions for tannin, it might seem that this theory would receive additional support. However, as he himself explains, the resinotannols con- tain a great deal more carbon than the tannins. Furthermore, Tschirch has shown that a number of the constituents of the resins give color reactions with Liebermann's reagent for phy- tosterbl. On the other hand, a number of these same constituents do not give the characteristic color reaction for phytosterol with Salkowsky-hesse's reagent. With 'regard to the resins of the resinolic acid series, Tschirch concludes that they are probably not derived from volatile oils, but that they are derivatives of a common mother substance. In a later publication Tschirch (" Chemie und Biologic der Pflanzlichen Sekrete ") states that in all probability all the secretory products, formed as a meta- morphosis or decomposition of the resinogenous lamellae, are the direct products of ferments accompanying these layers. LATEX OR MILK-JUICE is the product formed in special secre- tory organs in the plant, and exudes readily on even very slight injury of the plant. Under the microscope it is -seen to be in CELL-CONTENTS AND FORMS OF CELLS. 239 the nature of an emulsion, consisting of small globules, varying from 0.0005 to 0.005 mm- m diameter. It is of variable com- position and may contain certain hydrocarbons, as in pure caoutchouc and pure gutta percha, oils, resins, mucilage, starch, calcium oxalate, and alkaloids. Latex is found in three distinct types of tissues, differing FIG. 127. Study of Latex: A, tangential-longitudinal section through root of Taraxa- cum, showing laticiferous vessel (m), sieve tube (s), parenchyma (p). B, the bark of Euonymus, fractured and showing the thread-like latex (c) between the pieces (b). C, the fragments of thread-like latex of Euonymus viewed under the microscope, and distinguished from fibers by their dissolving in chloroform. — A, after Meyer; C, from drawing by Hogstad. from each other in origin and manner of development. I. Laticif- erous cells are long, tubular cells which arise in the initial cells of the embryo and continue to elongate, keeping pace with the growth of the plant, branching and traversing all of its organs'. They may extend through the cells of the pith, bast, and primary cortex, run along the veins of the leaf, being found occasionally in the mesophyll, and extend into the fruit. Cells of this kind 240 A TEXT-BOOK OF BOTANY. are present in the Apocynaceae, Asclepiadacese, Euphorbiaceae, Moraceae, and Urticaceae. 2. Laticiferous vessels are long tubes resembling the latex cells, but are formed by the absorption of the transverse walls in the superimposed cells. They develop very early, the cell-fusions taking place, in some instances, in the primary meristems. They may be either simple or branching, the branches connecting with other tubes and forming a net-work These anastomosing tubes can be separated readily from the sur- FIG. 128. Microscopical appearance of latex in Ficus elastica, showing small globules and sphere-crystals which separate soon after the removal of the fresh latex. — From a draw- ing by Hogstad. rounding tissues by boiling the material with dilute solutions of potassium hydroxide. The laticiferous vessels usually occur as- sociated with the leptome, although they may be found in other tissues of the axis and leaf. Milk vessels are found in the fol- lowing families : Araceae, Campanulaceae, Compositae, Convol- vulaceae, Euphorbiaceae, Geraniaceae, Musaceae, Oleaceae, and Papaveraceafr. 3. Secretory cells resembling laticiferous cells, in that they have a latex-like content, although probably of secondary origin, have been found in the Celastraceae, Oleaceae, CELL-CONTENTS AND FORMS OF CELLS. 241 Tiliaceae, and Urticaceae. The secretion in these cells is some- times visible even with the naked eye, and it is possible, on break- ing the bark, to obtain the latex in the form of delicate, elastic threads. These caoutchouc threads may be readily seen on break- ing the bark of euonymus, and may be distinguished from bast- fibers by their readily dissolving in chloroform (Fig. 127). The milk-juice varies in color in different plants, being color- less, as in oleander ; whitish, as in the Apocynaceae and Asclepiada- ceae ; or yellowish, as in chelidonium, or orange-red, as in sanguinaria. The latex, of a number of plants is collected to form a number of commercial products. Opium is the dried milk-juice obtained from the capsules of Papaver somniferum. Lactucarium is the dried milk-juice of Lactuca virosa and other species of Lactuca. Elastica or India rubber is the prepared milk-juice ob-' tained from a number of plants, the most important being the Brazilian or Para rubber tree (Hevea brasiliensis) , the Central American rubber tree (Castilloa elastica), the East Indian rubber tree (Ficus elastica), and the rubber vines of Africa (Landolphia species). Gutta percha is the concrete juice of Palaquium Gutta (Fam. Sapotaceae). ENZYMES OR FERMENTS. — In connection with the growth of the plant, there occurs a constant change in the substances which comprise it. These changes are brought about largely through the influence of a class of substances known as enzymes. Atten- tion has been directed to the decomposition of starch with the formation of sugar. This change is brought about by the secre- tion in the protoplasm of an enzyme called amylase (diastase). It is produced in the living cell, can be extracted from the plant, and will produce the same effect upon starch grains which have been separated from the cells. One of the interesting properties of the ferments is that in comparison with the amount of ferment employed the product formed through its influence is very large. Thus it is stated that amylase is able to hydrolyze 10,000 times its own bulk of starch. Results of this kind are considered to be due to catalytic action of the ferments, i.e., their power of inducing chemical reactions by their mere presence without themselves entering into the products formed. The ferments require specific temperatures for 16 242 A TEXT-BOOK OF BOTANY. their action, as, for example, emulsin or sinaptase, which decom- poses a number of the glucosides at a temperature of 35° to 40° C., while amylase, the ferment of germinating seeds, requires a somewhat higher temperature, namely, 50° to 70° C. Another property of these ferments, which is generally re- garded as characteristic of them, is that of becoming inactive when solutions are heated to a temperature of 100° C. Nothing is known with regard to the composition and constitution of the ferments, and they are usually classified according to the class of substances which they decompose. Thus, amylases act upon starch grains with the formation of sugar; proteinases break down the true proteins, etc. The following is an enumeration ot the principal plant enzymes, together with their occurrence and some of their properties : AMYLASE. — The ferment acting upon starch in germinating barley, with the formation of glucose and maltose, was separated by Payen and Persoz in 1833, and called "diastase." This fer- ment occurs, probably, in all parts of all green plants, and is especially abundant in all cells where starch is formed or stored. It is found in large amounts in various cereal grains, and also occurs in the fungi, yeasts, and bacteria. Recent investigation seems to show that in the cells with reserve starches there are two different kinds of diastatic enzymes, the one acting on the soluble starch, called amylase, and the other acting on the insoluble starch or amylopectin, and called amylopectinase. INULINASE is the ferment found in the cells of plants contain- ing inulin. It decomposes the latter, changing it into fruit sugar or fructose. Inulinase has no effect upon starch. It has been found in the Composite and also in Aspergillus, Penicillium, and a number of genera of the Eumycetes. MALTASE (a-glucosidase) is always associated with the diastases, and from which it has not been separated. It is widely found in the vegetable kingdom, and is especially abundant in malt and some of the yeasts. INVERTASE (a-fructosidase), sometimes also spoken of as in- vertin or sucrose, has the property of converting cane sugar into invert sugar (a mixture of glucose and fructose). It is found in CELL-CONTENTS AND FORMS OF CELLS. 243 wheat and barley, dates, bananas, mulberries, and especially in the green leaves and young shoots of higher plants. In yeast it is accompanied in many cases by maltase. EMULSINS are a class of glucoside-resolving enzymes found in the seeds of the almond, the bark of Prunus serotina, the leaves of Prunus Laurocerasus, and in a large number of plants of the Rosaceae. It is also found in the tuberous roots of Manihot utilissima, Monotropa, species of Polygala, Hedera Helix. Enzymes resembling emulsins, and capable of attacking gluco- sides, have been detected also in Aspergillus, several species of Polyporus, found growing in wood, lichens, mosses, and bacteria. A distinction is sometimes made between almond-emulsin, Asper- gillus-emulsin, etc. MYROSIN, an enzyme which hydrolyzes the sulphur-glucosides, occurs in the Cruci ferae and in certain species of Manihot. It is localized in the seeds of cells which are rich in proteins. Its presence may also be demonstrated in the mesophyll of young leaves, in the pericycle of stems, and in the cork-cells of roots. GAULTHERASE (Betulase), an enzyme which hydrolyzes the glucoside of methyl salicylate called " Gaultherin." This is present in Gaultheria and many other of the Ericaceae. It is probably very widely distributed in the vegetable kingdom. (See Amer. Jour. Pharm., 1898, p. 412.) PECTASE AND PECTINASE. — The name Pectase is applied to an enzyme that is always present in ripening fruit, and is capable of converting pectose, a product insoluble in water, into a soluble substance called pectin. The latter can be further decomposed into a number of closely related substances, known as pectinic acids, and which are usually combined with calcium. The term PECTINASE is applied to the enzymes which in the presence of lime coagulates the juices containing the dissolved pectinous sub- stances forming the so-called fruit jellies. This reaction is con- ditioned on the presence of lime and a certain equilibrium being established between the enzyme and the concentrations of the acid and calcium salts. Pectose originates by reason of certain changes in the lamellae of cell-walls. While it occurs in appreciable quan- tities in those fruits that have the properties of producing jelly, it is probably very widely distributed. 244 A TEXT-BOOK OF BOTANY. CYTASES (cellulases) is the name applied to those enzymes which are capable of dissolving cellulose. An enzyme of this character is located in the aleurone layer and in the epithelium of the scutellum in the germinating grain of barley. It is also found in the endosperm of the date palm, the cytase being formed in the embryo and the dissolved products being used up as food. Enzymes of this character are also found in wood-destroying fungi and bacteria. PROTEIN ASES (carbamases) is the name applied to those enzymes which break down the true proteins or carbamide deriva- tives. They are always accompanied in the plant cells by other ferments, and occur especially in seeds, being more abundant in those containing oil than starch, as hemp, mustard, castor oil, and flaxseed. They are also found in certain fleshy fruits, as figs and pineapple ; succulent leaves, as Agave, and in insectivo- rous plants. In the fruit and other parts of the papaw tree (Carica Papaya} occurs a proteolytic enzyme, called Papain, which readily digests fibrin, thus behaving like trypsin, a ferment in the pan- creatic juice. A similar ferment, called Bromelin, has been ex- tracted from the fleshy pulp of the pineapple. Ferments like Papain and Bromelin are naturally of very great interest, as they behave like the animal ferments, pepsin and trypsin. The Papain of commerce seems to be of varying composition, and unless ob- tained from authentic sources is not reliable. CHYMASES OR ENZYMES which effect the clotting of milk. The coagulating action of the fig (Ficus Carica} was known to the ancients. This action has been shown by Chodat and Rouge to be due to a vegetable chymase and called by them " sykochymase." A large number of plants possess the property of rendering milk ropy. Of these the following may be mentioned: Ranunculus bulbosus, Capsella Bursa-pastoris, Plantago lanceolata, Medicago lupulina, Pinguicula vulgaris. Artichokes, etc. An enzyme of this character has also been found in germinating seeds of Ricinus communis, Pisum, Datura, etc., and some of the fungi. ZYMASE, an enzyme causing the decomposition of glucose with the formation of alcohol and carbon dioxide. This decomposition, known as alcoholic fermentation, is considerably less simple than was formerly supposed, a number of enzymes and subsidiary sub- -CELL-CONTENTS AND FORMS OF CELLS. 245 stances taking part in the reaction. Zymases are widely dis- tributed throughout the entire plant kingdom, and occur in greatest amounts in yeasts and other organisms which induce alcoholic fermentation. The enzyme, which causes the transfor- mation of glucose into lactic acid and is secreted by lactic acid bacteria, has been given the name of " lactic acid bacteria-zymase." OXYDASES is the name applied to those enzymes in which the decomposition or reaction involves an oxidation. Several kinds of oxydases are recognized, depending upon the nature of the original substance that is broken down, (i) Alcoholase, the enzyme of acetic bacteria which oxidize ethyl alcohol to acetic acid. (2) Phenolases include the laccases, the oxidizing enzymes found in the lac-tree (Rhus succedanea}, and in some other plants. The black lacquer covering the beautiful Japanese vases and boxes, and which is the most indestructible varnish known to man, is formed by an oxidizing enzyme acting on the phenolic resins of the lac-tree. Catalases in their chemical action resemble some of the col- loidal metals, in that they are able to decompose hydrogen peroxide with the liberation of oxygen. Enzymes of this char- acter have been found in virtually all plant juices. Catalases are of two kinds, one soluble in water, occurring in the seeds of apple and peach, and an insoluble form found in the leaves of clover, rose, and spruce. Highly active catalases are also obtained from fungi, yeasts, and bacteria. While some of the vegetable ferments have been isolated and are prepared on a commercial scale, as diastase and the peptic enzyme papain found in the latex of Carica Papaya, in other cases the ferment-producing organisms themselves are used in a number of industries involving fermentation processes, as the yeast-plants and certain of the molds and bacteria. The microchemical study of the ferments is attended with cer- tain difficulty on account of the lack of specific reagents for their detection. The most that can be done is to study the products formed by their action upon certain other constituents of the cell. (Consult " General Chemistry of the Enzymes," by Hans Euler, translation by Thomas H. Pope.) 246 A TEXT-BOOK OF BOTANY. EXAMINATION OF CELL-CONTENTS NON-PROTOPLASMIC PROTOPLASMIC Crystalline Crystalloidal Amorphous i. Cytoplasm 4- Calcium oxalate 9. Starch ii. Mucilage 2. Nucleus 5- Sugars 10. Inulin 12. Tannin 3. Plastids 6. Alkaloids 13- Resin 7- Glucosides • 14. Oil 8. Phyto-globulins IS- Latex 16. Calcium carbonate i, 2, and 3 have characteristic appearance (see Frontispiece). 4. Crystals of characteristic forms, soluble in hydrochloric acid and insoluble in acetic acid. 5. Crystalline in fresh material treated with alcohol. The glucoses give a reddish precipitate with Fehling's solution. 6. Piperine separates in definite crystals in the plant cell ; the alkaloids of hydrastis form crystallizable salts with sulphuric or nitric acids ; the alkaloids in hydrastis, ipecac, coffee, tea, and guarana yield crystalline sublimates. 7. Concen- trated sulphuric acid gives with strophanthin a bright green color. 8. Phyto-globulins form definite crystals (see paragraph on aleurone grains). 9. Blue with dilute iodine solution, except the amylo-dextrin starches, as mace, which are colored red. 10. Sphero-crystals in fresh material treated with alcohol, n. Colored blue with alcoholic solutions of methylene blue. 12. Reddish- brown with copper acetate solutions. 13. Terpene resins are colored green with copper acetate solutions. 14. Separation in the form of large globules on the application of sulphuric acid or solution of hydrated chloral. The volatile oils are more soluble in alcohol than fixed oils, the latter being completely removed from the cells by the use of ether or other similar solvent. 15. Latex occurs as an emulsion consisting of numerous globules. 16. Calcium carbonate dissolves with an effervescence on the addi- tion of hydrochloric acid or acetic acid. Factors Influencing Growth. — Plants have certain inherent or inherited tendencies or characters which make up the inner constitution, and this cannot be modified by external agencies except within more or less narrow limits. Depending upon this character we find plants as different in kind as the apple tree and pine growing under precisely the same conditions. In other CELL-CONTENTS AND FORMS OF CELLS. 247 words, the character of the structure is determined in the main by the nature of the organism. It is true that an apple tree may grow better in one locality than another, but it is still an apple tree whether it be dwarfed or attain to the full measure of its growth. These slight changes in the character are known as accidental variations. Frequently they are the result of tempo- rary conditions and are not repeated in the succeeding genera- tion. On the other hand, if the special conditions remain these individual variations may be repeated in generation after gen- eration and finally become permanent characters. The gradual change in the structure and nature of organisms which takes place through long periods of time is spoken of as EVOLUTION. In some cases specific changes in the characters of plants arise rather suddenly without any known cause, and such changes are spoken of as saltations or MUTATIONS. The factors essential for growth in all cases are food, water, and a certain temperature. Among the food elements we may mention as of chief importance, carbon, hydrogen, oxygen, and nitrogen. Some of the other elements are also essential to most plants, although they occur in relatively small proportion in the plant, as potassium, magnesium, phosphorus, sulphur, iron, and calcium. The latter element does not seem to be necessary to the normal development of some of the Fungi and certain Algae. Water permeates all parts of the plant, and when the cells are in the normal turgescent state it contains more than half its weight of water. When the supply of water falls below the normal the plants begin to droop and finally die. The need of plants varies greatly in this particular ; some are aquatic in their habits and live wholly .in the water; others can live only on the land ; and still others are adapted to desert regions. The degree of temperature necessary for growth varies within certain limits for each kind of plant, but, as is stated by Pfeffer, the greatest extremes are shown by Fungi, Bacteria, and the lower Algae. Generally speaking, the most favorable temperature for growth is between 24° and 34° C. Besides the factors enumerated there are other factors which influence growth. They include light, gravity, mechanical agencies, etc., and are sometimes spoken of as external stimuli. 248 , A TEXT-BOOK OF BOTANY. It is difficult to separate those factors which act solely as external stimuli from those which are essential to the normal growth of the plant and which may be considered as physiological factors. For example, light under certain conditions may be regarded as in the nature of an external stimulus and not essen- tial to the growth of the plant, while in other cases it has a direct influence on normal growth and is essential to the life of the plant, as in all plants or parts of plants where photosynthesis takes place. In addition to the essential food elements, there are many substances which affect the growth of plants which may be grouped as chemical stimuli, such as (a) the substances secreted by gall- forming insects, (b) in a certain measure some of the substances produced by Fungi, (c) and numerous substances not found as normal constituents of the plant. Depending upon the amount of the substance present and the conditions under which it is supplied, the substance may act as a poison and injure the plant, or it may accelerate growth, or cause abnormal develop- ment. This subject has an important bearing on the physiological testing of drugs. Robert states that in determining the qualities of a new chemical, preliminary experiments should be conducted .on lower plants and animals before trying it on man. Of the plants which have been used in the testing of poisons the follow- ing may be mentioned : Oscillaria, Spirulina, Nostoc, Zygnema, Spirogyra, Saccharomyces, Mucor, Elodea, Lemna, Pistia, Potamogeton, Myriophyllum, Ceratophyllum, Tradescantia, seed- lings of grasses, lupine, bean, pea, corn, etc. Kraemer has em- ployed seedlings of Lupinus albus and Pisum sativum in testing solutions containing ethyl alcohol, strychnine nitrate, brucine sulphate, and tincture of nux vomica (Amer. Jour. Pharm., iqoo, p. 472; see also Saylor, Ibid., 1916, p. 8). FOOD OF PLANTS. — It has already been pointed out that certain of the chemical elements are necessary for the growth of plants, and that these are derived partly from the surrounding atmos- phere and partly from the soil. Those elements derived from the air are either themselves gases or exist in combination in the form of gas, and include oxygen, nitrogen in exceptional cases, CELL-CONTENTS AND FORMS OF CELLS. 249 and carbon dioxide, the source of the carbon entering into the carbon compounds formed by plants. The elements obtained by plants from the soil exist in com- bination with other elements and must be in the form of solution to be absorbed. The soil consists largely of mineral substances, together with certain organic products (humus). The water held in the soil not only acts as a medium for carrying the soluble constituents in the soil to the plant, but is itself an important food product, being the source of the hydrogen used by plants, as also of assimilable oxygen. Among the mineral constituents of the soil that are useful to plants are ammonium salts and nitrates, sulphates, phosphates, chlorides, silicates, and carbonates. When plants are collected and subjected to a temperature of about 110° C. the water is driven off, and then if heat sufficient to incinerate the material is applied the organic matter is driven off in the form of gases, leaving the mineral constituents in the form of ash, as calcium, magnesium, iron, potassium, sodium, and a few other elements. FORMATION OF LEAFMOLD. — When the leaves of a tree fall to the ground they begin to decay and ultimately they are dis- integrated, and their substances become incorporated with the other elements of the soil. The same thing happens with the leaves, stems, and roots of herbaceous plants. Such organic matter is one of the chief sources of food for plants, and its presence in the soil is therefore of fundamental importance in the maintenance of the vegetable mantle of the earth. Coville (Jour. Wash. Acad. Sci., 1913, p. 79) determined the sate in decomposi- tion of leaves and used silver maple, sugar maple, red oak, and Virginia pine. These were exposed to the weather in barrels and in concrete pits. In one experiment a mass of trodden silver maple leaves two feet in depth, with an initial acidity of 0.92 normal, was reduced in a single year to a three-inch layer of black mold containing only a few fragments of leaf skeletons and giving an alkaline reaction. Sugar maple leaves have shown a slower rate of decomposition than those of silver maple, while red oak leaves still showed an acidity of o.oio normal after three years' exposure, and leaves of Virginia pine an acidity of 0.055 normal under the same conditions. During the decomposition of 250 A TEXT-BOOK OF BOTANY. leaves the acid substances are decomposed and to some extent dissipated in the form of gases. The chief agents in the decay of leaves are fungi and bacteria. A number of forms of animal life also contribute greatly to the decay, as earthworms, larvae, flies and beetles and myriapods or thousand-legged worms. Coville distinguishes two kinds of leafmold: (a) In which the leaves show a condition of imperfect decomposition, due to the development and maintenance of an acid condition, which is inimical to the growth of microorganisms of decay. Because of the resemblance of this mat or turf to bog peat in appearance, structure, and chemical composition, and be- cause it supports a type of vegetation similar to that of bog peat, it has been named UPLAND PEAT. This is characteristic of the sandy pine and oak woods, where grow huckleberries, laurel, pipsissewa, pink lady's slipper, trailing arbutus, etc. (b) The other is characteristic of the black mellow mold made up of com- pletely rotted leaves, the acidity being neutralized in part by the calcium present in the leaves and partly by the underlying soil, which is usually of a calcareous nature. This is characteristic of forests of tulip poplar, ash, and oaks, in which grow sanguinaria, caulophyllum, hydrastis, trillium, etc. ORGANIC CONSTITUENTS IN SOIL. — During the past few years Schreiner and his associates in the Bureau of Soils, U. S. Depart- ment of Agriculture, have isolated and identified a number of soil constituents. They have found that certain of these con- stituents, as dihydroxystearic acid, are rather characteristic of poor soils, and that the effect of fertilizers on such soils was to increase their fertility by neutralizing their toxic constituents rather than by the addition of any food constituents to the soil. The compounds isolated by them have varied considerably, and may be grouped into the following classes: I, Paraffin hydro- carbons, represented by hentriacontane ; 2, hydroxy- fatty acids, represented by a-monohydroxystearic acid and dihydroxy- stearic acid ; 3, organic acids of unknown constitution, represented by agroceric acid, paraffinic acid, lignoceric acid, and a number of resin acids ; 4, esters and alcohols, represented by agrosterol, phy- tosterol, glycerides of fatty acids, and resin esters; 5, carbohy- drates, represented by pentosans and pentose sugars ; 6, hexone CELL-CONTENTS AND FORMS OF CELLS. 251 bases, represented by histicline and arginine ; 7, pyrimidine deriva- tives, represented by cytosine ; 8, purine bases, represented by xanthine and hypoxanthine ; 9, pyridine derivatives, represented by picoline carboxylic acid. ROOT ABSORPTION. — Notwithstanding the various agents which are at work tending to break down and dissolve the sub- stances contained in the soil, as soil bacteria, the liquids given to the soil by the roots of the plants themselves, the presence of the so-called humic acids, and the action of water and air, it has been shown that the soil water is an exceedingly weak solution. This is largely due to the peculiar absorptive and fixing power of the soil itself. The dilution of the aqueous solution of the soil constituents is a matter of very great significance, for upon this depends its absorption by the root hairs. While other parts of roots have cer- tain absorptive powers, the root hairs have been defined as the organs of absorption of the plant. They are very delicate in structure and contain protoplasm. Their absorbent function de- pends upon the principle that when a membrane (animal or vegetable) is interposed between two liquids of unequal density, the less dense liquid will pass through the membrane and mix with the denser liquid. This process is known as OSMOSIS, and when a liquid passes outward through a membrane or cell-wall it is called exosmosis, and when inward it is called endosmosis. The soil is made up of minute earth particles, each of which is surrounded by a thin film or envelope of water, and it is this por- tion of the soil liquid that is absorbed by the root hairs. The root hairs come into close contact with these soil particles ; in fact, appear to grow fast to them, arid the cell-liquid in the root hairs being denser than that surrounding the soil particles, the latter passes through the wall into the root hairs. If, on the other hand, the water supplied to the roots of plants should contain an excess of soluble material, the plant will be injured. In this case exosmosis ensues and the plant loses some of its own liquids or cell-sap and will show signs of wilting. It is well known that if cultivated plants are supplied with strong solutions of fertilizer the plants will be injured rather than benefited. 252 A TEXT-BOOK OF BOTANY. ROOT PRESSURE. — The distribution of the water absorbed by the roots to other parts of the plant is influenced by a number of factors, which are commonly spoken of together as root pressure. Among these are osmosis within the plant, due to unequal density of the liquids in different cells ; the changes in the equilibrium of the cell-liquids, due to chemical changes ; and the transpiration of water from the leaves, thus establishing a flow of liquids from the roots upward, which is usually spoken of as the ASCENT OF SAP. The cell-sap passes upward through the xylem for the most part, carrying constituents obtained from the soil to the growing parts, where they are combined with the products of photosyn- thesis, and through a series of reactions protoplasm is finally built up. OXIDATION. — The free oxygen taken in by plants through the stomata and lenticels serves the same purpose in plants as that inhaled by animals, namely, the oxidation of certain compounds, whereby part of the energy necessary for vital activity is lib- erated. Oxygen is required by all parts of the plant. When the roots of plants, such as those of Zea Mays, are surrounded by water so as to exclude the air the plants will become yellow. Germinating seeds consume a large amount of oxygen, but not all the energy formed is used by the plantlet, much of it escaping as heat, as in the germination of barley in the preparation of malt. Those plants dependent upon the presence of free atmospheric oxygen are called A ERODES, while those which are not thus de- oendent, as certain fungi and bacteria, are called ANAEROBES. METABOLISM. — Processes of construction and destruction are going on simultaneously in the plant, and these are all grouped under the general name of metabolism. The processes whereby complex substances are built up from simpler ones, as in photo- synthesis, are together spoken of as CONSTRUCTIVE METABOLISM (anabolism), while those which involve the breaking down of complex compounds into simpler ones, either through oxidation or other chemical action, as when sugar is changed into carbon dioxide and water, are grouped under the head of DESTRUCTIVE METABOLISM (catabolism) . Inasmuch as the carbon dioxide of the atmosphere and the water taken up by the roots together with the mineral salts which CELL-CONTENTS AND FORMS OF CELLS. 253 it holds in solution are the only sources of the food supply of green plants, it follows that the highly complex proteins trace their origin to these comparatively simple substances. By some it is supposed that the final stages in the building up or synthesis of the proteins take place in the leaves, but it is probable that they take place in all the growing parts of the plant. It has already been stated in the paragraph on proteins that seeds contain re- serve materials which are broken up into simpler compounds through the action of certain enzymes, and thus made available for the seedling. It is claimed that these compounds are prin- cipally amino acids, and that of these aspartic and glutaminic acids occur in largest amount and that these two acids are found in different relative amounts in different plants. It is furthermore claimed by some authors that by certain syntheses these com- pounds are respectively converted into asparagin and glutamin, both of which occur as reserve materials in seeds and in other parts of plants as well. Yet other syntheses take place whereby asparagin and similar bodies are converted into albumin and other proteins. In the Coniferae the part played by asparagin and glutamin in protein syntheses is taken by arginin, which substance is found in considerable amount in the seeds of the plants of this group. GROWING POINTS AND MERISTEMS. — Plants are distinguished, for the mos.t part, by having distinct growing points, known as vegetative points. These occur at the apex of shoots and roots and at definite lateral points, being in the stem near the surface and in roots beneath the endodermis. The walls of the cells in these regions are very thin and consist almost entirely of cellulose. The cells are compactly arranged and are more or less polygonal or somewhat elongated. They are rich in protoplasm,, capable of rapid division, and constitute the tissue known as PRIMARY MERI- STEM. In the root three kinds of primary meristem (Fig. 132) are distinguished: (i) The PLEROME (m, f, g), an axial meri- stem, which gives rise to the central cylinder or stele; (2) the PERIBLEM (x, r), or meristematic tissue, which gives rise to the 'primary cortex; and (3) the DERMATOGEN (e), from which the epidermis is developed. In addition to these three meristematic zones there is at the apex, lying next to the dermatogen, a meri- 254 A TEXT-BOOK OF BOTANY. stematic group of cells which give rise to the root-cap, known as the CALYTROGEN (s). At the growing point of the stem three meristematic zones are also distinguished, namely, plerome, periblem, and dermatogen. They are not, however, so well marked as in the case of roots. The tissues which are developed from the primary meristems constitute the PRIMARY STRUCTURE. With the growth in thickness of the stems and roots of Dicotyledons other meristematic cells, known as SECONDARY MERISTEMS, arise. These are of two kinds: ( i ) One which gives rise to the xylem and phloem, known as the CAMBIUM, and (2) another which gives rise to the cork, known as PHELLOGEN. The tissues formed from the secondary meristems constitute the SECONDARY STRUCTURE of older dicotyledonous stems and roots. While the point of vegetation in the higher plants (spermo- phytes) embraces a number of cells, in the lower plants the tissues can be traced back to a single APICAL CELL. CELL- WALL. — Origin and Composition. — It is formed by the protoplasm, and varies in composition at different stages of the growth of the cell, and according to the various functions it has to perform. In order to thoroughly understand the nature and composi- tion of the 'Cell-wall, it is necessary to study the origin and forma- tion of new cells. Growth of the plant is attended not only by an increase in the size of the cells, but by their division (Fig. 85) new cells are also formed. Cells that have the property to divide and form new cells are known as meristematic cells and constitute the MERISTEM. The new 'and dividing walls resulting from the division of the cells consist of a number of substances. When a cell divides, the two daughter protoplasts which result from the division of the nucleus and cytoplasm are separated by the forma- tion of a new wall between them (Fig. 85). The first layer formed is apparently different from the subsequent layers and is known as the middle plate or MIDDLE LAMELLA. This layer is soluble in, or readily attacked by, solutions of the alkalies or solu- tions containing free chlorine. It is insoluble in sulphuric acid,, and readily stained by the aniline dyes. While usually more or less permanent, this middle plate may be finally absorbed, as in CELL-CONTENTS AND FORMS OF CELLS. 255 the glandular hairs of kamala, or it may be changed into mucilage, as in chondrus, or transformed into pectin compounds, as in fleshy roots and fruits. To this middle plate is added on either side by the newly formed protoplasts a layer of substance closely resembling cellu- lose, this constituting the PRIMARY MEMBRANE or primary lamella. As the cells become older the wall increases in thickness through the addition of other layers, much in the same manner as the starch grain increases in size. These subsequent layers are known as SECONDARY LAMELLAE. In a few cells the secondary lamellae may consist of pure cellulose. As a rule, however, the wall is rather complex and consists of alternate layers of cellulose with other substances. Some of these, as mucilage, may be a simple modification of cellulose, others may consist of cellulose in combination with other substances, as in the ligno-cellulose walls of stone cells, or the walls may consist of cellulose and suberin as in cork cells, or of cutin-cellulose as in epidermal cells. Again, there may be, through the action of special enzymes, a decomposi- tion of the cellulose, resulting in the formation of oils, resin, and wax. Furthermore, it would not seem improbable that some of the secondary substances in the wall are direct products of the protoplasm and secreted in the cell-wall, as silica and calcium oxalate in epidermal cells. The substance called pectin originates as a modification of the intercellular substance, and is peculiar to some fruits. As showing, to some extent, the complexity of the lamellae in the cell-wall, the following modifications of the wall in secretion cells may be given: I. The entire outer cell-wall may consist of a thin layer of suberized lamellae, beneath which is a secondary mucilaginous layer that develps the secretion, e.g., Hedychium Gardnerianum. 2. The outer lamellae of the cell-wall may con- sist of suberin; beneath this is a cellulose lamellae, which only after treatment with a solution of potassium hydroxide is colored blue with chlor-zinc iodide; this is followed by a mucilaginous layer, e.g., Laurus nobilis, Curcuma Zedoaria, Cinnamomum Cas- sia, Zingiber officinale, Acorus Calamus. 3. The outer layer may consist of cork, beneath which is a cellulose layer that is colored blue upon treatment with chlor-zinc iodide without the previous 256 A TEXT-BOOK OF BOTANY. use of potassium hydroxide ; to this is then added a mucilaginous layer, as in the secretion cells of Valeriana officinalis and Magnolia grandiflora. 4. The outer layer may be suberized, but the cellulose layer beneath this is not colored blue until the walls have been first treated with Schultze's solution; this then is followed by a mucilaginous layer, e.g., Piper nigrntn, Piper Cubeba, and Sassa- fras officinale. 5. The outer and inner layers may be suberized, and between these are fine lamellae of cellulose, e.g., Croton Eluteria. 6. The outer layer may be suberized, beneath which is a layer of lignocellulose, followed by a mucilaginous layer, e.g., Calycanthus floridus. 7. The outer layer may be colored yellow with chlor-zinc iodide and dissolves in sulphuric acid, while the inner layer is suberized, e.g., fruit of Conium maculatnm. CELLULOSE in its various modifications constitutes the greater proportion of the cell-wall. The cellulose making up the cotton fiber may be said to be the typical cellulose, and is known as " cotton cellulose." It is soluble in copper ammonium sulphate solution ; is colored blue with chlor-zinc-iodide solution or iodine and sulphuric acid, and is stained by acid phenolic dyes, as alizarin, if previously treated with basic mordants, as basic salts of aluminum, etc. The following solutions are used in the testing of mixed fabrics containing cotton : i. A solution of i part of zinc chloride in 2 parts of hydrochloric acid will dissolve cellulose in about one-half minute. 2. Upon heating a piece of fabric in a saturated solution of aluminum chloride, the cotton becomes" friable, the wool remaining unaffected. According to their origin in the plant, or their behavior toward reagents, the cellulose walls may be divided into the following groups: (i) Lignocellulose walls; (2) protective cellulose walls; (3) reserve cellulose walls; (4) mucilage cellulose walls, and (5) mineral cellulose walls. Lignocellulose walls are composed of true cellulose and a non-cellulose (the so-called lignin or lignorte), these constituting the woody (so-called lignified) portion of plants and, in some instances, also the bast portion of the bark. The lignocelluloses are colored yellow with chlor-zinc iodide, or iodine and sulphuric acid. On account of their containing in some instances furfurol, CELL-CONTENTS AND FORMS OF CELLS. 257 coniferin, vanillin, cinnamic aldehyde, benzaldehyde or other alde- hydic substances, they give definite color-reactions with certain reagents. They are also stained by the aniline dyes, as fuchsin, safranin, gentian violet, aniline blue, methylene blue, etc. Aniline hydrochloride with hydrochloric acid and aniline sul- phate with sulphuric acid produce a golden-yellow color in cell- walls containing lignocelluloses. A 2 per cent, phloroglucin solution, used in conjunction with hydrochloric acid, gives a reddish-violet color with the lignocellu- loses, although there are some celluloses of this class which do not respond to this test, as flax (the bast fibers of Linum). In other plants phloroglucin may occur as a constituent of the cells. Hartwich and Winckel (Arch. d. Phann., 1904, p. 462) have shown that the red coloration formed upon the addition of vanillin and hydrochloric acid to phloroglucin is also produced by a number of other substances, viz., thymol, guaiacol, resorcin, cresorcin, .orcin, pyrogallol, pyrogallol dimethyl-ether, phloroglucin, oxy- hydroquinone, eugenol, and safrol, but not with phenol, pyro- catechin, hydroquinone, or pyrogallol trimethyl-ether. The re- action cannot, therefore, be longer designated as a phloroglucin reaction, but, in a limited sense, as a phenol reaction. The same color reaction is produced by a number of other substances which contain a phloroglucin molecule, e.g., phloridzin, maclurin, luteolin, morin, catechin, filizin, gentisin, and all the phloroglycotannoides, as in oak bark and cinchona bark. Protective cellulose walls are composed of mixtures of lig- nocellulose and oils and waxes, and frequently contain in addi- tion tannin, vanillin, and other compounds. In the cuticle or epi- dermis of leaves and green stems the cellulose is associated with a fatty compound known as cutin (or cutose), while in the cork of stems and roots it is combined with suberin (or suberose). This class of celluloses is distinguished from cotton cellulose and lignocellulose by being insoluble in sulphuric acid. Reserve cellulose walls are those found in various seeds, as in coffee, date, nux vomica, etc. They behave toward reagents much like the true celluloses (Fig. 135). Mucilage cellulose walls consist of cellulose and mucilage, and are found in all parts of the plant, and in the case of seeds A TEXT-BOOK OF BOTANY. are associated with the protective celluloses. They dissolve or swell in water, are colored blue (as in flaxseed) or yellowish with iodine, and are stained with alcoholic or glycerin solutions of methylene blue. Mineral cellulose walls are composed of cellulose and vari- ous inorganic substances, as silica, calcium oxalate, or calcium carbonate. These are more commonly found in the cell-wall of the lower plants, as Algae, Fungi, and Equisetaceae. Calcium car- bonate and silica also occur in the cystoliths of the various genera of the Moraceae and Acanthaceae (Fig. 113). From what has just been said of the chemical composition and structure of the cell-wall, it is seen that it consists of lamellae or FIG. 129. i, cross-section of a bast fiber of Begonia as seen by means of the micro- polariscope, and showing stratification of the wall. 2, polariscopic view of a spheio-crystal of inulin in Helianthus tuberosus. — After Dippel. layers of different substances, and in no case does it consist of but a single substance; but for convenience we speakrof a wall as consisting of cellulose, lignin, or suberin, meaning thereby that the wall gives characteristic reactions for these substances. PHYTOMELANE, an intercellular, carbon-like substance. It is a black, structureless substance, found only in the Compositae, being distributed around the sclerenchymatous fibers and stone cells in a number of fruits. It has also been found in the lignified cells of roots and stems (Fig. 131), and occasionally is found in the parenchyma cells of Inula. In the latter it occurs more or less crystalline, sometimes in the form of short needles or rods (Fig. 132). According to Hanausek (" Untersuchungen iiber die Kohlr ihnliche Masse der Kompositen "), phytomelane occurs in a largv number of genera in the Compositae. It arises in the middle lamellae and has a high content in carbon, ranging from 69.76 per CELL-CONTENTS AND FORMS OF CELLS. 259 cent, in Helianthus annuus to 76.47 per cent, in Dahlia variabilis. It is unaffected by most reagents except hydriodic acid. It may readily be separated in unaltered masses upon treatment of the tissues with Wiesner's chromic acid mixture or with Schultze's macerating solution. Hanausek considers the phytomelane layer to be in the nature of a mechanical protection to those fruits and seeds in which the epidermal and hypodermal layers scale off with the ripening of the fruit. (Consult Kraemer and Sollenberger, Amer. FIG. 130. Striation in cell-wall: I, a portion of bast fiber in Oleander, showing left spiral bands as seen from the outer surface (a) and the same as seen from the inner surface (b); II, portion of the bast cell of Asclepias syriaca as seen on the under surface; III, a view of the bast fiber of Asclepias syriaca as seen when looking through the middle of the cell; IV, portion of tracheid of Pinus sylvestns, showing two views of the striations of the wall. — After Dippel in "Das Mikroskop." Jour. Pharm., 1911, p. 315; Senft, Pharm. Post, 1914, No. 30: Hanausek, Ber. d. d. bot. Ges., 1911, p. 558.) LAMELLAE. — In some cells, as in lignified cells, the lamellae are quite apparent. In other cases the use of reagents, as chromic acid or chlor-zinc iodide, is necessary to bring out this structure. The layering which is observed in transverse sections of the cell- wall is spoken of as stratification of the wall (Fig. 129), whereas the layering observed in longitudinal or tangential sections is referred to as striation of the wall (Fig. 130). 260 A TEXT-BOOK OF BOTANY. Thickening or Marking of Walls. — In the formation of the wall each cell appears to work in unison with its neighbors for the building up of the plant. The thickening of the walls of the cell is primarily for the purpose of strengthening the walls, but if the walls were uniformly thickened, osmosis, or the trans- ferrai of cell-sap from one cell to another, would be hindered. FIG —^-^ — ^t — — — » i i t \ _i t. 131 . Phytomelane, an intercellular carbon-like substance occurring on the outer layers of the stone cells in Brauneria pallida (Echinacea angustifolia). Thus we find that the contiguous walls of the cells are thickened at definite places opposite each other, leaving pores or canals which permit rapid osmosis. The pores thus formed are known as simple pores, and when seen in surface view are somewhat elliptical or circular in outline, and may be mistaken for some of CELL-CONTENTS AND FORMS OF CELLS. 261 the cell-contents. These thickenings assume a number of forms, which are quite characteristic for the plants in which they are found. They may have the form of transverse or oblique rings, FIG. 132. Phytomelane in root of Inula Helenium. 1-3 showing intercellular spaces with carbon-like substance; 4-8, striated structure of intercellular phytomelane in sections which have been allowed to remain in solutions of hydrated chloral or potassium hydrate for some days; 9, a large crystal-like aggregate in a schizogenous-like reservoir formed in contiguous intercellular spaces of 5 parenchyma cells; 10, separated crystal-aggregates and rod-shaped masses of Phytomelane. — After Senft. longitudinal spirals, or may be ladder-like or reticulate in appear- ance (Figs. 141-144). In other instances the thickening of the wall is quite complex, as in the wood of the pines and other Conif- erae (Fig. 68). The thickening, or sculpturing, as it is sometimes ?62 A TEXT-BOOK OF BOTANY. called, may not only occur on the inner surface of the wall, when it is spoken of as CENTRIPETAL, but may also take place on the outer surface, when it is known as CENTRIFUGAL, as in the spores of lycopodium and the pollen grains of the Compositae. FORMS OF CELLS. Upon examining sections of various portions of the plant, it is observed that not only do the cell-contents and cell-wall yary in composition, but that the cells are of different forms, depend- ing more or less upon their functions. Groups of cells which are similar in form and function constitute the various tissues of the plant; and include: (i) parenchyma cells, (2) mechanical cells, (3) conducting cells, and (4) protective cells. Parenchyma. — Under the head of parenchyma are included those cells which are nearly isodiametric and thin-walled, the walls consisting of cellulose lamellae (Fig. 134). They may contain both protoplasmic and non-protoplasmic cell-contents. Accord- ing to the function and nature of contents, five kinds of paren- chyma cells are recognized : (a) CHLOROPHYLL-PARENCHYMA or assimilation parenchyma contains numerous chloroplastids and 'occurs in leaves and all green parts of the plant, (b) RESERVE 'PARENCHYMA occurs in seeds, roots, rhizomes, leaves, and contains starch, aleurone grains, fixed oils, and other reserve materials. In some instances the parenchyma, as in the endosperm of date, ivory nut, etc., may be very thick-walled (Fig. 135). The paren- chyma in stems and leaves of various of the orchids, as well as that of plants of arid regions, which store water, may be included in this group, (c) CONDUCTING PARENCHYMA is found either associated with the sieve or with the tracheae, the cells of the phloem conveying the plastic substances, while those of the xylem convey water and salts. The cells of the pith and cortex are, as a rule, not utilized for the rapid translocation of food materials to far distant parts, although every living cell and every tissue has a certain power of translocation, and no doubt different parenchymatous tissues exhibit varying degrees of functional activity and differentiation. Thus large quantities of reserve materials are rapidly transferred to the developing embryo through the cells of the endosperm, and in young seedlings further trans- CELL-CONTENTS AND FORMS OF CELLS. 263 ference probably takes place mainly through the cortical and medullary parenchyma, (rf) SPONGY PARENCHYMA, or loose, spongy tissue with large intercellular spaces. The cells of this xf, FIG. 133. A cell from sassafras pith showing intercellular space (i); middle lamella (m); layer of lignin (1); and layer of cellulose (c), which is subsequently modified to muci- lage; simple pores (p) which are seen in the lower wall, the section being slightly oblique. B, portion of wall showing the appearance of the pores when the view is transverse to the wall and the focus is at the upper part of the pore (a) or at the lower part (b). type vary from slightly branched cells, as in the mesophyll of leaves, to those which are strongly branched and stellate, as in Juncus, Pondederia, and the stems of various marsh plants. In 264 A TEXT-BOOK OF BOTANY. Calamus the cells are so arranged that very large intercellular spaces are formed (Fig. 134). (>) A number of modifications of typical parenchyma also occur, some of the cells being either quite thick-walled or considerably elongated. The walls of pith- C FIG. 134. Forms of cells. A. — Transverse section of the pith of Tradescantla vtr~ ginica: I, intercellular space; W, cell wall. Q. — Transverse section of calamus rhizome showing a large oil-secretion cell, smaller cells containing starch, and large intercellular spaces (I). C. — Transverse section of the stem of Phytolacca decandra showing collenchy- matous cells beneath the epidermis. D. — Longitudinal section of taraxacum root showing branched laticiferous tissue (L). E. — Transverse section of pyrethrum root: R, oil-secre- tion reservoir with oil globules; I, cells with sphere-crystals of inulin, such as separate in alcoholic material; L, cells containing irregular masses of inulin, as found in dried material. F.— Longitudinal section of stem of Cucurbita Pepo: S, sieve-cell with protoplasm-like contents, and transverse walls (sieve plates) showing simple pores. parenchyma may consist of lamellae of lignocellulose and mucilage, as in Sassafras pith (Fig. 133). MECHANICAL TISSUE includes all those cells which serve to keep the various parts, of the plant in their proper positions, one CELL-CONTENTS AND FORMS OF CELLS. 265 with reference to the other, and which enable it to withstand undue strain and pressure. There are two principal forms, namely, (a) collenchyma and (&) sclerenchyma. THE COLLENCHYMA CELL is elongated, prismatic, with soft FIG. I3S« A, cells of endosperm of the seed of the date palm (Phoenix dactylifera) , the one normal and the other showing the stratification of the wall after treatment with chlor- zinc-iodide. B, cell of endosperm of Phytelephas macrocarpa (vegetable ivory) showing lamellation and spherite structure in the wall after treatment with chlor-zinc-iodide', clove oil, chromic acid or certain other reagents. C, cell of endosperm of Stryclmos Nux-vomica after treatment with iodine and potas- sium iodide solution. D, opposite pores in the walls in contiguous cells of vegetable ivory showing striae between them after treatment with iodine solution. Walls consisting mainly of cellulose and never lignified ; the contents being rich in water. In transverse section it is readily distin- guished by the local thickening of the walls, i.e., at the angles of 266 A TEXT-BOOK OF BOTANY. the cells (Fig. 134, c). Pores are rare, but when present they are annular or slit-like. Collenchyma occurs near the surface of plant organs, as herbaceous stems, when they form ribs, as FIG. 136. Various forms of stone cells: A, epidermis of hyoscyamus seeds; B, pericarp of pimenta, containing brownish tannin masses; C, seed-coat of coffee; D, seed-coat of almond; E, transverse section of seed-coat of white mustard showing beaker cells; F, surface view of beaker cells of seed-coat of white mustard; G, transverse section through stone cells of endocarp of olive, the lumen containing air; H, a stone cell from the periderm of calumba, containing numerous monoclinic prisms of calcium oxalate; I, various forms of stone cells isolated from pericarp of star anise. in the Umbelliferae. It is also found in leaves and in fruits, as in the Umbelliferse. SCLERENCHYMA CELLS include all of those cells which have more or less uniformly thickened walls composed of lignocellulose, CELL-CONTENTS AND FORMS OF CELLS. 267 permeated by simple or branching pores. They have a thin layer of protoplasm enclosing large vacuoles, and may contain tannin or tannin-like masses, and occasionally calcium oxalate crystals or starch, and in dead cells the lumen or cell cavity contains air. Two kinds o>f sclerenchyma are recognized: i, in which the cells are more or less isodiametric (Figs. 136-138), known as stone cells (short sclerenchyma) ; and 2, in which the cells are elongated (Figs. 139-141), being from 0.5 to 2 mm. in length and known as sclerenchymatous fibers (or long scleren- chyma). Of these latter, two kinds are distinguished, chiefly according to their position in the plant, namely, bast fibers, or stereome, and wood fibers, or libriform. Seldom are the wood and FIG. 137. Several forms of stone cells: A, white oak bark; B, white cinnamon or canella bark (Canella alba) ; C, seed-coat of capsicum. bast fibers in the same plant uniform in structure and composition, as in glycyrrhiza and althaea. On the other hand, they are with difficulty distinguished in monocotyledonous roots, and the term sclerenchymatous fiber is here best employed to include both kinds of cells. In the study of powdered drugs the term sclerenchyma- tous fiber may be employed with advantage when speaking of wood and bast fibers, as in this condition they are not readily distinguish- able. It is usual in plant anatomy to include as stereome all ligni- fied fibers not directly associated with the vessels of the mestome strands (or vascular bundles). STONE CELLS or SCLEROTIC CELLS are parenchymatous cells with very thick, lignified walls, composed of numerous lamellae, 268 A TEXT-BOOK OF BOTANY. which are permeated with simple and not infrequently branching pores. They vary in form, being usually polygonal, or more or less irregular in outline, sometimes branching. The lamellation of the walls is brought out by the use of swelling reagents, as solu- tions of the alkalies, hydrated chloral, chromic acid, etc. In typical stone cells the walls always give the characteristic re- action for lignocellulose with acid solutions of either phloro- glucin or aniline sulphate. The lumina of the cells frequently contains a reddish, amorphous substance, seldom are crystals of calcium oxalate present (Fig. 136, //), and not infrequently they are filled with air (Fig. 136, G). In the identification of com- FIG. 138. Various forms of stone cells in star anise, the fruit of Illtcium anisatum. mercial products the study of the contents of the stone cells is frequently as important as that of the forms of cells. BAST FIBERS or STEREOMATIC CELLS are sclerenchymatous fibers, occurring in the bark and usually associated with sieve cells. They represent the skeleton of plants and are the most important mechanical tissues of the bark, being much firmer than the collen- chyma. They are very long, spindle-shaped, with more or less thick walls, and provided with slit-like, oblique pores. The walls may consist of cellulose, as in the fibers of flax, but they are usually more or less lignified; the lumina is narrow and usually contains air. In transverse sections the fibers are more or less CELL-CONTENTS AND FORMS OF CELLS. 269 circular, ellipsoidal or polygonal, depending upon the pressure upon the walls and whether they are isolated or in groups. They vary in diameter and length, and also in the thickness of the walls ; while most bast fibers are between i and 2 mm. in length, -they may be more than 200 mm. in length, as in Boehmeria nivea. The ends may be more or less obtuse or drawn out to a fine point ; c, rosette aggregates of calcium oxalate; p, parenchyma ce occasionally they are somewhat branched (Fig. 140). The pores in surface view are narrow elliptical and arranged according to a left-handed spiral. The spiral arrangement of the component elements of the wall is supposed to give strength to the fibers, and, according to Schwendener, they will sustain a weight nearly equivalent to that of wrought-iron and steel. 270 A TEXT-BOOK OF BOTANY. Bast fibers may be isolated by the use of Schulze's macerating fluid (which is prepared by dissolving a few crystals of potassium chlorate in nitric acid) and moderately heating the solution con- taining the material either on a slide or in a test-tube. The mechanical tissue consisting of cells resembling bast fibers and occurring in leaves and fruits is usually referred to as stereome. WOOD FIBERS or LIBRIFORM CELLS are sclerenchymatous fibers •m , | litlil w, \ I FIG. 140. A, C, bast fibers of the bark of Cinchona succirubra; B, bast fibers of the bark of Cinchona Ledgeriana; D, stone cells of Cuprea bark (Remijia peduncuiata). — After Oesterle and Tschirch. occurring in the wood and are usually associated with the tracheae. They are scarcely to be distinguished from the bast fibers except by their position, and are the strengthening cells of the xylem. While the bast fiber is frequently not lignified, the walls of the wood fibers usually consist of lignocellulose, and usually give quite pronounced color reactions with acid solutions of either phloroglucin or aniline sulphate. Wood fibers are usually more CELL-CONTENTS AND FORMS OF CELLS. 271 abundant than bast fibers in the same plant, and, while the bast fibers may be wanting, the wood fibers, with few exceptions, are always present. Wood fibers seldom attain the length of bast V rvst • " CF B'F O FIG. 141. Longitudinal-transverse section of licorice rhizome including the cambium: P, parenchyma; T, tracheae or ducts; WF, wood fibers; C, cambium; S, sieve; CF, crystal fibers; BF, bast fibers; MR, medullary ray. fibers. 'They are not infrequently branched at the ends, and, besides a thin protoplasmic layer, they usually have no other contents than water or air. They frequently have yellowish walls, characteristic of stone cells, and also exhibit a similar {amellation and refraction of the wall. 272 A TEXT-BOOK OF BOTANY. Conducting cells or mestome include those cells which are chiefly concerned in the transferral of either crude or assimilable FIG. 142. Developmentvof spiral bands in the mechanical cells of young fruits of Fegatella conica (Hepaticae) : I, young cell with vacuoles and small starch grains; II, portion of an older cell showing formation of large vacuoles in the protoplasm, the strands of which are arranged in a left-hand spiral; III, showing spiral arrangement of protoplasm; IV, portion of cell as in III treated with a sugar solution and showing plasmolysis of protoplast; V, showing formation of band; VI, a cell as in V treated with sugar solution, showing the protoplasm arranged along the thickened portions of the wall where the bands are forming; VII, the mature cell showing lignified spiral bands. — After Dippel in "Das Mikroskop." food materials. The more or less crude inorganic materials are carried from the root through the woody portion of the stem to CELL-CONTENTS AND FORMS OF CELLS. 273 the leaves, and from the leaves the products of photosynthesis, as well as other plastic substances, are distributed through some of the tissues of the bark to other parts of the plant. The tissues or elements of the wood which conduct food materials are of sev- eral forms and include tracheae or vessels (also called " ducts "), tracheids, and conducting parenchyma ; and the elements of the bark which transport the assimilable materials comprise the lep- tome and conducting parenchyma (Fig. 141). Water-conducting elements (TRACHEAL ELEMENTS) comprise the vessels (tracheae) and the tracheids, which resemble each other, except that the latter are single cells of prosenchymatic shape, while the former are very long tubes, varying from cylindrical to prismatic in shape, and consist of long rows of cells which are superimposed length- wise, the transverse walls being usually obliterated. A $ D c K FIG. 143. Forms of tracheae or vessels. A. — Longitudinal section of stem of Cucurbita Pepo showing various forms of trachese: A. annular; S, spiral; D, double spiral; C, close annular; R, reticulate. B. — Trachese in glycyrrhiza rhizome: W, wall; B, bordered pores; P, oblique simple pores. The tracheae or vessels are formed by the disintegration and removal of the transverse walls between certain superimposed cells, forming an elongated cell or tube, which occasionally retains some of the transverse walls (Figs. 142-144). The longitudinal walls are relatively thin and consist of lignocellulose, giving pro- nounced reactions with phloroglucin or aniline sulphate. Four types of vessels or tracheae are known : annular, spiral, reticulate, and porous. Those having the thickenings in the form of horizontal or oblique rings are known as ANNULAR TRACHEA; those having the thickenings in the form of spirals, which usually run from right to left, are known as SPIRAL TRACHEA; those having the thickenings in the form of a reticulation are known as 18 274 A TEXT-BOOK OF BOTANY. RETICULATED TRACHEA and those with spherical or oblique slit pores are known as POROUS TRACHEA or vessels (Figs. 142-144). In those vessels in which but few of the transverse walls are obliterated, the walls are marked by both simple and bordered FIG. 144. Types of tracheae or vessels. A, vessels with annular and spiral thickenings in Phlox Carolina; B, longitudinal section through fibrovascular bundle in aconite, showing porous (p) and spiral tracheae (t), bast fibers (b), and some of the collenchyma cells (c); C, longitudinal section showing reticulate tracheae in scopolia; D, longitudinal section of the woody part of the rhizome of Spigelia, showing tracheae (t), tracheids (h), tracheae (r) with yellowish-brown, gum-like masses; E, portion of xylem of stem showing in Hyos- cyamus tracheae (t) with bordered pores and wood fibers (w), with simple oblique pores. pores, which latter are described under tracheids. Vessels contain water, water-vapor, and air; in some cases they contain sugar, tannin, mucilage, or resin. CELL-CONTENTS AND FORMS OF CELLS. 275 The tracheids are intermediate in character between tracheae and libriform, resembling the former in possessing bordered pores (Fig. 145) and scalariform thickenings; and the latter in being true cells, which are usually elongated 'and quite thick-walled, the walls giving distinct reactions for lignocellulose with phloro- glucin or aniline sulphate. One of the chief characteristics of tracheids is the BORDERED PORES (Fig. 145). These differ from simple pores in that the wall surrounding the pore forms a dome-shaped or blister-like iX FIG. 145. Bordered pores of the tracheids of the wood of Abies alba as viewed in longitudinal section: m, middle lamella; v, i, middle and inner layers of walls of contigu- ous cells ; C, pore-canal through which sap passes from one cell to another ; L, dome- shaped cavity of pore; S, separating wall or closing membrane which is usually thickened in the middle as shown at t. In older cells the separating membrane is broken as shown in the lower pore in figure 2. At the right in figure 4 is shown a surf r.ce view of a bordered pore, the dotted lines indicating the relation of the circles to the structure of the pore. — After Vogl. protrusion into the cell. On surface view the pores are either circular or elliptical in outline, the dome being circular or, if the pores are numerous and arranged close together, more or less polygonal (Figs. 143, 144). The number and distribution of bordered pores in the Coni- ferse are quite characteristic for some of the genera, and may be studied in any of the pines, the pores being most numerous in the radial walls (Fig. 69). 276 A TEXT-BOOK OF BOTANY. The leptome or sieve is distinguished from the other con- ducting elements in that the walls are thin and are composed of cellulose (Fig. 146). It consists of superimposed elongated cells, the transverse walls of which possess numerous pores which are supposed to be in the nature of openings, permitting of the FIG. 146. Different forms of sieve pores: I, portion of sieve tube of Bryonia alba, II of Cucurbita Pepo, A longitudinal section and B in transverse section; III, portion of a sieve cell of Larix europaa showing round sieve pores; IV, an old sieve plate in Bryonia alba treated with chlor-zinc-iodide. showing the striated callous plates (c), (z) cell-wall, (s) sieve plate, (i) contents of sieve tube, (h) cell membrane, (c) callous plates. — After Dippel in "Das Mikroskop." direct passage of the contents from one cell 'to the other. This transverse wall, which may be either horizontal or oblique, is known as the SIEVE PLATE, and the thin places as pores of the sieve. The sieve plates are sometimes also formed on the longi- CELL-CONTENTS AND FORMS OF CELLS. 277 tudinal walls. When the activities of plants are suspended during the winter, there is formed on either side of the sieve plates a layer of a colorless, mucilaginous substance, known as callus, which has somewhat the appearance of collenchyma, but is colored brownish by chlor-zinc iodide. The sieve cells contain an albuminous substance somewhat resembling protoplasm ; in some instances starch grains have also been found. When the activities of the sieve tubes have ceased, they be- come altered in shape, and are then known as altered sieve. In the drying of plants a similar alteration is produced, and the sieve of vegetable drugs is referred to as " obliterated " sieve. Protecting cells include those cells which are located on the outer parts of the plant. The function of these cells is to lessen the rate of transpiration, or the giving off of water ; to furnish protection against changes of temperature, and to protect the inner tissues against the attack of fungi and insects ; they also have a mechanical function (Figs. 147, 157). Depending principally upon their composition, these cells may be divided into two classes, namely, epidermal cells and cork cells. The epidermal cells constitute the outermost layer of the plant. They contain cytoplasm, but the plastids in some instances are wanting; in petals, etc., they also contain dissolved color- ing principles ; and on account of the relatively large amount of water which they contain they are classed among the important water-reservoirs of the plant. The outer walls are principally characterized by one or more lamellae of cutin, these uniting to form a continuous wall. The cutin is often associated with wax, this constituting the bloom of fruits ; less frequently such inorganic substances as calcium car- bonate, calcium oxalate, and silica are present, and not infre- quently mucilage is present, as in the walls of certain seeds (Fig. 119. A). On surface view the form of these cells varies from nearly isodiametric to oblong; they may also be polygonal or branched. In transverse section their radial diameter is much the shorter. In some instances the inner and side walls are considerably thick- ened, as in the seeds of a number of the Solanacese (Fig. 136, A). 278 A TEXT-BOOK OF BOTANY. The epidermis usually consists of a single layer of cells, but may have additional layers underneath forming the HYPODEKMIS, as in the upper surface of the leaves of species of Ficus (Fig. 113) ; FIG. 147. Stomata and water-pores. A. — Transverse section through lower surface of leaf of stramonium: stoma, with guard cells (G), containing cytoplasm, nucleus and chloroplastids; N, surrounding cells; A, intercellular cavity usually filled with cell-sap or watery vapor; E, epidermal cells; M, mesophyll. B. — Surface section of upper surface of leaf of Viola tricolor showing four stomata. C. — Surface section of under surface of leaf of Viola tricolor showing five stomata. D. — A section through the margin of the leaf of Viola tricolor showing a tooth with three water-pores. E. — A water-pore of Viola tricolor in surface section. in some instances the hypodermis undergoes a mucilage modifica- tion, as in the leaves of buchu. Stomata. — Distributed among the epidermal cells are pairs of crescent-shaped cells known as a STOMA, and having an open- CELL-CONTENTS AND FORMS OF CELLS. 279 ing or pore between them, which leads to a cavity beneath it. The t\vo cells of the stoma are known as GUARD CELLS (Fig. 147, G). The adjoining walls of the guard cells are alike in transverse sec- tion, but the cells vary in shape in different plants. The guard cells are more or less elastic, and when the cells are turgescent, as when there is an abundance of water and root pressure is strongest, the contiguous walls of the cells recede f rom each other, forming an opening between them, thus permitting the exit of the excess of water taken up by the plant and the exhalation of the oxygen given off during assimilation, as well as the intake of the carbon dioxide used in photosynthesis. On the other hand, when the amount of water in the plant is reduced below the normal and the plant shows signs of wilting the guard cells flatten and the open- ing or pore is closed (Fig. 214). The cells beneath the stoma are loosely arranged, so that the air containing carbon dioxide may be readily diffused to the cells containing the chloroplastids. -The guard cells may be slightly raised above or sunk below the surrounding epidermal cells, the number of the latter being characteristic for certain plants. (Compare Figs. 147, 211-218.) Stomata occur in the largest numbers on the blades of foliage leaves, being more numerous on the under surface, except in aquatic plants, where they occur only upon the upper surface. Water Pores. — Near the margin of the leaf and directly over the ends of conducting cells, not infrequently occur stomata, in which the function of opening and closing is wanting, and which contain in the cavity below the opening water and not air, thus differing from true stomata (Fig. 147, D, £). These are known as WATER PORES, and they give off water in the liquid form, the drops being visible on the edges of the leaves of nasturtiums, fuchsias, roses, etc., at certain times. Plant Hairs. — The epidermal cells are sometimes specially modified centrifugally, giving rise to papillae, to which the velvety appearance of the petals of flowers is due ; in other cases this modification is in the form of hairs or trichomes (Figs. 148-155). These may be unicellular or multicellular, and in addition the latter may be glandular or non-glandular. Glandular hairs possess a head-like apex, consisting of one or more cells, and they secrete oil, mucilage, and other substances (Figs. 124, 125, 149, 150). A TEXT-BOOK OF BOTANY. In the examination of technical products, as also in taxonomic work, the study of plant hairs is very important. They show a great diversity in form in not only genera and. families but even in related species. They vary considerably in their distribution \J FIG. 148. Mostly non-glandular hairs and a few of the small glandular hairs covering the surface of the fruits of several species of Rhus: g, hairs on Rhus glabra, being more or less broadly top-shaped or carrot-shape to spatulate and occasionally narrow elliptical and from o.ioo to 0.400 mm. in length; b, hairs on Rhus typhina, being long and needle-like, varying from 0.750 to 1.500 mm. in length; c, hairs of Rhus glabra borealis, being intermedi- ate between those of Rhus glabra and Rhus typhina, varying from elongate spatulate and narrow cylindrical to needle-shaped, and from o.ioo to i.ooo mm. in length. not only in related species, but sometimes in varieties of the same species they show marked variation in size and form. In some natural hybrids intermediate forms of hairs of the parent species CELL-CONTENTS AND FORMS OF CELLS. 281 are found. This was pointed out by Kraemer in some studies on Rhus glabra and Rhus typhina (Amer. Jour. Phann., 1913, p. 404), in which a herbarium specimen in the New York Botanical Garden and labelled by Britton as Rhus glabra borealis shows hairs which in form and size are intermediate between those of R. glabra and R. typhina (Fig. 148). Plant hairs may be divided into two principal groups: i. GLANDULAR HAIRS, or those in which the summit consists of one or more cells which secrete beneath the cuticle either mucilage, oils, or oleo-resins, and the summit of the hair possesses a more or less globular form. II. NON-GLANDULAR HAIRS, or those in which the summit of the hair consists of one or more rounded or pointed cells in which no secretion is formed beneath the cuticle. GLANDULAR HAIRS may be divided into five different groups : 1. Unicellular glandular hairs consist of a single tubular cell, the upper portion being more or less swollen and rounded (Fig. 149, A, B). Hairs of this type occur in the Euphorbiacese, in Which they more or less resemble Papillae-. In the Compositse they contain a latex and appear to be connected with the laticifer- ous vessels. They also occur in the Anacardiacese, Cornacese, Geraniaceae, Leguminosae, Malvaceae, Menispermaceae, Onagraceae, Piperaceae, Ranunculaceae, Tiliaceae and Zygophyllaceae. 2. Multicellular glandular hairs consist of a number of forms ; either they are differentiated into a stalk and a head, or the stalk may be wanting when the hair has a spatulate or clavate form. These are often very characteristic for certain families, as the glandular hairs in the Labiatae (Fig. 124), which possess a short stalk and a head portion with eight cells, the cuticle being raised like a bladder owing to the great accumulation of secretion. There are a great many types of multicellular glandular hairs (Fig. 149). They may be uniseriate, i.e., consisting of a series of cells with either a unicellular head (Fig. 149, C, E, K, M), as in the Meni- spermaceae, Araliaceae, Malvaceae, Caryophyllaceae, Geraniaceae, etc., or they may be bicellular (Fig. 149, D, F, H, J, L, O), as in the Cruci ferae. The heads may consist of two to four cells (Fig. 149, G, V , Y), as in the Burseraceae, or eight cells, as in the Labiatae (Fig. 149, W). Multicellular glandular hairs have been found in the following families: Aceraceae, Anacardiaceae, Araliaceae, Be- 282 A TEXT-BOOK OF BOTANY. FIG. 149. Various types of glandular hairs. Unicellular hairs on Julocroton fus- cescens (A), Croton monanthogynus (B). Uniseriate uni-glandular hairs on Zollikoferia nudicaulis (C), Silene villosa (E), Geranium favosum (K), Boerhaavia repens (M). Glandular hairs with two-celled heads on Hesperis glutinosa (D), Pityrodia salvifolia (F), Cyclamen persicum (H), Lysimachia Nummularia (J), Chenopodium Botrys (L), Diospyros Kaki (O). Glandular hairs with four-celled heads on Humulus Lupulus (G), Boswellia papyri/era (V), Humulus Lupulus (Y). Glandular hairs with five-celled heads on Combretum aculeatum (Z), Humulus Lupulus (Y). Glandular hairs with six-celled heads on Rhododendron Dalhousia (X), hair characteristic on the Phaseolece (U). Glandular hairs with eight-celled heads on Lavandula vera (W). Glandular hairs with multicellular heads on Pieris floribunda (N), Begonia caroliniaefolia (S), Begonia pretoniensis (s). Glandular hairs with four and eight cells respectively on Picramnia coccinea (P). Glandular hairs with two and four cells re- spectively on Cistus ladaniferus (R). Double glandular hair on Rhododendron lanatum (T) — Adapted from Solereder and redrawn by Hogstad. CELL-CONTENTS AND FORMS OF CELLS. 283 goniaceae, Berberidaceae, Bixaceae, Borraginaceae, Burseraceae. Capparidaceae, Caprifoliaceae, Caryopyhllaceae, Chenopodiaceae, .Combretaceae, Compositae, Convolvulaceae, Cornaceae, Crassulaceae, Cruciferae, Cucurbitaceae, Dipsaceae, Ericaceae, Euphorbiaceae, Fagaceae, Geraniaceae, Hippocastanaceae, Hydrophyllaceae, Labi- atae, Leguminosae, Malvaceae, Melastomataceae, Meliaceae, Meni- spermaceae, Moraceae, Myrsinaceae, Nolanaceae, Nyctaginaceae, Nymphaeaceae, Piperaceae, Platanaceae. Plantaginaceae, Polemoni- aceae, Polygonaceae, Portulacaceae, Primulaceae, Rosaceae, Ru- taceae, Sapindaceae, Saxifragaceae, Scrophulariaceae, Simarubaceae, Solanaceae, Sterculiaceae, Theaceae, Tiliaceae, Umbelli ferae, Ul- maceae, and Valerianaceae. 3. Glandular leaf-teeth, as the name would signify, include the glandular hairs formed on the lobes of leaves. They vary in structure and may secrete mucilage, as in the Violaceae (Fig. 120) and in some of the Compositae, or they may secrete, in addi- tion, resin, as in the Rosaceae, or calcium oxalate, as in the Saxifragaceae. 4. Special forms of multicellular glands are found in the Aceraceae, in which a pair of glands are fused together. In some of the Compositae and Moraceae a group of glandular hairs are united. Other special types also occur in the Droseraceae, Ana- cardiaceae, Leguminosae, etc. 5. Hair-like external glands having a complicated structure have been observed in a number of families. They are limited to certain portions of the plant, being found in the Apocynacese at the base of the leaves and in the Rubiaceae only on the stipules. They are usually very large, secreting considerable mucilage and resin. The glandular, shaggy hairs occurring on the stipules in the Rubiaceae are of this type, the secretion being often so abundant that the young leaves emerging from the stipular sheath are coated with this resin, which is even retained by the mature leaves. II. NON-GLANDULAR HAIRS are of three general types: I. Simple hairs (Figs. 148, 151), which may be unicellular or uni- seriate, — i.e., consisting .of a series of superimposed cells. 2. Peltate or stellate groups (Fig. 153, D, E, H, K], consisting of two or more hairs united at the base and spreading like a star. 284 A TEXT-BOOK OF BOTANY. o FIG. 150. Forms of glandular hairs: A, corkscrew-like hairs from the inner surface of the spurred corolla of lavender; B, longitudinal section of rhizome of Uryopteris mar- ginalis showing large intercellular space and an internal oil-secretion hair; C, hairs from stramonium leaf; D, hairs from Digitalis; E, hair from sage; F, hair from eriodictyon; G hairs from inner walls of pericarp of vanilla; H, hair from cannabis indica; I, hairs from surface of fruit of Rhus glabra; K, hairs from belladonna leaf. CELL-CONTENTS AND FORMS OF CELLS. 285 These may consist of one or more series of cells, separated by a columnar cell. 3. Shaggy hairs (Fig. 153, G), in which the epidermal layer of the column of cells is modified to papillae FIG. 151. Forms of non-glandular hairs: A, hair from the epidermis of strophanthus; B, a hail irom the capsule of Mallotus philippinensis (found in the drug known as kamala); C, hairs from the leaves and bracts of cannabis indica, two of them containing cystoliths ol calcium carbonate; D, a hair from the under surface of the leaf of senna; E, hairs from leaf of digitalis; F, two forms of hairs from sage leaf; G, two forms of hairs from the leaves of wormwood (Artemisia Absinthium): a T-shaped non-glandular hair and a short glandular hair. which are directed upwards, giving the surface of the plant the appearance of being covered with rough hairs or wool. Non-glandular hairs occur on a large number of plants. They 286 A TEXT-BOOK OF BOTANY. vary in form and are very characteristic in a great many plants. The terms used to describe the various types of hairs are in a few instances rather simple, but there are so many modifications that nothing short of an illustration will suffice to define them. The simple hairs may be divided into a number of sub-divisions : (a) Papillose hairs, being short outgrowths of the epidermal cells, somewhat resembling the papillae found on the ventral surfaces of petals. This form is found in a relatively few families. (&) Unicellular hairs, being outgrowths considerably longer than papillae and occur in a Jarge number of plants. This is also true of a third type (c), known as uniseriate hairs and in which there B G FIG. 152. Forms of non-glandular hairs: A, twisted hairs from under surface of leaf of eriodictyon; B, Hgnified hairs from the epidermis of nux vomica; C, branching hairs from the leaf of mullein (Verbascum Thapsus). are two or more cells connected as in a chain. Among special terms frequently used the following may be mentioned: (d) Hooked hairs (Fig. 154, A, B), in which the summit is bent in the form of a hook, (e) Two-armed hairs (Fig. 153, D), in which the summit consists of two cells which diverge from each other and spread out horizontally or parallel to the surface of the leaf. (/) Stellate hairs (Fig. 151, J5) consist of a group of cells ar- ranged around a simple point, as in the Cruciferae and Saxifra- gaceae. (g) Peltate hairs (Fig. 153, £) consist of a group of radially arranged cells, of which all or only some reach the centre of the shield, as in the Solanaceae, Malvaceae, Loganiaceae, and CELL-CONTENTS AND FORMS OF CELLS. 287 Rosaceae. (h) Candelabra or abietiform hairs (Fig. 153, L) are those which have a uniseriate main axis, interrupted at intervals by whorls of ray cells. These show considerable variation and are very characteristic in the Solanaceae, Acanthaceae, Leguminosae, Labiatae, and Euphorbiaceae. (t) Stinging hairs (Fig. 153, /), or those containing an irritating substance, as in the stinging nettle and other plants of the Urticaceae. The hairs are rather long, the FIG. 153. Several types of non-glandular hairs. Crystal hairs on Malanea macro- Phylla: A, showing hair with a single row of crystals; B, cell with 2 rows of crystals; C, transverse section of B, showing crystals. Two-armed hairs on Artemisia Absinthium (D) and Dichondra repens (H); F, uniseriate non-glandular hair on Pongamia glabra; E, longi- tudinal view showing two of the cells of a peltate hair on Solanum argenteum; G, shaggy hair on Calandrinia umbellate; J, upper portion of stinging hairs of Urtica dioica; K, cup- shaped peltate hair on Rhododendron A nthopogon; L, candelabra hair on Verbascum Thap- sus. — Adapted from Solereder and redrawn by Hogstad. summit bearing a spherical or ovoid head, which is obliquely in- serted and rather easily detached, thus leading to the emission of the contents. The stinging sensation was formerly stated to be due to formic acid, but it is now supposed to be in the nature of a substance related to the ferments. (/) Crystal-containing hairs. Calcium oxalate (Fig. 153, A, B, C), either in the form of rosette aggregates or prisms or needles, is sometimes present in the 288 A TEXT-BOOK OF BOTANY. FIG. 154. Hairs in the Compositae: A, slightly curved or hooked hairs on the corolla of Dandelion; B, hooked hairs on the filaments of Inula; C, hairs on pappus of Tragopogon pralensis; D, hair from akene of Tragopogon pratensis; E, portion of barbed hair upon pappus of Inula: F and G, double hairs fromacheneof Tagetes tenuifolia; H, double hairs from achene of Jnuja; J, double hair from corolla of Calendula. CELL-CONTENTS AND FORMS OF CELLS. 280 FIG. 155. Characteristic branching hairs found on the stem, leaves, and calyx of Hyoscyamus muticus. stinging hairs of some of the Euphorbiacese, as well as in some of the genera of the Cornaceae, Geraniaceae, Rosaceae, and Saxi- fragacese. 19 290 A TEXT-BOOK OF BOTANY. LIGNIFIED HAIRS. — In some seeds, as in nux vomica, the hairs are strongly lignified, as are also the bases of the hairs of Stro- phantus hispidus. This is due to a lignocellulose modification of the wall, and, since broken hairs look more or less like fibers, one might easily be led astray in the study of powdered drugs. It is not usual to make a microchemical study of the walls of non- glandular hairs, but this subject is well worthy the attention of investigators. . FALSE PLANT HAIRS. — While it is impossible for the careful student of plant morphology to mistake anything else for plant hairs, it is, nevertheless, worth while to call attention to some of the mistakes that are liable to be made. In works on systematic botany sometimes occur contradictory statements concerning the abundance or scarcity of hairs, especially as they relate to the flower. In a superficial examination, for instance, in the violets, large masses of germinating pollen grains with their tubes matted together are not at all uncommon in the throat of the corolla, and these have been mistaken for hairs. Furthermore, the mycelia of fungi may be mistaken for hairs, especially in young seedlings, as of hyoscyamus, belladonna, etc., where thread-like delicate branching hairs may occur. In the examination of economic prod- ucts, especially powdered drugs and spices, mistakes of this kind may occur, unless the student has devoted some attention to this study. In all studies of plant hairs the student should carefully locate the summits and bases, and unless these can be recognized, or if broken made to correspond to each other, one cannot say that hairs are present. CORK CELLS replace the epidermal cells of roots and stems that persist year after year. They are formed, as has already been stated, from a distinct meristem, called the phellogen. Cork cells differ from the epidermal cells in that the walls are uniformly thickened and on surface view are polygonal in shape. The walls consist of suberin, a substance allied to cutin; in some instances they also contan lignocellulose, forming cork stone-cells, as in asclepias and calumba. The young cells may contain a thin layer of cytoplasm and a nucleus; they usually also contain brownish masses of tannin or tannin-like compounds, and occasionally crys- tals of cerin or calcium oxalate. CELL-CONTENTS AND FORMS OF CELLS. 291 Cork not only occurs as a secondary protective layer, but may also arise in other parts of the plant as a result of injury, as in leaves, fruits, stems, and tubers. It also arises as a result of the disarticulation of the leaf in autumn. PERIDERM. — The epidermis is not adapted for the protection of the perennial plant organs on account of its thin, frequently delicate structure and its inability to continue with the increase in thickness of stems and roots. Hence it becomes replaced by the periderm, which consists of a lasting tissue, the CORK, and of a meristematic tissue, the PHELLOGEN, which reproduces the cork when it becomes torn or destroyed, by the continued growth in fihil FIG. 156. Section through a secondary lenticel in the bark of Sassafras; e, epidermis', st, stone cells; phel, phelloderm derived from secondary phellogen and having thick lignj. fied wall; p, parenchyma; c, cork; com, complementary cells. — After Weiss. thickness of stems or roots. Cork is not only of sub-epidermal origin, but may occur deeper in the cortex (Fig. 158), or even in- side the endodermis. In the latter case, as in roots, it owes its existence to the activity of the pericambium. Superficial, i.e., hypodermal cork, is extremely rare in roots. Not infrequently a layer of cells is formed inside of the phellogen, being termed the phelloderm. They usually contain plastids ; the walls are moder- ately thick and free from intercellular spaces (Fig. 156). Lenticels may be described as biconvex fissures in the periderm which permit of the easy access of air to the intercellular spaces of the rather loosely arranged cells lying beneath them (Fig. 292 A TEXT-BOOK OF BOTANY. 156). They usually arise as the product of a meristem situated beneath the stomata of the epidermis, the stomata being replaced by them when cork is developed. Several types of lenticels are FIG. 157- Bark of Rhamnus Pttrsliianus showing large whitish patches of lichens, and numerous lens-shaped lenticels. .listinguished. They are quite characteristic and prominent in a number of barks, as those of species of Betula, Prunus, Rham- nus (Fig. 157), etc. CELL-CONTENTS AND FORMS OF CELLS. 293 FIG. 158. Development of Cork: A, in epidermal cells of stem of Oleander; B, development of cork in upper row of collenchymatous cells in the stem of Sambucus nigra; C, development of cork meristem in cells of cortex immediately above the primary bast fibers in Rubus fruticosus; D, development of primary cork In cells above the secondary bast fibers of Clematis Vitalba; e, epidermal cells; k, cork; km, cork-meristem ; c, collen- chyma; b, parenchyma; b, b, primary bast fibers; b', secondary bast fibers; K, young cork cells. — After Dippel in "Das Mikroskop." BORK. — The cork cambium or phellogen develops before ma- turity in the green stems of woody plants belonging to the dico- tyledons. It may develop in the primary or secondary tissues 294 A TEXT-BOOK OF BOTANY. (Fig. 158). When the phellogen develops in the deep-seated tissues, the cells outside of the corky layer sooner or later die and slough off. This is due to the fact that the cork cells are suberized and do not permit the passage of the cell-sap containing food sub- stances. In large shrubs and trees with thick stems and trunks A B Bf Bf FIG. 159. Development of Bork: A, in bark of cherry (Prunus Cerasus), showing a layer of periderm (k) with thin-walled «ork cells; bast fibers (Bf); parenchyma (p); stone cells (st) occasionally branching and lengthened into fibers. B, inner layer of periderm of Quercus Robur, showing compactly arranged, thick- walled cork cells (P) filled with a reddish phlobaphene or altered tannin; starch-bearing parenchyma (p); stone cells (st); sieve tubes (Bg) ; bast fibers (Bf) ; prism of calcium oxalate (kr) ; several rows of thick- walled, porous cells (x). — After Dippel in "Das Mikroskop." a number of successive layers of cork or periderm are formed. These layers with the dead cortical tissues between them persist to some extent and constitute what is known as bork, i.e., bork consists of a number of alternate layers of periderm and cortical CELL-CONTENTS AND FORMS OF CELLS. 295 tissues. The cork cells in different trees are variously developed and accordingly two types of bork formation may be distinguished. In sycamore, cherry and plum trees the cork cells are only slightly thickened (Fig. 159) and the periderm in the form of layers FIG. 160. White oak bark with the fissured corky layers (bork). separates from the tree annually. In the oaks, chestnuts and tulip poplar the cork cells (Fig. 159) are thick walled and com- pactly arranged so' that, under the stress of growth and thickness of the bark, the layers of periderm are split longitudinally, giving 296 A TEXT-BOOK OF BOTANY. rise to the deep furrows (Fig. 160) which are so characteristic of the outer surface of our large trees. Laticiferous or milk tissue occurs in all those plants which emit a milk-juice on being cut or otherwise wounded. The juice may be colorless, as in the oleander; whitish, as in the Asclepia- dacess, Apocynacese, etc. ; or yellowish, as in the Papaveracese. It contains caoutchouc, oils, resins, mucilage, starch, calcium oxalate and alkaloids as well. The walls are relatively thin and consist chiefly of cellulose. The tissue consists either of single cells of definite length, as in the Papaveraceae, or the cells may be of indefinite length, as in the Asclepiadacese, or it may consist of a more or less branching network (Fig. 127) formed by the anastomosing of a number of cells, as in Taraxacum (consult paragraph on Latex, pp. 238-241). As has already been stated, the latex of plants contains a num- ber of plastic or trophic substances, — i.e., those which, either at '" once or after being stored for a time as reserve food, are drawn into metabolism and serve as nutrient material. They also con- tain a number of aplastic or non-trophic substances, as caoutchouc, resin, alkaloids, volatile oils and tannin, which are in the nature of metabolic by-products and are incapable of further metabolism. While it is highly probable that the laticiferous tissue, on account of its being always associated with the phloem, functions to some extent for the transportation of plastic substances, yet it serves another purpose, viz., to protect the underlying cells after injury of the plant by insects or herbivorous animals. This protection results from the rapid coagulation of the exuding latex upon exposure to the air and forming a varnish-like surface. In some cases the latex contains a poisonous principle which exercises a protective function. In Rhus Toxicodendron the principle causing the eczema, namely toxicodendrol, is supposed to be formed in laticiferous tissues being transferred to the hairs, which upon being broken liberate the poison. CELL-CONTENTS AND FORMS OF CELLS. 297 0 g a? O P O *% £.•0 g ? c ^ f IE ° 3 3 >-i re i u> 3 re 01 »§ 3 0 is fig Ss'S' sfils o S> P T) il'3 •B i III ££.§ r+ 3 r+- a ^ 3 a O 3^ « 01 re c* o "" 3*P 2 o re 3 p re * if "O 3*2 O 2. £ So ._. CD " ^3 5> w 5" 3 R) a* •83 cj ftg g o a I re S 3 w 3 si *d ^ B*^ o" = Choi ^,3 o-p ^ S- q 3 o^ "i Q. O >-) ^"•0.3 01 B 01 ?"* o sfS-S-B1 « o O •0^, H M o 5 ^ £T.*o 3 O M O W* 3. re •<• X §. M ^ 53 igf'gsF If Us III 01 o *- BgB P " ft rt- O "1 o"1 ? 3" It —8 0 -»o? ^ffi n O P tQ z £§•0 w o i^rSjB1 «o 0 O^"^-'P ^ H o c •-» o *-i o w* 3. re •<; Q m; re •-) ^ HI o 5'?o3 If 89 If 8 ||I re 55 2.01 C UB P ft rt O 1 K§| 2. H 5 o TO g M o. ° S ?'<''1> ffi |*re re"p ft o ni o 0 01 (B t-1 ^ o O «g, p M c+ ^ 01 C r> oV o *^- t^ rl "^ C/3 re 3 ~ ill c 1 re 1.8 ll 3§3' rt O 1 o'o 2. re -^3 3g.OQ re' re re B o 2 re 5' ^ r* Ol r . Isbdiametric polygonal or branching The outer layer of herbaceous plants Epidermis PROTEC (t> •-! - M "* H JPfi re 31 o tr* <* O z 0 •a o 8 1 o en o | c 2, 5' £5 £L5> 5' B 5' 5' 3 3 _ 05 P 80 ° 2-c °s 13 ft £.P' "< 3 ll 3 o ^ re O o to- CELLS. M •<" 3 2. «"' 01 ot o 6) " B' 5T i-h CHAPTER III THE OUTER AND INNER MORPHOLOGY OF HIGHER PLANTS. INTRODUCTORY. IT may be well to repeat at this point that on germination of the megaspore the female gametophyte bearing the egg-cell is formed, and that on germination of a microspore the male gameto- phyte bearing male nuclei is organized. The union of egg-cell and a male nucleus gives rise to the sporophyte embryo contained in the seed, which develops into the plant we see, namely, the sporophyte. The female gametophyte always remains concealed within the embryo-sac, and the male gametophyte may be said to embody the protoplasmic contents of the pollen tube. A complete flower is made up of floral leaves and sporophylls, the latter being essential for the reason that they give rise to the spores. While the flower belongs to the sporophyte generation, the propagative organs may be said to be derived from both the sporophyte and gametophyte, and hence may be distinguished as asexual and sexual. The following outline illustrates their derivation : Propagative Organs Sexual, derived from gametophytes (sex- ual generation) Egg-apparatus, containing egg-cell female gamete or Asexual, derived from sporophyte ( asex- ual generation) 298 Male Generative-cell, giving rise to male nuclei or male gametes Microsporangium (pollen sacs) giving rise to microspores (pollen grains) Megasporangium (nucel- lus) giving rise to mega- spore (embryo-sac) MORPHOLOGY OF HIGHER PLANTS. 299 The vegetative organs comprise the root and shoot, the latter leing usually differentiated into shoot axis or stem, and leaves. The usual type of shoot is one which bears leaves and is exposed to the light. The work of carbon dioxide assimilation (photosyn- thesis) being carried on for the most part by the leaves, the axis is sometimes spoken of as the " assimilation shoot." FIG. 161. A, advanced stage of germination of the common garden pea (Pisum sa- tivum) showing growing point of root protected by root-cap (p) ; root branches or second- ary roots (rb) ; hypocotyl (he) ; epicotyl or stem above the cotyledons (ec) ; cotyledons (one in view) (c). B, plantlet of white or yellow mustard (Sinafis alba) showing copious development of root-hairs (h). I. OUTER MORPHOLOGY OF THE ROOT. THE ROOT, or descending axis of the plant, normally pene- trates the soil, absorbing inorganic substances in solution and act- ing as an anchor and support for the shoot. True roots are found only among plants having a vascular system, as the Spermophytes and the higher Pteridophytes, although, on the other hand, some of the higher plants do not possess them, as certain of the sapro- phytic orchids and some of the aquatic plants as Utricularia. 300 A TEXT-BOOK OF BOTANY. Lemna, etc. If we take a germinating plant and mark the root into ten equal divisions, beginning at the apex, and place the plant in a moist chamber, it will be found in the course of one or two days that the marks between I and 5 have become much FIG. 162. Longitudinal section through the tip of the root of Indian corn (Zea Mays) •bowing root-cap: a, outer layer; i, inner layer. — After Sachs. farther apart, and that the growth in this region is about three times that between 5 and 10. This experiment indicates that the growth of the root takes place at or near the apex, this region being known as the point of growth, or point of vegetation (Fig. 162). MORPHOLOGY OF HIGHER PLANTS. 301 Upon examining the tip of a very young root by means of the microscope, it will be seen that the growing point is protected by a cup-shaped body of a more or less solid structure and frequently mucilaginous ; this is known as a ROOT-CAP. Its function is to protect the growing point, and it exists in all roots of terrestrial, epiphytic, and aquatic plants except the parasites. Just above the root-cap there is developed a narrow zone of delicate hairs, which arise from the surface cells and are usually thin-walled and unicellular. These are known as ROOT-HAIRS (Fig. 161, B) and their function is twofold: (i) They secrete an acid which renders the inorganic substances of the earth soluble, and (2) they absorb these and other substances for the nourish- ment of the plant. It should be stated that there are a number of plants which for various reasons do not possess root-hairs, such as water-plants, marsh-plants, certain Coniferae, Ericaceae, etc. When the primary root persists (as in Gymnosperms and Dicotyledons) it increases considerably in length and becomes ramified ; if, at the same time, it increases in thickness, and much more so than its branches, then it is called a TAP-ROOT (as in carrot, beet, etc.). In the vascular cryptogams (Pteridophytes) and the monocoty- ledons the primary root is generally thin and weak, frequently but little ramified, and disappears at an early stage, being re- placed by SECONDARY ROOTS, as in Zea. Secondary roots may arise not only upon the stem but even upon leaves, as in Begonia and Bryophyllum. The term LATERAL ROOTS is restricted to those that develop from the root alone. The development of roots upon shoots or of so-called " AD- VENTITIOUS ROOTS" occurs in nearly all of the woody plants of the Spermophyta. Many annual herbaceous plants do not possess this capacity at all. The adventitious roots arise from " root- primordia " which are formed under the cortex of the shoots. While ordinarily they do not develop upon the shoots, yet if cuttings are made, as of Coleus, Geranium, Rosa, etc., we find " either singly or on both sides of the axillary buds " the develop- ment of adventitious roots from the latent root-primordia. Influence of Gravity. — The root is popularly supposed to grow downward, in order to avoid the light. On the other hand, 302 A TEXT-BOOK OF BOTANY. the theory has been established (as a result of Knight's experi- ments) that the root grows downward by reason of the influence of gravity. In addition it may be said that the principal functions of the root, namely, those of absorbing inorganic food materials and of fixing the plant to the soil, determine in a measure the direction of its growth. . The tendency of the root to grow down- ward is a characteristic which distinguishes it from other parts of the plant, and it is said to be POSITIVELY GEOTROPIC (Fig. 163, A). FIG. 163. A, seedling of Brassica nigra in which root and stem have curved into a vertical position after being Liid horizontally. B, seedling of Sinapis alba, the hypocotyl showing a positive, the root in water a negative heliotropic curvature. The arrows show the direction of the incident rays of light. — After Pfeffer. The influence which gravity has on plants may be best under- stood by bearing in mind that gravity is a constant force which acts perpendicularly to the surface of the earth, and that all parts of the plant are subject to its influence. The organs of plants respond in different ways to the action of gravity, but a clear distinction should be made between mere mass attraction, or that manifestation of the force of gravity whereby the heavily laden branch of a fruit tree bends downward, and the stimulus which causes the primary root of a plant to grozv downward and the shoot to grow upward. While all parts of the plant are subject to the influence of gravity, not all the organs of plants respond in an equal degree. This is well illustrated by roots themselves. MORPHOLOGY OF HIGHER PLANTS. 303 It is well known that, whatever the position of the seed at the time of germination, the young radicle begins to grow perpen- dicularly downward ( Fig. 163, A ) . The branches, however, which arise on the primary root are less positively geotropic and, instead of growing downward parallel with the primary or tap root, di- verge at an angle from it (Fig. 161 ) . The secondary branches are still less affected by gravity and diverge still more from the per- pendicular, or grow out horizontally, while still others do not FIG. 164. Over-turned tree trunk showing spreading root-system, the main or tap root having died away appear to be in the least affected by gravity and grow freely in any direction. In the case of large trees we frequently find that the lateral roots spread out in a more or less horizontal plane near the surface of the earth, and if the main root has died the influence of gravity is not very evident (Fig. 164). But here it must be re- membered that gravity was instrumental in determining the direc- tion of growth at an earlier stage. This spreading of the roots near the surface of the earth is of decided advantage to plants, for it enables them to avail themselves of the better soil of the surface 304 A TEXT-BOOK OF BOTANY. layers. As indicated, gravity also determines the upward perpen- dicular direction of the shoot, which is therefore said to be NEGATIVELY GEOTROPic, but, as in the case of the root, the branches are less influenced by it .and hence diverge at various angles from the main axis. Some of the other effects of gravity may be noted. If the end of a shoot be cut off, the branches -next to the top will grow per- FIG. 165. Mangrove forest (Rhizophora Mangle}, showing the habit of growth, es- pecially the numerous aerial roots which form an almost impenetrable thicket. The man- grove is common along the southern shores of Florida, in the Bahama Islands, and in the West Indies. Many shellfish, lobsters, and other forms of sea life are often found clinging or attached far up on the roots where they become lodged during high tides. — -Photograph from article by Henry Trimble on Mangrove Tannin in Contributions from the Botanical Laboratory of the University of Pennsylvania, 1892, p. 50. pendicularly upward and thus assume the work of the main axis. Likewise in the case of roots, if the apex of the main or tap root be cut off, the branches near the end will assume a perpendicular direction. It will frequently be noticed in the case of trees which have been uprooted or where branches have been bent over hori- zontally that the new branches which arise grow perpendicularly upward. Creeping shoots furnish another good example showing MORPHOLOGY OF HIGHER PLANTS. 305 FIG. 166. Tuberous root of Ginseng (Panax quinquefolium). The root on the left is a fresh specimen and was grown in the United States. The one to the right was purchased at a Chinese bazaar. It is translucent, of a yellowish-brown color, and has the characteristic shape and markings considered desirable by the Chinese. The markings on the upper segment of the specimen are stern scars which are usually found on old roots. The trans- lucent appearance is no doubt due to the manner of treatment. While the method is not generally known, similar specimens may be prepared by treating the recently gathered roots with freshly slaked lime. the influence of gravity, the branches growing upward and the roots downward. The root exerts a certain amount of upward pressure on the liquids in the stem. This fact can be demonstrated by cutting off 20 306 A TEXT-BOOK OF BOTANY. the stem just above the surface of the earth and attaching thereto a glass tube by means of a tightly-fitting rubber tube. It is de- sirable to perform this part of the operation under water and to have the glass tube partly filled with water at the beginning of the experiment. This is done to prevent the clogging up of the vessels with air, which prevents the ready passage of fluids through them. If the root is now kept moist, the osmotic pressure of its cells forces water up into the glass tube, sometimes to a height of several feet. Experiments on the begonia and on many other plants succeed very well, but for some reason the geranium is impracticable to work with. The manometer devised by Ganong, while not showing the quantity of water forced up by the root, shows the amount of pressure exerted, which is really the most important fact to be ascertained. Modified Roots. — Roots which arise from the nodes of the stem or other parts of the plant are known as secondary or adventi- tious roots. These include the aerial roots of the banyan tree and the Mangrove (Fig. 165), which are for the purpose of sup- port; the roots of the ivy, which are both for support and climb- ing, and the roots of Indian corn and many palms which serve both for support and the absorption of nourishment. Under this head may also be included the aerial roots of orchids and the root-like structures, or haustoria, of parasites, as of mistletoe and dodder, which penetrate the tissues of their host plants and whose vascular strands come into most intimate relations with those of hosts. Of special interest also are the breathing roots of certain marsh-plants which serve to convey oxygen to the submerged parts ; and the assimilation roots of certain water-plants and epiphytes, which are unique in that they produce chlorophyll. In certain plants the roots give rise to adventitious shoots, as in Prunus, Rubus, Ailanthus, etc., and in this way these plants some- times form small groves. Root Tubercles. — The roots of the plants belonging to the Leguminosae are characterized by the production of tubercles, nodules or swellings (Fig. 167) which have been shown to have a direct relation to -the assimilation of nitrogen by the plants of this family. Like carbon, nitrogen is one of the elements essential to plant-life, being one of the constituents of protoplasm and MORPHOLOGY OF HIGHER PLANTS. 307 present in various nitrogenous (protein) compounds which occur as normal constituents of the plant. The nitrogen required by plants is derived either from nitrogen salts contained in the soil, as nitrates and ammonium salts, or from the free nitrogen of the atmosphere. While most of the higher plants are able to assimilate nitrogen compounds existing in the soil, only the Leguminosge and Aristolochiaceae, with possibly a few exceptions, are able to assimilate atmospheric nitrogen, and in this respect the FIG. 167. Root tubercles on Lupinus, one of the Leguminosce: A, roots with tubercles; B, transverse section of root showing the cells (b) which contain the nitrogen bacteria. — A. after Taubert; B, after Frank. majority of the Leguminosge stand as a class by themselves. Apparently in direct relation to this character stands the fact that the seeds of these plants contain a high percentage of nitrogen. This special ability of the Leguminosae to fix atmospheric nitrogen in the plants depends upon the presence of the nodules, which are due to the infection of the roots by a soil-bacterium (Pseudomonas radicicola), although the precise mode of fixing the nitrogen is 3o8 A TEXT-BOOK OF BOTANY. not known. The bacteria seem to be localized in the nodules and are not found in any other part of the plant. It has been shown that when the roots of leguminous plants are free from nodules they do not have the power of assimilating free nitrogen. On the other hand, when the nodules produced by the bacteria are developed, the plants will grow in soil practically free from nitrogen salts. Because of this power the plants of this family are useful in restoring worn-out land, i.e., land in which FIG. 168. Transverse section of a root bearing root hairs; the latter are thin walled, irregularly bent, and attached at various places to small particles of soil. The hairs secrete an acid, rendering the inorganic substances soluble, which are then diffused through the walls of the hairs, transmitted to the cortical parenchyma and distributed through the conducting cells of the xylem to the shoot. — After Frank. the supply of nitrogen is exhausted, and they thus play an impor- tant role in agricultural pursuits. The enriching of the soil is. accomplished by ploughing under the leguminous crops, as of clover or alfalfa, or allowing the nodule-producing roots to decay, when the nitrogen compounds are distributed in the soil. (Consult Bulletins on " Soil Inoculation for Legumes," issued by the Bureau of Plant Industry, U. S. Department of Agri- culture.) MORPHOLOGY OF HIGHER PLANTS. THE INNER STRUCTURE OF THE ROOT. 309 Primary Structure. — If we make a transverse section of the young portion of a root (Vascular Cryptogam, Gymnosperm, or Phenogam), we notice the following tissues (Figs. 169-174). The outermost tissue is EPIDERMIS (E), it being generally thin- walled and destitute of cuticle ; it is, as a rule, hairy, and these hairs, which are relatively long, but always unicellular, are known as ROOT-HAIRS (Figs. 161, 168) ; they ramify but very seldom. Inside the epidermis there is frequently present a HYPODERMIS FIG. 169. Radial vascular bundle in root of Allium ascalonicum, showing a larg«. central trachea from which radiate five small groups of trachea and between which are th< groups of leptome or sieve; p, layer of pericambium or pericycle; d, transition cells or pas- sage cells in the endodermal layer, and which permit the easy transfer of substances between the cortical parenchyma and the tracheae of the stele. — After Haberlandt. (sometimes referred to as 'an EXODERMIS) composed of a single layer of cells or, at the most, of but several layers, the cells of which differ in shape and size from those of the epidermis and the adjoining cortical parenchyma. The hypodermis takes the place of the epidermis when the latter is worn off, except in the few cases where hypodermal cork becomes developed, as in Cephalanthus, Solidago, and in the Bignoniaceae. The root bark is composed of parenchymatous cells, being 310 A TEXT-BOOK OF BOTANY. commonly referred to as the CORTEX, and is either homogeneous or divided into two zones, the outer or peripheral being composed of thick-walled cells which naturally belong to the hypodermis and an inner or internal strata made up of thin-walled cells. The cells of the cortical p*arenchyma may contain starch, calcium oxalate, calcium carbonate, and there may be associated with them FIG. 170. Cross-section of the primary root of a germinating plant of Phaseolus multiflorus, showing development of secondary structures: p, group of primary vessels; g, larger tracheae of secondary development formed between the four primary strands of xylem; b, the four groups of phloem alternating with the four initial groups of xylem and beneath which secondary tracheae are forming (g'); pc, pericambium (pericycle), a layer of cells beneath the endodermis (s). A few layers of cortical parenchyma are shown outside of the endodermis. In the middle is a well-developed pith (M) which sometimes is developed in roots. — After Sachs. secretory cells or receptacles. Immediately beneath the innermost layer of cortical parenchyma is a distinct layer of cells usually considered part of the cortex and known as the ENDODERMIS. It consists always of a single layer of cells, without any intercellular spaces, and the radial walls show in transverse section Casparyan spots,1 depending upon a local folding of the cell-wall, which is here suberized. In the course of time the cell-walls of the en- 1 " Physiologische Pflanzenanatomie," by Dr. G. Haberlandt, p. 245. MORPHOLOGY OF HIGHER PLANTS. 311 dodermis frequently become thickened, either all around, or only on the inner or radial walls, so that we might speak of an O- endodermis as in Honduras sarsaparilla or an U-endodermis as in Mexican sarsaparilla, according to the manner of thickening. FIG. 171. Cimicifuga. Transverse section of the central part of a mature root in which the secondary changes are completed: a, parenchyma of primary cortex; b, endo- dermis; c, cambium zone; d, tracheae in secondary xylem; e, broad, wedge-shaped medullary ray; f, outer portion of one of the primary xylem bundles; g, pericycle-parenchyma beneath the endodermis; h, inter-fascicular cambium. — After Bastin. This is especially the case in the monocotyledons where the walls of the endodermal cells become completely suberized and im- permeable to water. In some roots the cells of the endodermis may be uniformly thick-walled throughout, while in others some 312 A TEXT-BOOK OF BOTANY. of the cells may remain thin-walled, and these cells, the so-called " transition cells " or " passage cells," form channels of com- munication between the cortical parenchyma and the vessels of the stele (Fig. 169) ; they are therefore located just outside the peripheral vessels of each ray of the xylem (or hadrome). Inside the emlodermis is the STELE, formerly called the central- cylinder. In this the peripheral stratum, sometimes composed of two or three layers of cells, represents the PERICAMBIUM (or PERICYCLE). The cells are generally thin-walled, and in Dicotyle- dons and Gymnosperms are able by cell-division to form cork and — RB FIG. 172. A transverse section through the root of a germinating pea-plant (Pisum) about 40 mm. from the tip, showing the origin of a root-branch (RB); E, epidermis; C, pri- mary cortex; X, hadrome (vessels); P, leptome (sieve); EN, endodermis. secondary cortex, but in all vascular plants it is capable of giving rise to "lateral branches" or "lateral roots" (Figs. 161, 172), hence it is frequently referred to as the " RHIZOGENOUS LAYER." Inside the pericambium (by some authors compared with the pericycle.of the stem) we find strands of phloem (or leptome) (P) alternating radially with a corresponding number of strands of xylem (or hadrome) (X). The number of these strands vary in the different groups of plants (Figs. 169-174), being highest in the monocotyledons where a pith is developed, as in sarsaparilla, several grasses, palms, etc. This peculiar arrangement of the MORPHOLOGY OF HIGHER PLANTS. 313 phloem and xylem, as separate strands alternating with each other and not being located, as in stems, in the same radii, has given rise to several adverse views. Some authors have considered the root-stele as one single mestome-strand (or fibrovasculaf strand), while others, especially of recent date, consider it to be composed of several MESTOME STRANDS. The xylem or hadrome contains tracheae or vessels, the periph- eral being spiral and narrower than the inner, which are scalari- form or reticulate. The tissue in the center of the stele in mono- cotyledons is not uncommonly made up of parenchyma cells, and 01 Liacueic; r, lepiorne. composed 01 sieve ct forming a triarch radial fibrovascular bundle. corresponds exactly with the pith of the stem. In roots it is often called CONJUNCTIVE TISSUE, and the cells may contain starch and crystals of calcium oxalate. Secondary Structure. — In roots that are able to increase in thickness (as in Gymnosperms and Dicotyledons), the increase depends upon the activity in the pericambium, some of the cells becoming meristematic. These meristematic cells are known as phellogen, developing cork outwardly and secondary cortex in- wardly. The meristem of the stele or cambium also becomes very active and develops on the inner face of the phloem and extends A TEXT-BOOK OF BOTANY. from there to the outside of the peripheral vessels of the xylem (Fig. 174) ; thus a continuous cambial zone gradually arises. From this zone secondary tracheae or vessels become developed on the inner face of the primary phloem, while secondary phloem becomes differentiated outside the primary rays of xylem ; or only parenchyma develops outside the primary xylem, resulting in the formation of secondary PARENCHYMA-RAYS (or medullary rays). In other words, the original radial structure of the stele changes to the collateral type (Fig. 175). Owing to this increase within the stele, the peripheral tissues from the endodermis to the epidermis naturally become broken and are subsequently thrown off, but are replaced by the pericambial cork and secondary cor- tex derived from the pericambium. The older roots, then, of Gymnosperms and Dicotyledons thus resemble the structure of stems, except that no pith exists in these roots, at least not usually. MORPHOLOGY OF HIGHER PLANTS. 315 Some differences are, however, quite noticeable in some instances, as in the thick roots of Beta, Radish, etc., where the wood paren- E — EN FIG. 175. Fully developed secondary structure in root. Transverse section of root of pea (Pisum) at the end of the summer's growth: E, some epidermal cells with fragments of root-hairs; C, primary cortex; EN, endodermis; K, pericambial cork; B, bast fibers; SC, secondary cortex; S, sieve; T, trachea?; W, wood fibers; WP, wood parenchyma; M, medullary rays; the tracheae (or vessels) and leptome (or sieve) forming open collateral fibrovascular bundles, these being found in dicotyledons with but few exceptions. chyma is usually abundant, thin-walled, and not lignified, the annual rings also being mostly indistinct. The characteristic distinguishing the primary and secondary A TEXT-BOOK OF BOTANY. -ph -8 * ssipppiMiWl^ B FlG. 176. Glycyrrhiza: A, transverse section; B, longitudinal section. B, bark; H, wood; X, cambium zone; ph, cork cells; rp. cortex; p, parenchyma; k, crystal fibers; s, sclerenchyma fibers, including wood fibers occurring in the wood and bast fibers present in the bark; t, traches; m, medullary rays. — After Meyer. MORPHOLOGY OF HIGHER PLANTS. 317 structures of dicotyledonous roots may be summarized as follows : PRIMARY STRUCTURE: Epidermis and root-hairs. Hypoder- mis. Primary cortex consisting of parenchyma. Endodermis, pericambium, xylem arranged in radial rays which alternate with phloem or sieve strands, constituting a radial fibrovascular bundle (Figs. 169-174). SECONDARY STRUCTURE: Cork cells, phellogen, secondary cor- tex consisting of parenchyma. Phloem, cambium, and xylem arranged in radial groups, forming open collateral fibrovascular bundles. Medullary rays separating the fibrovascular bundles (Figs. 175-177). Sometimes, as in glycyrrhiza and valerian, a number of paren- chyma cells are found in the center of the root, these constituting the PITH (Fig. 176) or medulla; but they are usually wanting in dicotyledonous roots. Wood and bark are terms used to distinguish those portions of the root or stem separated by the cambium; all that portion inside of the cambium, including xylem, medullary rays, and pith, being known as the WOOD. The BARK includes the hadrome, the medullary rays outside of the cambium, and the tissues formed by the phellogen, viz., secondary cortical tissue and cork. The following diagram of the secondary structure of a dicoty- ledonous root may be of assistance in understanding the origin and relation of the tissues comprising it : Wood made up of Cambium produces Pith, which may be wanting. /'Composed of vessels, wood parenchy- \ ma and wood fibers ; or tracheids may Xylem. . J replace these cells, or be associated ' ' j with them. These are arranged in / groups forming radial rows which \ are separated by medullary rays. Consisting of leptome and companion cells; bast fibers may also be present. Phloem . . 1 These are arranged in collateral groups and form radial rows which are separated by medullary rays. Meristem of pericambium producing pericambial- cork and parenchyma. Phellogen later forming periderm in stems several years old, and bork in the trunk of large shrubs and trees. A TEXT-BOOK OF BOTANY. FIG. 177. A, transverse section of Phytolacca root, showing the fibrovascular bundles (V, V, V",) which are produced by distinct cambiums (C). The parenchyma contains little starch, and some of the cells (R) show short raphidesof calcium oxalate.many of the crystals being distributed in the section. B. Transverse section of Belladonna root which is two or three years old. There is but one cambium zone (C). Most of the parenchyma contains starch (St), the remaining cells containing cryptocrystalline crystals of calcium oxalate. K, cork; S, sieve; W, wood fibers and T, tracheaj, both of which are strongly lignified in Belladonna root; M. medullary rays. MORPHOLOGY OF HIGHER PLANTS. 319 The root branches arise as the result of the development of primary meristems in the pericambium (Figs. 161, 172). The tissues forming the branches are directly connected with the fibrovascular tissues of the root and protrude through the over- lying tissues without having any connection with them. The structure of the branches thus formed corresponds to the primary structure of the roots, and in the case of dicotyledonous roots may also subsequently develop a secondary structure. Goebel states that in plants which grow in moist soil, or whose roots func-' tion only for a short time, the branches may be altogether sup- pressed, as in Colchicum, Arisaema, etc. Contraction of roots is observed in both monocotyledons and dicotyledons, it being most apparent in the former, as in the roots of Veratrum viride (Fig. 178). The uneven or corkscrew- like appearance is due to a contraction, which arises as follows : Some of the longitudinally elongated cells beneath the epidermis, as well as cells extending to and including the endodermis, absorb large quantities of water, which causes them to assume a spherical form (as the cells of a potato are altered on boiling), the result being a longitudinal contraction of the root at this point. In this way the plant is fastened more securely to the earth, and at the end of the season's growth the apical buds of plants, with upright rhizomes, as of Veratrum viride, Dracontium, etc., are drawn into the earth and thus protected during the winter season. Abnormal Structure of Roots. — It is often difficult to recog- nize the type- structure of dicotyledonous roots in drugs, owing to the anomalous and abnormal secondary structure. Scleren- chymatous fibers, while present in glycyrrhiza (Fig. 176) and althaea, are not infrequently wanting. Wood fibers may be spar- ingly developed, as in young belladonna roots (Fig. 177), or even wanting, as in gentian. In other cases the medullary rays are abnormal, being replaced in calumba by wood parenchyma, and in ipecac and taraxacum by sclerenchymatous cells. In asclepias and calumba a layer of stone cells occurs near the periphery; in gelsemium sieve cells develop in the xylem ; in senega the xylem is not uniformly developed, and in still other cases, as in jalap, pareira, and phytolacca (Fig. 177, A), successive cambiums de- velop, producing concentric series of open collateral fibrovascular bundles. 320 A TEXT-BOOK OF BOTANY. II. THE OUTER MORPHOLOGY OF THE STEM. The stem, or ascending axis of the plant, usually grows in a direction opposite to that of the root, seeking the light and air. The tendency of the stem to grow upward is characteristic of the majority of plants, and is spoken of as NEGATIVE GEOTROPISM. The growing point of the stem is at the apex, and it is protected by a layer of bud scales (Fig. 179, £). FIG. 178. Longitudinal section through a root of Veratrum viride showing the nature of the contraction of the root: E, epidermis; CS, cells of cortex containing starch; CO, cells of cortex containing raphides; F. fibrovascular bundle; A, rifts or cavities formed as a result of the radial swelling of the cells of the cortex. Stems are further characterized by bearing leaves, or modi- fications of them. The leaves occur at regular intervals in the same species, and that portion of the stem from which they arise is spoken of as a NODE, while the intervening portion is called an internode. Stem branches usually arise in the axils of the leaves, first MORPHOLOGY OF HIGHER PLANTS. 321 appearing as little protuberances, sometimes spoken of as pri- mordia, on the stem. Their origin differs from that of the root branches, in that they arise from meristematic or embryonic tissue developed just beneath the epidermis. The branches, like the main axis, manifest negative geotropism, although to a lesser degree. They likewise possess a growing point at the apex, covered with embryonic leaves (Fig. 179). Not infrequently more than one branch arises in the leaf axil. Buds may be defined as undeveloped shoots in which the foliage is yet rudimentary. The buds at the ends of stems or -P FIG. 179. A, longitudinal section through the apical region of the stem of the embryo of a bean (Phaseolus mv.ltif.orus); ss, apex; pb, parts of the two first leaves, and their axillary buds (k, k,); r, periblem or primary cortex. B, diagram of longitudinal section through winter bud of Quercus coccinea: P, growing point; L, young leaves; SB, stem branches; P, nbrovascular bundle. — A. after Sachs. branches are known as APICAL, or TERMINAL BUDS, and those situ- ated in the axils of the leaves, as AXILLARY BUDS. In some cases they are protected by scales, as in hickory, when they are known as scaly buds; while buds which are not thus protected are called naked buds. They are further distinguished as leaf, flower, and mixed buds, as they develop into leaves or flowers, or both. We have to distinguish between overground shoots and under- ground shoots. The former' are sometimes designated as epi- geous (upon the earth) and the latter as hypogeous (under the earth). 21 322 A TEXT-BOOK OF BOTANY. Epigeous Shoots. — As would be supposed, these two kinds of shoots vary to a certain extent. In epigeous shoots a number of features may be noted. If the internodes are long the leaves do not usually interfere with one another so far as exposure to light is concerned, but if the internodes are short, the leaves are all brought close together on the axis, and hence, were it not for FIG. 180. A, woody vine of Canada moonseed (Menispermum canadense), which ascends by twining to the right. B, stem of wild yamroot (Dioscorea villosa), which ascends by twining to the left. and several of the characteristic 3-winged capsules at the top. The twining movements of stem climbers are due to the stimulus of gravity rathet than to contact stimulus, and in the majority of twining plants the revolving movements, as seen from the side, are from the left to the right, i.e., in a direction opposite to that of the hands of a watch if represented diagrammatically. various modifications, their relation to light would be very un- equal. Sometimes the shoot-axis may share with the leaves the work of assimilation, as in the case of certain green stems. Then again there are cases in which the leaves are reduced, and the work of assimilation is carried on exclusively by the shoot-axis, as in most Cactaceae, certain marsh-plants, and others. On the MORPHOLOGY OF HIGHER PLANTS. 323 other hand, the shoot-axis may be modified so as to increase the assimilating surface, as by a flattening of the axis, as in some of the Cacti, the leaves being suppressed or considerably reduced. FIG. 181. Bryonia dioica. a, young, spirally coiled tendril; b, expanded and irritable tendril; c, tendril which has grasped a support; d, tendril which has not grasped a sup- port, and has undergone the old-age coiling.* — After Pfeffer. Branches are not infrequently modified to hard, pointed, and spiny structures, as in the Japanese quince, when they are spoken of as thorns. Leaves and even flowers may arise upon thorns, which shows that they are modified branches. 324 A TEXT-BOOK OF BOTANY. A number of plants ascend into the air on other plants, or other objects which serve as supports, either by attaching them- selves to them or by twining around them, when they are dis- tinguished as twiners and climbers. TWINERS ascend by a special circumnutating movement of the stem, as in the morning glory, Menispermum (Fig. 180), etc. CLIMBERS, however, ascend by means of special structures, as the aerial roots of the ivy (root climbers) ; or they may climb by means of leaves, as in Clematis (leaf climbers) ; still others climb by means of tendrils, as in the grape and Bryonia (tendril climbers) (Fig. 181) ; and again plants may climb by means of hooked hairs or spines, as in Rubus, FIG. 182. Rhizome of Podophyllum representing three years' growth: y.the terminal bud of last year; b2, the corresponding one of the present year; B, the terminal one of the entire rhizome will develop in the spring of next year. L1 and L- indicate the scars of aerial leaves of the two preceding years' growth; b1 and b2, latent buds. — After Holm. Rosa, etc. The tendrils, which are thread-like modifications of the stem, are in some cases provided with disk-like atachments for holding the plant in position, as in the Virginia creeper. Twiners and climbers are sometimes spoken of as LI AXES (lianas), particu- larly those of tropical regions, where they form a prominent feature of the forest vegetation. The lianes usually have rope- like, woody stems, the formation of leaves being either suppressed or retarded, and they often run for long distances over the ground and climb to the tops of the tallest trees. They are also frequently characterized by an anomalous stem-structure, the tracheae being very large. Stems vary, furthermore, in size and form. While most stems are more or less cylindrical or terete, other forms also occur, as MORPHOLOGY OF HIGHER PLANTS. 325 the flattened stems in the Cactaceae ; triangular in the Cyperaceae, and quadrangular in the Labiatae and Scrophulariaceae. Hypogeous Shoots. — While most stems attain a more or less erect position, as in trees and shrubs, there are others which bend over to one side, or lie prostrate on the ground, and in some cases FIG. 183. Polygonatum multiflorum, a plant growing in the Northern Hemispheres and Japan and producing a rhizome resembling our Solomon's Seal (Polygonatum biftorum}. A, rhizome placed artificially higher in the soil than the normal depth; its continuation shoot has grown downwards. B, rhizome placed deeper than the normal depth; its con- tinuation shoot has grown upwards. The dotted lines at n indicate the amount of annual growth in the rhizomes A and B. C, a seedling rhizome. At the right is the seed, which encloses the haustorial end of the cotyledon; H, primary root; n, lateral roots arising within the axis of the shoot; a, posterior side of cotylar sheath; v, anterior side of the same; b, c, katophyls (or leaves on hypogeous shoots) on the axis of the seedling. — A and B, after Rimbach; C, after Irmisch. (From Goebel's "Organography of Plants.") produce roots from the nodes, as in Mentha spicata (Fig. 184). These latter are known as STOLONS or runners. Furthermore, the stems of a number of plants grow under- ground, and these are known as RHIZOMES or ROOT-STOCKS (Figs. 182-190) ; from the upper portion of the nodes overground branches arise which bear leaves (so that the work of assimilation 326 A TEXT-BOOK OF BOTANY. may be carried on) as well as flowers, and from the lower, surf ace, roots (Fig. 182). While most rhizomes are perceptibly thickened, and more or less fleshy when fresh, as Sanguinaria, in other instances they are of the ordinary thickness of the overground stem. FIG. 184. Plant of spearmint (Mentha spicata) showing procumbent stems or leafy runners from which roots are developed at the nodes, and one erect branch at the left from which a new plant will be developed. There are some rhizomes that are excessively thickened, as in the common white potato (Fig. 185), and these are called TUBERS. The so-called " eyes " are small buds covered with small, scale-like leaves which develop into shoots. Tubers should MORPHOLOGY OF HIGHER PLANTS. 327 not be confounded with tuberous roots, as those of the sweet potato and jalap, for these latter have the morphological char- acters of roots (compare Figs. 185 and 186). Instead of the node, or internode, or both, becoming exces- sively thickened, they may be reduced in size and crowded upon FIG. 185. A potato plant grown from seed and showing the branches upon which the potato tubers are formed, r, primary root; ct, cotyledons; c, hypocotyl; f, foliage leaves; f', a primary branch the summit of which has developed foliage leaves; e'c, scales on upper portion of primary branch; e'c', scales representing the eyes of the potato tubers formed from the swollen branches; br, buds formed in the axils of the scales on the tubers; r', sec- ondary roots formed on the stem branches. — After Duchartre. each other, the leaves at the same time becoming thickened and filled with nutriment. Such a modified stem and leaves, as in the onion and tulip, is called a BULB (Fig. 188). Bulbs are sometimes produced in the axils of the leaves of overground stems, as in some lilies, and are then called bulbils or bulblets. They are also found in Allium forming what are commonly known as " onion sets." 328 A TEXT-BOOK OF BOTANY. FIG. 1 86. Several tubers formed by a 2-year non-flowering plant of Aconitum Napellus, gathered in September. The parent tuber on the right shows a portion of the overground stem and a small bud (k); to the left has been developed an offspring tuber connected by the branch (a) ; K, nearly full grown bud which will produce the foliage stem of the growing plant the succeeding year. The long, filiform and branching roots are in the nature of true root branches. — After Meyer. Bulbs and tubers serve not only as storage-organs and carry the life of the plant over from one season to another, but may form, as in MORPHOLOGY OF HIGHER PLANTS. 329 bulblets, an important means of distributing the plants. The thickened fleshy stems of Cactaceae are also regarded as storage- organs. A CORM is intermediate between a true tuber and a bulb ; it is more in the nature of a thickened internode, being surrounded in some cases by thin, membranous scales, as in Crocus and Colchicum. The function of the vegetative shoot is to absorb nutrition from the earth as well as from the air. The shoot may be AERIAL or SUBTERRANEAN. Some plants possess only aerial shoots or UGHT-SHOOTS, as, for instance, trees, shrubs, and herbs that flower FIG. 187. Rhizome of African ginger showing scars of overground branch (Ls) and hue's (k). The more or less parallel lines represent leaf-scars and scars of bud-scales, and the small circles, root-scars. — After Meyer. but once. Other plants possess both aerial and subterranean shoots, and of these the subterranean shoot may exhibit some of the peculiarities of roots, in that they do not develop chlorophyll and produce secondary roots for the purpose of obtaining nutri- tive substances from the soil. The SUBTERRANEAN SHOOTS are generally destitute of true leaves and are furnished only with membranous or sometimes thick, fleshy leaves which are bladeless, pale, scale-like, or tubular. Depending upon the duration of the shoot (or, better, the stem), plants are divided into HERBS, SHRUBS, and TREES. In herbs the aerial shoots are herbaceous, while in shrubs and trees they become woody and persist throughout many years. 330 A TEXT-BOOK OF BOTANY. Many of the herbs have subterranean shoots, but these are generally absent from woody plants, excepting in Sambucus, Ailanthus, Calycanthus, etc. The herbs may be further sub- divided as annual, biennial, and perennial. FIG. 188. Longitudinal section through a germinating bulb of Tulipa pracox: h, the brown enveloping membrane; k. the flattened stem which forms the base of the bulb and bears the bulb-scales (sh) ; si, the elongated part of the stem which bears the foliage- leaves (!'!')• and terminates in the flower; c, the ovary; p, perianth; a, anthers; 2, a lateral bulb in the axil of the youngest bud-scale, which develops into the bud of next year's bulb; w, the roots which arise from the fibrovascular bundles at the base of the bulb. — After Sachs. In ANNUAL herbs the individual possesses only aerial shoots and the plant sets fruit the same year that the individual has de- veloped from the seed. In BIENNIAL herbs the plant does not produce flowers until the second season. The PERENNIAL herbs, MORPHOLOGY OF HIGHER PLANTS. 331 on the other hand, develop flowers continuously for many (or at least several) years and also produce subterranean shoots, such as creeping rhizomes, tubers, bulbs, etc. D FIG. 189. Upper portion of rhizome of Gentiana lutea showing the structure of terminal buds: A, terminal bud cut open to show the foliage leaves (b), which lie close to one another, leaving only a narrow canal (s) in the middle. B, four-angled bud removed from A, showing the foliage leaves having a strongly developed basal region (s) and relatively small lamina (sp). C, a small bud removed from the axis of the young leaves (B). D, upper portion of rhizome of a flowering plant showing the stem base (S) and several buds (k). E, upper portion of rhizome of a plant 6 years old showing scar (n) of the flowering branch and the strongly developed side branches with terminal buds (k). The annulations are scars formed from the bud scales which have dropped off. — After Meyer. The roots of annuals, biennials, and perennials differ in a num- ber of particulars. In the annuals, belonging to the monocoty- ledons, the roots are fibrous, possessing numerous lateral branches, whereas in the annuals belonging to the dicotyledons only the 332 A TEXT-BOOK OF BOTANY. primary roots develop. The biennials are nearly all dicotyledons and have a persistent primary root which, while usually slender, may become fleshy, as in Beta. In the perennials, on the other hand, we find a number of different types of roots, varying from the slender aerial roots of epiphytes to the smaller tuberous, fleshy roots of many terrestrial plants, and the peculiar roots of parasites. ALTERATIONS IN THE FORM OF PLANTS. — The shoot, in its nsisting of peeled pieces of the course of development, is subject to a great many hostile external conditions, and there results more or less mutilation and alteration in the form of the plant. One of the most destructive influences to plants is that of strong winds when they attain the velocity of gales. They stunt the growth of woody plants and cause the branches to assume a horizontal position (Fig. 191). This un- usual growth is further accentuated if at times during the winter they are covered with snow and sleet. If they grow in close MORPHOLOGY OF HIGHER PLANTS. 333 334 A TEXT-BOOK OF BOTANY. proximity their limbs will lash each other, causing a flattening of the top which is very characteristic in the groves of trees on the sea coast. In this way it is possible for the whip-like branches of the birch to mutilate even the tops of the fir tree, changing their spire-like summits to deliquescent crowns. Injuries causing an alteration in the form of plants are also caused by ruminating animals and leaf-devouring insects. GALLS. — These are abnormal developments on the young twigs, leaves, and flowers, being caused by the punctures and presence of the deposited ova of quite a variety of insects. Galls vary in size, form, and general appearance. They are only capable of being produced either in meristematic cells or in tissues that are capable of exercising this function. They are never formed on mature stems, leaves, or flowers. The older parts may be eaten and destroyed by insects, but they are not capable of being meta- morphosed. In these growing tissues the mother insect lays her eggs, which upon further growth, either through the secretion of particular substances or otherwise, determine the direction of growth of the cells and the final product which shall be formed. As has already been stated, galls show considerable variation, and, as there are many hundreds of distinct galls, various attempts have been made to classify them. Kiister has proposed an ana- tomical classification as follows: I. Galls in which there may be an enlargement of cells, but no cell multiplication ; '2. Soft galls, composed of numerous cells, the resulting product being more or less fleshy ; 3. Hard galls, in which there is an active cell division, and sclerotic modification of the external layer so as to prevent the drying up of the gall in summer and to guard against attack by birds and other animals. Modry (Beitrage zur Gallenbiologie), on the basis of Kuster's classification, has given a very compre- hensive review of the various structural (both external and in- ternal) characters of the various groups of zoo-cecidia. In a classification of galls Thomas has suggested as a class name for these structures the word CECIDIEN (meaning nut-gall). The cecidien or galls are divided into two main groups, as fol- lows : I. PHYTO-CECIDIEN or fungus galls, including the parasitic fungi which cause a metamorphosis in the shoots of larger shrubs and trees forming the structures commonly known as " Witches' MORPHOLOGY OF HIGHER PLANTS. 335 brooms." Galls exhibiting strange forms are also produced by the Gymnosporangia on the stems of the common juniper, the leaves of the mountain ash, etc. In this group would also be included the CROWN-GALLS occurring on a large number of plants, as grapes, peach, juniper, and field crops. At one time it was thought that these galls were due to frosts or mechanical injuries. The extended researches of Smith (Bulletin No. 213, Bureau of Plant Industry, U. S. Department of Agriculture) have -shown that crown-galls are in the nature of bacterial diseases. He showed that crown-galls not only resembled malignant animal tumors, especially sarcoma, but demonstrated that this resemblance was more than superficial. II. ZOO-CECIDIEN, or those galls which are formed within the body of the plant and due to attacks by insects. This group includes by far the larger number of galls, and is further subdivided according to the various animal-groups causing them. Galls differ in structure, but the general nature of the anat- omy may be seen in a study of the common " ink ball " or " ink gall," formed on Quercus coccinea by Cynips aciculata. These galls are produced during the summer months on the young branches and sometimes on the acorns. When mature they fall from the trees and are nearly globular in shape, varying from 20 to 30 mm. in diameter. They are solid throughout and of the consistency of the pulp of a green apple. Externally they are smooth, and are colored a mottled green, yellow, or brownish- red. At this stage they are made up of three distinct zones: (i) A central area, made up of nearly isodiametric starch-bear- ing, parenchymatous cells. (2) The middle zone is composed of radially elongated parenchymatous cells, possessing thick, porous cellulose walls containing a lining of protoplasm and a few starch grains. With the development of the egg of the insect there also appear in the cells of this middle zone numerous starch grains closely resembling those found in the central zone. (3) An external layer made up of irregular parenchymatous cells, somewhat collenchymatic in character, with a lining of protoplasm as in the cells of the middle zone. In some studies on the origin of tannin in galls Kraemer (Bot. Gas., 1900, p. 275) showed that in the " ink gall " there are three 336 A TEXT-BOOK OF BOTANY. stages in their development, corresponding to the life periods of the insects and changes in the constituents of the cells: (i) When the galls are first formed and the larva is beginning to de- velop, the cells of the outer zone, as well as those of the central FIG. 192. Transverse section of one of the collateral mestome strands of the stem of Viola tricolor arvensis: o, portion of cells of pericycle: e, endodermis; 1, leptome or sieve cells, in among which are some collenchymatous cells (c) ; m, cam- bium; t, spiral tracheae or vessels; g, strongly lignified tracheae; rp, medullary ray cells, the walls of which are composed of cellulose; rs, medullary ray cells the walls of which are strongly lignified; s, strongly lignified cells separating the mestome strands; c, collenchyma; p, pith. zone, contain numerous small starch grains. (2) When the in- sect reaches the chrysalis stage the starch in the cells near the middle of the galls is replaced in part by gallic acid, while the cells at the center and near the periphery contain masses of tannic MORPHOLOGY OF HIGHER PLANTS. 337 W FIG. 193. Collateral fibrovascular bundle in Menispermum: C, cortex; B, bast fibers; St, stone cells connecting groups of bast fibers; S, sieve; M, cambium; T, tracheae; W, wood fibers; R, medullary rays; P, pith, 22 338 A TEXT-BOOK OF BOTANY. acid. (3) When the winged insect is developed nearly all of the cells contain amorphous masses of tannic acid with some adhering crystals of gallic acid. After the insect has emerged from the gall the constituents again undergo change, depending largely on the presence of moisture, when the tannic acid is changed into more or less insoluble products and the galls become more porous. THE INNER STRUCTURE OF THE STEM. If we make a transverse section of a young herbaceous stem, we observe a differentiation of the tissues, which in several re- spects agrees with that of the root previously described. In the primary structure of the stem the following tissues are to be noticed: The outermost layer is the epidermis with a more or less distinct cuticle; the second is the cortical parenchyma, fre- quently having strands of collenchyma near the epidermis. The cortex often contains secretory cells or receptacles, and not infre- quently the innermost layer is differentiated as an endodermis. The latter surrounds the so-called pericycle, a sheath consisting of more or less distinct stereomatic strands, either forming a closed sheath or merely representing isolated arches outside the leptome of the stele. Inside the pericycle we observe the mestome strands constituting mostly one circular band (in cross section) in the Dicotyledons and Gymnosperms, or several more or less concentric bands in the Monocotyledons. The mesjome strands or fibrovascular bundles may be collateral (Figs. 192-194), bi- collateral or concentric, the last of which being found only in the Monocotyledons (Fig. 195) and Ferns (Fig. 56). In the DICOTYLEDONS the collateral fibrovascular bundles occur most frequently and consist of three distinct portions, viz., phloem, xylem, and cambium. The phloem consists of sieve tubes, com- panion cells (or accompanying cells), and cambiform. The last two are thin-walled parenchymatous cells, those of the cambiform being considerably elongated. In addition there may be included in the phloem the stereomatic tissues or bast fibers, which are not infrequently well developed. The xylem includes tracheae or vessels, tracheids, wood parenchyma, and libriform or wood fibers. To the student some confusion may arise as to the apparent indiscriminate use of the terms, leptome and hadrome, the former MORPHOLOGY OF HIGHER PLANTS. T FIG. 194. Dicotyledonous stem structure. Transverse section through menispermum rhizome: E, epidermis; K, sub-epidermal cork; C, cortex; B, ba_gt fibers; S, sieve; ST, Stone cells; CA, cambium; T, vessels; W, w^ood fibers; M. medullary ray cells; P, pith. 340 A TEXT-BOOK OF -BOTANY FIG. 195. Monocotyledonous stem structure. Transverse section of convallaria rhizome: E, epidermis; H, hypodermis composed of collenchyma; C, cortex; EN, endc- dermis; S, perihadromatic sieve; T, tracheae or vessels; P, parenchyma. The bundles are of the collateral and concentric types. MORPHOLOGY OF HIGHER PLANTS. 341 being used as being apparently synonymous with phloem and the latter being equivalent to xylem. As a matter of fact, these terms are not equivalent, the phloem proper including bast fibers in addition to leptome; and the xylem being composed of wood fibers in addition to hadrome ; nor is the fibrovascular bundle synonymous with mestome strand, as the former includes not only the conducting tissues but the mechanical tissues as comprised in the xylem and phloem ; while the mestome strand includes only the conducting cells comprised in the leptome and in the hadrome, there being no sclerenchymatous fibers present. The following table will doubtless make clear to the student the relationship of these tissues to each other: Mestome or vascular bundle Leptome or Sieve portion Hadrome or Tracheal portion Stereome or Bast fibers f Sieve tubes < Accompanying cells (.Cambiform Cambium f Tracheae Phloem Xylem Fibro- vascular bundle Libriform or Wood fibers When the collateral mestome strand increases in thickness, the increase is due to the activity of the cambium, here called the INTRAFASCICULAR CAMBIUM, which then develops phloem or lep- tome outwardly and xylem or hadrome inwardly. Between the primary mestome strands there is frequently a procambium, which connects these strands with each other, and which gener- ally gives rise to secondary mestome strands, or the connection may be effected by means of the intrafascicular cambium, which often extends itself from one strand to another and develops lep- tome and hadrome, as in the primary strands ; such cambium is distinguished as INTERFASCICULAR CAMBIUM and is commonly referred to as the CAMBIUM RING. The BICOLLATERAL mestome strands or fibrovascular bundles, characteristic of some Dicotyledons (Labiatae, Solanaceae, Cucurbi- taceae, etc. ) , differ from the COLLATERAL type by having a leptome 342 A TEXT-BOOK OF BOTANY. strand developed on the inner face of the hadrome ; thus each mestome strand carries two strands of leptome (Fig. 197, C). In the CONCENTRIC mestome strands the leptome may encircle the hadrome, as in the Ferns (Fig. 56), or the hadrome may partly FIG. 196. The outer bark and part of the inner bark of Rhamnus Purshianus in trans- verse, radial-longitudinal, and tangential-longitudinal sections. Me, transverse section of inner bark ; Mt, tangential-longitudinal section of inner bark ; Mr, radial-longitudinal section of inner bark; Sc, transverse section of stone cell area; St. tangential-longitudinal section of stone cell area; Sr, radial-longitudinal section of stone cell area; He, transverse section of outer layers of cortex; Hr, radial-longitudinal section of outer layers of cortex. Kc, Kt, Kr, transverse, tangential-longitudinal, and radial-longitudinal sections of cork; b, bast fibers; f, crystal fibers; p, parenchyma; e, sieve; sk, stone cells; m, medullary ray cells; c, collenchyma. (as in the rhizomes of many Monocotyledons) surround the lep- tome (Fig. 195). While thus the collateral type of strand or bundle occurs in both Monocotyledons (Fig. 195) and Dicotyle- dons (Figs. 192, 193), etc., the presence of a cambium is found only in the Dicotyledons and occurs extremely seldom in the Mono- MORPHOLOGY OF HIGHER PLANTS. 343 cotyledons. The central portion of the stele is frequently differ- entiated into a PITH of parenchymatic structure, the cells of which often contain large quantities of starch. In addition in the pith, we often find the same types of secretory cells or receptacles as occur in the cortex (as in Apocynum). The pith may constitute a homogeneous tissue or be broken, as in Phytolacca, Carya, Halesia, etc., where a longitudinal section shows the pith divided into a row of broad cavities formed by a separation of the cells as a result of the rapid longitudinal growth of the stem. Finally it may be mentioned that cork is of frequent occur- rence, especially upon stems that persist more than one year. The cork may arise in the epidermis itself, or it may develop in the hypodermal strata of the cortex, or in still other cases we find its development much deeper, even within the pericycle. In regard to the increase in thickness, the stem develops much like the root, as in the throwing off the peripheral tissues extend- ing from the epidermis to the endodermis, or of the epidermis and adjoining cortex, the displaced tissues are replaced by strata of cork and secondary cortex. The mestome strands in the stem, however, grow in a more regular manner than is the case with those of the root, as is seen in the very distinct and frequently very regular layering of the tissues of woody stems, forming the so-called " Annual Rings," where each ring represents the growth that occurs during a single year. The development of these annual rings depends especially upon the fact that the growth of the perennial stem does not take place continuously, but is in- terrupted during certain periods of the season, for instance dur- ing the winter or during the dry seasons of tropical climates. And since the tissues which are formed at tHe beginning of each A TEXT-BOOK OF BOTANY. season's growth are distinct from those already formed during the previous season in both color and structure of the wood (espe- cially in the thickness of cell-walls and the width of the tracheae or vessels), we perceive in this manner distinct zones of wood, or the " annual rings " as they are called, the larger vessels with thin walls being produced in the spring and early summer. Various abnormal stem-structures are known which are due PIG. 198. Transverse section of wood of Rhamnus Frangula showing that the annular rings seen in woody portion of plants is due to a difference in the nature and structure of the cells formed in the spring and in the fall. In the spring numerous large tracheae or vessels (v) are formed, whereas in the fall very few vessels and mostly wood fibers are developed, the cells of these being smaller as they approach the end of the year's growth. — After Rossmann. to certain peculiarities in the growth in thickness of stems. These are especially noticeable in lianes. In some of the Monocotyledons, as in Dracaena, Yucca, Agave and Aloe, we find a secondary in- crease in growth of the stems. In summarizing the root and stem structures of Monocotyle- dons and Dicotyledons the following general facts should be borne in mind. Monocotyledonous stems resemble Monocotyle- donous roots except that the fibrovascular bundle or mestome MORPHOLOGY OF HIGHER PLANTS. 345 strand of the former is concentric, whereas in the latter it is radial. The primary structure of Dicotyledonous roots is much the same as in Monocotyledonous roots. The primary structures of Dicotyledonous stems resemble the primary structure in Dicoty- ledonous roots except that the fibrovascular bundles of the former are of the collateral type. The secondary structures of both roots and stems of Dicotyledons are oractically alike. The characteristics ma' FIG. 199. Section of a four-year-old stem of a pine cut in winter; q, view in trans- verse section; 1, radial-longitudinal section; t, tangential-longitudinal section; f, spring wood; s, fall wood; m, pith; i, 2, 3, 4, successive years' rings of growth inwhichis shown the dividing line; ms, medullary rays in transverse section; ms1, ms11, medullary rays in radial-longitudinal section; ms111, medullary rays in tangential-longitudinal section? c. cambium; b, bast; h, resin-canals; br. bork. — After Strasburger. distinguishing the primary and secondary structures of Dicotyle- donous stems may be summarized as follows: PRIMARY STRUCTURES. — Epidermis, hypodermis, primary cor- tex, endodermis, pericambium or pericycle, stele consisting of collateral fibrovascular bundles and pith. SECONDARY STRUCTURES. — Periderm derived from phellogen; secondary cortex, consisting of parenchyma and occasionally stone cells or secretory cells or vessels ; phloem consisting of sieve, accompanying cells and sometimes bast fibers ; cambium in A TEXT-BOOK OF BOTANY. A B FIG. 200. Coarse structure of a number of woods as seen with a Coddington lens: A, English walnut (Juglans regia) showing the tracheae evenly distributed in the form of pores, which can be seen in the wood with the naked eye; the medullary rays are rather faint and arranged in closely radiating, parallel rows; in the fall wood are numerous fine transverse lines parallel with the annular markings. B, shell-bark hickory (Carya ovata) showing a row of large tracheae (g) in the summer wood and somewhat smaller tracheae (g1) scattered throughout the subsequent growth; medullary rays numerous, as are also the somewhat undulating transverse lines (F). C, white or canoe birch (Betula pendula) showing distinct annular rings and numerous medullary rays between which are scattered the small tracheae indicated by black dots. D, chestnut (Castanea dentata) showing large tracheae arranged in circular groups, those of the successive layers being smaller and arranged some- what obliquely, forming triangular groups; medullary rays very faint; E, Elm (Ulmus campestris) showing tracheae arranged in circles in the summer wood and in the later growth a number of broad more or less undulating plates composed of very small tracheae; medullary rays quite distinct; F, Cherry (Prunus domestica), tracheae quite distinct in the summer wood, forming several circular rows; medullary rays broad and distinct. — B, after Wiesner; the remainder after R. Hartig. MORPHOLOGY OF HIGHER PLANTS. 347 the form of a ring known as interfascicular cambium ; xylem com- posed of tracheae, wood parenchyma, usually wood fibers and sometimes tracheids ; medullary rays separating the collateral bundles ; pith composed of parenchyma and sometimes having stone cells and secretory cells similar to those found in the cortex. In stems having bicollateral bundles, strands of phloem also occur on the inner surface of the xylem rays. IMPORTANCE OF THE STUDY OF THE STRUCTURE OF WOOD. — The structure of stems in woody plants is very characteristic, not only in different families but in genera and at times in species. In the Pinaceae, for instance, the wood is entirely made up of tracheids, the tracheae being wanting. In most of the Dicotyledons tracheae are present, being absent only in certain water plants as Nymphaeacese and in Drimys, a genus of the Magnoliaceae. In the Cactaceae the secondary wood is provided with annular and spiral tracheids. In practical work, whether it be in the study of plants for taxonomic purposes or for their industrial uses, the following are some of the observations that should be made : i. Structure of the walls and nature of the perforations or mark- ings in the tracheae or vessels. 2. The presence or absence and relative distribution of libriform or wood fibers (often referred to as wood prosenchyma). 3. The structure of the medullary rays not only as regards thickening of the walls and contents of the cells, but the number of the cells both as to width and height entering into the individual groups of rays. 4. Wood paren- chyma is variously distributed, the cells aggregated about the vessels being distinguished from those that form tangential bands separating the circles of vessels. The distribution of the crystals is also of importance, as they may occur in isolated cells or in superimposed cells adjoining the wood fibers and form the so- called crystal fibers. In the study of different commercial woods it is customary in practice to study the coarser features such as can be recog- nized by the help of an ordinary hand lens. In this superficial study many distinctive characteristics can be readily determined, as the nature of the annual rings, the size of the lumina of the ves- sels, as well as their abundance and arrangement, etc. (Fig. 200). 348 A TEXT-BOOK OF BOTANY. III. THE OUTER MORPHOLOGY OF THE LEAF. Leaves are lateral formations upon the stem and their growth is definite. They never occur on other portions of the plant than stems, from the surface of which they are developed. Leaves appear in acropetal succession, so that the youngest leaves occur nearest the apex of the stem. Terminal leaves are extremely rare, but arise in some instances from the flowers of certain Euphorbiaceae. FIG. 201. A, leaf of violet (Viola tricolor) showing broad lamina, long petiole, and one of the palmately-lobed stipules at the base of the petiole. B, C, stages in the development of the leaf. The lobes of the stipules (s) develop before the lamina (1). A Simple Leaf consists of a LAMINA or blade, which is usually membranous and of a green color, and a PETIOLE or stalk, which, however, may be wanting when the leaf is said to be sessile. Leaves may also possess a pair of leaf-like structures at the base, known as STIPULES (Figs. 201, 204). The principal function of the latter appears to be that of protecting the buds, as in the tulip poplar (Liriodendron] (Fig. 204), although they may be- come leaf-like and assist in the functions of the lamina, as in Viola tricolor (Fig. 201). MORPHOLOGY OF HIGHER PLANTS. 349 Light Relation of Leaves. — While the lamina of the leaf appears to assume a more or less horizontal position, it usually inclines at such an angle as to receive the greatest amount of dif- fused daylight. Wiesner has shown, for instance, that when plants are so situated that they receive direct sunlight only for a time in the morning, and diffused daylight during the rest of the day, the position of the upper surface is at right angles to the incident rays of daylight, and not to that of the rays of the morning sun. This phenomenon may be studied in the house geranium and other window plants. In endeavoring to explain this behavior of the leaves, Frank assumes it to be due to a kind of heliotropic irritability peculiar to dorsiventral organs, and terms it TRANSVERSE HELIOTROPISM. The stem, as well as the petiole or stalk of the leaf, is also influenced by the light, and is said to manifest positive helio- tropism. Those parts of plants that turn away from the light, as the aerial roots of the ivy, are said to possess negative helio- tropism. Depending upon their relation to external agents, several forms of leaves are distinguished. In those which assume a more or less horizontal position the two surfaces of the lamina are quite different, and the leaves are said to be DORSIVENTRAL, or bifacial. Usually there is a more compact arrangement or stronger development of chlorophyll tissue on the upper or ventral surface, while on the lower or dorsal surface the veins stand out more prominently, and there is a greater number of stomata. In contrast with this type of leaf may be mentioned those which grow edgewise and in which both surfaces of the leaf are more or less alike, as in the Eucalypts and Acacias of Australia. In Iris and Calamus, the leaf-like organ is actually not the blade, but merely a part of the dorsal face, which, in the bud, has already pushed out so as to exceed the apex. Such leaves are called SWORD-SHAPED and are frequently referred to as EQUITANT. The leaves of certain species of Juncus, Carex and some of the grasses are commonly spoken of as CYLINDRIC. Such leaves are, how- ever, only apparently cylindrical, since the ventral surface is often distinct, though much narrower than the dorsal. They are also frequently hollow. 350 A TEXT-BOOK OF BOTANY. Functions of the Leaf.— When we speak of the leaves of the plant we usually have in mind the foliage leaves or green chlorophyll leaves. Under the influence of sunlight the chloroplasts are able to rearrange the elements in carbon dioxide and water, which are looked upon as inorganic substances, . into starch or related com- pounds which are of an organic nature. This process is known as carbon dioxide assimilation, or PHOTOSYNTHESIS, which latter term means the building up of a compound under the influence of light. In this process, which is sometimes expressed by the fol- lowing formula, oxygen is given off : 6C02 + 5H20 =. C6H1005 + 602 Carbon dioxide Water Starch Oxygen The importance of .this function can be best appreciated by bearing in mind that all of the organic products built up by the plant are derived almost entirely from the carbon dioxide of the air which is taken in through the leaves. (Consult also pages I57-I59-) Transpiration and respiration are also functions of the leaf. TRANSPIRATION is the giving off of water (through water-pores), or watery vapor (through the stomata), which has been absorbed by the root-hairs and transported through the tissues of the root, stem and leaf ; the process of breathing, or RESPIRATION, consists in the taking in of oxygen and giving off of carbon dioxide, the exchange being just the reverse of what it is in photosynthesis. These several functions are, however, not confined to the leaf alone, but are carried on by all the green parts of the plant. PHYSIOLOGICAL EXPERIMENTS. — The leaf is undoubtedly the most active part of the plant from the physiological point of view. Some of its activities can be demonstrated by comparatively sim- ple means. For instance, it can readily be shown, that leaves or rather chloroplastids form starch when exposed to sunlight but that no starch is formed when the light is not admitted, by a simple con- trivance called a leaf shield. This is a device by which a thin piece of glass can be clamped against the leaf. Over a portion of this glass a piece of tinfoil may be pasted, thereby shutting off the light from the underlying area. The procedure consists as MORPHOLOGY OF HIGHER PLANTS. 351 follows : On the day previous to the demonstration of the experi- ment the leaf shield is clamped on the leaf. On the following day the leaf is allowed to stand well exposed to the sunlight for several hours. The leaf is then removed from the plant, separated from the leaf shield, and after the chlorophyll is extracted by boiling in alcohol it is placed in weak iodine solution, whereby the entire part of the leaf exposed to the light is darkened in color, while the area protected by the tinfoil remains unchanged. The phenomenon of photosynthesis whereby the leaf uses carbon dioxide and gives off oxygen can be demonstrated by means of a photosynthometer. Ganong gives a detailed description of its construction and use. The underlying principle is that a known volume of leaf material is supplied with a known volume of carbon dioxide. After submitting the leaf to the sunlight a test is made of the proportion of carbon dioxide and oxygen in the graduated tube, from which the activity of the leaf may be accurately deduced. The process of transpiration in leaves can also be readily shown. The mere fact of transpiration can be shown by inserting the leaves of a plant into a bell-jar which has at its base a sheet of rubber or other suitable material stretched over the opening with just sufficient aperture to admit the stem. The root being outside of the bell-jar can be kept moist and as transpiration takes place the moisture condenses on the inside of the glass. By means of an arm balance and devices for measuring the water supplied the plant, together with some covering to prevent evaporation from the surface of the soil, rather accurate deter- minations can be made of the quantities of water given off by the plant and calculations made for each square unit of leaf surface. The potometer is another ingenious sfmple contrivance which measures most accurately the amount of water transpired. It consists of a horizontally placed graduated tube which ends in a short vertical portion into which a stem bearing leaves can be tightly inserted after the instrument is filled with water. By means of a reservoir at the side and a stop-cock more water can be admitted as needed. Accurate readings over short periods of time are facilitated by admitting a small bubble of air as an index and observing the time of its passage along the graduated tube. (Consult Ganong: Plant Physiology.) 352 A TEXT-BOOK OF BOTANY. Leaf Venation. — The foliage leaves of higher plants are traversed by vascular bundles, which enter the blade through the petiole and diverge at the base, or, as in the case of Dicotyledons, branch in various ways ; and it will be seen that the form of the leaves corresponds to the distribution of the bundles. These bundles are known as veins or nerves, and they have two func- tions, namely, (i) that of a mechanical support, and (2) that of carrying nutritive materials to and from the leaves. The mode of venation in Monocotyledons and Dicotyledons differs somewhat, but it will be found that in a number of instances FIG. 202. Leaf venation: A, parallel-veined leaf of Solomon's seal (Smilacina race- mosa); B, pinnately-reticulate leaf of chestnut; C, palmately-veined leaf of Menispermutn canadense. the venation of leaves of plants belonging to one of these great groups will resemble that of the leaves of certain plants in the other group. However, there are certain general types belonging to each. group (Fig. 202). VENATION IN MONOCOTYLEDONS. — An examination of the leaf of lily-of-the-valley shows that the primary veins run more or less parallel to the apex with short though distinct anastomoses. Such a leaf is said to be PARALLEL-VEINED or NERVED. It will moreover be noticed that the distribution of the veins in this manner produces a lamina with an even, or entire margin, and MORPHOLOGY OF HIGHER PLANTS. 353- such a system of venation is known as a closed system of venation (Fig. 202, A). The leaves of Veratrum and Zea Mays furnish other examples of parallel-nerved leaves. In palms the venation is somewhat different. The veins, instead of converging toward the apex as they do in the more or less lanceolate leaf of lily-of -the- valley, radiate from the base to the margin of the more or less round leaf, and a leaf of this type is said to be PALMI-NERVED. There is still a third type of venation in Monocotyledons. In this instance one principal vein runs from the base to the apex of the leaf, and from this branches run parallel to the margin. The banana furnishes an example of this type, and is said to be PINNI-NERVED. VENATION IN DICOTYLEDONS. — Here the veins are character- ized by their habit of repeatedly branching and anastomosing, whatever the general type of venation may be, and thus form a net-work or reticulum, hence the leaves are said to be RETICULATE or NETTED-VEINED. The principal types are as follows : A chest- nut or chinquapin leaf (Fig. 202) furnishes a good illustration of a pinnately-reticulate leaf. The principal vein which runs from the base to the apex is called the MIDRIB, while the secondary veins which arise from it and run more or less parallel to the margin are sometimes spoken of as ribs and may be likened to the plumes on the shaft of a feather. In other cases several large veins arise at the base and diverge toward the margin, giving rise to PALMATELY-VEINED leaves, as in the leaf of maple. There are still other types, as in cinnamon, which is said to be rib-netted, etc. Surface of Leaves. — In addition to the markings of leaves due to veining there are certain other characters which serve to distinguish them. Hairs are of frequent occurrence on leaves, being generally most abundant on the dorsal surface, especially the veins, and various terms having reference to the kinds of hairs have been applied to leaves. Plant Hairs. — When the surface of the plant (either of stems or leaves) is covered with short, fine hairs, which are not very dense and not matted, the surface is described as PUBESCENT; when the hairs are relatively long but scattered the surface is said 23 354 A TEXT-BOOK OF BOTANY. to be VILLOUS; or when the hairs cover each other in one direction it is described as SERICEOUS or silky. When the hairs are stiff though slender we speak of a HIRSUTE covering; when the hairs are vernate, thickish and stiff, as in Borago, the surface is spoken of as being HISPID. If the hairs are bristle-like the surface is described as STRIGOSE; or if they are terminated by a globular, glandular head (Figs. 100, 124), as GLANDULAR. Again, when the hairs are matted the surface is described as LANATE; when they are long it is said to be WOOLLY; or when they are short and soft as in Mullein it is said to be TOMENTOSE. When the hairs are hard and prickle-like the surface is described as HISPID or STRIGOSE; when they are modified to spines it is said to be SPINOSE; and when they are hooked it is described as ECHINATE. In still other cases the epidermal cells, particularly of leaves, are uneven, forming depressions and protuberances which if slight give the surface the appearance described as RUGOSE ; or if wart-like, give the. appearance known as VERRUCOSE. Further- more, the veins of leaves may be quite prominent, particularly in the lower surface, and if they are much reticulated in addition, the surface is described as RETICULATE. Texture of Leaves. — Leaves also vary in texture. A thin pliable leaf is called membranous ; one which is thick and leathery, coriaceous ; and one which is thick and fleshy, succulent, as that of the century plant and Aloe (Fig. 130). Forms of Leaves. — The leaves of plants exhibit an almost innumerable variety of forms ; even on the same plant there are not infrequently several forms, as in Viola tricolor and sassafras (Fig. 203) ; even the two margins of the same leaf may vary, as in Hamamelis and Begonia, when it is known as an inequilateral or asymmetric leaf. It frequently happens that the lower leaves on a shoot are lobed while the upper ones are entire, or some of the leaves may be sessile and other petiolate. Many of the terms used in ordinary language in describing the forms of objects are applied here also, as linear, lanceolate, oblong, elliptical, spatulate, wedge-shaped, etc. SUMMIT OF LEAF. — A number of terms are used to describe the summit or apex of the lamina, as ACUTE, when the form is MORPHOLOGY OF HIGHER PLANTS. 355 that of an acute angle; OBTUSE, when the angle is blunt; ACUMI- NATE, when the angle is prolonged ; TRUNCATE, when the end of FIG. 203. Variation in the form of leaves on the same plant: A, B, C, Leaves or sassafras; D, young castor oil plant showing cotyledons (t) and variously lobed older leaves. 1, lamina; p, petiole. the leaf appears to be cut off; RETUSE, when it is slightly notched at the apex; OBCORDATE, when the notch is pronounced; EMAR- GINATE, when the degree of notching is between retuse and 356 A TEXT-BOOK OF BOTANY. obcordate. Sometimes the apex appears like the continuation of the midrib, when it is termed CUSPIDATE or mucronate. BASE OF LEAF. — Some of the terms used in describing the gen- eral outline, as well as the apex of the leaf, are also applied to the base, as obtuse, truncate, cordate, reniform, etc. Other terms, however, especially apply to the base, as CUNEATE or wedge- shaped ; CONNATE-PERFOLIATE, when opposite leaves are con- nected at the base and surround the stem ; PERFOLIATE, when the leaf simply clasps the stem. In Monocotyledons the base of the leaf is frequently developed as a closed or open sheath, some- times provided with a membranous protuberance between the sheath and the blade, as in the LIGULE of grasses and sedges. MARGIN OF LEAF. — The leaves of many woody dicotyledonous plants of temperate regions possess an even margin. The others, according to the degree and character of the incisions or inden- tations, are described as SERRATE, when the apex of the divisions or teeth is sharp and directed forward like the teeth of a saw ; DENTATE, when the divisions project outward; CRENATE, when the teeth are more or less rounded ; REPAND, when the margin is somewhat wavy ; SINUATE, when the wavy character is pro- nounced ; LOBED, when the incisions extend not more than half- way into the lamina, and the sinus (or hollow) and the lobes are more or less rounded ; CLEFT, when the incisions are still deeper and the sinuses and lobes are somewhat acute ; and DIVIDED ( Fig. 205), when the incisions extend almost to the midrib. Compound Leaves. — The divisions of a parted leaf may assume the form of a simple leaf, when the divisions are known as LEAFLETS and the whole as a compound leaf. The distinction between a simple leaf and a leaflet is, that the former has a bud in the axil. The difference between the divisions of a simple leaf and those of a compound leaf is this, — in the former they never become detached from the petiole or midrib, whereas in the com- pound leaf they are articulated and drop off individually. Com- pound leaves may be divided into piNNATELY-compound (Fig. 204) or PALMATELY-compound (Fig. 210, E), this distinction depend- ing upon whether the leaflets are arranged pinnately or palmately. A number of forms of pinnately-compound leaves are recognized. When the leaflets are all lateral (Fig. 207) the leaf is said to be MORPHOLOGY OF HIGHER PLANTS. 357 PARI-PINNATE; when there is an odd or terminal leaflet as in the locust (Fig. 204) the leaf is IMPARI-PINNATE; when the midrib FIG. 204. Leaves having different forms of stipules (s) : A, bud-scale stipules of Lirio- dendron Tulipifera; B, thorny stipules and odd-pinnate compound leaf of the locust tree (Robinia Pseud-acacia) ;-C, adnate stipules of rose; D, filiform stipules of the pear; E, fringed clasping stipules (ocrea) characteristic of all of the Polygonums; F, adnate stipules of clover. is prolonged into a tendril as in the garden-pea (Pisum) the leaf is said to be CIRRHIFEROUS-PINNATE. Movements of Leaves. — The leaves as well as other organs of plants exhibit a variety of movements or curvatures in response 358 A TEXT-BOOK OF BOTANY. , to stimuli of different kinds, and are said to possess the property of irritability. Movements of organs are of two general classes: (i) Those due to stimuli which originate in the plant and (2) those due to the influence of external factors. To the former class PIG. 205. Limnophila heterophylla, a marsh-plant belonging to the Scrophulariaceae and growing in tropical Asia. The submerged or water leaves, below, are much divided and arranged in apparent whorls; while the leaves at the end of the shoot above water are entire and arranged in decussate dimerous whorls. In between occur transition forms, which are divided and variously lobed and arranged in decussate whorls. — After Goebel. belong all those movements which occur during the course of development from the young to the mature stage. These are known as growth movements or NUTATION. They are especially noticeable in tips of growing branches, which instead of growing MORPHOLOGY OF HIGHER PLANTS. 359 FIG. 206. i, Leaf, fruits and flowers of Anemone Pulsatilla. 2. Leaf, flower and fruit of Anemone pratensis. The leaves are pinnately divided, the divisions being further incised or dissected. 360 A TEXT-BOOK OF BOTANY. in a straight line, move either from one side to the other, or coil or curve about an imaginary axis. This spiral movement is known as circumnutation and is characteristic of twining stems and tendrils, as the hop vine and tendrils of Bryonia ( Fig. 181 ) . Nuta- tion curvatures are due to unequal growth on two sides of the organ and cease when there is a cessation in growth or when the plant has reached maturity. The movements of organs due to external stimuli are usually in a direction which shows a relation to the direction of the stim- ulus, as those produced by gravity and light (Fig. 207), and these FIG. 207. American senna (Cassia marilandica) . The figure at the left shows the pin- nately-compound leaves in the day position when under the influence of light, and the one to the right the drooping position of the leaflets at night. movements are of use in bringing the organs into more favorable positions for growth. Stimuli of this kind are spoken of as orienting or TROPIC. The compound leaves of a number of plants exhibit in addition certain variable and periodic movements, which have their origin in a special mechanism known as the PULVINIS. The pulvinis appears as a swelling on the petiole and consists of parenchymatous tissue which is highly turgid, i.e., full of water. Any stimulus, such as mechanical shock, which causes a differ- ence in the degree of turgidity on two sides, will result in a move- ment of the leaves in such plants as Mimosa, Oxalis and locust. The leaves of Mimosa pudica, a common cultivated sensitive plant, show a very rapid response to such stimuli, the leaflets folding MORPHOLOGY OF HIGHER PLANTS. 361 together and the petiole and petiolules drooping. In other cases there is a change in the position of the leaves following the alter- nations of day and night. During the day the leaflets are spread out freely, but at night or in darkness they droop and fold together. These are spoken of as nyctinastic (nyctitropic) or " sleep movements," and are exhibited by a number of leguminous plants, as clover, bean, Cassia (Fig. 207), and by wood-sorrel (Oxalis Acctosella*) and various cultivated species of Oxalis. The leaves of Oxalis as well as of some other plants fold together II FIG. 208. So-called carnivorous plants. I, the pitcher plant (Sarracenia purpurea) showing the modified pitcher-like leaves (A) with inflated portion which narrows into the petiole, and a terminal, more or less spreading winged portion; and a flower and flower-bud (B). II, three species of sundew: A, Drosera rotundifolia; B, D. intermedia; C, D. longi folia. — I, after Gray; II, after Drude. under the influence of intense light as well as at night or when the amount of light is reduced. Of special interest also are the lateral leaflets of Desmodium gyrans (telegraph plant) which describe curvatures at more or less regular intervals day and night when the temperature is favorable. The leaves of the sundew (Drosera} are remarkable for their sensitiveness to touch. The upper surface and margin are provided with peculiar hairs or 362 A TEXT-BOOK OF BOTANY. tentacles (Fig. 208, 77) which when touched, as by an insect, gradually curve inward. Not only this, the stimulus may be trans- mitted to other tentacles and sometimes even the blade itself may FIG. 209. Flowering plant of Venus's Flytrap (Dioncea muscipula) of North Carolina, showing the sensitive armed leaves both open and closed, in one of which an insect has been imprisoned. — Drawn from nature by Florence Newton. roll inward to some extent, thus entrapping small insects which serve as food to the plant. The leaves of a related plant Dioncea are even more sensitive and when special hairs on the blade are touched that part of the lamina bearing these hairs closes with a MORPHOLOGY OF HIGHER PLANTS. 363 quick, trap-like movement, imprisoning its insect prey (Fig. 209). Phyllotaxy, or phyllotaxis, is the study of the distribution of leaves upon the stem, and of the laws which govern it. If we examine germinating plants of the beech, the elm, or the oak, we observe that, while the seed-leaves are opposite to each other, the subsequent leaves are arranged according to a different order in these several plants, but in a definite manner in each. In the elm, the distribution of the leaves is such that the third leaf is directly above the first; in the beech, the fourth leaf is above the first, and in the oak, the sixth leaf is above the first. If these leaves are con- nected in the order of their development, it will be seen that they describe a spiral in their arrangement, and it will also be found that one or more circuits of the stem are made between the super- imposing leaves. Furthermore, it will be found that this arrange- ment constitutes a mathematical series which may be expressed in degrees, or the parts of a circle that the leaves are from each other, this measure being known as DIVERGENCE; or by the number of perpendicular rows of leaves on the stem, which are known as ORTHOSTICHIES. The following may serve to illustrate the terms used : LEAVES. DIVERGENCE. ORTHOSTICHIES. Degrees. Parts of a Circle. Elm 1 80 1 2O 144 i i i Distichous Tristichous Pentastichous Beech Oak If we examine the fractions used, we will find that the numer- ator indicates the number of turns around the stem before encoun- tering a superimposed leaf, and that the denominator indicates the number of leaves found ; the latter also expresses the number of orthostichies. On adding the numerators and denominators of any two successive fractions, a fraction is obtained which ex- presses the next highest arrangement, as In quite a number of plants two leaves arise at the nodes, as in the Labiatse. These are invariably situated opposite each other 364 A TEXT-BOOK OF BOTANY on the stem, and the successive pairs alternate with one another, forming the decussate arrangement of leaves (Figs. 180, 181, 184). Modified Leaves. — Leaves are variously modified and serve for other purposes than those already described. They may be fleshy in character and serve as storehouses for nutritive material, as the seed-leaves of the oak, or they may serve for the stor- age of water, as in Agave, Aloe and succulents. In some instances, particularly when situated near the flowers, they lose their green color, as in the dogwood, skunk cabbage and others. In other cases they are modified so that they serve as a trap for insects, as in Dioncca, Sarracenia and Drosera (Figs. 208, 209). The peti- ole may become enlarged and perform the functions of the leaf, as in the Acacias of Australia ; or it may become bladder-like and serve as a means for floating the plant, as in the water hyacinth. The stipules may likewise be modified, becoming leaf-like, as in the pansy (Fig. 201 ) ; or metamorphosed into thorns, as in the locust ; or clasping, as in Polygonum. In some cases the leaves are very much reduced, their functions being performed by the stem, as in Cactaceae, or even by the roots, as in some orchids which have assimilating roots. Prefoliation or vernation is the disposition of leaves in the bud. The terms used to describe the folding of the leaves in the bud are derived from an examination of transverse sections of the bud. The following are some of the terms which are em- ployed: CONDUPLICATE, when the lamina of the leaf is folded lengthwise along the midrib so that the two halves of the upper surface lie together, as in the Magnolia cccc; PLICATE or plaited, when the lamina is folded along the veins, like a closed fan, as in the maples; CONVOLUTE, when rolled lengthwise and forming a coil in cross section, as in the Rosaceoc ; INVOLUTE, when both mar- gins are inrolled lengthwise on the upper surface, as in the violets ; REVOLUTE, when both margins are inrolled lengthwise on the lower surface, as in Azalea. In addition, there are several terms used which are derived from the appearance of the bud, as RECLINATE or inflexed, when the upper part is bent on the lower, as in Liriodendron ; and CIRCINATE, when the upper part is coiled on the lower so that the tip of the leaf is in the center of the coil, as in the ferns. MORPHOLOGY OF HIGHER PLANTS. THE INNER STRUCTURE OF THE LEAF. 365 In all green leaves the typical structure is as follows : A cuticle covert the outer cell-wall of the epidermis, while the epidermis itself shows much of the same modifications as exist in the stem ; frequently the lumen of the cells of the epidermis is wider on the FIG. 210. Group of transplanted wild plants showing variation in form of leaves. A, Cinnamon fern (Osmunda cinnamomea) showing sporophylls (fertile leaves) and a cluster of pinnatifid sterile leaves, the pinnae being linear-lanceolate and deeply pinnatifid; B, wild ginger (Asarum canadense) showing basal, reniform, long-petiolate leaves with cordate base and slightly pointed apex; C, young hickory (Hicoria ovatd) showing the odd-pinnate (imparipinnate), 5- to 7-foliate leaves; D, ternate, decompound leaf of Virginia grape fern (Botrychium virginianum); E, digitately compound leaves of cinquefoil (Potentilla). ventral face than on the dorsal. Hairs abound on the leaves in many plants, and stomata are especially frequent on the dorsal surface. The upper epidermis may further be characterized by the presence of water-pores, the origin and function of which have already been described (Fig. 147). 366 A TEXT-BOOK OF BOTANY. The green chlorophyll-bearing tissue is called CHLORENCHYMA (frequently spoken of as mesophyll), and is frequently differen- tiated into a ventral PALISADE TISSUE, composed of long. cells which are placed vertically to those of the epidermis ; and a DORSAL PNEUMATIC TISSUE, made up of irregularly branched or lobed cells with very large intercellular spaces. Secretory cells or receptacles occur in the chlorenchyma of many plants and corre- spond with those found in the cortex of the stem. When the palisade tissue occurs on both faces of the leaf blade with the pneu- ST- FIG. 211. Transverse section of midrib of leaf of stramonium: EU, upper epidermis; CO, collenchyma; PA, palisade cells; O, layer of cells containing rosette aggregates of calcium oxalate; M, loose mesophyll; EL, lower epidermis; OP, prisms of calcium oxalate; OS, sphenoidal micro-crystals of calcium oxalate; ST, stoma; T, tracheae; SU, leptome or sieve on upper side of tracheae or vessels; SL, sieve on lower side of tracheae, this arrange- ment of leptome or sieve and tracheae forming bicollateral fibrovascular bundles. matic tissue in the center, the leaf is called " unifacial " or " iso- lateral " (Figs. 211, 215) ; otherwise the leaf is said to be "bi- facial " or " dorsiventral," i.e., with two distinct surfaces. Mechanical tissues, as collenchyma and stereome, are frequent and these accompany the veins as hypodermal strands, being best developed usually on the dorsal face of the latter, as underneath the leptome. The mestome-strands of the leaf blade generally lie in a single plane. They are collateral and have the leptome situated towards the dorsal face. They are nearly always sur- MORPHOLOGY OF HIGHER PLANTS. 367 rounded by thin-walled PAREXCHYMA-SHEATHS, or as in several grasses and sedges by thick-walled mestome-sheaths. In some plants of various families, the midrib is not only stronger devel- FIG. 212. Study of the stomata on leaves of Beta vulgaris: A and B, surface sections of the leaf, and C and D, transverse sections of the stomata. In A and C, the stomata are shown with the guard cells (s) distended and the pore (sp) open to allow the passage of vapors and gases. B and D, showing the pore or opening closed due to the plasmolysis of the contents of the guard cells, the internal pressure or tension having been relieved, e, epidermal cells; a, large cavity or intercellular space beneath stomata; and m, loose mesophyll cells with chloroplasts. — After Frank. oped than the lateral veins, but it may be composed of several, instead of only one, mestome-strand, sometimes representing a true stele. 368 A TEXT-BOOK OF BOTANY. The petiole generally shows the structure of the midrib as far as concerns the mestome-strands, but possesses furthermore a more or less strongly developed parenchyma, the cells of which FIG. 213. Development of stomata on leaves of Sedum purpurascens: in A very early stages of growth, and B nearly completed stoma. In B are shown a stoma with two guard cells, three neighboring cells and two of the epidermal cells (e); the numbers in B correspond to those in A and show the origin of the several cells from the division of a single epidermal cell. — After Sachs. are colorless, thin-walled and which may often be traced to the leaf-blade itself, where it surrounds the stronger veins, causing FIG. 214. Transverse section through a stomata showing how by a slight difference in the tension the pore is either opened or closed; the dark lines show contour of cells when -open, the light lines show when they are closed. — After Schwendener (See Haberlandt. Physiologische Pflanzenanatomie). them to project as ribs and to be much thicker in cross-section than the adjoining chlorenchyma. From a histological point of view the leaf structure of MORPHOLOGY OF HIGHER PLANTS. 369 Dicotyledons resembles very closely that of the Monocotyledons, except that in the latter the palisade-cells often radiate towards the center of the mestome-strands. There are, however, many instances of a similar development in the leaves of Dicotyledons. Abnormal structures are common in leaves, especially in such FlG. 215. Transverse section of leaf of Phytolacca decandra showing upper epidermis (ue), palisade cells (p), raphides (r), spiral tracheae (v), loose mesophyll (m) with large intercellular spaces, and lower epidermis (le) with a stoma. as are not held in a horizontal position, but vertical, as those of Eucalyptus, the Irideae, etc. The Epidermis forms the surface of the leaf and may con- sist of one or more layers of cells. The outer walls are cutinized, and when nearly smooth the leaf is said to be GLABROUS. They may be covered or whitened with a bloom, as in magnolia, when 24 370 A TEXT-BOOK OF BOTANY . the leaves are spoken of as GLAUCOUS. In other cases the outer walls of the epidermal cells are modified to hairs (Figs. 100, 124, 125, 148^155)- ANATOMICAL DIFFERENCES IN LEAVES. — The walls of the epidermal cells, although usually isodiametric, are often very zig-zag in outline. In size, the upper epidermal cells are usually larger in a given species than those of the lower surface, and sometimes are rather linear, resembling a palisade layer. The FIG. 216. A, transverse section of leaf of Lobelia inflata showing the large irregular epidermal cells (e), palisade cells (p), trachea (t). loose parenchyma (m), and lower epider- mis (i). B, transverse section of leaf of Matico showing oil-secretion reservoir (o), upper epidermis (e), lower epidermis (1), with non-glandular hairs (h), palisade layers (p), loose mesophyll (m). cuticle may be thin or leathery and tough, and sometimes is pro- vided with minute ridges or crests, especially on the under sur- face, thereby giving a dull appearance to the leaf. Many leaves, too, excrete wax on the surface and consequently have a glaucous or hoary appearance, notably some of the poppies, the common jewel-weed and many others. Other modifications may have to do with the gelatinization of the epidermis of the leaf, assisting in the storage of water, as in the leaves of the violets. The differentiation in forms of calcium oxalate crystals is also im- MORPHOLOGY OF HIGHER PLANTS. 371 portant in distinguishing plants that resemble 'each other. The size and number of stomata as well as their distribution and arrangement with respect to each other varies in different plants. For example, in certain saprophytic or submerged plants the num- ber of stomata is greatly or even completely reduced, and when pres- ent are quite functionless. Sometimes the stomata are depressed below the surface of the leaf, this being true in plants occurring in dry or cold districts, and is distinctly characteristic of many 'Coni ferae. There is a marked difference in the arrangement of the pali- sade tissues, the following types being distinguished : i . In bifacial 372 A TEXT-BOOK OF BOTANY. FIG. 218. Digitalis leaves: A, transverse section near one of the veins showing the separated or extra-epidermal layer occurring on the lower surface (S) with two non-glandular hairs (N) and glandular hair (G), epidermal layer (E), lower epidermis (LE), chlorophyll layer (M), upper epidermis (UE), and tracheae (T). B, transverse section of portion of leaf showing the separated or additional epidermal layer; c, collenchyma. or dorsiventral leaves the palisade cells are distributed only below the upper epidermal layer (Figs. 211, 21^5). 2. In unifacial or MORPHOLOGY OF HIGHER PLANTS. 373 isolateral leaves the palisade cells occur beneath the epidermal layers of both leaf surfaces, as in senna. 3. In some leaves, as in Eucalyptus, the entire parenchyma is made up of palisade cells. 4. In a few leaves there is no differentiation of a palisade layer, and these are sometimes referred to as centric leaves. The palisade cells may contain not only chloroplastids but crystals of calcium oxalate (Fig. 215), tannin-inclusions (Fig. 114), etc. Distributed among the palisade cells may be the oil-secretion reservoirs (Fig. 216, B). Furthermore, the palisade cells may be of equal length or the stratification may be quite uneven and irregular. In shape they may vary from long, narrow cells to short, broad cells. In some special instances they are narrowed at the lower end in the form of a blunt cone forming the so-called " funnel cells," which are especially characteristic of plants in- habiting moist localities. There is still another common form known as arm-palisade parenchyma, in which the cells are branch- ing and connected with each other by means of the branches. Tissues of this type occur in the Equisetaceae, Filices, Coniferse, Gramineae, and in a number of Dicotyledons, such as Aconitum, Adonis, Anemone, Caltha, Clematis, Delphinium, Nigella, Paeonia, and Trollius in the Ranunculaceae ; Sambucus and Viburnum in the Caprifoliaceae; Lysimachia and Trientalis in the Primulaceae. The spongy tissue or dorsal pneumatic tissue shows consider- able variation in the arrangement and shape of the cells. In some leaves the cells are arranged in strata or layers, while in others they are more or less irregular. The cells may be spherical or provided with a number of arms, the latter developing parallel to the surface of the leaf or radiating in any direction, thus caus- ing a variation in the nature and size of the intercellular spaces. In some instances there are included in the mesophyll certain mechanical cells, of which the simplest are like ordinary stone cells. They may be more or less elongated or branched or even quite fibrous, and are known as SPICULAR CELLS. The latter are sometimes quite prominent when they traverse the leaf in a verti- cal direction, giving rise to translucent spots. Spicular cells have been found in the mesophyll of quite a number of families. They are quite characteristic, although absolutely not constant, in the rgenuinp tea leaf (Thea sinensis). 374 A TEXT-BOOK OF BOTANY. IV. OUTER MORPHOLOGY OF THE FLOWER. It is well known if the stem of a plant, as the carnation, rose, geranium, etc., be cut into pieces so that each portion has at least one node and placed under suitable conditions for growth, roots will arise from the nodes that are in the ground and a new plant will be developed. The same result can be achieved if plants like Ficus, growing in a greenhouse, have placed around the nodes near the tip of the branches a clump of sphagnum, and if the latter be kept moist roots will arise from the joints. This method of increasing the number of individual plants, while it is limited to certain perennials and cannot be followed with annuals or bien- nials, is frequently resorted to by horticulturists, and is known as vegetative propagation. The production of independent plants in this manner is dependent upon the property of the meristematic cells in the pericycle of the stem to produce the meristems that give rise to the tissues of the root. As this process of propagation for plants growing in temperate regions and in cold climates would be more or less uncertain for the perpetuation of the species, it is fortunate that in Nature safer methods of reproduction are followed, depending upon the development of flowers and the production of seed. In the latter there is a young plant with all of the elements of root and shoot contained therein and so pro- tected by a seed-coat that it may withstand extremes of climatic conditions, as well as the various hostile forces to which it might be subjected. THE FLOWER is a shoot which has undergone a metamorphosis so as to serve as a means of propagating the individual. It is an unbranched and definite shoot, or an apex of a shoot. It might be termed a " dwarf-branch " that dies and drops off the plant after the maturation of the fruit. The most complete flower has four kinds of leaves: sepals, petals, stamens, and carpels. The sepals, usually green and leaf-like, make up the outer spiral known as the calyx. The petals being frequently highly colored form an inner spiral known as the corolla. The stamens are the polliniferous organs of the flower, and the carpels bear the ovules which later- develop into seeds. While the flower is a very complicated structure in many MORPHOLOGY OF HIGHER PLANTS. 375 cases, the definition given it by some writers is very simple. It is defined as a branch which bears sporophylls. As we have seen, a sporophyll is a leaf which bears sporangia. According to the definition given, the strobiles or cones of the Gymnosperms and certain Pteridophytes, as the horsetails and club mosses, are entitled to rank as flowers. In Angiosperms other leaves may be present, and these are known as the FLORAL LEAVES. The flower, then, in Angiosperms is made up of sporophylls which are essential, and floral leaves which may or may not be present. But in speaking of the sporophylls of the flower in Angiosperms it is customary to use terms which were applied to them before their relation to the similar organs in the Gymnosperms and Pterido- phytes was understood. Thus the microsporophylls, as already pointed out, are known as STAMENS, and the megasporophylls as CARPELS. For a great many years botanists taught that the stamens and carpels are transformed foliage leaves, — in other words, that they are derived from foliage leaves, — but in more recent years the view has been established that they arise as independent members, — are, in fact, as independent as the foliage leaves themselves. Various transformations or modifications may and do occur, but these are not confined to the foliage leaves alone, for under cer- tain conditions the sporophylls may assume the character of floral leaves. It is true that in the case of some ferns the sporophylls bear a strong resemblance to foliage leaves, as in Dryopteris Filix-mas (Fig. 53), but this does not necessarily prove that the sporophylls of Angiosperms are transformed leaves, but only that the further back we go, the less the degree of differentiation of parts until we reach the unicellular algae. The flowers of the Angiosperms differ from those of the Gymnosperms in that the ovules (megasporangia) are enclosed, before pollination, in an ovary which has developed a special organ — the stigma — for the reception of the pollen grains (micro- spores), and the Angiosperms having in addition floral envelopes. The several parts of the flower are arranged more or less compactly at the terminus of an axis known as the flower branch, the special portion bearing these parts being known as the TORUS 376 A TEXT-BOOK OF BOTANY. (sometimes spoken of as the receptacle), and that portion below the flower proper as the flower stalk (Fig. 78, PE). The carpel or carpels occupy the terminal portion of the branch, while the stamens and floral leaves occur in circles or whorls below. Pistil. — There may be only one carpel present in a flower, or there may be more. In the latter case the carpels may remain distinct or they may be united, but, whatever the number or the degree of union, it is the carpel or carpels which constitute the closed structure known as the pistil. The pistil is usually differ- entiated into three quite distinct regions: (i) A lower bulbour, portion which contains the ovules, known as the OVARY; (2) a neck-like portion known as the STYLE; and (3) at the top of the style a specialized portion which receives the pollen, known as the STIGMA (Figs. 78 and 219). When the pistil is made up of a single carpel it is said to be SIMPLE, and when composed of more than one carpel it is called COMPOUND. The carpels in the compound pistil appear to be united in different ways. Sometimes they appear to have coalesced or grown together at the margins, thus forming an ovary with but one chamber or compartment ( Fig. 223, B ) . In the other cases the carpels appear as though they were incurved or folded together at the margins along the line of union, thus forming septa or walls which divide the inner cavity into several compartments or locules (Fig. 223, A, C}. When the carpels are not united but remain separate, there are as many pistils as carpels, as in the flowers of buttercup (Fig. 223, D). Thus a unilocular ovary may belong to a simple or com- pound pistil. GYN^CIUM. — The aggregate of pistils in a flower constitutes the gynaecium. If the gynaecium is made up of a number of simple pistils, as in the flower of buttercup (Fig. 223, D}, it is said to be APOCARPOUS. But if the carpels are united into one structure, then the gynsecium is said to be SYNCARPOUS, as in the orange flower, which is in reality equivalent to a compound pistil. Inasmuch as the styles and stigmas are frequently not united, the expression compound ovary is usually employed. According as the gynae- cium consists of one, two, three, or many carpels, it is said to be monocarpellary, dicarpellary, tricarpellary, or polycarpellary. MORPHOLOGY OF HIGHER PLANTS. The pistil of the flower of the pea is simple and has an elon- gated ovary, and upon dissecting the ovary and also making a transverse section of it, it is observed that the ovules are borne upon the part which projects from the concrescent margins into the cavity, this part being known as the PLACENTA, and the united FIG. 219. Pistils and different kinds of stigmas. A, simple (monocarpellary) pistil of willow with lobed stigma; B, compound pistil of Fourcroya with head-like stigma; C, longitudinal section through flower of Spondias with five separate styles and stigmas, only three of which are shown; D, flower of Peperomia showing bristly stigma; E, recurved, thread-like stigmas of the Upas-tree (Antiaris); F, flower of a Canary grass showing the two simple plumose stigmas; G, pistillate flower of couch grass showing the two compound plumose stigmas; H, thread-like stigmas of pistillate inflorescence of EuM&na one of the grasses; J, tri-parted stigmas of the pistillate flower of the castor-oil plant; K, L, two forms of stigmas of Begonia. — After Engler. margins of the carpel forming the " inner " or VENTRAL SUTURE. In the syncarpous gynaecium the ventral suture of the carpels is directed toward the axis of the flower ; in some cases that portion of the carpel corresponding to the midrib is very prominent, as in the Papilionatse, and has received the name of " outer " or DORSAL SUTURE. There are as many locules in the ovary as fhere are carpels, A TEXT-BOOK OF BOTANY. and the walls or partitions between the locules of a syncarpous gynaecium are known as DISSEPIMENTS; when three or more carpels are united the .number of dissepiments corresponds to the number of carpels. It sometimes happens that a partition or wall is intruded from the mid-vein of the carpel, dividing a unilocular ovary into one that is bilocular, as in species of Astragalus, and such a partition is termed a FALSE DISSEPIMENT. When no other than the true dissepiments exist in the syn- carpous gynaecium the placentas are borne along the axis of the flower and are termed axial placentas. In the Caryophyllaceae the ovules are borne upon a central axis, and the dissepiments having been absorbed by the gynaecium is said to possess a free central placenta. In other cases the placentas grow backward from the central axis toward the mid-vein of the carpel, carrying the ovules with them, when they are spoken of as parietal pla- centas, as in colocynth fruit and watermelon. The STYLE not only varies in shape and size but in the manner of attachment to the ovary (Fig. 219) ; it may be very short, as in the clove; long and filiform, as in (Enothera; club-shaped (clav- ate), as in the orange; or broad and petalloid, as in Iris. It is usually situated at the summit of the ovary, when it is said to be apical or terminal; it may, however, be laterally attached, as in the strawberry, or, as in a few instances, attached to the base of the ovary. It is usually smooth, but may be hairy, as in the Com- positae. The styles, like the carpels, may be separate or united, and in the latter case may have a central canal connecting the stigma with the ovary, as in the violets. While usually deciduous, the style may be more or less persistent — forming a part of the fruit — or even become much elongated, as in the dandelion. The STIGMA is an essential part of the pistil in that it is the germinating surface for the pollen grains, it being viscid and espe- cially adapted for this purpose (Fig. 219). The stigmas may be separate, as in the Compositae, or they may be united into a more or less club-shaped or globular head, consisting of as many lobes as there are stigmas, as in the poppy. The stigma, while usually solid, may have an opening, as in the violets, which sometimes has a lid-like appendage, as in Viola tricolor. The OVULES (Fig. 219), as we have already seen, are small MORPHOLOGY OF HIGHER PLANTS. 379 bodies which are borne on the placentas, and which, after fertiliza- tion, develop into seeds. The number of ovules varies considerably — there may be but one, as in the almond, or there may be a large number, as in the watermelon. There are several principal forms of ovules (Fig. 220) recog- nized, of which the following may be mentioned: (i) ATROPOUS, in which the ovule is straight and erect on its stalk, as in the Urticacese 5(2) AN ATROPOUS, in which the ovule is bent over on to the stalk so as to be in an inverted position, the line of attachment of the ovule and stalk being known as the raphe (Fig. 230, «) ; (3) CAMPYLOTROPOUS, in which the ovule is bent upon itself, as in Stramonium, this form being less frequent than the other two. Most of the ovules of flowering plants are anatropous. FIG. 220. Three positions of ovules. A, atropous; B, anatropous; C, campylotropous. (f) funiculus or stalk ; (c) chalaza, or point of union of nucellus and integuments ; (k) nucellus or megasporangium; (em) embryo-sac or megaspore; (ai) outer integument; (ii) inner integument; (m) foramen or orifice for entrance of pollen tube, known as the micro pyle in the seed ; (r) raphe. — After Prantl. Stamen. — As already indicated, the stamen consists of a stalk-like portion called the FILAMENT, and a specialized portion which bears the sporangia, called the ANTHER (Fig. 78). The filament may be long or short or wanting. It is commonly thread- like, but varies considerably, and is sometimes leaf-like. The ANTHER is the essential part of the stamen (Fig. 221) and consists of two lobes, each of which is composed of two divi- sions or pollen sacs (Fig. 79). These sacs contain the pollen, which is commonly discharged either through a longitudinal suture or line of dehiscence, or through an opening at the tip. The anthers may be variously attached to the filament (Fig. 221). When they face the axis of the flower they are said to be INTRORSE, as in the Violaceae, and when they face the perianth they are said 38o . A TEXT-BOOK OF BOTANY. FIG. 221. Different types of stamens. Abbreviations: filament (f), pollen sacs or ;heca (sporangia) (th), connective (c). A, stamens of a water lily (Nymph&a) showing variation in the stamens (a-d) ; B, theca near middle of the stamen of Popowia; C, anther of another species of Popowia with fleshy connective and pollen sacs on either side; D, stamen of Tradescantia with transverse connective; E, F, G, stamens of several Commelinacece with broad connectives; H, stamen of Salvia with peculiar swinging connective and an aborted pollen sac or staminodium (std) at the lower end and the fertile pollen sac above; J, peculiar elongated connective of Unona; K, elongated connective of Humiri; L, androe- cium of violet showing two spurred sessile stamens; M, stamen of Columelia with sinuous confluent anthers, broad connective and short filament; N, confluent transverse pollen sacs of Arisarum; O, united pollen sacs of Columbine showing small connective; P, spherical pollen sacs of Calla, with slightly developed connective; Q, versatile anther and long, slen- der filament of dead nettle (Lamiv.ni album); R, dehiscence of anther of Solanum by means of terminal pores; S, spurred anther of Arbutus with terminal pores; various kinds of val- vular dehiscence, as in Berberis (T), Atkerosperma (U) and Persea (V). — A, after Caspary; B, H-R, U, V, after Baillon; S, T, after Sachs; D-G. after Schonland. to be EXTRORSE, as in the Magnoliaceae ; when they lie horizontally on the tip of the filament, so that they swing as on a pivot, as in the tiger lily, they are said to be VERSATILE; when they adhere MORPHOLOGY OF HIGHER PLANTS. 381 longitudinally to the sides of the filament and the dehiscence is marginal, they are said to be INNATE; when they adhere longi- tudinally to the filament and the latter extends slightly beyond them, they are said to be ADNATE, in which case they may be extrorse or introrse. In some of the Labiatse the lobes of the anther are united at the apex of the filament, but diverge from the point of attachment and are said to be connate, coherent, or CONFLUENT. The CONNECTIVE is that portion of the filament to which the lobes of the anther are attached or which connects them (Fig. 221) ; usually it is not very prominent ; but in some of the Labiatae, as in Salvia, it is rather broad ; in some of the Malvaceae it is entirely wanting, the two lobes being confluent ; in other cases it may be extended beyond the lobes of the anther, as in species of Asarum. APPENDAGES OF ANTHER. — In certain instances the anthers are appendaged (Fig. 221) : In the violets there is a triangular growth at the apex ; in the oleander the apex is plumose ; in deer berry (V actinium stamineum) there are two awn-like append- ages upon the back of the anther; in the violets the two stamens that project into the spurred petal are also spurred and secrete a nectar ; in the Asclepiadaceae the anthers possess wing-like ap- pendages, each sac or division of which contains a pear-shaped coherent mass of pollen grains (pollinium). When a flower has but one stamen it is termed MONANDROUS ; and when there are two, three, or many stamens, it is said to be diandrous, triandrous, or polyandrous (Fig. 223). The aggregate of stamens in the flower is called the ANDRCECIUM. In the Labi- atae there are four stamens arranged in a longer and shorter pair, and the stamens are said to be DIDYNAMOUS; in the Cruciferae the flowers possess six stamens, four of which are longer than the other two, and the stamens are described as TETRADYNAMOUS; in some plants, as in the Lobeliaceae, Papilionatae, etc., the fila- ments cohere, forming groups (Fig. 222) which are termed mona- delphous, diadelphous, etc. ; in the flowers of the potato the anthers lie close together but are not united, forming apparently a continuous ring or band around the pistil, when they are said to be connivent ; in the tubular flowers of the Compositae the I 382 A TEXT-BOOK OF BOTANY. anthers are united, forming a closed ring, and the stamens are spoken of as SYNGENESIOUS (Fig. 222, A) ; in many of the Cucur- bitacece the filaments and anthers both are confluent ; in the flowers of the Orchidaceae the stamens are borne upon the pistil and are said to be GYNANDROUS. Floral Envelopes. — As their name indicates, the floral en- velopes occupy the outermost or lowest position in the arrange- ment of the parts of the flower. In the bud condition they protect the essential elements, and in the expanded flower are considered to play an important role in securing pollination through the visitation of insects. The floral envelopes are made up generally of two kinds of leaves, petals and sepals (Figs. 224 to 227). FIG. 222. Union of stamens. A, united anthers of flower of Composite; B, diadelphous stamens of Pisum with i free stamen and 9 united; several types of monadelphous stamens, as in Erythroxylon (C), Melia Azcdarach (D),and common mallow (E). — After Baillon. The IZTALS form a spiral which surrounds the andrcecium. They are, as a rule, quite bright and attractive, being frequently highly colored, as in the rose, Fuchsia, violet, etc., and are known collectively as the COROLLA. The SEPALS form the next and lowermost spiral. They are usually green and leaf-like, as in the rose and carnation, and together constitute the CALYX. Sometimes the corolla and calyx are spoken of together as the PERIANTH, although, strictly speak- ing, the term has a more special application, and is used mostly in speaking of the sepals and petals of monocotyledonous flowers, MORPHOLOGY OF HIGHER PLANTS. 383 these parts being much alike and not distinguishable, save in posi- tion, as in certain lilies. FIG. 223 Types of flowers: A, hypogynous flower of flax; B, perigynous flower of cherry, showing perianth tube with sepals, petals and stamens on its border; p, epigynous flower of American sarsaparilla; D, flower of buttercup showing apocarpous gyn£ecium and large conical torus; E, irregular (bilateral or zygomorphic) flower of aconite showing half of helmet-like sepal (a), other sepals (b, c), long-clawed nectary (k) developed from one of the posterior petals, separate pistils (f); F, corolla of Salvia spread open and showing the two rudimentary stamens and two fertile stamens. The connectives in the latter are long and filamentous and each bears at the upper part a normal pollen sac and at the lower end a non-fertile enlarged portion which the insect pushes against in entering the flower and thus causes the pollen to be deposited on its back. — A-C, after Gray; D-F, after Warming. When the divisions of the calyx and corolla remain separate and distinct the latter are spoken of as CHORISEPALOUS and CHORI- PETALOUS, respectively; but when the divisions are united or 384 A TEXT-BOOK OF BOTANY. FIG. 224. Lobelia inflata: A. upper portion of shoot showing the dentate-denticulate leaves, the bracted racemes with flowers and inflated capsules, the latter developing soon after fertilization; B, flower showing linear calyx teeth and 2-lipped corolla, the upper lip with 2 rather erect lobes and the lower lip spreading and 3-cleft; C, longitudinal section of flower showing the ovary with ovules (o), style (s), hairy bifid stigma (t), united stamens (a), corolla (p) and calyx (c) ; D, longitudinal section of stamen showing the hairy summit. Scutellaria pilosa: E, branch showing crenate leaves and helmet-shaped capsular fruits; F, capsule after dehiscence showing nutlets (n). G, section of flower of Scutellaria lateri flora showing calyx (c) with crest on one side, 2-lipped corolla (p), the didynamous stamens (s), and 4-locular ovary (n). Spearmint (Mentha spicata): H. showing flowers in slender interrupted spikes; J, flower with bell-shaped calyx, tubular corolla and 2-lobed stigma; K, ellipsoidal poller grains. MORPHOLOGY OF HIGHER PLANTS. 385 coalesced the calyx and corolla are called GAMOSEPALOUS (syn- sepalous) and GAMOPETALOUS (sympetalous), respectively. When the divisions of the calyx or corolla are entirely united these elements are said to be ENTIRE, and when the divisions are FIG. 225. Flowers of Solanaceae. Solatium carolinense: A, portion of shoot showing a short raceme of flowers and the spinose leaves and stems; B, diagram of cross section of flower showing sepals (s),, petals (p), stamens (a) and ovary (c); C, longitudinal section of flower, the letters the same as in B; D, stamen showing terminal pores; E, two spheroidal pollen grains; F, cross section of 2-locular berry. Hyoscyamus muticus: G, section of flower showing calyx (c), lobed corolla (p), stamens inserted on corolla tube (s) and ovary (o) bearing at the summit a long style; H, pollen grains in different views; J, portion of stalk with fruits showing cylindrical calyx, the fruit really being enclosed within the calyx and in the nature of a pyxis. partly united they are spoken of as " toothed," " lobed," or " parted," according to the degree of union. In the flowers of the Cruciferae and Caryophyllaceae there is a conspicuous stalk to each of the separate petals, which is known as the UNGUIS or CLAW; while the upper outspreading portion is known as the LAMINA or blade. In the gamosepalous calyx and 25 386 A TEXT-BOOK OF BOTANY. the gamopetalous corolla the lower united portion is known as the TUBE, and the upper outspreading portion as the LIMB or " border." The form of the calyx and corolla is quite characteristic for a number of important families. In the Compositae there are two characteristic forms of corolla, namely, the tubular in the disk FIG. 226. Apocynum androsamifolium: A, portion of a flowering branch; B, a flower showing the short calyx tube and the corolla with more or less spreading lobes; C, longi- tudinal section of flower: c, calyx teeth; p, corolla lobes; a, anthers; and p, ovary; D, single stamen with long spurs (s). E, a flower of A. cannabinum showing the corolla with ascending lobes. flowers and the ligulate in the ray flowers; in the Papilionatae the corolla, from its fancied resemblance to a butterfly, is de- scribed as PAPILIONACEOUS (Fig. 221, #) ; in the Labiatae the petals are united into two lip-like divisions, and the corolla is said to be BILABIATE (Fig. 223, F). There are two kinds of bilabiate MORPHOLOGY OF HIGHER PLANTS. -t _ -Mn A Jt, 387 K FIG. 227. Flowers of the Compositse. Inula Helenium: A, ligulate floret; B, tubular floret; C, achene with pappus; D, pollen grains; E, united anthers showing hooked hairs (h) at the base. F, tubular floret of Safflower (Carthamus tinctorius). Dandelion (Taraxacum officinale): G, ligulate floret; H, one of the achenes showing spreading pappus on a long stalk which develops after fertilization. J, ligulate floret of Coltsfoot (Tussilago Farfara). Marigold (Calendula officinalis): K, ligulate floret; L, one of the double hairs from corolla, c, corolla; s, stamens; t, stigmas; p, pappus; h, hairs. 388 A TEXT-BOOK OF BOTANY. corollas — one, as in lavender, where the mouth of the tube is open, known as RINGENT; and another, where the mouth is closed, as in Linaria, called PERSONATE. There are a number of other special forms of calyx and corolla, particularly the latter, and of these may be mentioned the follow- ing : A corolla, like that of the harebell, which is more or less bell- shaped, is termed CAMPANULATE; a more or less campanulate corolla contracted near the opening, as in Gaultheria, is spoken of as URCEOLATE or urn-shaped ; in the morning glory and other Convolvulaceae the corolla is said to be INFUNDIBULIFORM or funnel-shaped; a corolla in which the limb spreads abruptly from the tube, as in Phlox and coffee, is termed HYPOCRATERIFORM or salver-shaped ; a corolla with a short tube and outspreading limb, as in potato, is said to be ROTATE or wheel-shaped ; a rotate corolla with the margin more or less upturned is called CRATERI- FORM or saucer-shaped ; in aconite the upper petal is hood- or hel- met-shaped, and the corolla is spoken of as GALEATE ; in the violets one of the petals has a spurred appendage and the corolla is de- scribed as SACCATE or calcarate, while the modified petal in the orchids is known as the LABELLUM. DURATION OF CALYX AND COROLLA. — There is considerable difference in the length of time that the calyx and corolla persist, not only with reference to each other but in different plants. The parts are said to be CADUCOUS when they drop from the flower as soon as it opens, as the calyx of the poppy ; when they remain for a day or so, they are said to be EPHEMERAL or fugacious, as in the petals of the poppy ; in the rose and apple the petals fall away soon after the pollen reaches the stigma and they are said to be DECIDUOUS ; in some flowers the petals wither but persist until the maturing of the fruit, as in the Droseraceae, and are known as MARCESCENT ; the calyx may remain unaffected until the maturing of the fruit, as in the Labiatae, when it is said to be PERSISTENT. Bracts. — In addition to the floral envelopes, other more or less modified leaves are borne on the flower branch below the flower, frequently at the base of the flower stalk, and these have received the name BRACTS. The bracts closely resemble the foli- age leaves, but usually are smaller and frequently are mere scales, without chlorophyll. In some cases, however., they are large and MORPHOLOGY OF HIGHER PLANTS. 389 showy, looking like petals (petaloid), as in the water arum (Fig. 263), the common dogwood; Bougainvillea and Poinsettia seen in greenhouses. The Torus constitutes the terminal portion of the flower axis or stalk, and is usually more or less conical and somewhat enlarged. When the torus is of this shape the parts of the flower are inserted upon it in serial succession, all of the other parts arising below the pistil. It may, however, be modified into a hollow or cup-like structure which grows up around the ovary, carrying the other parts of the flower (sepals, petals, and stamens) with it, thus changing the relative position of the parts, although it should be understood that the ovary occupies practically the same position in the two cases. When the torus is of the first type and the other parts of the flower are inserted below the ovary, the flower is said to be HYPO- GYNOUS, as in the orange flower (Fig. 78, A) and the ovary superior; but when the torus forms a cup-shaped receptacle and the other parts of the flower arise on its margin above the ovary, the flower is called EPIGYNOUS, as in the clove (Fig. 78, B; 223 C) and the ovary inferior. In other cases a ring of leaf-like tissue arises from the torus, forming a cup-like receptacle or tube which is known as the perianth tube, the sepals, petals, and stamens being inserted on its margin. The perianth tube may be free from the ovary, when the flower is said to be PERIGYNOUS and the ovary half inferior or half superior, as in cherry (Fig. 223, B) ; or in the case of an epigynous flower it may form a prolongation of the cup-shaped torus. Prefloration or estivation is the arrangement of the parts of the flower — more especially the calyx and corolla — in the bud. Some of the terms used in this connection are also employed in the study of vernation. The following are some of the terms which are employed: VALVATE, when the sepals or petals meet each other at the edges, as in Malvaceae; IMBRICATED, when the sepals or petals overlap each other, as in the Magnoliaceae ; PLICATE or PLAITED, when the divisions are united and folded together, as in the petals of Convolvulus and Datura. The sepals and petals do not necessarily possess the same arrangement, as in the Onagracese, where the sepals are valvate 390 A TEXT-BOOK OF BOTANY. and the petals are convolute. Furthermore, in addition to the principal types of estivation and vernation already given, there are a number of special modifications of these, depending upon the number and arrangement as well as direction of the over- lapping parts of the flower- or leaf-bud. Coalescence and Adhesion. — Not only may the divisions of the same circle or whorl of the flower be united, but even those of different circles, and a number of terms are used to describe these modifications. When the divisions of the same circle are united there is said to be a COHESION or COALESCENCE of the parts. When the divi- sions of different circles are united, as of stamens with corolla, the union is spoken of as ADHESION or adnation, as in Convolvulus. Chorisis and Multiplication of Parts. — In contrast with the reduction in number of parts of the flower due to union, there may be an increase in the number of parts due to simple division or splitting of the parts, and this is known as chorisis or deduplica- tion. An illustration of this is furnished by the stamens of the orange flower, where from a single initial stamen or primordium a group of from 3 to 1 1 stamens may be produced. In other cases there may be a multiplication in the number of parts from the beginning, each part arising independently on the torus, as in the stamens of rose. This, of course, would not be termed chorisis, as no splitting or branching takes place. Double Flowers. — In double flowers there is an increase in the number of petals, which is considered to be due to the methods of cultivation and the stimulus of an increased food- supply. This results in several ways: (i) By transformation of the sporophylls, more particularly the stamens, into petals; (2) by division or chorisis of the stamens or carpels with subsequent transformation into petals; (3) by division or branching of the petals; and (4) by the production of new series of petals. The extra petals in double carnations and double roses trace their origin to the stamens, while in Fuchsia they are the result of chorisis of the petals. In the snow-ball (Viburnum Opulus) and hydrangea the essen- tial elements have undergone a complete transformation, and the flowers, while large and showy, are sterile. In the white water lily MORPHOLOGY OF HIGHER PLANTS. 391 (Nymphcea) there is a series of parts ranging from stamens with narrow filaments and stamens with broad petaloid filaments to petals tipped with a small anther and regular petals (Fig. 221, A). In this case the stamens are considered to result from the trans- formation of the petals. In the case of green roses and green strawberry flowers the petals become green and leaf-like, and the change is spoken of as CHLOROSIS or CHLORANTHY. In some flowers even the ovules are replaced by leaf-like processes or appendages, as in Drosera and clover. Arrested Development. — The arrest or suppression of parts of the plant, particularly of the flower, is of very common occur- rence. Just as there are millions of seeds that never find suitable conditions for germination, so in the flowers of a large number of plants a very large proportion of the ovules never develop into seeds, the plants in many instances not furnishing sufficient nutriment for all of the ovules to mature. Under Leaves it was stated that in the axil of each leaf there is a bud. This is not always apparent, but if the plant be subjected to some special stimulus, some of the latent buds will become evident. For example, the rubber plant (Ficus), so commonly cultivated as an ornamental plant, shows a tendency to develop a straight, un- branched shoot, but if the tip of the shoot be cut off, the buds in the axils of the upper leaves will develop into branches, while some of those lower down will form small protuberances, but develop no further. In other cases there is a loss of parts which seems to be due to loss of function. When there is a partial loss of the element, as of the anthers in the flower of catalpa, it is said to be imperfectly developed or ABORTIVE. When the entire ele- ment remains undeveloped, as in some of the stamens of the Labi- atae, it is said to be SUPPRESSED (Fig. 223, F). In flax the stamens of the outer whorl are reduced to thread-like processes. Such sterile or aborted stamens are called STAMINODES (staminodia). In other plants the parts are not apparently arrested, but have not yet been differentiated, as is the case in the Lily family, where the perianth is composed of segments which are more or less alike (Fig. 269). In other cases, however, there seems to be a suppres- sion or arrest of the floral envelopes. Cleistogamous Flowers. — In addition to the regular flowers 392 A TEXT-BOOK OF BOTANY. some plants produce cleistogamous or closed flowers. In these flowers the corolla is usually suppressed. The flowers develop stamens and pistils but remain closed, and thus there is no chance for cross-pollination. The cleistogamous flowers appear later than the regular flowers and are more or less inconspicuous, developing under the leaves and sometimes underground. Of the plants producing cleistogamous flowers, the following may be mentioned : various species of Viola, Polygala, etc. Classes of Flowers. — As we have seen, the megasporophylls and microsporophylls in the Gymnosperms are borne on separate branches, thus giving rise to two kinds of flowers or cones. While the separation of the stamens and pistils is exemplified in a number of plants in the Angiosperms, still it is not the rule, and these two elements are usually borne close together on the same axis, — i.e., they both enter into a single flower structure. Such a flower is said to be HERMAPHRODITE or bisexual, and most of the conspicuous flowers are of this kind, as roses, buttercups, lilies, etc. Inasmuch as the stamens and pistils constitute the essen- tial elements of the flower, hermaphrodite flowers are also spoken of as PERFECT, providing the stamens and pistils are capable of exercising their generative functions. When the stamens and pistils occur in separate flowers the flowers are said to be UNI- SEXUAL or IMPERFECT, as in willow, oak, hickory, etc. A flower having only a pistil or pistils is called PISTILLATE (Fig. 219, A}, while one having only a stamen or stamens is STAMINATE, as in oaks. The staminate and pistillate flowers may be borne on the same plant, when it is said to be MONCECIOUS, as in castor bean, chestnut, hickory, alder ; or they may be borne on separate plants, when the plant is called DICECIOUS, as in willows and poplars. Plants bearing hermaphrodite and unisexual flowers on the same individual plant or on different individuals are called POLYGAMOUS, as in Ailanthus. A COMPLETE flower is one which possesses both kinds of essen- tial elements and both kinds of floral envelopes, and is SYMMET- RICAL when a plane can be laid in all directions, the parts being alike, and when the number of parts in each circle is the same or when the number in one circle is a multiple of that in the others ; as a rule, the number of stamens is some multiple of one of the MORPHOLOGY OF HIGHER PLANTS. 393 other parts, as in geranium (Fig. 223), where we find five sepals, five petals, ten stamens, and five pistils. Flowers are also spoken of as REGULAR or IRREGULAR, accord- ing to whether all the parts of a circle are uniform in shape or not; the flowers of geranium are regular, while those of violets are irregular. Regular flowers are also spoken of as ACTINO- MORPHIC or RADIAL, and irregular flowers as ZYGOMORPHIC. The latter are also spoken of as DORSIVENTRAL. Dorsiventral flowers either arise as such, as in some of the Leguminosae (Fig. 231), or they may arise as radial flowers and become dorsiventral dur- ing the course of development, as in willow herb (Fig. 224). In some flowers the floral envelopes are wanting, and the flowers are said to be NAKED, as in the willows and grasses. ANTHOTAXY. — The study of the arrangement of flowers on the stem is known as anthotaxy. The flowering axis may bear only a single terminal flower, as in Tulipa ; or the flowers may occur singly in the axils of the leaves, as in Viola canadensis. When, on the other hand, the flowers are borne upon a branch shoot, the internodes of which are more or less condensed, and the leaves smaller and of a more simple structure than the foliaceous leaves, the whole shoot is known as an INFLORESCENCE, and the leaves are called BRACTS. The flower thus represents a single unbranched shoot, while the inflorescence represents a branched or ramified shoot. The so-called bracts, besides being generally smaller than the leaves proper, are mostly sessile ; they may, however, be green, or membranaceous, or they may exhibit a bright coloration, as in Monarda. The stalk of the individual flower is called a PEDICEL, and may be naked, or bear one or two small bracts, which are called FORE-LEAVES or PROPHYLLA. In the monocotyledons there is usually only one fore-leaf, which turns its back to the mother-axis and is frequently two-nerved and two-keeled. In the dicotyledons there are generally two fore-leaves, which are placed to the right and left of the flower, as in the violets. The position of the floral leaves (the sepals, the petals and those of the perianth) depends upon the arrangement of the fore-leaves, so that in most of the monocotyledons, where there 394 A TEXT-BOOK OF BOTANY. is one mediane prophyllon, the first leaf of the perianth is placed on the front, while the two succeeding leaves of the perianth occupy a position of 120° £rom this (Fig. 254). When, on the other hand, as in the dicotyledons with pentamerous flowers, two fore-leaves are developed, the first floral leaf (sepal) is situated obliquely above the last fore-leaf, usually on the frontal part of. the flower; the second sepal is directly behind the first or diagonally opposite to it, the remaining three leaves (sepals) occurring in a spiral of two-fifths (Fig. 280). Several deviations from this type occur, as in Lobelia (Fig. 224), Polygala, etc. Two types of inflorescence are distinguished: (i) The IN- DEFINITE, in which the flowers open or develop in acropetalous or centripetal succession, and (2) the DEFINITE, in which the flowers open in basipetalous or centrifugal succession. The in* definite type of inflorescence is seldom terminated by an ex- panded flower, and two classes of this type are distinguished : (a) Those in which the flowers are pedicelled, as in the raceme (Fig. 267) and umbel (Fig. 344), and (b) in which the flowers are sessile, as in the spike (Fig. 230) and head (Fig. 228). The RACEME is a long inflorescence with pedicelled flowers, which are frequently subtended by bracts (Figs. 224, 225, and 293). The CORYMB is a modified raceme in which the pedicels of the basal flowers are much longer than those of the apical, and thus the inflorescence looks like an umbel. In the milkweed the flowers have pedicels of the same length which arise from the apex of the shoot or peduncle, and this form of inflorescence is known as an UMBEL. In the Umbelliferse a flower cluster or umbellet takes the place of the individual flowers of the umbel, and is known as a COMPOUND UMBEL (Figs. 346-348). The SPIKE is also generally a long inflorescence, the flowers being sessile (Fig. 230, illus. 3), the secondary spikes in grasses being known as SPIKELETS. The SPADIX is a form of spike, which is readily distinguished by the fleshy stem, in which the flowers are frequently deeply imbedded, and which is frequently surrounded by a large bract, the so-called SPATHE, as in Arisaema. The CATKIN is a kind of spike with small, often imperfect flowers, which falls off as a whole, as in the staminate catkins of the oak. The catkins are mostly decompound, and in some species MORPHOLOGY OF HIGHER PLANTS. 395 of Populus the single flowers are pedicelled, and hence are actually racemose rather than spicate inflorescences. In the head and the umbel the main inflorescential axis is exceedingly short and the innermost flowers are often destitute of bracts, in contrast with the external, which are frequently provided with bracts that are of quite considerable size. Sterile bracts also occur in these two types, and are called involucral leaves, as in Cornus florida, where they are white or pink. There is also a difference in sex of the outer and inner flowers. While the head occurs as typical inflorescence in the Compositae, it also exists in some of the Umbelliferse. The flowers of the Compositor are borne on a common torus, known as the disk, which is subtended by one or more circles of bracts, these constituting an INVOLUCRE. The flowers are of two, kinds, and they receive different names because of their form and, position. Those situated near the margin of the disk are known as RAY-FLOWERS, and because they possess more or less strap- shaped corollas are also known as LIGULATE FLOWERS. Those occupying the central portion of the disk are knpwn as DISK- FLOWERS, or as TUBULAR FLOWERS because of the tubular shape of the corolla. Most of the Compositae possess both ligulate and tubular flowers, as Arnica, Matricaria (Fig. 228), the common daisy, etc. But some of the members of the family have only ligulate flowers, as chicory and dandelion, and a relatively few have only tubular flowers. Two types of definite inflorescence are distinguished : ( i ) the DIBRACHIOUS (bifurcate) CYME in which the inflorescence represents a series of very regularly arranged lateral axes, one on each side of the terminal or median flower, as in the Caryo- phyllaceae; and (2) the MONOBRACHIOUS (simple) CYME, of which there are several modifications, but common to all of them is the development of only one lateral branch to each terminal flower. In the SCORPIOID cyme the lateral axes are arranged alternately to the right and left, while in the HELICOID cyme the lateral axes are all on the same side of the main axis, as in Hypericum. The so-called flower cluster is a cymose inflorescence of either the definite or indefinite type in which the flowers are almost sessile or very short pedicelled, as in Chenopodium, Juncus, etc. Somej 396 A TEXT-BOOK OF BOTANY. times the inflorescence may be decompound or complex, as in several Composite, where the heads may be arranged in cymes or racemes ; or, as in the Gramineae, where the spikelets, which FIG. 228. Matricaria: A, longitudinal section of head showing torus (a), involucre (b), ray florets (c) and disk florets (d). B, head with the florets removed, showing the long conical torus and the involucre (H). C, tubular floret showing the ovary (f) with glandular hairs (D1) and the embryo (S), which develops after fertilization; style (g) and bifid stigma (N), the surface of which is covered with hairs; n, nectaries; b, corolla tube with narrow lobes (a); stamens showing filaments (st), united anthers (A) and apex of connective (sp). D, ligulate floret showing ovary (F), and bifid stigma (N); tube of corolla (R) and the upper ligulate portion (Z). — After Meyer. are spikes, may be arranged in panicles, i.e., branched racemes ; or finally, as in Cryptotaenia (Umbelli ferae), where the umbels are arranged in cymes. MORPHOLOGY OF HIGHER PLANTS. 397 Pollination and Fertilization. — Fertilization represents the final stage in the work of the flower as a whole, and has already been defined as the union of the egg-cell and a male nucleus. Pollination may be considered to include the transferral of the pollen grains from the anther to stigma and their subsequent germination thereon, this latter process resulting in the produc- tion of the male nuclei. Pollination thus represents but one series of changes or processes which precede fertilization, for, while the pollen grain is going through the various stages in development which lead to the formation of the male nuclei, a series of com- plex changes are going on in the embryo-sac leading to the develop- ment of the egg-cell. Our special interest in pollination arises from the fact that the pollen grains are not retained in the pollen sacs and are dependent upon various agencies for transferral to the stigma. This is a matter of great biological significance, for it is claimed that many of the special characters of flowers have a direct relation to pollination. The various ways in which the anthers open for the discharge of the pollen when it is ripe have already been considered (Fig. 221), but it may be added that the manner in which this is done usually appears to have a relation to the manner in which the pollen is to be carried to the stigma. In order that pollination may be effected, the stigma must be ripe or mature, when it is said to be receptive. It then usually secretes a sticky, sugary liquid which causes the pollen grains to adhere to the stigmatic surface (Fig. 83), and which at the same time serves as a nutrient to them. Usually the pollen grains begin to germinate in a short time after reaching the stigma, which is made evident by the pro- trusion of the pollen tubes. The stigma seems also to have the power of selection, for in many cases the pollen does not germi- nate as readily on the stigma of the same flower as on that of another flower, provided it be of the same or a nearly related species. When a flower possesses both stamens and pistils, — that is, is bisexual or hermaphrodite, — and its pollen germinates upon its own stigma, the process is known as close or SELF-POLLINATION, and if fertilization follows, this is known as SELF-FERTILIZATION. 398 A TEXT-BOOK OF BOTANY. While most hermaphrodite flowers are self-pollinated, there are some that are not, and this is brought about in several ways : ( i ) As already pointed out, the pollen may germinate better on the stigma of another flower than on the stigma of the same flower. (2) The anthers and pistils of the same flower may mature at different times, and this is one of the commonest ways of preventing self-pollination. Usually in such cases the stamens mature first. The common plantain (Plantago} furnishes an example of the maturing of the stigma before the anther. The flowers of this plant are arranged in spikes (Fig. 230, illus. 3 and 4) which belong to the indefinite class, and hence the lower flowers on the spike expand first. As stated, the pistil of each flower matures first, and after it withers the stamens protrude and discharge their pollen. It is evident that the flowers can not be self-pollinated, nor is it likely that one flower will be pollinated by another of the same spike. (3) The stamens and pistils of the same flower may vary in length, as in Polygonum (Fig. 230, illus. i and 2) and Lythrum (Fig. 230, illus. 5), or stand in such other relation to each other that self-pollination will not be effected, as in some of the irregular or zygomorphic flowers, like those of Orchids. In these several cases the pollen grains either fall upon or are carried by various agents to the stigmas of other flowers, and this is known as CROSS-POLLINATION, and the fertilization which follows as CROSS-FERTILIZATION. Cross- fertilization is an advantage to the species, for usually the seeds which result from this process give rise to plants which are more vigorous and otherwise superior to those which result from self-fertilization. In some cases, in order to insure the pro- duction of fruit, hand-pollination is practised, as by the growers of vanilla and some other tropical plants of economic importance. In the case of unisexual flowers, or those in which the stamens and pistils are in separate flowers, there is, of course, no chance for self-pollination. Here, as in the case of cross-pollinated her- maphrodite flowers, pollination may be more or less close or it may be remote, as between flowers of the same cluster or inflores- cence, between flowers of different clusters or inflorescences on the same plant, or between flowers on different plants. In buckwheat (Fig. 230, illus. i and 2) and partridge berry MORPHOLOGY OF HIGHER PLANTS. . 399 (Mitchella repens) two kinds of flowers are produced, viz.: (a) one with short styles and long filaments, and another (b) with long styles and short filaments, and thus the flowers appear to be especially adapted for insect cross-pollination and are called DIMORPHIC. In still other cases one species gives rise to three kinds of flowers, depending upon the difference in the relative lengths of the styles and filaments, as in the purple loosestrife (Lythrum calcaratum), and such flowers are called TRIMORPHIC. The external agents which are instrumental in carrying pollen from one flower to another and thereby promoting cross-pollina- FIG. 229. Visitation of flowers by insects showing how they gather the pollen and assist in cross-pollination, the one on the left being Lilium Martagon visited by a hawk moth, showing that while the proboscis is removing honey from the nectary the under side of the body is becoming covered with pollen; at the right Cydonia vulgaris, the common quince, visited by a bee, whose legs are becoming covered with pollen. — After Dodel-Port. tion are the wind, water currents, insects, small animals and birds, such as humming-birds, which are, even in temperate regions, to be observed visiting the garden nasturtium. In many of the early-flowering trees, as well as pines, Indian corn, etc., the flowers are devoid of showy, attractive features, but produce large quantities of pollen which is more or less dry and powdery and carried by the wind to other flowers. Flowers which are wind-pollinated are classed as ANEMOPHILOUS, and it is estimated that about one-tenth of all the flower-producing plants belong to this class. Plants which are pollinated by the aid of water currents are 400 A TEXT-BOOK OF BOTANY. FIG. 230. Manner of cross- pollination in some hermaphrodite flowers, i, 2. Flowers of buckwheat, showing long style and short filaments in i, and short styles and long filaments in 2: a, anthers; st, stigmas; n, nectaries. 3, Spike of plantain showing maturing of stamens below and pistils above. 4, Dissected flower of plantain: b, bract; c, calyx; p, corolla tube; s, stamens; t, protruding withered style. 5, Flowers of Purple willow-herb (Lythrum Salicaria), one side of the perianth removed from each. A is long- styled, B, medium-styled, and C, short -styled. The direction of the arrows and dotted lines indicates the best methods of crossing. — i, 2, 5, adapted from Warming. MORPHOLOGY OF HIGHER PLANTS. 401 FIG. 231. A, flowering and fruiting plant of peanut (Arachis hypogaa). After fertiliza- tion the carpophore (or stalk between calyx and ovary) grows in length, sometimes 4 to 8 cm., and curves downward penetrating the soil (el), after which the fruit develops. B, longitudinal section through the papilionaceous (bilateral) flower; C. longitudinal section through the pod (peanut). — After Taubert. known as HYDROPHILOUS, and under this head are included those plants which live under the water and those that produce flowers at or near the surface of the water. Those plants which depend upon the visitation of insects for 26 402 A TEXT-BOOK. OF BOTANY. the transferral of the pollen in cross-pollination are called ENTO- MOPHILOUS (Fig. 229). They frequently possess bright, highly colored flowers, and it is considered that these serve as an attrac- tion to the insects which visit them. The insects are, however, probably more attracted by the odor and food products which they obtain, such as the nectar. The nectar is secreted by glands known as nectaries, which are variously located ; frequently they are on the torus, either between the ovary and stamens (Fig. 78) or between the stamens and petals. Sometimes the stamen is modified to a nectar-secreting spur, as in the violets. In aconite the nectary is developed from one of the posterior petals (Fig. 223, £). In seeking, the nectar the pollen of the ripe anther may fall upon or adhere to the insects and thus be carried from one flower to another (Fig. 230). HONEY is a product formed through transformation of the plant nectar by honey bees. The nectar is supposed to be acted upon by certain salivary secretions of the bee and changed into a fruit-sugar, the so-called honey, consisting of a mixture of dex- trose and levulose. The nectar of buckwheat and clover (partic- ularly white clover) is the principal source of the commercial article. The nectar of some plants is poisonous and may furnish a poisonous honey (see discussion under Ericaceae). THE INNER STRUCTURE OF THE FLOWER. The inner structure of the flower bears a close resemblance to that of the stem and leaf. The BRACTS in almost all particulars are like the foliage leaf of the same plant, and the FLOWER STALK closely resembles the foliage stem. The CALYX, while resembling the foliage leaf, usually contains calcium oxalate in greater amount, and the chlorenchyma consists wholly of rather loose chlorophyll parenchyma ; the outer or under epidermis contains the stomata, and if hairs are present, they also arise from this surface; the fibrovascular bundles are generally simple in structure, although in some cases, as in lavender, sclerenchymatous fibers are strongly developed. In the COROLLA the epidermal cells are generally more or less centrifugally developed, forming prominent papillae (Fig. 232, A, B), which give the petals a velvety or satiny appearance, as in MORPHOLOGY OF HIGHER PLANTS. 403 the rose; glandular and non-glandular hairs are also developed which are peculiar to the corollas of irregular flowers, as in La- vandula vera and Viola tricolor (Figs. 124, 149-155, 232) ; stomata are comparatively few in number. The epidermal cells FIG. 232. Inner morphology of the flower as illustrated in Viola tricolor. A, epider- mal cells from the outer surface of the spurred petal showing papillae; B, epidermal cells from the under surface of the petals, some of the cells showing centripetal thickenings, the two without thickenings indicating the epidermal mucilage-cells; C, epidermal cells from the under surface of the petals showing a zigzag outline and short centripetal thickenings; D, surface view of the mesophyll of the petals; E, corkscrew-like hair from the inner sur- face of the spurred corolla near the throat; F, a hair from the edge of an anther; G, epider- mal cells of the anthers; H, surface view of the mesophyll cells from the spurred stamen showing collenchymatous thickening; I, surface view of cells of endothecium; K, pollen grain viewed from the side; L, pollen grain examined in water; M, pollen grain observed in chloral solution. are but slightly cutinized, and in surface view are strongly undu- late and appear striate owing to the papillose development (Figs. 232 and 235). The chlorenchyma is made up of rather loose, branching parenchyma cells (Fig. 232, D), with large, intercellular spaces. The cells are free from chloroplastids, may contain 404 A TEXT-BOOK OF BOTANY. chromoplastids, or, like the epidermal cells, a colored sap; in some instances, as in the buttercups, starch grains are also found in the mesophyll. Calcium oxalate crystals are usually present, and milk vessels are sometimes found, as in the Papaveraceae. The FILAMENT and connective possess a central fibrovascular bundle, around which are arranged comparatively small paren- chyma cells and among which secretion cells are sometimes scat- tered, as in Tilia. The pollen sacs consist of but two layers of cells — an outer layer called the "exothecium," which resembles the epidermis of the corolla, and an inner layer called the " endo- thecium," the cells of which are contractile and peculiarly thick- ened, this feature being rather characteristic for certain species (Fig. 232, /). Lining the pollen sacs during their development, FIG. 233. Several forms of pollen grains: A, crocus; B, arnica, with three thin places in the wall through one of which the pollen tube may protrude; C, lavender showing six thin places in the wall. there is a layer of cells, called the " tapetal cells " ; but these are usually sooner or later absorbed. The POLLEN GRAINS vary greatly in number, as well as in size and shape. They are usually more or less ellipsoidal, but may be spherical, as in Crocus (Fig. 233, A) ; more or less three- sided, as in the Composite and in cloves ; four- or five-sided, as in Viola tricolor (Fig. 232, K, L, M}, and in some cases, as in the Pinacese, they may be winged. In addition to protoplasm and one or more nuclei, pollen grains contain considerable oil and starch. The outer or enclosing membrane (Fig. 233) consists of two parts : an inner one, known as the " intine," and consisting of cellulose, and an outer, known as the " exine," apparently con- sisting chiefly of cutin; in some cases the exine also contains an oil which is colorless, as in Salvia, or yellowish, as in lavender, and in some instances it may contain a viscid substance, causing MORPHOLOGY OF HIGHER PLANTS. 405 the pollen grains to adhere, as in CEnothera. The grains may be smooth or variously sculptured ; in most instances the exine is unevenly developed, leaving thin places through which the pollen tubes protrude in germination ; these give the appearance of FIG. 234. A, Crocus (Spanish saffron) showing two spherical pollen grains, a fragment of stigma with papillae, and fragment of an anther; B, Calendula showing 3 spinose pollen grains and fragment of corolla, the cells of which contain oil-like globules; C, Carthamus (so-called American saffron) showing 2 slightly spinose pollen grains and a fragment of the corolla with brown laticiferous vessels and numerous unicellular hairs. — After Weakley. grooves when the grains are dry, and the number of grooves is characteristic for different species; in most of the Composite they are three in number; in the Labiatae there are six, while in Crocus they are wanting (Fig. 234). The epidermal cells of the STIGMA are quite characteristic. 4o6 A TEXT-BOOK OF BOTANY. The cells of the epidermis, or so-called " stigma-epithel," may be palisade-like, forming a more or less wart-like mass, as in the viscous stigmas of the Umbelliferse, or the outer walls may be modified to rather broad papillae, as in matricaria and arnica, or they may be developed into hair-like processes, as in crocus. The pollen tubes either enter the style through an open canal, as in the violets, or they penetrate into the conducting tissues of the style, either through the papillae, as in malva, or through the middle lamella of two neighboring papillae, as in Atropa Belladonna. The important tissue of the STYLE is the conducting tissue ; in styles which are hollow it forms the lining of the canal, the cells resembling those of the stigma-epithel; in styles that are solid the conducting tissue occupies the central axis and consists of somewhat elongated cells, the walls of which are generally thick, frequently strongly refractive and possess the property of swell- ing, being furthermore separated by large intercellular spaces. Surrounding the conducting tissue are thin-walled parenchyma cells, in which the fibrovascular bundles are distributed, the num- ber of groups of the latter corresponding to the number of carpels that compose the gynaecium. There may also occur secretion cells, containing mucilage, as in malva, or oil and resin, as in matri- caria. Occasionally, the parenchyma is replaced either in part or entirely by mechanical cells, and the epidermal cells may be modified to hairs. The tissues of the OVARY are, as a rule, in a very rudimentary condition ; in fact, so rudimentary that it is difficult to distinguish the ovaries of two flowers that develop into quite different fruits. In some instances it is said that, notwithstanding the subsequent changes, each cell of the fruit is already indicated in the ovary. The ovary possesses an outer and an inner epidermis; the outer is provided with stomata and may also possess hairs; the inner may also have stomata and after fertilization may develop secre- tion hairs, as in the orange. Between the epidermal layers occur thin-walled parenchyma cells which contain leucoplastids and chloroplastids, and in which the fibrovascular bundles are dis- tributed, these being usually simple, or complex, as in the pea. The number of fibrovascular bundles is more or less dependent MORPHOLOGY OF HIGHER PLANTS. 407 FIG. 235. Inner morphology of flower of Primula officinalis: A. papillae on stigma of flower with long styles; B, papillae from stigma of flower with short styles; C, sec- tion through petals showing papillose epidermal layers and branching cells of mesophyll ; D. section through corolla tube showing glandular hairs on epidermis; E, surface view of epidermal cells of petals, those of the corolla tube being elongated and shown on the left, while those of the outspreading petals are polygonal and striated from the folds in the papillae; F, a pollen grain. — Redraw* by Haase from drawing of Hans Kramer <'n Ber. d. d. pharm. Ges., 1907, p. 352. 408 A TEXT-BOOK OF BOTANY. upon the number of carpels that make up the gynsecium; as a rule, there is a strong fibrovascular bundle which corresponds to the mid-vein of each carpel. The PLACENTA is a development from the inner epidermis. It is traversed by a fibrovascular bundle from which branches are given off to the individual ovules ; it may have a conducting tissue similar to that found in the style, and in some cases the epidermis of the stalk of the ovule may be developed to a stigma-epithel. The OVULE not only possesses a distinct form as already given, but the internal structure, by reason of the changes associated with fertilization, is more or less characteristic for certain species and genera. It has an epidermal layer, the outer walls of which are more or less cutinized, and it consists for the most part of paren- chyma cells rich in protoplasm and food-materials ; in addition the embryo-sac contains a number of nuclei. The stalk and raphe are connected with the placenta by means of a fibrovascular bundle. The NECTAR may be secreted by certain of the epidermal cells of various parts of the flower; these may resemble the ordinary epidermal cells or they may be modified to papillae, as in the spurred stamens of the violets, or to hair-like processes, as in malva. The cells which secrete nectar constitute the " nectar- apparatus," and the walls are usually thin and more or less cutin- ized. The nectar-apparatus is found more generally upon some part of the stamen, but the sepals and petals are not infrequently saccate or spurred, which adapts them for holding the nectar. V. OUTER MORPHOLOGY OF THE FRUIT. After the fertilization of the ovule or ovules, the parts of the flower that play no further part either in protecting the seed or aiding in its dispersal soon wither and are cast off ; in most flowers the petals lose their color and, together with the stamens, style, and stigma, wither and fall away shortly after fertilization. The stigma may, however, persist, as in the poppy ; the style may like- wise remain, as in Ranunculus, or even continue to grow or lengthen, as in Taraxacum; in other cases the calyx persists, as in orange and belladonna ; in still other cases the torus may be- come fleshy and form a part of the fruit, as in pimenta and apple. The fruit may consist, therefore, not only of the ripened pistil, MORPHOLOGY OF HIGHER PLANTS. 409 FIG. 236. Different types of fruits. A, silique of mustard showing the separation of the two valves leaving the seeds attached to the central axis; B, spinous capsule of Stra- monium showing septifragal dehiscence into four valves, the capsule being strictly 2- locular but apparently 4-locular owing to the formation of false dissepiments; C, s-valved capsule of Geranium in which the carpels become detached from one another and roll up- wards remaining attached to the beak-like compound style; D, capsule of Hyoscyamus showing transverse dehiscence by means of a lid (i) and the two loculi containing numerous small seeds; E, fruit of strawberry showing fleshy torus and numerous embedded akenes; F, silicula of shepherd's-purse showing seeds attached to central axis and longitudinal dehiscence of the valves which remain attached below; G, fruit of rose, so-called rose "hip," the akenes being enclosed by the hollow oval torus which shows remains of calyx at the apex; H, multiple fruit of mulberry composed of small drupes, the pulpy portion of each consisting of the fleshy perianth. — Adapted from Warming. but also of other parts of the flower and torus which persist or develop with it. 4io A TEXT-BOOK OF BOTANY. The wall of the fruit is called the PERICARP, and, like the leaf, it consists of three distinct layers, viz. : ( i ) the outer layer corre- sponding to the outer epidermis of the ovary is called the EPICARP or EXOCARP; (2) the inner layer corresponding to the inner epidermis of the ovary is called the ENDOCARP, or, from the fact that it is sometimes hard and stone-like, it is called the PUTAMEN, as in the prune; and (3) the middle layer situated between the epicarp and endocarp is called the MESOCARP ; and from the fact that it is sometimes succulent or fleshy, as in the prune, it is also called the SARCOCARP. There are a number of distinctive and descriptive names applied to fruits. Some of the more important are as follows : FIG. 237. A, transverse section of colocynth showing seeds (s) borne on parietal placentas; B, transverse section of fruit of Ricinus communis showing septicidal dehis- cence of capsule, the seeds (s) being borne on axial placentas; C, transverse section of card- amom showing loculicidal dehiscence, the seeds (s), as in B, being borne on axial placentas. An Achene is a non-fleshy, or so-called dry, unilocular and one-seeded, indehiscent fruit, in which the pericarp is more or less firm, and may or may not be united with the seed. Achenes may be inferior, as in the Composite (Fig. 227), where they develop from inferior ovaries, being frequently surmounted by the pappus or calyx; or half inferior, as in the rose (Fig. 236, G), where they develop from half inferior ovaries ; or superior, as in the buttercup (Fig. 223, £>). A Berry is a fleshy, indehiscent fruit, the seeds of which are embedded in the sarcocarp; berries are superior when they develop free from the torus, as in belladonna (Fig. 239), capsi- cum, grape, etc., and inferior when the torus forms a part of the fruit, as in banana, cranberry (Fig. 244), and gooseberry (Fig. 245). MORPHOLOGY OF HIGHER PLANTS. 411 A Capsule is a dry, dehiscent fruit, consisting of two or more united carpels. Dehiscence in capsules may occur in five different ways : In the castor-bean ( Fig. 237, B ) the carpels separate from each other along the walls or septa (dissepiments), the seeds being dischareed along the ventral suture of the separated carpels, and this mode of dehiscence is called SEPTICIDAL. In mustard (Fig. FIG. 238. Capsules of poppy (Papaver somniferum) , whole and in transverse and longitudinal sections, showing dissepiments and remains of radiate stigmas at the apex, which are porous and through which the seeds are discharged, i, French capsules; 2, German capsules. 236, A ) the dissepiments remain intact and dehiscence occurs along the margin of the capsule, and is therefore called MARGINICIDAL ; but as the partial carpels (or valves, as they are termed) separate from the walls or septa, the dehiscence is also known as SEPTI- FRAGAL. In cardamom (Fig. 237, C-) the septa as well as valves are united, and at maturity the latter separate and dehisce at points in the margin corresponding to the mid-vein of the carpel, and 412 A TEXT-BOOK OF BOTANY. this form of dehiscence is known as LOCULICTDAL. In poppy capsules (Fig. 238) there are a few openings beneath the united FIG. 239. Several forms of fruits: A, branch of Apocynum androsamifolium showing numerous flowers and a single fruit with 2 long, slender follicles. Comparative size of follicles in A. androsamifolium (B), and A. cannabinum (C). Branch of Solatium carolinense showing a number of small superior berries (D). Pyxis of Scopolia carniolica showing slightly lobed calyx and upper portion of fruit (E). Pyxis in Hyoscyamus niger showing calyx lobes extending much above the fruit (P). Berry of Atropa Belladonna cut trans- versely and showing the numerous small seeds (G). Young spinose capsule of Datura Stramonium (H). stigmas through which the seeds are expelled, and this form of dehiscence is known as POROUS. In hyoscyamus (Fig. 236, D} a MORPHOLOGY OF HIGHER PLANTS. 413 portion of the capsule comes off from the remainder like a lid, and this form of dehiscence being circular or transverse to the qst FIG. 240. The fruit of the cocoanut palm (Cocos nucifera): I, ripe cocoanut fruit eye (K); II, longitudinal-radial section of endocarp through the stone cells and edge of bundle showing transversely elongated and isodiametric stone cells (qst), longitudinally elongated stone cells (ist), thick-walled porous cells (f), pitted tracheae (g) and spiral trachea (sp); III, longitudinal section of a large (mesocarp) fiber showing stegmata (ste), silicious body (Si), bast fibers (f). tracheids with small pits (t), tracheids with large pits (f), spiral trachea (sp), reticulated tracheae (r), scalariform tracheae (sc), sieve tube (s) and cambiform cells (c and c'). — After Winton. sutures of the carpel, it is called CIRCUMCISSILE. A capsule of this kind is known as a Pyxis or Pyxidium. 414. A TEXT-BOOK OF BOTANY, VI End FIG. 241. Fruit of the huckleberry (Gaylussacia resinosa): I. fruit- seen from above; II, transverse section of fruit; III, stone; IV, transverse section of stone showing endocarp (End), testa (S), endosperm (E) and embryo (em); V, transverse section of outer portion of the pericarp showing epicarp (epi), hypoderm (hy), mesocarp (mes) and stone cells (st); VI, transverse section of endocarp and seed showing large isodiametric stone cells (End), narrow longitudinally extended fibers (If), testa (S), hyaline layer or nucellus ',N) and endosperm (E). — After Winton. MORPHOLOGY OF HIGHER PLANTS. ,Sti 415 FIG. 242. Cultivated strawberry (Pragaria chiMnsis): I, Compound fruit showing fleshy receptacle bearing the achenes in deep depressions; II, isolated achene; III, achene showing style (Sty), stigma (Sti) and connecting bundle (B); IV, achene in transverse section, pericarp (F) , testa (S) , raphe (R) , endosperm (E) and embryo (Em) ; V, receptacle in surface view showing epidermis (Ep), with hair (h), and stoma (sto); hypoderm (hy) and sphere-crystals (k); VI, achene in transverse section showing pericarp (F) consisting of epicarp (epi), mesocarp (mes), spiral vessels (sp), crystal layer (k) , outer endocarp (If) with longitudinally extended fibers and inner endocarp (qf) with transversely extended fibers; testa (S) consisting of epidermis (ep) with reticulated cells, elongated Drown cells (br), hyaline layer or nucellus (N) and endosperm (E) consisting of a single layer of aleurone grains; VII, style and stigma. — After Winton. 416 • A TEXT-BOOK OF BOTANY. V FIG. 243. Red Raspberry (Rubus Idceus): I, Compound fruit consisting of a number of drupelets crowded together on the top and sides of the receptacle; II, transverse section of a drupelet showing'epicarp (epi), hypoderm (Hy), mesocarp (Mes), outer endocarp (F), inner endocarp (F'), testa (S), raphe (R), endosperm (E), and embryo (Em); III, stone including endocarp and seed; IV, stone somewhat magnified; V, style and stigma; VI, surface section of epicarp showing straight hair (h')f sinuous hairs (h) and stoma (sto); VII, transverse section of endocarp and seed showing endocarp (End) consisting of longi- tudinally extended fibers (If), transversely extended fibers (qf), testa (S) consisting of epidermis (ep), parenchyma or nutritive layer (p), and inner epidermis (iep); hyaline layer or nucellus (N), endosperm (E) with aleurone grains (k). — After Winton. MORPHOLOGY OF HIGHER PLANTS. A Caryopsis, or Grain, is an indehiscent, non-fleshy fruit possessing a thin pericarp, which is closely adherent to the thin seed-coats, as in wheat, corn, and other Gramine?e (Figs., 255, 256). VII FIG. 244. The fruit of the cultivated cranberry (Vaccinium macrocarpon): I, berry seen from above; II, transverse section of berry; III, single seed; IV, transverse section of seed showing outer epidermis (S), inner layer of seed-coat (S'), raphe (R), endosperm (E) and embryo (Em); V, surface section of endocarp with stoma; VI, seed in transverse sec- tion showing epidermis of seed-coat (ep) with sclerenchymatized and mucilaginous layers, inner layer of seed-coat (m) and endosperm (E); VII, surface section of epidermis of seed- coat. — After Winton. A Cremocarp is a dry, indehiscent fruit which consists of two inferior achenes, known as MERICARPS; these are separated from each other by means of a stalk known as a CARPOPHORE. 27 A TEXT-BOOK OF BOTANY. FIG. 245. The fruit of the American Gooseberry (Ribes oxyacanthoides): I, whole fruit; II, transverse section of fruit with seeds; III, seeds deprived of gelatinous coat; IV, floral parts; V, surface section of epidermis from margin of calyx with hairs; VI, surface section of epidermis from throat of calyx with hair. — After Winton. This fruit is characteristic of the Umbelliferc?. (Consult Volume II for pharmacognosy of medicinal umbelliferous fruits.) A Drupe is a fleshy, indehiscent fruit with a more or less succulent and well-developed sarcocarp and an indurated endo- MORPHOLOGY OF HIGHER PLANTS. 419 carp. Drupes are superior when they are free from the torus, as in prune ; inferior when the torus forms a part of the fruit, as in pimenta. Drupes are also spoken of as " dry " when the sarco- carp is less succulent, as in Rhus glabra, or when they are col- lected unripe, as in pepper, pimenta, and cubeb. The fruits of the raspberry and blackberry consist of a collection of little drupes, the whole being known as an ET^RIO. In the blackberry the drupelets cohere with the fleshy torus, while in the raspberry the drupelets cohere with one another, forming a cap which is sepa- rable from the cone-shaped torus. If the drupelets of the rasp- berry are examined closely it will be found (Fig. 243) that each has from 4 to 7 facets on the sides formed by the pressure of the adjoining drupelets. These facets are usually slightly convex or concave. Tschierske states that the individuals cling together, first, because of the closely-fitting adjoining facets, the slightly convex surface of one fitting into a corresponding concave surface of another; and, second, because of the interlocking of the sinuous hairs. A Follicle is a dry, dehiscent fruit which consists of one or more separate carpels, the dehiscence being usually along the ventral suture (Fig. 239) ; in Delphinium the carpels are single ; in aconite from 3 to 5, and in star-anise (Illicium) from 7 to 8; in magnolia the carpels are numerous, forming a kind of succulent cone, and dehisce along the dorsal suture. A Galbalus is a berry-like fruit, formed by the coalescence of fleshy, open scales, as in juniper (Fig. 75). Hesperidium. — The fleshy, indehiscent, superior fruit of citrus, as lemon and orange, is known as a hesperidium. The pericarp is more or less coriaceous, and from the inner walls secretion hairs develop, which contain sugar and an acid cell-sap, these consti- tuting the fleshy portion in which the seeds are embedded. A Legume is an elongated, monocarpellary, usually dry, dehiscent fruit, in which dehiscence takes place along both sutures, the carpel thus dividing into two halves, or valves, as in the garden pea (Piswn) and other members of the Leguminosse (Fig. 231). In some cases legumes are jointed or articulated and indehiscent, breaking up at maturity into a number of parts which are dis- persed in much the same manner as samara-fruits, as in Meibomia, 420 A TEXT-BOOK OF BOTANY. Legumes may be not only indehiscent but fleshy, as in Cassia fistula. A Nut is an achene-like fruit, the pericarp of which is more or less indurated. Nuts are sometimes subtended (as in acorns) or enclosed (as in chestnuts) by a kind of involucre, forming what is technically known as a cupule ; and a fruit consisting of a nut and cupule is known as a GLANS. The achene-like fruit of the Labiatae is spoken of as a Nutlet. A Pepo is an inferior berry, in which the placentas have become developed into succulent layers, as in the watermelon, cucumber, and colocynth. A Pod is a general term used to designate all dry, dehiscent, apocarpous, or syncarpous fruits, as capsules, follicles, and legumes. A Pome is an indehiscent, half-inferior, fleshy, syncarpous fruit, as in the apple. The carpels constitute the core, and the fleshy part is developed from the torus. A Samara is a winged, achene-like fruit. The winged ap- pendage may be at the apex, as in white ash, or around the edge, as in elm. Two samaras may be united into one fruit, which is called a " double samara," as in maple. A Silique is a narrow, elongated, 2-valved capsule which is separated by the formation of a false dissepiment into 2 locules, as in the Cruciferae (Fig. 236, A). A Sorosis is a fleshy fruit resulting from the aggregation of the carpels of several flowers, as in mulberry (Fig. 236, H) and pineapple. A Strobile or cone is a scaly fruit, at the base of each scale of which there is either a seed, as in the Pinacecc, or an achene-like body, as in hop. A Syconium consists of a succulent hollow torus, which en- closes a number of achene-like bodies, as in the fig (Ficus). An Utricle is an inferior achene with a thin and loose pericarp, as in Chenopodium. Classification of Fruits. — More or less artificial classifications of fruits have been made. They may be grouped either according to structure or according to their manner of protection or dispersal, the following classification being based on the structure : MORPHOLOGY OF HIGHER PLANTS. 421 From a number of flowers. 'Dry. 'A. With a compound pistil. From a single flower a. Indehiscent . . . b. Dehiscent. Fleshy . Dry. . Strobile or Cone Sorosis Syconium Achene Caryopsis Cremocarp Nut Samara Utricle Berry Drupe Etsjrio Hc-peridium Pepo Pome Capsule Follicle B. With a simple pistil a. Indehiscent . . . j Fleshy . . I Drupe Follicle Legume b. Dehiscent \ Dry THE INNER STRUCTURE OF FRUITS. The inner structure of fruits is quite variable and it is difficult to treat of this in a general way. In the simplest fruits there are three distinct layers, as in the capsule of cardamom, in which there is an outer epidermis of isodiametric or polygonal cells, an inner epidermis of more or less obliterated and elongated cells, between which is a thin-walled parenchyma traversed by a number of fibrovascular bundles. In some cases the other epidermis contains numerous stomata, as in poppy capsules, or is developed into hairs and other out- growths or appendages, as in anise, arnica, sumach (Fig. 148), and raspberry (Fig. 243). The inner epidermis may also contain stomata, as in the poppy, or be developed into hairs, as in vanilla and orange, or more or less obliterated, as in achene-like fruits, or modified to sclerenchy- matous elements, as in drupes. 422 A TEXT-BOOK OF BOTANY. The middle layer, which is composed of parenchyma, may con- tain protoplasm, starch, sugars, calcium oxalate, coloring princi- ples, alkaloids and other principles, and it may also have oil-secre- tion cells, as in cubeb and pepper, or oil-secretion canals, as in orange (Fig. 121) and the fruits of the Umbelliferae, in the latter FIG. 246. Rliamnus ratliarticus. A, cross-section through wall of the pericarp. E, epi- carp; F, sarcocarp; H, endocarp; e, epidermis; o, calcium oxalate in cells of hypodermis; p parenchyma; h, secretion cells. containing a substance which is insoluble in alcohol or chlora. solutions, soluble in solutions of potassium hydroxide, and colored reddish brown or greet ish with ferric chloride solutions; c, calcium oxalate cells of endocarp; w, sclerotic cells; t, stereome cells. B, cross-section of entire fruit, showing one seed; E, F. H, g, f, w, as in A; S, seed-coat; S1, outer wall of seed-coat; End, endosperm; c, cotyledons; g, vascular bundle. C, cross-section of a seed: S1, S2, S3, different layers of the seed-coat; R, vascular bundle of raphe; t, position of vessels of mestome strand; g, mestome strand; Rf, cleft in which raphe is situated; End, endosperm; C cotyledons; Sv, cells with thick walls ;Sp, pare nchymatous cells. — After Meyer. of which they are known as vittae (see Volume II) ; milk vessels sometimes occur, as in poppy; a collenchymatous layer is some- times developed beneath the epidermis, as in capsicum ; in some cases sclerenchymatous cells may be present, as in pimenta and cubeb (Fig. 135) ; and in still other instances the entire pericarp may be made up of stone cells, as in the nuts. MORPHOLOGY OF HIGHER PLANTS. 423 VI. THE OUTER MORPHOLOGY OF THE SEED. The seed may be defined as the fertilized and developed ovule. The seeds of different fruits vary in number as well as in size FIG. 247. Transverse (I) and longitudinal (II) sections of oat grain (Avena satfva): i, 2, cells of pericarp; 3, seed-coat; 4, remains of perisperm; 5, cells containing gluten; 7, endosperm cells containing considerable proteins and some starch; 6, endosperm cells With polygonal compound starch grains; 8, fibrovascular bundle of the pericarp. — After Harz. and shape. In form they correspond to the ovules; in size they vary from about 0.600 mm., as in lobelia, belladonna, etc., to 10 or 15 centimeters in diameter, as in the cocoanut palm. Seldom are 424 A TEXT-BOOK OF BOTANY. all of the ovules of the pistil fertilized, hence the number of seeds is usually less than the number of ovules. Structure of Seed. — After the fertilization of the egg-cell certain changes take place in the embryo-sac: At one end the developing embryo is attached to the wall by a short stalk or suspensor (Fig. 82) ; the nuclei, lying in a mass of cytoplasm FIG. 248. Citrullus Colocynthis. A, seed: a, in longitudinal section, and b, surface view; S, deep clef ts or fissures ; m, micropyle; g, hilum; w, radicle; c, cotyledons. B, parenchyma which the fruit for the most part consists. D, cross-section of seed-coat showing, G, an outer layer which is more or less easily separable from the rest of the seed and the walls of which are somewhat mucilaginous; E, epidermis of palisade-like cells; Sc, sclerotic cells; PI, a layer of tabular cells with undulate walls; T, a layer of small somewhat branching cells, the walls of which are not strongly thickened and either porous or reticulate; P, several layers of parenchyma and the collapsed epidermis; Pe, perisperm; En, endosperm. E, tangential section of tabular sclerotic cells of seed-coat shown in PI in Fig. D. — After Meyer. around the wall of the embryo-sac, divide and re-divide ; the large vacuole in the center becomes filled with a watery or milky fluid, and later the nuclei, with portions of the cytoplasm, may be enclosed by a cellulose wall and become permanent cells, in which the embryo is embedded. Likewise in the nucellus, changes are also taking place ; the cells are found to be dividing, and storing starch, oil, aleurone, and other food materials, like the cells of the MORPHOLOGY OF HIGHER PLANTS. 425 embryo-sac. The cells in which these materials are stored are known as reserve cells, and in the nucellus they constitute the PERISPERM, while those formed in the embryo-sac make up the ENDOSPERM. Usually the endosperm of seeds is prominently de- veloped, while the perisperm occurs as a thin layer ; in some seeds, however, the endosperm and perisperm are both well developed. In some instances the embryo may not fill the embryo-sac, as in cocoanut, and sometimes, as in the almond, both of the reserve layers are consumed in the development of the embryo, when the seed is said to be without endosperm (Fig. 248). The perisperm and endosperm are sometimes spoken of to- gether as the albumen of the seed, but as the cells comprised in these layers contain not only protoplasmic contents and aleurone grains, but starches, oils, and other substances, the term is mis- leading. On this basis, seeds containing either endosperm or perisperm, or both, have been designated as albuminous, but on account of these layers containing larger proportions of other substances than proteins it would be better to speak of them as RESERVE LAYERS (FigS. 247, 250). While these changes in the nucellus and embryo-sac have been going on there have been equally great changes in the coats of the ovules, which develop into the seed-coats. In the seed the two coats are generally readily distinguishable. The inner, as in Ricinus, Pepo, etc., is thin, light in color, of a delicate structure, and is known as the TEGMEN ; the outer is more or less thickened, of a darker color and firmer in structure, and is known as the TESTA. In some instances the perisperm, or both perisperm and endosperm, may be reduced to a thin layer when it is considered to form a part of the seed-coat, as in mustard. In other cases the two coats are so closely united that they are not easily distin- guished, as in stramonium. The terms used in describing the kinds of ovules (atropous, anatropous, campylotropous, etc.) are retained in the description of the seeds ; and in describing the different parts of the seed some of the terms which were applied to the ovule are also retained, as chalaza and raphe-; the seed when ripe usually becomes detached from its stalk, and the resulting scar is called the HILUM ; that part of the seed corresponding to the foramen of the ovule is more or less closed and is known as the MICROPYLE; the embryo 426 A TEXT-BOOK OF BOTANY. develops in such a way that the tip of the young root always points in the direction of the micropyle. In the fully developed embryo three distinct parts may be dif- ferentiated (Fig. 161) : (i) The COTYLEDONS; (2) the part below the cotyledons, known as the HYPOCOTYL, the apical portion of which constitutes the young root or RADICLE;-^) the part above pc, FIG. 249. Forms of embryo and distribution of endosperm in various seeds and fruits. A, Ricinus seed: car, caruncle; m, micropyle; e, embryo. B, superior drupe of Piper: per, pericarp; e, endosperm; p, perisperm. C, spinach fruit and D, corn cockle seed (Agrostemma Githago): per, pericarp; t, seed-coat; h, hilum; p, perisperm; e, endosperm C, curved embryo. — A, C, D, after Harz; B, after Baillon. the cotyledons, known as the EPICOTYL, the apex of which con- sists of a more or less developed bud spoken of as the PLUMULE. The position of the embryo (Figs. 249, 250) in the seed varies somewhat : in most seeds it lies in the center, as in strophanthus and linum ; it may, however, be excentral, as in colchicum and nutmeg. The cotyledons are usually situated above the hypocotyl, but in the Cruciferse, either their edges lie against the hypocotyl, as in the mustards, when they are said to be ACCUMBENT or con- MORPHOLOGY OF HIGHER PLANTS. 427 duplicate, or they lie so that the back of one is against the hypo- cotyl, as in Lepidium, which position is known as INCUMBENT. Externally, the seed-coats vary considerably; they may be nearly smooth, as in ricinus ; finely pitted, as in the mustards ; prominently reticulate, as in staphisagria ; hairy, as in cotton, strophanthus, and apocynum (Fig. 251 ) ; or winged, as in the seeds of the catalpa. There are also a number of other appendages, these having received special names: the wart-like development at the micropyle or hilum of some seeds, as in castor-bean and violet, is known as the CARUNCLE; in the case of sanguinaria, a wing-like development extends along the raphe, and this is known as the STROPHIOLE ; in some cases the appendage may completely envelop the seed, when it is termed an ARILLUS ; when such an envelope arises at or near the micropyle of the seed, as the mace in nutmeg, it is known as a " false arillus," or ARILLODE. Seed Dispersal. — Seeds and fruits are distributed in various ways, and so are often found growing in localities far from their native habitat. In some instances seeds are adapted for distribu- tion by the wind, being winged, as in Paulownia, Catalpa, and Bignonia, or plumed and awned, as in Strophanthus Kombe, Asclepias, and Apocynum (Fig. 251). As examples of fruits hav- ing special parts which aid in their distribution may be mentioned the achene of Taraxacum which is provided with a pappus (Fig. 227), the bladder-like pericarp of Chenopodium, and the winged fruit or samara of maple. The hooked or barbed appendages on some fruits serve to attach them to animals, and thus they may be widely distributed, as in the burdock and Spanish needles (Bidens bipinnata). In still other cases fruits may be carried long distances by water currents, or even by ocean currents, as those of the Double-cocoanut palm (Lodo'icea sechellarum) , which while native of the Seychelles Islands is now found on many of the islands in the Pacific and Indian Oceans. It may also be mentioned in this connection that a number of fruits, as the garden balsam, castor-oil plant, violets (pansy, etc.), Wistaria, etc., are elastically dehiscent and discharge the seeds with considerable force. THE INNER STRUCTURE OF THE SEED. The SEED-COAT usually consists of from two to six layers of cells: (i) an outer layer or so-called epidermis, (2) a layer of 428 A TEXT-BOOK OF BOTANY. sclerenchymatous cells or stone cells, (3) a pigment layer, (4, 5) one or two rows of parenchymatous cells, (6) a row of more or less obliterated parenchyma cells. The EPIDERMAL CELLS vary considerably in different species H M D PIG. 250. A. — Longitudinal section through anatropous seed of linum: R, raphe; SC, seed-coat; M, hilum; H, micropyle; EN, endosperm; C, cotyledon; HY, hypocotyl. B. — Longitudinal section through stramonium seed: SC, seed-coat; H, micropyle; M, hilum; EN, endosperm; E, curved embryo. C. — Transverse section through endosperm of nux vomica showing thick-walled parenchyma, the cells containing oil and protoplasm. D. — Transverse section through endosperm of seed of Ricinus communis, one cell filled with aleurone grains, each with a crystalloid and globoid, and another in which the aleurone grains have been dissolved, the cytoplasm and nucleus remaining. both as regards the form of the cells and the composition of the walls (Eig. 136). The cells may be more or less isodiametric in cross-section, as in cardamom (see Vol. II) ; elliptical, as in almond (Fig. 136, D) ; palisade-like, as in Abrus precatorius, or more or MORPHOLOGY OF HIGHER PLANTS. 429 less irregular, as in Delphinium. While the outer and side walls are usually thickened, in hyoscyamus (Fig. 251), it is the inner and side walls which are thickened, the outer wall remaining thin. The outer wall may be in part modified to mucilage, as in mustard and flaxseed (Fig. 119) ; or to non-glandular hairs which consist either of cellulose, as in cotton (Fig. 139), or lignocellulose, as in nux vomica (Fig. 119). The PERISPERM and ENDOSPERM (Fig. 249) consist chiefly of parenchyma cells, which contain, besides protoplasm, starch, as FIG. 251. Seeds: A, of Hyoscyamus muticus with epidermal cells having wavy, thick- ened walls, those at the edge are seen in section and showing that the outer wall is not thickened. B, of Lobelia tnflata showing reticulate seed-coat composed of uniformly thick- ened and strongly lignified cells. C, of Apocynum cannabinum with numerous long i -celled hyaline hairs. in physostigma ; oil, as in flaxseed and cottonseed ; aleurone grains, as in ricinus (Fig. 250); glucosides, as in almond; alkaloids, as in stramonium. The walls are usually thin, but may in some instances be considerably thickened, as in coffee, colchicum, and nux vomica (Fig. 135). The embryo consists chiefly of parenchyma cells with a few fibrovascular bundles: the cotyledons may be thin and leaf-like, as in ricinus and nux vomica, or thick and fleshy, as in almond and cola, or partly developed, as in strophanthus ; the hypocotyl is usually small, but in the Umbelliferse it is as large as the cotyledons. CHAPTER IV. BOTANICAL NOMENCLATURE. LET the student consult the various manuals on Botany and even some of the larger authoritative works and he will be imme- diately impressed that there is more or less confusion concerning the names of certain plants. For instance, in looking up the botanical origin of the False Solomon's Seal, one author will give it as Smilacina racemosa, while another writer will use the name of Vagnera racemosa. Again, if the student desires to use the correct family name he will be confused both as to the correct spelling of the name as well as the name of the family itself, the Grass Family being 'given as Graminaceae or Gramineae ; the Leguminosae may be* divided into the Mimosacese, Caesalpinaceae and Papilionaceae. At first thought it might seem that this incon- sistency is peculiar to botanical science, but as a matter of facl we find the same difficulties in the language of other sciences. This confusion is due to the fact thai? up until now there has not been an international agreement or even one of a national character regarding the rules to be observed in botanical nomenclature. " For many decades it has been almost universally felt that botanical nomenclature should rest in a general way on the prin- ciple of priority of publication, or, in other words, that the name of a plant was the first one assigned to it. Nearly all botanists of note have readily assented to this general idea, but great difficulties have arisen regarding the precise limitations which should be imposed upon the principle. Thus, botanists of past generations, including such great leaders as the De Candolles, Bentham, the Hookers, Gray, von Martius, Eichler, Baillon, and others, have followed the principle of priority, yet they have made frequent exceptions based on considerations of taste and convenience as well as practicality." " With the expansion of the subject the difficulty of agreement on these exceptions has increased, and some recent writers have been disposed at times to criticise rather harshly the earlier bot- anists for making any exceptions whatever. It should be noticed, 430 BOTANICAL NOMENCLATURE. 431 however, that even the more strenuous of these reformers them- selves admit certain exceptions. They have found it necessary, for instance, to fix initial dates, and to rule out certain names as too vague in their definition or too uncouth in their form to be accepted." " Ideas as to the best mode of establishing rules or reaching a general agreement regarding the necessary exceptions to the bald principle of priority have differed widely and given rise to lively controversy. To some it has seemed best to advise an ideal system and then, without much reference to the wishes or convenience of their colleagues, to apply it in local publication. To the vast majority, however, it has been clear that the subject was a broad one, involving much mutual sacrifice before the now divergent usages at different botanical centers could be brought into har- mony. The question is also an international one, requiring the botanists of different nations to attain a common agreement. For some years there was a growing desire for an international meet- ing of representative botanists who should give the matter of nomenclature careful consideration and come, if possible, to some agreement on the fundamental rules to be followed. This feeling took definite form in the year 1900, when preliminary sessions of such a gathering were held in connection with the Paris Congress of Botanists. At this meeting a bureau was formed for the organization of an International Botanical Con- gress to be held at Vienna in June, 1905." This congress convened in Vienna and was attended by between five and six hundred bota- nists, representing the leading botanical institutions of the world. They framed international rules which should be used in the botanical nomenclature of vascular plants, and a complete list of these will be found in Rhodora, the journal of the New England Botanical Club, for March, 1907. A few of the general considerations and leading principles will be mentioned, however, in order that the student may have some understanding of the subject. According to the Vienna Congress, the prescriptions, which should govern the system of botanical nomenclature, are divided into (i) principles, (2) rules, and (3) recommendations. Among the principles that should be adhered to is that scientific 432 A TEXT-BOOK OF BOTANY. names are to be in Latin for all groups. When taken from another language, a Latin termination is given them, except in cases sanctioned by custom. If translated into a modern language, it is desirable that they should preserve as great a resemblance as possible to the original Latin names. Among the rules to be followed in designating the nature and the subordination of the several groups, the following were adopted : Every individual plant belongs to a species (species], every species to a genus (genus), every genus to a family (familia), every family to an order (ordo), every order to a class (classts), every class to a division (divisio). In a number of species varie- ties and forms are also distinguished. In some cultivated species there are unlimited modifications. The crossing of one species with another species gives rise to a hybrid. Regarding the point of nomenclature and limitation of principle of priority, it was agreed at the congress that botanical nomen- clature should begin with the Species Plantarum of Linnaeus, ed. i (1753), for all groups of vascular plants. It was further agreed to associate genera, the names of which appear in this work, with descriptions given of them by him in his Genera Plan- tarum, ed. 5 (1754). However, to avoid disadvantageous changes in the nomenclature of genera by the strict application of the rules of nomenclature, and especially of the principle of priority in starting from 1753, the rules provide a list of names which must be retained in all cases. These names are by preference those which have come into general use in the fifty years following their publication, or which have been used in monographs and important floristic works up to the year 1890. Among the recommendations, the following suggestions were made in regard to the nomenclature of divisions, classes, families, genera; and species : i. Names of divisions and subdivisions, of classes and sub- classes are taken from one of their characters. They are expressed by words of Greek or Latin origin, some similarity of form and termination being given to those that designate groups of the same nature, as Angiospermae, Gymnospermse ; Monocotyledoneae, Di- cotyledoneae ; Coniferae; Pteridophyta. Among Cryptogams old BOTANICAL NOMENCLATURE. 433 family names such as Fungi, Lichenes, Algae, may be used for names of groups above the rank of family. 2. Orders are designated preferably by the name of one of their principal families, with the ending -ales, e.g., Polygonales from Polygonaceae. Suborders are designated in a similar manner, with the ending -ineae, e.g., Malvineae from Malvaceae. But other terminations may be retained for these names, provided that they do not lead to confusion or error. 3. The names of families are designated by the name of one of their genera or ancient generic names with the ending -aceae, e.g., Rosaceae from Rosa, etc. The following names, owing to long usage, are an exception to the rule : Palmae, Graminese, Cruciferae, Leguminosae, Guttiferae, Umbelliferae, Labiatae, and Compositae. 4. The names of genera should be substantives (or adjectives used as substantives) in the singular number and written with a capital letter, which may be compared with our own family names. These names may be taken from any source whatever and may even be composed in an absolutely arbitrary manner, as Rosa, Convolvulus, Liquidambar, Impatiens, and Manihot. 5. The names of all species, even those that singly constitute a genus, are designated by the name of the genus to which they be- long, followed by a name (or epithet) termed specific, usually of the nature of an adjective (forming a combination of two names, a binomial, or binary name). The specific name should, in general, give some indication of the appearance, the characters, the origin, the history, or the properties of the species. If taken from the name of a person, it usually recalls the name of the one who discov- ered or described it, or was in some way concerned with it. Specific names begin with a small letter, except those which are taken from names of persons or those which are taken from generic names. The student should endeavor to fix in mind the general prin- ciples concerning botanical nomenclature and should devote special attention to the generic and specific names and the rules which govern their formation. In addition he should familiarize himself with the meaning of the names, as this will enable him to memorize and spell them correctly. The following is a partial list of some of the principal generic and specific names, giving as far as possible the origin of the names and their significance; 434 A TEXT-BOOK OF BOTANY. Abelmoschus. Muskmallow. From Arab. Abu-l-misk, father of musk; producing musk. Abies. Fir. The classical Latin name. Abrotanum. Southernwood. Gr. aflpdrovnv ; from aflporoc, sacred to the gods, immortal ; probably in allusion to the odor. Abrus. Indian licorice. From Gr. a/fyw>f, graceful ; in allusion to the flowers. Absinthium. Wormwood. The ancient Greek name. Abyssinicus-a-um. Pertaining to Abyssinia. Acacia. The ancient Greek name of an Egyptian species. From a**?, a point ; referring to the thorns. Acer. Maple. The classical Latin name. Acer, acris, acre. Sharp, pungent. From root ak, to be sharp. Achillea. Yarrow, Milfoil. Named for the Greek warrior Achilles, who is said to have discovered the virtues of the plant. Aconitum. Monkshood, Wolfsbane. The ancient Greek name. Acorus. Sweet flag. The ancient classical name. Actaea. Baneberry, Cohosh. Ancient Greek name of the elder. Acuminatus-a-um. Acuminate, tapering. Lat. acumino, to make pointed. Acutifolius-a-um. Having sharp-pointed leaves. Lat. acutus, sharp, -j- folium, a leaf. Adiantum. Maidenhair. The ancient name. From Gr. « priv., + &iaivut to wet, hence unwetted, incapable of being wet. Adonis. Pheasant's eye. A plant fabled to have sprung from the blood of the beautiful Adonis. Advena. Yellow pond lily. From Lat. ad-vena, strange, foreign. (Of doubtful application.) Aegle. Bengal quince. Name of a nymph in Greek mythology. Perhaps from aty/U?, brightness, splendor. yEsculus. Horsechestnut. The Latin name of an oak or some other mast- bearing tree. ^Estivalis-e. Pertaining to the summer. The classical Latin word is ccstivalis. Agaricus. Mushrooms. Gr. ayapmov, Lat. agaricum, a tree fungus. Agave. American aloe. Gr. ayavr], noble, illustrious. Appropriately applied to Agave americana, the century plant. Agrimonia. Probably a corruption from argemone. According to others, it is derived from Gr. dypdf, field, + fiovoq, alone. Agropyron. Wheat grass. From Gr. ayp6c:, field, + Trvpos, wheat ; alluding to the fact that it grows wild in wheat fields. Agrostemma. Corn cockle. From Gr. dyp(5f, field, + orffifin, a crown. Ailanthus. Tree of heaven. Said to be from aylanto, the name of the tree in the Moluccas, in allusion to its height. Ajuga. Bugle weed. From Gr. a priv., + (vyov (Lat. iugum), a yoke. From the fact that the lower lip of the corolla has a single, con- spicuous middle lobe. , BOTANICAL NOMENCLATURE. 435 Albizzia. Name derived from the Albizzi, a noble family of Italy, one of whom is said to have introduced this genus into European culti- vation. Albus-a-um. White. Alchemilla. Lady's mantle. From the Arabic name alkemelyeh; in refer- ence to the silky pubescence of some species. Aletris. Star grass, Colic-root. From Gr. afor/Wf, a female slave who grinds ; in allusion to the mealy appearance of the blossoms. Algae. Plural of alga, sea-weed ; probably a shortened form of alliga, from ad, to, + ligo, to bind. Allium. Onion, Garlic. The ancient Latin name for garlic ; perhaps con- nected with Lat. oleo, to emit a smell. Alnus. Alder. The ancient Latin name. Aloe. The ancient Greek name. Alsine. Chickweed. Greek name of a plant. Alstonia. Dita. Named for Dr. Charles Alston, botanist, of Edinburgh (1683-1760). Althaea. Marshmallow. Hollyhock. The classical name. From Gr. aWaivu, to heal, cure ; in allusion to the medicinal properties of the plant. Alyssum. Greek name of a plant believed to check hydrophobia ; from a priv., + /U'dffa, raging madness. Or a plant used to check hiccup ; from a priv., + /W>C«, to have the hiccup. Amaranthus. Amaranth. From Gr.d/idpavrog> unfading; because the bracts are dry and persistent. Amarus-a-um. Bitter. Amaryllis. Belladonna lily. Greek name of a shepherdess. Ambrosia. Ragweed. The Greek and Latin name of several plants, as well as of the food of the immortals. Ambrosioides. Gr. afiflpoaia -f- o- «<%, like, resembling ambrosia. Americanus-a-um. Belonging to America. Ammania. Named for Paul Ammann, a German botanist prior to Linnaeus. Ammoniacum. A resinous gum which exudes from a tree that grew near the temple of Jupiter Ammon. The Greek name. Amomum. Cardamom. Greek name of an Indian spice plant. Amorpha. False indigo. From Gr. apopipog, deformed, o priv., + pnpQii, form ; in allusion to the absence of four of the petals. Amygdalus. Almond. Peach. Ancient Greek name. From a/ivcau, to tear, rend ; in allusion to the furrows on the endocarp. Amylum. Starch. The Greek name. From « priv., + nv\y, a mill ; re- ferring to its fineness, which makes it unnece3sary for it to be ground. Anacardium. Cashew. From Gr. avdt similar to, + xapdia, heart. The fruit of the plant is thought to resemble the heart of a bird. Anacyclus. Pellitory. An abbreviation for ananthocydus. From Gr. a priv., -+- avttof, flower, + /cwc/lo?, circle ; in allusion to the pistillate or infertile rays. Meaning rather vague. 436 A TEXT-BOOK OF BOTANY. Anagallis. Pimpernel. The ancient Greek name. Probably from dvd, again, -f dyd\\uy to delight in. Anamirta. An Indian name synonymous with Menispermum. Ananas. Pineapple. Sp. ananas, from the native American name. Andira. Vouacapoua. From the vernacular Brazilian name. Andropogon. Beard grass. From avfo, avf>p6q^ man, + TTW>WV, beard. Anemone. Wind flower. The ancient Greek name. From dvf/wc, wind. Anethum. Dill. The ancient Greek name. Probably related to aviaov, anise. Angelica. From Gr. 077^0?, messenger, angel; in allusion to its cordial and medicinal properties. Angostura. Name of a city in Venezuela, whence angustura bark is im- ported. Angustifolius-a-um. Having narrow leaves. From Lat. angustus, narrow, 4- folium, leaf. Anisum. Anise. Gr. dv«rov, avrfiov* Annuus-a-um. Of one year's duration. Lat. annus, a year. Anogra. Evening primrose. Name formed by transposition of letters of Onagra, another name for this plant. Anthelminticus-a-um. Worm-destroying. From Gr. avr/, against, + etytvj, worm. Anthemis. The ancient Greek name of chamomile. Anthoxanthum. Sweet vernal grass. From Gr. avttos, flower, -(- f«vW6f , yellow. Aparine. Cleaverwort. The ancient Greek name of a plant. Apocynum. Dogbane. Indian Hemp. The classical name. From an6t from, + K.VUV, dog. Aquaticus-a-um. Growing in or by the water. Aquifolium. Holly-leaved barberry. Ancient Latin name for the holly tree or the scarlet holm. Arabicus-a-um. Pertaining to Arabia. Aralia. Derivation of name unknown. Araroba. From East Indian name ar(ar)oba as applied to the bark. Arctium. Burdock. From Gr. apKTOf, a bear, or apKTiov, a plant. Arctostaphylos. Bearberry. From Gr. dp/crof , a bear, -f- OTaQvsJ/, a bunch of grapes. Areca. Betel-nut. Sp. and Port, areca, from East Indian vernacular name. Argemone. Prickly poppy. The ancient Greek name for poppy. Accord- ing to others, from apyefia, a disease of the eye, for which the juice of a plant so called by the Greeks was a supposed remedy. Argithamnia. From Gr. apyvpof, silver, 4- dd/uvof, bush ; from the hoari- ness of the original species. Arissema. Indian turnip. From Gr. apif, a kind of arum, -\- alfia, blood ; from the spotted leaves of some species. Aristolochia. Birthwort. From Gr. aptaros, best, 4" /lo^et'a, child-birth ; pnce thought to ease labor, BOTANICAL NOMENCLATURE. 437 Arnica. From Gr. apvarif, sheepskin, Lat. arnacis, a coat of sheepskin; in reference to the hairy stem and leaves ; or, according to others, from Gi-. irTapfiiK6s, Lat. ptarmicus, causing to sneeze. Aromaticus-a-um. Aromatic, fragrant. Artemisia. Wormwood, ancient Greek name of an herb. From the queen Artemisia, wife of Mausolus. Artemisiaefolius-a-um. Having leaves resembling those of Artemisia. Artocarpus. Breadfruit. From Gr. d/arof, bread, + Kapir6s, fruit. Arum. Also Aron. The ancient Greek name apov. Arundinaceus-a-um. Reed-like. From Lat. arundo, a reed. Arvensis-e. Cultivated. From Lat. arva, an arable field. Asagraea. From Asa Gray, the eminent American botanist. Asarum. Hazelwort, Wild ginger. The ancient Greek name. Asclepias. Milkweed, Silkweed. Named in honor of ^sculapius, the Latin tutelary god of medicine. Asimina. North American papaw. The Northern Algonkin corruption of rassimina, in allusion to the shape of the fruit. Asparagus. From the ancient Greek name aanapayos, asparagus. Asperula. Woodruff weed. From Lat. asper, rough ; in allusion to some scabrous species. Aspidium. Shield fern. From Gr. aairiSiov, a little shield ; from the shape of the indusium. Aspidosperma. From Gr. aairift a shield, + anipp.at seed ; from the shape of the seed. Asplenium. Spleenwort. From Gr. a priv., + crn-A^v, the spleen ; because of its supposed remedial properties. Astragalus. Milk vetch. Gr. aarpayakoq, a leguminous plant. Athamanticus-a-um. Of Athamas, a mountain in Thessaly ; with reference to the habitat of the plant. Atriplex. The ancient Latin name for orach; a corruption of the Greek Atropa. Name from ' ArpoTrof, one of the Greek Fates ; from o priv., -j- T/307T//, a turn ; hence unchangeable, inflexible. Atropurpureus-a-um. From Lat. ater, dark, -\- purpureus, purple ; dark purple. Aurantium. Orange. From Lat. aurum, gold, referring to the color of the fruit. Australis-e. Southern. Lat. ouster, the South wind. Autumnalis-e. In the autumn ; referring to the time of blooming. Avena. Oats. The classical Latin name. Baccharis. Groundsel tree. The classical name of a shrub dedicated to Bacchus. Baccifer-a-um. Producing berries. Lat. bacca, a berry, + fero, to bear. Ballota. Fetid horehound. The ancient Greek name. 438 A TEXT-BOOK OF BOTANY. Balsamifer-a-um. Producing balsam. Lat. balsamum, balsam, + fero, to bear. Balsamum-ea. The classical name of the several trees yielding a balsam ; also in allusion to the balsamic oleo-resins obtained from the trees. Baptisia. False indigo. From Gr. f}airT%ut to dye. Barbarea. Winter cress. Anciently called the Herb of St. Barbara. Barosma. Buchu. From Gr. fiapvc, heavy, + barf, odor ; in reference to its strong smell. Belladonna. Ital. bella, beautiful, + donna, lady. It is said that Italian ladies used the berries as a cosmetic and to dilate the pupil of the eye, thus giving themselves a striking appearance. Benedictus-a-um. Blessed, consecrated. Past participle of Lat. benedico, to bless. Benzoin. Wild allspice, Fever bush. Named from its odor, which resem- bles that of benzoinum. Benzoinum. A resinous substance from Styrax Benzoin, a tree of Sumatra, Java. French benjoin, from Arabic luban-jawi, incense of Java. Berberis. Barberry. Name derived from berberys, the Arabic name of the fruit. Beta. Beet. The ancient Latin name. Betonica. Betony. The ancient Latin name (betonica, vc itemed) of wood betony. Betula. Birch. The ancient Latin name. Betulinus-a-um. Pertaining to birch ; alluding to the fact that the leaves resemble birch leaves. Bidens. Bur marigold. From Lat. bidens, two-toothed. Biennis-e. Of two years' duration. Lat. bis, twice, -f- annus, year. Biflorus-a-um. Bearing two flowers, biflorate. Bignonia. Named for the Abbe Jean Paul Bignon, court-librarian at Paris and friend of Tournefort. Bistorta. Adderswort. From bis, twice, -f- tortus (past participle of tor- que o), twisted. Boehmeria. False nettle. Named after G. "R. Boehmer, German botanist and professor at Wittenberg in the eighteenth century. Botrychium. Moonwort. From Gr. florpvc, a bunch of grapes ; from the appearance of the fructification. Brachycerus-a-um. Having short horns. From Gr. fipax'vs, short, + nipaq1 a horn. Brasiliensis-e. Belonging to Brazil. Brassica. Mustard. Turnip. The ancient Latin name for cabbage. Brauneria. Purple cone-flower. Named for Jacob Brauner, Germar botanist of the eighteenth century. Bryonia. Bryony. The ancient Greek name. From j3/ww, to swell, grow luxuriantly. Bursa. Capsella. Bursa is a late Latin word meaning purse. BOTANICAL NOMENCLATURE. 439 Bursa-pastoris. Shepherd's purse. Butneria. Spice bush. Buxus. Boxwood. The ancient Latin name. Gr. irifof. Cacao. Span, from Mex. kakahuatl; native name of the tree Theobroma Cacao. Cactus. The ancient Greek name of some thorny plant. Caesalpinia. Sappan. Named for Andreas Csesalpinus, Italian botanist, who died in 1603. Cajuputi. Name of Malayan origin. From kayu, tree, -J- putih, white; in reference to the appearance of the branches. Calamus. Reed, cane. The classical word. So named because its scape is reed-like. Calendula. Marigold. Lat. calender, calends, the first day of the month; so called because it flowers every month. Californicus-a-um. Pertaining to California. Calisaya. A name given to the bark of a tree of Peru by Spaniards and Indians. Calla. Water arum. Linnaeus derived calla from Gr. Kd?.AauMov, a leaf. Caltha. Marsh marigold. An ancient Latin name for the common mari- gold. Calumba. From kalumb, its native name in Mozambique. Cambogia. From Cambodia, a French protectorate in Farther India. Camelina. False flax. From Gr. ^a/^a/, dwarf, + Mvuv, flax. Campechianus-a-um. Belonging to Campeachy. Campestris-e. Growing in uncultivated fields. Camphora. Gr. Knovfjd, from Arab, kafur, camphor. Camptosorus. Walking leaf. From Gr. Kapirrds, flexible, -f- aup6^t sorus, fruit dot. Canadensis-e. Of or belonging to Canada. Cannabinus-a-um. Pertaining to cannabis. Cannabis. Hemp. The ancient Greek name. Caoutchouc. Native South American name for the milky sap of several plants. Also called India rubber. Capillaceus-a-um. Hairy, very slender, like a hair. From Lat. capillus, hair. Capillus-Veneris. Maidenhair. The Latin- for hair of Venus. Capsella. Shepherd's purse. Diminutive of capsa, a box. Capsicum. Red pepper. From Lat. capsa, a box ; alluding to the shape of the fruit. Or from Gr. (tdnrw, to bite, from its hot, pungent properties. Cardamomum. The ancient classical name for the spice cardamom. Carex. Sedge. The ancient Latin name. 440 A TEXT-BOOK OF BOTANY. Carica. Papaw. The Latin name for dried fig, from Caria, in Asia Minor. Carolinensis-e. i /- i- • f Belonging to Carolina. Carolmianus-a-um. j Carota. Carrot. The classical Latin word. Carpinus. Hornbeam. The ancient Latin name. Carum. Caraway. Gr. xdpov, Lat. careum. Probably from Caria, in Asia Minor. Carvi or Carui. Probably an assimilated Latin genitive, as in Carui semina. Caryophyllus. Cloves. From Gr. napvov, nut, -{- QV^AOV, a leaf ; referring to the appearance of the flower buds. Cascara Sagrada. Span. Cascara, bark, and sagrada, sacred ; holy bark. Cascarilla. The bark of a Peruvian tree. Diminutive of cascara. Cassia. Senna. An ancient Greek plant name Kaaia, probably from the Hebrew gctsiah, gatsa, to cut, peel off. Castanea. The chestnut tree. The ancient Latin name, from a town in Thessaly. Catalpa. Indian bean. The aboriginal name. Cataria. Catnip. From late Latin catus, a cat. Catechu. East Indian name of extract from the acacia tree, applied natively to all astringent extracts. Cathartocarpus. Cleansing, purgative. From Gr. KaffapTiKOf, cleansing, -f /cap7T(5f, fruit. Caulophyllum. Blue cohosh. From Gr. xavMt, a stem, + i>7JXov, a leaf ; a stem-leaf. Ceanothus. Red root. Gr. Keavuflof, a kind of thistle. Cedron. Cedron seed. From Gr. Ketipov, the fruit of the cedar. Celastrus. Staff tree. The ancient Greek name of an evergreen tree. Centaurea. Star thistle. Ancient Greek- name of a plant. The plant of the Centaurs. Centifolius-a-um. Having a hundred leaves or petals. From Lat. centum, hundred, + folium, a leaf. Cephaelis. Ipecacuanha. From Gr. /ce^a/tj?, head, + eitu, to collect, roll up. The flowers are collected into a capitulum. Cephalanthus. Buttonbush. From Gr. Kea.7f]} head, -f- avdot, flower. Flowers aggregated in spherical peduncled heads. Ceratonia. St. John's bread. Greek name for the carrob or locust tree. From (dpcf, a horn; alluding to the horn-shaped pods. Cerealis-e. Pertaining to grain or agriculture. From Ceres, the Latin goddess of agriculture. Cetraria. Iceland moss. From Lat. c&tra, a shield ; in reference to the shield-shaped apothecia. Chamsenerion. Willow-herb. From Gr. xa^> on tne ground, -f- vyptov, rose-laurel. Chamomilla. Earth apple. From Gr. xafial, on the earth, + pf/Zov, an apple. From the apple-like odor of the flowers. BOTANICAL NOMENCLATURE. 441 Cheican. The Chilian name of Eugenia Chekan. Chelidonium. Celandine. From Gr. xehttiuv, a swallow, the flowers appearing at the same time as the swallows. Chelone. Turtlehead. Snakehead. From Gr. ^t/Ujw?, a tortoise, the corolla being shaped like the head of a reptile. Chenopodium. Goose foot. Pigweed. The ancient Greek name. From X*lvi goose, + Tot'f, foot. Chimaphila. Pipsissewa. Bitter wintergreen. Love-in-winter. From Gr. Xtipa, winter, -f- ^Aew, to love ; in allusion to the several popular names. Chionanthus. Fringe-tree. From Gr. xi&v, snow, + ai>0oft flower ; in refer- ence to the snow-white clusters of the flowers. Chirata or Chirayita. From the Hindoo name chiraita. Chondrodendron. From Gr. ^wfpof, 'a granule + 6ev6povt a tree ; allud- ing to the warty protuberances on the bark. Chondrus. Sea moss. From Gr. x6v6pof, cartilage ; in reference to the cartilaginous fronds. Chrysanthemum. Gold-flower. The ancient Greek name. Chrysarobinum. From Gr. xPV(*6a} gold, -|- araroba, a foreign name of Goa powder. Chrysophyllum. Star apple. From Gr. XPVC^, gold, + 0MAov, leaf. Chrysosplenium. Golden saxifrage. From Gr. xpva6$t gold, + OTTM/V, the spleen. From its reputed medicinal properties. Cichorium. Gr. K/^opa, 'Succory, Chicory. Cicuta. Water hemlock. The ancient Latin name of the hemlock. Cimicifuga. Bugbane. From Lat. cimex, a bug, -f- fugo, to drive away. Cinchona. Named for the countess of Chinchon, who brought the remedy to Europe, when she returned with her husband, viceroy of Peru, in 1640. Cinereus-a-um. Ash-colored. From Lat. cinis, ashes. Cinnamomum. Cinnamon. The classical name. Circsea. Enchanter's nightshade. Named after the enchantress Circe. Cissampelos. From Gr. Kioa6fy ivy, + o^TreAof, vine. From the fact that it climbs like the ivy. Citrullus. Melon. From Lat. citrus, the citron tree. Citrus. Citron, Orange. The Latin name for the citron tree. Clava-Herculis. Club of Hercules ; from the appearance of the cone-like cork-wings. Clavatus-a-um. Club-like. From clava, a club. Claviceps. Ergot. From Lat. clava, a club, + caput, head ; alluding to the shape of the mycelium or sclerotium. Clematis. Virgin's bower. Greek name of a creeping plant with long, lithe branches. Probably clematis or periwinkle. Clinopodium. Field thyme. Calamint. From Gr. K^IVJJ, a bed, + irovf, foot. Clove. From Lat. clavus, a nail ; in allusion to the shape of the dried fruit. 442 A TEXT-BOOK OF BOTANY. Cnicus. Blessed thistle. Latin name of the safflower, from the Gr. Coca. Span, from native name of tree. Cocculus. Diminutive of coccus, a berry. Cochlearia. Scurvy grass. From Gr. KoXfadpiov, a spoon ; with reference to the shape of the leaves. Coffea. Coffee. From Turk, qahveh, Arab, qahuah, name of a beverage. Colchicum. Meadow saffron. From Gr. KoZx'f, Colchis, an ancient province in Asia Minor, where this plant flourished. Collinsonia. Horsebalm. Named in honor of Peter Collinson, English botanist of the eighteenth century. Colocynthis. From Gr. KoloKvvOq, a gourd or pumpkin. Commelina. Day-flower. Named after the Dutch botanists J. and G. Commelin, who lived in the seventeenth century. Commiphora. Myrrh. From Gr. Kop/ut, gum, -(- (j>of>6f, bearing ; in allusion to the exudation. Communis-e. Common, general. Conifer-a-um. From Lat. conus, a cone, -j- fero, to bear, cone-bearing. Conium. Poison hemlock. From *6/i6ft man. Delphinium. Larkspur. Ancient Greek name, from oaep6f dewy. The glands of the leaves exude drops of a clear glutinous fluid, which glitter like dewdrops. Dryopteris. Greek name of a fern growing on oaks. From Sovqt oak, + Trrepif, a fern. Dulcamara. Bittersweet. From Lat. dulcis, sweet, + amarus, bitter. Dulcis-e. Sweet. Dysentericus-a-um. Pertaining to dysentery, dysenteric. Gr. SvaevTepinds, afflicted with dysentery. Ebenaceae. Ebony family. From Gr. eA?ewf, Lat. ebenus, ebony. Ecballium. Squirting cucumber. From Gr. £Kt out of, + /JdWw, to throw. Elasticus-a-um. Elasticvgummy. Probably formed from GT.E/MVVU, to drive. Elaterium. Classic name for a medicine prepared from the juice of the wild cucumber. From Gr. shavvu, to drive away. Eleocharis. Spike rush. From Gr. lAof, a marsh, + x^PLf , grace ; being marsh plants. Elettaria. Cardamom. From elettari, native name of plant in Malabar. Eleuteria. From Eleuthera, one of the Bahama Islands. Epigaea. Ground laurel. Trailing arbutus. From Gr. en-/, upon, -j- yi/t earth, in reference to its trailing growth. Equisetaceae. Horsetail family. Ancient Latin name equiscetum (equi- seta), the plant horsetail. Equisetum. Horsetail. Ancient Latin name. Derived from equus, horse, -f- sata (seta), a bristle. Erectus-a-um. Upright, elevated, lofty. Ergota. Ergot. From French ergot, a spur. Ericaceae. Heath family. From Gr. epelia), heath, heather. Erigeron. Fleabane. Ancient Greek name of a groundsel, probably Senecio vulgaris. From /}pt( early, -f- ylpuv, old man, from the hoary appearance of some vernal species. Eriodictyon. From Gr. kptm>t wool, + dinTvov, a net ; in allusion to the woolly, net-veined leaves. BOTANICAL NOMENCLATURE. 445 Erysimum. Treacle mustard. The Greek name of the hedge mustard; from £/>{'«, to draw. Erythroxylon. From Gr. tpvtipos, red, + f/vW, wood; referring to the color of the trees or shrubs. Esculentus-a-um. Good to eat, edible, esculent. Eucalyptus. From Gr. evt well, + /eaAuTrrdf, covered ; from the conical covering of the buds, which falls off at anthesis. Eugenia. Clove-tree. Named in honor of Prince Eugene of Savoy. Euonymus. Spindle tree. Ancient classical name for a shrub. From Gr. evt well, -f- 6vo/ia, name. Eupatorium. Thoroughwort. Dedicated to Eupator, king of Pontus, who is said to have used one of the specie^ in medicine. Euphorbia. Spurge. Gr. tvtydpfliov, name of an African plant. Named for Euphorbus, physician to king Juba. Europaeus-a-um. Belonging to Europe. Excelsus-a-um. Lofty, high, surpassing. Exogonium. From Gr. £fw, outside, + yo\>r>$, offspring ; in allusion to the exserted stamens and pistils. Fagus. Beech. The ancient Latin name, from Gr. onyen1, to eat; in allusion to the esculent nuts. Compare n^t, a kind of oak bearing esculent acorn. Fagopyrum. Buckwheat. From Lat. fagus, beech, -f- Gr. nrpoc, wheat ; from the resemblance of the grain to the beech-nut. Farfara. Colt's-foot. Feminine form of farfarus, the ancient Latin name. Farinosus-a-um. Pertaining to meal, mealy ; Lat. farina, meal. Fastigiatus-a-um. High, pointed, tapering; with reference to the shape of the fruit. From Lat. fastigium, the top of a gable, summit. Fertilis-e. Fruitful, fertile. Ferula. Asafoetida. Latin name for the plant fennel-giant. From fcrio, to strike. Ficus. The ancient Latin name for fig. Filix-mas. Male fern. Lat. Filix, fern. Mas, male. In reference to its asexual fructification. Fistula. Reed, pipe, cane ; from the appearance of the long, slender fruit. Foeniculum. Fennel. The classical Latin name. Diminutive of fccnum, hay. Fnetidus-a-um. Fetid, stinking. From Lat. factor, an offensive smell. Fragaria. Strawberry. Lat. fraga, strawberries. From fragro, to emit fragrance. Fragrans. Fragrant, sweet-scented. Pres. partic. of fragro, to emit fra- grance. Frangula. Buckthorn. From Lat. frango, to break ; in allusion to the brittle stems. Frasera. American Ca'.umba. Named for John Fraser, an English botani- cal collector of the eighteenth century. 446 A TEXT-BOOK OF BOTANY. Fraseri. Of Fraser. Latinized genitive. Fraxinus. Ash. The classical Latin name. Perhaps from Gr. $pdoauy to hedge in. Fulvus-a-um. Yellow, tawny. Fumaria. Fumitory. From Lat. fumus, smoke. Probably from the nitrous odor of the fresh roots. Galeopsis. Hemp nettle. Gr. yaXi6^t a kind of dead nettle. Galium. Bedstraw. Cleavers. Ancient Greek name of a plant. Perhaps from yaka, milk, which is coagulated by some species. Galla. Nutgall. Ancient Latin word for oak-apple, gall-nut. Gallicus-a-um. Belonging to Gaul, now France. Garcinia. Mangosteen. Named for Laurent Garcin, French botanist of the early part of tin eighteenth century. Gardenia. Cape Jasmine. Named after the author, Alexander Garden of South Carolina (1757-1829). Gaultheria. Aromatic wintergreen. Named for Dr. Gaulthier, of Quebec, a court physician about the middle of the eighteenth century. Gaylussacia. Huckleberry. Named for the French chemist, Gay-Lussac. Gelsemium. Yellow Jasmine. From gelsomino, the Italian name of Jas- mine. Genista. Woad-waxen. Whin. From the Celtic gen, a bush. Gentiana. Gentian. The ancient classical name. From Gentius, king of Illyria, who according to Pliny discovered the medicinal property of the plant. Geranium. Cranesbill. The Greek name. From yepavot, a crane. The long fruit-bearing beak was thought to resemble the bill of the crane. Geum. Avens. Latin name of plant, found by Pliny. Gigartina. Sea moss. From Gr. yiyapTovt a grape stone. From the resem- blance of the fruit bodies (cystocarps), which appear as elevated tubercles on the frond or thallus. Githago. Corn-cockle. Provincial Eng. and Welsh Gith. Glaber-bra-brum. Smooth, hairless ; referring to the leaves. Glandulifer-a-um. Gland-bearing. Lat. glandula, gland, -(- fcro, to bear. Glandulosus-a-um. Full of glands, glandulous. Glaucium. Horned poppy. From Gr. yArcwcrfc, glaucous. From the glau- cous foliage. Globulus. Latin diminutive of globus; a little ball, globular; referring to the button-like form of the fruit. 'Glutinosus-a-um. Glutinous, viscous ; referring to the resinous leaves and stems. From Lat. gluten, glue. Glycyrrhiza. Liquorice. From Gr. y/lwct^ sweet, + p/Ca, root ; referring to the taste of the root. Gnaphalium. Cudweed. Everlasting. Ancient Greek name of a downy plant. Probably allied with Kwz0«/Uov, a lock of wool. Gossypium. Cotton. From Lat. gossypion, the cotton-tree. BOTANICAL NOMENCLATURE. 447 Gouania. Chew-stick. Gramineae. Grass family. From Lat. gramen, grass. Granatum. Pomegranate. The ancient Latin name. Gratiola. Hedge hyssop. From Lat. gratia, favor ; because of its supposed medicinal virtue. Graveolens. Strong-smelling. Lat. gravis, strong, + oleo, to emit a smell. Grindelia. Gum-plant. Tar-weed. Named for Prof. D. H. Grindel, a Russian botanist, who died in 1836. Guaiacum. Guaiac. From Span, guayaco, the native Haytian name of the plant. Guarana. Portuguese name formed from the native Brazilian name. Gummifer-a-um. Gum-producing. From Lat. gummi, gum, -\-fcro, to bear. Guttifer-a-um. Gum-exuding. From Lat. gutta, a drop, + fero, to bear. Gymnocladus. Kentucky coffee-tree. From Gr. yvftvfy, naked, + xAddof, a branch, the branches being for long periods destitute of spray. Gypsophila. From Gr. yin/wc, chalk, gypsum, -f- 0s, a flower. Heliotropium. Heliotrope. Turnsole. The ancient Greek name. From >yA«>f , the sun, + rpoirfi, a turn ; alluding to the flowering at the summer solstice. Helleborus. Hellebore. The ancient classical name. Hepatica. Liver-leaf. From Gr. jJ;ra77K(5f, belonging to the liver. The leaves were thought to resemble the liver in shape. Herbaceus-a-um. Herbaceous, grassy. From Lat. herba, grass, herbage. Hesperis. Rocket. Greek name for evening flower. From ecrirepa, even- ing; alluding to the evening fragrance. Heuchera. Alum root. Named for Prof. J. H. Heucher, who died in 1747. Hevea. Brazilian rubber tree. From vernacular name heve. 448 A TEXT-BOOK OF BOTANY. Hibiscus. Rose mallow. The ancient classical name. Hierochloe. Holy grass. From Gr. tfywf, sacred, + x^o'i, grass. Sweet- scented grasses strewn before church doors on saints' days. Hippocastanum. Horsechestnut. From Gr. ITTKOS, horse, + Kaaravov. chestnut. Hirsutus-a-um. Hirsute, rough, hairy. Hispidus-a-um. Rough, shaggy, bristly. Hordeum. Barley. The ancient Latin name. Houstonia. Bluets. Named for Dr. William Houston, an English botanist. Humulus. Hop. Name of uncertain origin. Perhaps from Lat. humus, ground, alluding to the fact that the plant creeps on the ground unless supported. Hydrangea. From Gr. t6upt water, + ayyeiov, a vessel ; from the shape of the capsule. Hydrastis. Golden seal. Orange root. From Gr. vfiupt- water, -f- ffy>(k>, to act, accomplish. Probably with reference to the active properties of the juice. Hydropiper. Smartweed. Water pepper. Gr. v6upt water, -j- piper, pepper. Hymenocallis. Spider lily. From Gr. vu.ijv, membrane, -f- /td/l/lof, beauty ; alluding to the crown. Hyoscyamus. Henbane. The ancient Greek and Latin name. From Gr. {jf? a hog, + Kva/Mft a bean ; said to be poisonous to swine. Hypericum. St. John's-wort. The ancient Greek name. Probably from vn6, under, -f- iptim)^ heather. Icthyomethia. Jamaica dogwood. From Gr. J^ftitf, a fish, + fteHt)t strong drink, intoxicant. Idaeus. From Gr. 'fdalof, pertaining to Mt. Ida, near Troy, where the raspberry once flourished. Ilex. Holly. The ancient Latin name for the holm oak or holly oak. Illicium. Star anise. A Latin word meaning an allurement; alluding to the odor and attractive appearance. Impatiens. Touch-me-not. A Latin word meaning " that cannot bear or suffer," from in, not, + patiens, enduring ; from the sudden bursting of the pods when touched. Indicus-a-um. Pertaining to India. Inflatus-a-um. Inflated, swollen, puffed up. Inula. Elecampane. The ancient Latin name. Ipecacuanha. Ipecac. Portuguese name from Brazilian ipe-kaa-guena, properly a creeping plant that causes vomiting. Ipomoea. Morning glory. From Gr. ty} Iir6q , a worm, + bfioiof, like ; allud- ing to the twining stems. Iris. Fleur-de-lis. Blue flag. From Gr. lpi$t the rainbow. Islandicus-a-um. Belonging to Iceland. Isoetes. Quillwort. Ancient name used by Pliny, probably for a house- leek or evergreen. BOTANICAL NOMENCLATURE. 449 Iva. Marsh elder. Name of unknown derivation. Ixina. From native Ixine, at Cumana, Venezuela, where Loefling discov- ered the plant in 1754. Jaborandi. Native name of a South American rutaceous shrub. Jalapa. So called from Jalapa, a town in Mexico, whence it was first obtained. Jateorrhiza. Calumba. From Gr. idretpa, healing, -f- pi^a, root ; a healing root. Jeffersonia. Twinleaf. Named in honor of Thomas Jefferson. Juglans. Walnut. Name contracted from Jovis glans, nut or acorn of Jupiter. Juncus. Rush. Bog rush. Ancient Latin name; from jungo, to join, the stems being used for bands. Juniperus. Juniper. The classical Latin name ; probably from juvenis, young, -f- Pario, to produce. Youth-producing ; in allusion to its ever- green appearance. Kalmia. Sheep laurel. Named for Peter Kalm, pupii of Linnaeus. Kamala. Hindoo name of the dusty hairs of the capsules of Mallotus Philip pin ensis, used as an orange dye for silks. Kino. East Indian name of the dried juice of Pterocarpus Marsupium. Krameria. Rhatany. Named for Drs. J. G. H. and W. H. Kramer, Ger- man botanists of the eighteenth century. Kuhnia. False boneset. Named for Dr. Adam Kuhn, of Philadelphia, who carried the living plant to Linnaeus. Kuhnistera. Prairie clover. Named from its resemblance to Kuhnia. Labiatae. Mint family. From Lat. labium, lip; referring to the irregular corolla. Lacinaria. Blazing star. From Lat. lacinia, the lappet or flap of a gar- ment ; hence fringed, from the appearance of the flower heads. Laciniatus-a-um. Slashed, having a fringed border. Lat. lacinia, fiap, lappet. Lactuca. Lettuce. The ancient Latin name ; from lac, milk ; referring to the milky juice. Lactucarium. The inspissated juice of the lettuce (lactuca). Lamium. Dead nettle. From Gr. /Uw//of, throat ; alluding to the ringent corolla. Lanceolatus-a-um. Armed with little lance or point, lanceolate. From Lat. lanceola, a small lance. Langsdorffii. Named after M. Langsdorff, Russian consul at Rio, 1829, from whom Desfontaines received his specimens. Laportea. Wood nettle. Named for Frangois L. de Laporte, Count of Castlenan, an entomologist of the nineteenth century. Lappa. Burdock. The ancient Latin word for burr. Laterifolius-a-um. Growing by the side of the leaf at its base, as a laterifolius flower. Lat. latus, side, -f- folium, leaf. 29 450 A TEXT-BOOK OF BOTANY. Lathyrus. Vetchling. Everlasting pea. Ancient name of a plant of Theophrastus. Lauraceae. Laurel family. From Lat. laurus, laurel tree. Lavandula. Lavender. From Lat. lavo, to wash; alluding to the use made of its distilled water. Lawsonia. Henna plant. Named for Dr. John Lawson, who lived in the eighteenth century. Ledum. Labrador tea. Ancient Greek name of an Oriental shrub. Leguminosae. Pulse family. From Lat. legumen, pulse. Lemnaceae. Duckweed family. From Gr. Muva, a water plant. Lens. Lentil. The ancient Latin name. Lentiscus. Classical Latin name for the mastic-tree. Lentus-a-um. Pliant, flexible. Leonurus. Motherwort. From Gr. 7iiuvt a lion, + ovpat a tail. Lepidium. Peppergrass. Classical name of a cress. Also meaning a little scale ; in allusion to the fruit. Leptandra. Culver's root. From Gr. fo7fr<5?, slender, -f- avfip, av6p6s, man ; referring to the slender stamens. Leucadendron. From Gr. Aev/c<5?, white, -f- d.ev6pov, a tree. Levisticum. Lovage. Name said to be a corruption of ligusticum. Ligusticum. Lovage. The ancient Latin name. Derived from Liguria, an Italian province where the plant abounded. Ligustrum. Privet. The ancient Latin name. Liliaceae. Lily family. From Lat. lilium (Gr. Tieipiov), a lily. Limoniura Sea lavender. The ancient Greek name ; probably from feipuv. a meadow. Limonium. Lemon. Ital. limone, from Arabic laimun. Linaceae. Flax family. From Lat. linum (Gr. Ah>ov), flax, linen, thread. Lippia. Fog-fruit. Named for Agostino Lippi, Italian naturalist. Liquidambar. Sweet gum tree. From Lat. liquidus, fluid, -(- Arabic ambar, amber; alluding to the color and fragrance of the exudation. Liriodendron. Tulip tree. From Gr. faipiov, lily, flower, -j- 6tv6povt a tree. Lithospermum. Gromwell. Puccoon. The ancient Greek name. From /U0of, stone, -j- oirtppa, seed ; alluding to the hard nutlets. Lobeliaceae. Lobelia family. From lobelia. Named after Matthias de 1'Obel, an early Flemish botanist. Loganiaceae. Logania family. Named after J. Logan, a distinguished botanist. Lonicera. Honeysuckle. Named for Ada,m Lonitzer, German botanist, who died in 1586. Loranthaceae. Mistletoe family. From Gr. hupov, a thong, + di^of, a flower. Lotus. Bird's-foot trefoil. An ancient Greek plant name. Lunaria. Moonwort. From Lat. luna, the moon; alluding to the silver septum of the fruit. BOTANICAL NOMENCLATURE. 451 Lupinus. Lupine. Sun-dial. Ancient Latin name of a plant. From lupus, a wolf ; because these plants were thought to devour the fertility of the soil. Lupulus. Diminutive of Lat. lupus, wolf; wolfish, because it chokes the shrubbery on which it climbs. Lusitanicus-a-um. Pertaining to Lusitania, the western part of Spain. Luteus-a-um. Of or belonging to the yellow- weed (luteum) ; hence golden yellow, flame-colored. Lychnis. Campion. Ancient Greek name for a plant with flame-colored flower. From At^of, a light or lamp. Lycopodiaceae. Club-moss family. From Lycopodium, club-moss. Lycopodium. Club-moss. From Gr. Ar/cof, a wolf, -f- Toi-f a foot ; in reference to the appearance of the shoots. Lycopus. Bugleweed, Water horehound. From Gr. Awcof, a wolf, -j- Trodf, a foot ; from a fancied likeness in the leaves. Lythrum. Loosestrife. From Gr. Xvffpov, blood; perhaps because of its styptic properties. Macis. Mace. From Gr. pdicep, an Indian spice. Maclura. Osage orange. Named for William Maclure, an early American geologist. Maculatus-a-um. Spotted, mottled. From Lat. macula, a spot. Magnolia. Named for Pierre Magnol, professor of botany at Montpellier, France, during the early seventeenth century. Majalis. Emasculated. From Latin majalis, a barren hog. Majorana. Marjoram. Old Eng. majoran, late Latin majoraca, classical Latin amaracus. Major-us. Larger, greater. Comparative of magnus, large. Mallotus. Kamala. From Gr.^a/JWdf woolly, fleecy ; the young branches, leaves and capsules being covered with fine hair or wool. Malvaceae. Mallow family. From Lat. malva, mallow. Mamillosus-a-um. Filled with papillae or " little breasts." From Lat. mamilla, little breast, in allusion to the stalked cystocarps. Manna. The dried exudation of Fraxinus Ornus. Gr. (idwa, a grain, from Hebrew man, gift. Marginalis-e. Marginal, belonging to the margin. From Lat. margo, margin, edge; with reference to the marginal position of the sori. Mariana. Carduus. Milk thistle, Virgin Mary's thistle, named from Maria, Latin name for Mary. Marilandicus-a-um. Pertaining to Maryland. Maritimus-a-um. Belonging to the sea. From Lat. mare, the sea. Marmelos. Bengal quince. From Portuguese marmelo, quince. Marrubium. Horehound. Latin classical name, derived from the Hebrew marrob, bitter; a bitter juice. Marsilea. Named for Aloysius Marsili, an early Italian naturalist. Marsupium. A pouch, bag. Gr. papainriov; referring to the shape of the fruit. 452 A TEXT-BOOK OF BOTANY. Mastic. Gr. jiaarixti, from fiaaa.onait to chew. Used in the East as a chewing gum. Matico. Dried leaves of Piper angusti folium. Said to have been named from a Spanish soldier, who applied the green plant to a wound and stopped the bleeding. Matricaria. Wild chamomile. From Lat, matrix, the womb ; in allusion to its supposed effect on that organ. Medicus-a-um. Medical, curative. Melaleuca. Cajaputi. From Gr. ptAaf, black, + Aewdf, white; the bark of the trunk being black, that of the branches white. Melilotus. Sweet clover. From Gr. /*£/U, honey, + Awrof, a kind of clover. Melissa. Balm. From Gr. peAtoaa, a bee ; the flowers yielding an abund- ance of honey. Menispermum. Moonseed. From Gr. p^Wf, crescent, -f- oiripfia, seed ; in reference to the crescent-shaped seeds. Mentha. Mint. The ancient Latin name. From Gr. piv0tit mint. Menyanthes. Buckbean. Probably from Gr. fj.ijvt month, -f- &v0oft a flower. Perhaps because it blooms for about a month. Mercurialis. Mercury. Ancient Latin name of a plant ; meaning belong- ing to Mercury, the messenger of the gods. Methysticum. Kava-kava. Gr. pe6vani(6ft intoxicating; from fttOv, wine. Meum. Spignel. Bearwort. The ancient Greek name .(^ot/). Mezereum. French mczercon, from Persian mdzriyun. Microcarpus-a-um. Having small fruit. From Gr. fUKp6f} small, -f- Kapir6ft fruit. Mikania. Climbing hempwood. Named for J. G. Mikan, professor in the University of Prague, who died in 1814. Milaceus-a-um. Of or pertaining to millet, Lat. milium, millet. Millefolium. Yarrow. The ancient Latin name; from mille, thousand, -f- folium, leaf. Mitchella. Partridge berry. Named for Dr. John Mitchell, a botanist of Virginia, eighteenth century. Mitella. Mitrewort. Bishop's cap. Diminutive of Lat. mitra, a cap; alluding to the form of the young pod. MolHs-e. Pliant, soft, mild. Monarda. Horse mint. Named for Nicholas Monardes, Spanish botanist and author of the sixteenth century. Monniera. Hedge hyssop. Named for Prof. L. Guillaume le Monnier, a French botanist of the eighteenth century. Monotropa. Indian pipe. From Gr. fidvof, one, + rpom/, a turn ; the summit of the stem being turned to one side. Montanus-a-um. Belonging to the mountain, mountainous. Morus. Mulberry. Ancient Latin name for the mulberry tree. Mucuna. Cowhage. From the vernacular Brazilian name. BOTANICAL NOMENCLATURE. 453 Muricatus-a-um. Rough with short, hard points. Lat. murex, a pointed rock. Myosotis. Forget-me-not. The ancient classical name. From Gr. fivg , a mouse, ovf, "wrdf, the ear. From the short and soft leaves in some species. Myrica. Wax myrtle. Bayberry. From Gr. pvpiM], ancient name of the tamarisk. Myristica. Nutmeg. From Gr. ftvpifa, to be fragrant. Myrrha. Myrrh. Ancient classical name for the balsamic juice of the Arabian myrtle. Myrtus. Myrtle tree. The ancient classical name. Napaea. Glade mallow. From Gr. vany, a woody dell. Napellus. Little turnip. Diminutive of Lat. napus, a turnip. Narcissus. The ancient Greek name. From vdpict}, numbness, because of its narcotic properties. Or, according to others, from Narcissus, a youth, who according to a myth was changed into this flower. Nardus. Spikenard. The ancient Greek name. Nectandra. Bebeeru. Pichury beans. From Gr. veKrap, nectar, -f- aw/p, man, nectar stamen. Nelumbo. Sacred bean. Lotus lily. From vernacular, Ceylon. Nepeta. Catnip. Cat mint. The ancient Latin name. Neslia. Ball mustard. Named for J. A. N. de Nesle, French botanist. Nicotiana. Tobacco. Named for Jean Nicot, a French diplomat, who was thought to have introduced tobacco into Europe (1530-1600). Nigella. Fennel flower. Diminutive of Lat. niger, black, from the color of the seeds. Niger-gra-grum. Black, dark. Nobilis-e. Famous, noted, well-born. Nux-vomica. Lat. nux, a nut, and vomo, to vomit. Nymphsea. Yellow pond lily. Ancient Greek name for the water lily, which was dedicated to the water nymphs. Nyssa. Tupelo. Pepperidge. The Latin name of a water nymph, nurse of Bacchus ; because the original species of the plant grows in water. Obtusifolius-a-um. Having leaves blunted or rounded at the end. Lat. obtusus, blunted, + folium, leaf. Occidentalis-e. Occidental. Western. Odontorhizon. Crawley-root. From Gr. 6rf?, sour. Oxycedrus. Prickly cedar. Ancient Greek name ; from 6ft>f, sharp, -f /c^pof, cedar. Cedar with pointed leaves. Paeonia. Peony. The ancient Greek name. From Haiuv, physician to the gods. Palmatus-a-um. Pertaining to a palm, like a palm. From Lat. palma,^. palm. Palustris-e. Fenny, marshy, swampy. From Lat. palus, a marsh. Panax. Ginseng. Greek name of a plant. From imf, all, + d«of , a cure ; all-healing, panacea. Paniculatus-a-um. Having panicles. From Lat. panicula, a tuft or panicle. Panicum. Panic grass. Ancient Latin name of Italian panic grass. Papaver. Poppy. The classical Latin name. Papyrifer-a-um. Producing papyrus. Lai. papyrus, + fero, to bear. Parviflorus-a-um. Having small flowers. Lat. parvus, small, -f- flos, a flower. Passiflora. Passion flower. Adaptation of the Latin flos passionis, flower of passion. From a supposed resemblance of the parts of the flower to the implements of the crucifixion. Pauciflorus-a-um. Having few flowers. Lat. paucus, few, + flos, a flower. Paullinia. Guarana. Named for C. F. Paullini, a German botanist (1643- 1712). Pedatus-a-um. Having pedates or lobes. Lat. pedo, to supply with feet. Peltatus-a-um. Peltate or shield-like. Lat. pelta, a shield. Pennatifolius-a-um. Feathered, winged. Lat. pennatus, winged, -f folium, leaf. Penthorum. Ditch stonecrop. From Gr. irtvre, five, + opof, a rule ; refer- ring to the quinary order of the flower. Pepo. Pumpkin. Melon. The ancient Latin word. Pereirae. Of Pereira. Named in honor of Jonathan Pereira, an Eng- lish pharmacologist, who visited South America (1804-1853). Perfoliatus-a-um. Perfoliate. Stem apparently passing through the leaves. Lat. per, through, + folium, leaf. BOTANICAL NOMENCLATURE. 455 Perforatus-^-um. Perforate, having holes as if pricked through. Lat. perforo, to pierce through. Persea. Avocado. Ancient name of an Egyptian tree with fruit growing on the stem. Persicaria. Lady's thumb. From Lat. persicus, a peach tree. Petroselinum. Parsley. An ancient Greek plant-name. From ntrpa, a rock, + oihtvov, parsley. Phaseolus. Kidney bean. The ancient classical name. Philadelphus. Mock orange or Syringa. Ancient Greek name of a sweet flowering shrub ; applied by Linnaeus to this genus. Phillipinensis-e. Belonging to the Philippine Islands. Phlox. Greek name of a plant with flame-colored flowers. From 0/ldf a flame. Physostigma. Calabar bean. From Gr. (j>vaat a bladder, + ariyfia, a mark, stigma. Phytolacca. Pokeweed. From Gr. fvr6vt plant, -\- Ital. lacca, lake color ; alluding to the coloring matter which the berries yield. Picea. Spruce. The classical Latin name of the pitch-pine. Picrasma. Quassia. From Gr. m/cpaer^?, bitterness. Picrotoxinum. From Gr. iriicp6ft bitter, + rot-triv, poison. Pilocarpus. Jaborandi. From Gr. jrZAof, a -hair, -f- nap^, fruit ; refer- ring to the shape of the fruit Pimenta. Allspice. From Spanish pimicnta, allspice. Derived from Latin pigmentum, spice. Pimpinella. Pimpernel. Said to be formed from Lat. bipinnula, equiva- lent to bipennis, two-winged ; referring to the bipinnate leaves. Pinus. Pine. The ancient Latin name. Probably akin to pinna, a feather. Piper. Pepper. The classical Latin name. Piperitus-a-um. Peppery, pungent. Lat. piper, pepper. Pipsissewa. Chimaphila. An American Indian name. Piscipula. From Lat. piscis, fish. Pistacia. Pistachio. The ancient classical name. Planifolius-a-um. Having flat leaves. Lat. planus, flat, plane, + folium, leaf. Plantago. Plantain. The ancient Latin name. Podophyllum. Mandrake. From Greek irovs, foot, + Qvhhov; referring to the foot-like leaves. Podostemon. Riverweed. From Gr. Tro&f, foot, + orr/yuwv, thread, stamen ; the two stamens being apparently raised on a stalk by the side of the ovary. Polemonium. Greek valerian. An ancient Greek name of a plant. From Tr^e/wf, war. Polygala. Milkwort. From Gr. noMryahov, the ancient name. much, + yd^,a, milk. 456 A TEXT-BOOK OF BOTANY. Polygamus-a-um. Having some perfect flowers and others with stamens only, or pistils only, on the same plant ; polygamous. From Gr. iro/.vf much, -f- j-a/u.su, to marry. Polygonatum. Solomon's seal. Ancient Greek name of a plant. From froAi'f, much, many, + y6wt ydvoroc, knee; having many joints. Polygonum. Knotweed. The ancient classical name. From Gr. Tro/li'f, much, many, + -y6wt knee; having many knots or joints. Polypodium. Polypody. The ancient Greek name. From TTO/J'?, much, many, -\- irovq, foot ; alluding to the branching rootstock. Polyporus. Agaric. From Gr. jro/iff, many, + w6f>nft a pore; referring to the porous texture of the plant. Populus. Poplar. Aspen. The classical Latin name. Potentilla. Cinquefoil. Five-finger. Name is a diminutive form of Lat. potens, powerful ; from the reputed medicinal powers of one of the species. Pratensis-e. Growing in meadow-land. Lat. pratum, meadow. Precatorius-a-um. Imploring, beseeching. From Lat. prccor, to pray; in allusion to the use of the seeds as beads in rosaries. Primula. Primrose. Cowslip. The name is a diminutive of Lat. primus, first ; from the flowering of the primrose in early spring. Procumbens. Lying on the ground. From Lat. procumbo, to incline for- ward. Prunifolius-a-um. Having leaves resembling those of the plum tree. From Lat. prunus, plum tree, + folium, leaf. Prunum. Plum. Classical Latin name for the fruit. Prunus. Plum, cherry. Classical Latin name for the plum tree. Pruriens. Itching. From Lat. prurio, to itch ; in reference to the hairs, which occasion an intolerable itching. Psyllium. Flea-seed. Ancient Greek name for fleawort. Psoralea. From Gr. ipupateof, scurfy; in reference to the glandular dots on the calyx and pods. Ptelea. Hop-tree. Ancient Greek name for the elm. Pteris. Brake or Bracken. Ancient Greek name for a kind of fern. From Trrepdv, a wing; alluding to the pinnate or feathery fronds. Pterocarpus. From Gr. irrepov, a wing, + Kapirof, fruit ; in allusion to the winged legumes. Puber-a-um. Downy. Pubescens. Downy, hairy, woolly. From Lat. pubesco, to become downy. Pulegioides. Like fleabane. From Lat. pulegium (Gr. ^tvUi'ov), fleabane, -f- -o-e«tyf, resembling ; in allusion to the appearance and odor. Pulicaria. Fleawort. The ancient Latin name. Pulmonaria. Lungwort. From Lat. pulmonarius, beneficial to the lungs. From its supposed curative properties. Pulsatilla. Pasque flower. From Lat. pulso, to strike, agitate ; of uncertain application. BOTANICAL NOMENCLATURE. 457 Punica. Pomegranate. From Lat. punicum, pomegranate tree. Purpureus-a-um. Purple-colored. Purshianus-a-um. Adjective formed from Purshia. Named for Fred. Pursh, a German botanist and author of Flora America: Septentrionalis. Pyrethrum. Pellitory. Feverfew. Ancient Greek name for a hot, spicy plant. Pyrus. Pear, Apple. Ancient Latin name for the pear tree. Quassia. Named for a negro, Quassy or Quash, who prescribed this remedy as a specific. Quebracho-bianco. From Sp. quebrantar, to break, -f- hacha, an axe; in allusion to the hard and tough bark. Blanco, white. Quercus. Oak. The classical Latin name. Quillaja. Soap bark. From vernacular quillai, Chili. Racemosus-a-um. Having racemes or clusters. Radicans. Rooting. From Lat. radico, to take root ; alluding to the fact that the stems send out roots. Ranunculus. Crowfoot. Buttercup. The Latin name for a little frog ; some species being aquatic. Raphanus. Radish. The classical name. From Gr. pa, quickly, + aivofiat, to appear ; alluding to the rapid germination. Repens. Creeping. From Lat. repo, to creep. Reptans. Creeping. From Lat. repto, to creep. Reseda. Mignonette. From Lat. rcsedo, to calm, heal ; from its supposed sedative properties. Reticulatus-a-um. Reticulate, net-like. Lat. retia, a net; leaf-veins form- ing a net-work. Rhamnus. Buckthorn. The ancient classical name. Rhaponticus-a-um. Rhapontic. From Lat Rha, the Volga river, -f- ponticus, pertaining to the Pontic or Black Sea. The rhubarb growing on the banks of the Rha. Rheum. Rhubarb. From Lat. Rha, the river Volga, on whose banks the plant grew. Rhododendron. Rose-bay. The ancient name. From Gr. 'p66ov) a rose, + Sivfipov, a tree. Rhus. Sumach. The ancient classical name. Ribes. Currant. Gooseberry. From Arabic ribas, a plant with an acid juice. Ricinus. Castor bean. The ancient Latin name. Robinia. Locust. Named for John and Vespasian Robin, royal gardeners of Paris, seventeenth century. Robustus-a-um. Robust, strong, oaken. Lat. robur, oak. Rosa. Rose. The ancient Latin name. Roseus-a-um. Rose-colored, rosy. Lat. rosa, a rose. Rosmarinus. Rosemary. From Lat. ros, dew, + marinus, belonging to the sea; from its maritime habitat. 45$ A TEXT-BOOK OF BOTANY. Rostratus-a-um. Beaked, curved, rostrate. Lat. rostrum, a beak. Rotundifolius-a-um. Having round leaves. Latin rotundus, round, + folium, leaf. Ruber-ra-rum. Red, ruddy. Rubus. Bramble. Blackberry. Ancient Latin name, akin to ruber, red. Rugosus-a-um. Wrinkled, creased. Lat. ruga, a wrinkle. Rumex. Dock Sorrel. The classical Latin name. Ruta. Rue. The ancient classical name. Sabadilla. Cevadilla. From Span, ccvadilla. Probably from Lat. cibus, food, though the seeds are poisonous. Sabal. Palmetto. From vernacular, Mexico or South America. Sabina. From Lat. Sabinus, of the Sabines ; a people of Italy who used the juniper as an incense. Saccharum. The classical name for sugar. Saigonicus-a-um. Of Saigon, a city and province in southern Annam. Salix. Willow. The classical Latin name. Salyia. Sage. The ancient Latin name. From salvo, to save ; because of its supposed healing qualities. Sambucus. Elder. The old Latin name, perhaps from Gr. oaftfivKt), a musi- cal instrument. Sanctus-a-um. Holy, sacred, consecrated. Sanguinaria. Bloodroot. From Lat. sanguinarius, bloody; from the color of the juice. Sanicula. Black snakeroot. Sanicle. From Lat. sano, to heal. Santalinus-a-um. Of the sandal-tree, of sandal-wood. Gr. aavratov the > sandal-tree. Santalum. Sandal-wood. The ancient Greek name for sandal-tree. Saponaria. Soapwort. From Lat. sapo, soap; the juice forming a lather with water. Sarracenia. Pitcher plant. Named for Dr. Michel Sarrasin, of Quebec. Sassafras. The Spanish name. Probably a modification of saxifrage. Sativus-a-um. Cultivated. Propagated by seed. Scammonia. Scammony. Classical name of a plant. Scandens. Climbing. Lat. scando, to climb. Scilla. Squill. The ancient Greek name for the medicinal squill. Scirpus. Rush. The ancient Latin name. Scolopendrium. Adder's tongue. The ancient Greek name. From onoA6nev6f>a, the centipede ; alluding to the sori. Scoparia. Broom-weed. From Lat scopa, a broom. Scutellaria. Skullcap. From Lat. scutella, a dish ; alluding to the calyx. Secale. Rye. Latin name for a kind of grain. From seco, to cut. Sedum. Stonecrop. Orpine. Latin name of a houseleek. From sedeo, to sit; alluding to the manner in which the plants attach themselves to walls and rocks. Semecarpus. Cashew-nut. From Gr. ar,fj.at a mark, + Kapnos, fruit. BOTANICAL NOMENCLATURE. 459 Sempervirens. Evergreen. Lat semper, always, -(- vireo, to be green. Senecio. Groundsel. Ragwort. Squaw-weed. From Lat. senex, old man ; alluding to the hoariness of some species. Senega. Seneca root. From the Seneca tribe, North American Indians, who used it as a remedy for snake bites. Senegal. Name of a country and river in W. Africa. Habitat of the plant Acacia Senegal. Senna. Senna leaves. Name derived from Arabic Sana or sena. Serenoa. Saw palmetto. Named for Prof. Sereno Watson of Harvard University (1826-1892). Serotinus-a-um. Late, backward ; relating to the flowers and fruit. Serpentaria. Snakeroot. The ancient Latin name. From serpens, a serpent. Serrulatus-a-um. Serrulate, notched. From Lat. serrula, a saw. Sesamum. Sesame. The classical name of the sesame. Siliqua. The classical Latin name for a pod. Silphium. Rosin weed. Ancient Greek name of some resinous plant. Simaba. Cedron. From vernacular name, Guiana. Sinapis. Mustard. The ancient Greek name was oivcnri. The Latin had both forms, sinapis and sinapi. Sinensis-e. More commonly Chinensis. Pertaining to China. Sisymbrium. Hedge mustard. The ancient Greek name of a sweet-scented plant. Smilax. Green brier, cat brier. An ancient Greek name for the yew, and for several plants. Socotrinus-a-um. Of Socotra, an island east of Africa. Solanum. Nightshade. The ancient Latin name. Solidago. Goldenrod. From Lat. solido, to make whole, to heal; in refer- ence to its supposed healing properties. Somnifer-a-um. Sleep-producing. From Lat. somnus, sleep, + f^ro, to bear, bring. Sorbilis-e. Sorbile, fit to be drunk or sipped. Lat. sorbeo, to suck. Sorbus. Mountain ash. The ancient Latin name. Sorghum. Derivation uncertain. Probably of Chinese or East Indian origin. Spicatus-a-um. Supplied with spikes, spicate. Spigelia. Pink root. Worm-grass. Named for Adrian von der Spiegel, Flemish botanist of the seventeenth century. Spiraea. Hardhack. Meadow-sweet. The ancient Greek name. From aTTflpa, a coil or twist ; from the twisting of the pods in some species. Squarrosus-a-um. Scabby, scurfy, ragged. Staphisagria. Stavesacre. From Gr. oTaqis, raisin, + aypios, wild ; the fruit clusters resemble wild grapes. Stillingia. Named for Dr. B. Stillingfleet, English botanist of the eighteenth century. 460 A TEXT-BOOK OF BOTANY. Stramonium. Stinkweed. From French stramoine. Striatus-a-um. Marked with lines or ridges, striate ; Lat. strio, to groove, mark. Strophanthus. From Gr. •jarp^t a turn, twist, + avftaf, a flower; from the twisted and tailed lobes of the corolla. Strychnos. The ancient Greek name of a poisonous plant. Styraciflua. A tree producing storax. From Lat. styrax, storax, -(- fluo, to flow. Styrax. Storax. The ancient Greek name of the storax tree. Succirubra. From Lat. succus, juice, -(- ruber, red; — the sap becomes red on exposure. Swertia. Chiretta. Named for Emanuel Sweert, herbalist of the seven- teenth century. Sylvaticus-a-um. ) _ . . \. Pertaining to the woods. Lat. silva, a wood, forest. Sylvesins-e. ) Symphoricarpos. Snowberry. From Gr. av(i^Hptut to bring together, -j- Ka[>TTo<;t fruit ; from the clustered berries. Symphytum. Comfrey. The ancient Greek name. From ffiy/prw, to cause to grow together ; because of its reputed healing virtues. Syringa. Lilac. From Gr. avpiyt;, a pipe ; in reference to the tubular corolla, or to the use of the wood for pipe-stems. Tabacum. Tobacco. Span, tabaco, from the Indian word denoting the tube or pipe used in smoking the plant. Tamarindus. Indian date. From Arabic tamarhindi, tamar, a dried date, -f- Hind, India. Tanacetum. Tansy. From the French name, tanaisie, derived from Gr. aWdwzrof, immortal. Taraxacum. Dandelion. From rapaaau, to stir up, disorder ; in allusion to its medicinal properties. Terebinthina. Turpentine. From Gr. ript^ivOo^^ the turpentine tree. Teucrium. Germander. Named for Teucer, king of Troy. Thalictroides. Resembling thalictrum. From Gr. Hal.tKTpov, -f- o-etdwt like. Thalictrum. Meadow rue. Ancient Greek name of a plant. Thea. Tea. French The, from Chinese tsha. Theobroma. Cacao. From Gr. tffof, a god, -f- ftpa/ia, food. Thuja. Arbor Vita?, Cedar. Ancient Greek name for an African tree with sweet-smelling wood. Thymus. Thyme. Ancient Greek name. From ffvo, to sacrifice ; alluding to the sweet odor. Tiarella. False mitrewort. Coolwort. Diminutive of Lat. tiara, cap; from some fancied resemblance of the capsules. Tilia. Linden. Basswood. The classical Latin name. Tinctorius-a-um. Pertaining to dyeing, containing coloring matter. Lat. tinge, to dye, color. BOTANICAL NOMENCLATURE. 461 Tinctorum. Of the dyers. Genitive plural of tinctor, a dyer. Toluifera. Balsam tree. Said to be formed from Tolu ( Santiago de Tolu, in New Granada), whence balsam was first brought, -f- fero, to bear. Tomentosus-a-um. Tomentose. Woolly. Lat. tomentum, stuffing. Toxicodendron. From Gr. TO^LKOV^ poison, -)- 6i vdpov, tree ; poisonous shrubs. Tradescantia. Spiderwort. Named for John Tradescant, gardener to Charles I. Tragacantha. Tragacanth. The ancient Greek name for the Astragalus. From Tfuiyof, a goat, + uKavHa, a thorn ; in allusion to the character of the gummy exudation. Tragopogon. Salsify. Goat's beard. Ancient Greek name of a plant. From rpdyof, a goat, + irayuv, beard ; alluding to the pappus. Triandrus-a-um. Having three stamens. Gr. r/jtic, three, -f- &VVP, man. Tricolor. Having three colors, tricolored. Lat. trcs, three, -f- color, color. Tricuspidatus-a-um. Ending in three points. Lat. tricuspis, three-pointed. Trifolium. Clover. Trefoil. The ancient Latin name. Three-leafed. Trilisa. Vanilla-leaf. Deer's tongue. Name an anagram of Liatris. Trillium. Wake robin. Birthroot. From Lat. ires, three ; all the parts being in threes. Triphyllus-a-um. Having three leaves. Gr. rpelq, three, QvHov, leaf. Triticum. Wheat. The ancient Latin name. From tritus, past participle of tero, threshed or ground. Trivialis-e. Common, trivial. Lat. tres, three, + via, road ; three roads, growing along many roads. Tsuga. Hemlock. The Japanese name of one of the species. Tuberosus-a-um. Tuberous. Lat. tuber, lump, tumor. Turpethum. Turpeth. From Persian tirbid, a cathartic ; lurbad, a purga- tive root. Tussilago. Coltsfoot. The ancient Latin name. From tussis, a cough, for which the plant is a reputed remedy. Ulmaria. Queen of the meadow. From ulmus, elm ; hence elm-like. Ulmus. Elm. The classical Latin name. Umbellatus-a-um. Umbellated, like an umbel. Lat. umbel la, little shade, umbel. Umbellularia. Bay-laurel. From umbellula, little umbel, a late Latin diminutive of umbella. Uniflorus-a-um. Bearing one flower only. Lat. unus, one, -(- flos, flower. Urginea. Squill. Sea onion. From Lat. urgeo, to press ; alluding to its flattened seeds. Urtica. Nettle. The ancient Latin name. Usitatissimus-a-um. Most useful, common, familiar ; superlative degree of usitatus. Ustilago. Smut, Bunt. An ancient Latin name of a plant. Uva-ursi. Bearberry. From Latin uva, a grape, -f- ursi, of a bear. 462 A TEXT-BOOK OF BOTANY. Valeriana. Valerian. Probably from Lat. valeo, to be strong. Vanilla. From Spanish vainilla, diminutive of vaina, a sheath, pod ; be- cause its seeds are contained in little pods. Variifolius-a-um. With varying leaves. Lat. varius, various, changing, + folium, a leaf. Venenosus-a-um. Poisonous, deadly. Lat. venenum, poison. Veratrum. False hellebore. The classical Latin name. Veronica. Speedwell. Dedicated to St. Veronica. Versicolor. Having various colors. Lat. verflo, to turn, change, -\- color, color. Verticillatus-a-um. Disposed in a whorl. Lat. vcrticillus, diminutive of •vertex, a whirl ; referring to the leaves or flowers. Verus-a-um. True, genuine, original. Viburnum. Black haw. Arrow-wood. The ancient Latin name. Victorialis. Ancient Latin name of a plant. Villosus-a-um. Hairy, shaggy, villous. Vinifer-a-um. Wine-producing. Lat. vinum, wine, + fero, to bear. Viola. Violet. Heart's ease. The ancient Latin name of the genus. Virginianus-a-um. ) . . . ,,. . . }• Of or belonging to Virginia. Virgmicus-a-um. ) Viridiflorus-a-um. Having green flowers. Lat. viridis, green, + flos, a flower. Viridis-e. Green. Virosus-a-um. Having a bad odor, fetid. Lat. -virus, an offensive smell. Vitis. Grape. The classical Latin name. Vouacapoua. Araroba tree. From vernacular name, Central America. Vulgaris-e. Common, general, ordinary. Wisteria. Named in honor of Prof. Caspar Wistar, distinguished anatomist of Philadelphia. Xanthium. Clotbur, Cocklebur. Greek name of some plant used to dye the hair. From gav66f,\ yellow. Xanthoxylum. Prickly Ash. From Gr. £av66f, yellow, -f- f vfov, wood ; referring to the color of the roots. Zea. Maize. Indian corn. Ancient classical name for a kind of grain. Zeylonicus-a-um. Of or belonging to Ceylon. Zingiber. Ginger. The ancient Greek name. CHAPTER V CLASSIFICATION OF ANGIOSPERMS YIELDING ECONOMIC PRODUCTS IN this chapter will be given in natural sequence a list of the principal orders of plants that yield medicinal and other economical products. While great stress will be laid upon the plants used in medicine, yet considerable attention will also be given to the other economic substances furnished by the angiosperms, as food- products, fibers, coloring principles, woods, and timbers, as well as to the plants commonly cultivated for ornamental purposes. It will be found that the number of plants useful to man is a very large one, being derived from all the important families, so that in their consideration the student will gain a rather comprehensive view of the entire group. A. CLASS MONOCOTYLEDONE^:. The Monocotyledons are mainly distinguished as follows : The embryo has only one cotyledon ; the leaves are mostly scattered and parallel-veined ; the fibrovascular bundles of the stem are of the closed type, and the flowers are typically trimerous. I. ORDER PANDANALES. This order includes members which are aquatic or marsh plants, with narrow, elongated leaves and very small, imperfect and incomplete flowers in spikes or heads. The TYPHACE^: or Cat-tail family has the flowers borne in densely crowded terminal spikes, the staminate flowers being at the upper end of the spike, while the pistillate flowers which are beneath are more persistent. The SPARGANIACE/E or Bur-reed family have the flowers borne in densely globose heads, the staminate heads being rather small and near the upper part of the stalk, while the pistillate heads are larger and situated a short distance below the staminate ones (Fig. 252). 463 464 A TEXT-BOOK OF BOTANY. FIG. 252. Bur-reed (Sparganium eurycarpum), a perennial plant flowering throughout the summer and growing on the borders of ponds, lakes, and rivers throughout the United States. It grows to a height of 8 to 12 dm., and produces long, ribbon-like leaves. The flowers are in heads, becoming bur-like from the divergent beaks. — After Brown. CLASSIFICATION OF ANGIOSPERMS. 465 FlG. 253. Arrow-head (Sagittaria latifolia), a common marsh or aquatic plant and very widely distributed. The leaves are variable, but almost always sagittate. It produces naked scapes which are sheathed by the bases of the petioles; the white flowers are produced all summer. — After Troth. 30 466 A TEXT-BOOK OF BOTANY. II. ORDER NAIADALES. This order, as with other rather primitive orders, is made up mostly of aquatic and marsh plants, the flowers frequently being spicated. The NAIADACE^: or Pond-weed family comprises such genera as Potamogeton, the common Pond-weed, and Zostera, or Eel- grass, which is extremely common in bays and estuaries in all parts of the country, and in many places its collection forms an active industry. It is used in upholstery work and as a packing material. To the ALISMACE^: or Water-Plantain family belong Alisma, the Water- Plantain, and Sagittaria, or Arrow-head, which is a very attractive plant ( Fig. 253 ) . Of the latter there are a large number of species which are widely distributed. III. ORDER GRAMINALES OR GLUMIFLOR^. This order is composed of the two families, grasses (Gram- ineae) and sedges (Cyperacese). a. GRAMINEyE OR GRASS FAMILY.— The plants of this family are nearly all herbs having cylindric, generally hollow culms with swollen nodes. The leaves are exactly alternate, and have long sheaths which are split or seldom closed, tubular, and nearly always with a distinct ligule. The flowers are mostly hermaphrodite and borne in spikelets with alternate floral-leaves, the spikelets themselves being borne in spicate or paniculate in- florescences. Each spikelet (Figs. 255, 256) consists of two (seldom more) empty glumes, which are the lowest floral-leaves in each spikelet ; a varied number of flowering glumes, frequently awned or toothed, are situated inside the empty glumes, and each of which subtends a short branch (the rhachilla), the latter bearing an adorsed fore leaf (the pale), which is generally two- keeled and two-toothed, enclosing two minute scales (lodicules) and the flower. The flower has mostly three stamens (there being six stamens in Oryza and Bambusa), with the anthers versa- tile, and a simple gynaecium consisting of one carpel having two styles and a plumose stigma. The ovary is unilocular with one ascending or pendulous ovule. The fruit is a grain or caryopsis. CLASSIFICATION OF ANGIOSPERMS. 467 the seed being always firmly united with the thin pericarp (except in Sporobolus, Eleusine, etc.). The embryo is situated at the base, on the outer convex surface of the seed, outside the endo- sperm. On germination the cotyledons remain in the seed. The endosperm contains numerous starch grains and oil, while the gluten layer around the endosperm contains proteins. The number of layers of gluten- or aleurone-containing cells varies in the different cereals. In corn, wheat, and rye it consists of but a single layer ; in oat (Fig. 247) and rice, of i or 2 layers ; while in barley it is made up of 2 to 4 layers. The Grasses comprise about 3500 species and are distributed in all parts of the world. While most of the plants are grass-like, FIG. 254. Diagrams of cross-sections of monocotyledonous flowers: t, stem of plant; f, bract; s, sepals or outer circle of perianth; p, petals or inner circle of perianth; a, stamens; c, ovary. A, regular flower of the lily; B, irregular flower of iris. C, flower of an orchid, in which 1 is the position of the lip and & S of the two staminodes. — After Warming. still some of them, as the bamboos of the Tropics, become quite tall, having woody siliceous stems and' bearing many branches in the axils of the leaves. The grasses yield the cereal grains forming so large a proportion of the food of man, and forage constituting the food of many of the lower animals. The following are some of the important cereals: Wheat (Triticum sativum and its varie- ties), corn (Zea Mays), oat (Avena sativa), rice (Oryza saliva), barley (Hordeum sativum and its varieties), rye (Secale cereale). A number of the species yield a sweet cell-sap from which cane sugar is made, of which the most important are the sugar cane (Saccharum officinarum) and sorghum (Andropogon arundina- ceus saccharatus and other varieties). (Consult pp. 148, 156, 198.) 468 A TEXT-BOOK OF BOTANY. A large number of the grasses are used in medicine, one of which, couch-grass (Agropyron rcpens}, is official. Agropyron repens is a common perennial grass, forming slen- der jointed rhizomes, by means of which the plant is extensively propagated ; the culms vary from one to four feet in height, the spikelets are 3- to 7-flowered ; and the empty glumes, 5- to 7-nerved, acute or with an awn-like apex. Hordeum sativum is an annual grass with the flowers in ter- FIG. 255. Wheat (Triticum): A, zigzag axis or rachis of ear showing the notches where the spikelets were inserted; B, an entire spikelet; C, a flower with the pales; D, a flower without the pales, showing the lodicules at the base; E, glume; F, outer pale; G. inner pale; H, fruit (caryopsis); I, longitudinal section of fruit. — After Warming. minal cylindrical spikes resembling wheat. The spikelets are ses- sile, i-flowered, and usually in clusters of three on opposite sides of the notched rachis. The empty glumes are long and narrow, forming a kind of involucre around the spikelet. It is supposed that Hordeum sativum is a cultivated form of H. spontaneum growing in the countries between Asia Minor and other parts of Western and Southwestern Asia. Three important varieties are distinguished, depending upon the number of rows of grains in CLASSIFICATION OF ANGIOSPERMS. 469 the ear. H. sativum distichon includes the plants having 2-rowed ears, and these are chiefly grown in Middle Europe and England. //. sativum hexastichon includes the plants having the grains in 6 rows, these having been cultivated since prehistoric times and furnishes the winter barley. //. sativum vulgarc includes the plants in which the grains are in 6 irregular rows, and these are cultivated in northern temperate regions. The latter plant is cultivated in the United States and furnishes the spring or summer barley, largely used in the preparation of malt. Zea Mays (Indian Corn) is a cereal plant probably indigenous to Central Mexico. It is extensively cultivated in the United FIG 256. Diagrammatic outline of a spikelet: nY, lower glume; <}> Y, upper glume; nl, outer pale; I, inner pale; 1, 1, lodicules; st, stamens; I-I, main axis; II, lateral axes or branches. — After Warming. States and other parts of the world for its grain. From a multi- ple, primary, somewhat fibrous root arise one or more erect simple culms, which are grooved on alternate sides in the successive internodes and from the nodes of which arise aerial secondary roots. The leaves are alternate and consist of 3 parts : (a) a blade, which is long, broadly-linear and tapering toward the apex, the tip being pendulous; (b) a lower sheathing portion which is open; and (c) a short, translucent, somewhat hairy ligule, situated between the sheath and the blade. The flowers are monoecious, the staminate, which are arranged in a terminal pan- icle, maturing first ; the pistillate occur in axillary spikes, the axes of which constitute the corn cob. They are enclosed in 470 A TEXT-BOOK OF BOTANY. spathe-like bracts or husks, from which the long filiform styles (p. 178) protrude. The grain is somewhat ovate or triangular, flattened, pointed at the base, grooved on one side, indicating the position of the embryo, from 10 to 15 mm. long and about 10 mm. broad, more or less translucent, and varies in color in the different varieties. The constituents of the corn grain are 50 to 75 per cent. of starch ; about 10 per cent, of proteins ; 4.29 per cent, of a fixed oil; about 5 per cent, of sugar, and 1.29 per cent, of ash. There are a large number of varieties and sub-varieties of Zca Mays, some of the former being ranked as species. The follow- ing well-defined varieties may be mentioned : 1 i ) Zea Mays everta, to which belong the POP-CORNS. The size of the ears and grains is about one-half or less that of the other corns ; the grains have a more or less translucent and horny endosperm, the cells of the latter containing numerous compactly arranged polygonal starch grains, which are from 7 to 10/1 in diameter and have a central rarefied area from 2 to 7 ^ in diam- eter. It is owing to the structure of the starch grains that the peculiar popping of the corn grains results when they are heated. Heating the corn grains at 145° to 160° C. for from 4 to 10 min- utes causes the bursting of the starch grains, and at the same time a rupture of the cells and splitting of the pericarp into 4 parts. The white appearance of the popped grains is due to the inclusion of air in the bursted cells. During the heating the starch is con- verted into a soluble form, and this gives popped corn its nutritive value. Some of the flint and dent corns show a similar tendency to pop when heated, but it is only in those parts of the endo- sperm that are horny and the cells of which contain compactly arranged polygonal starch grains in which the rarefied area is at least from one-tenth to one-fifth the diameter of the entire grain. Pieces of the pop-corn, as well as the horny portions of some of the flint and dent corns, will pop as readily as the whole grains. (2) Zea Mays indentata yields the DENT or FLINT CORNS, the grains of which have a corneous (horny) endosperm on the sides and are indented at the summit, owing to the shrinking of the cells which contain more cell-sap and less compactly ai ranged starch grains. The starch grains in the cells of the horny endosperm resem- CLASSIFICATION OF ANGIOSPERMS. .471 FIG. 257. Carex lurida, one of the Sedge family (Cyperacece) , found throughout the summer in swamps and wet meadows in the eastern and central United States. It is a perennial grass-like herb with triangular culms, 3-ranked leaves, and with 2 to 4 spikes of flowers. The genus is a vast one of more than a thousand species, widely distributed and most abundant in the temperate zones. — After Troth. ble those of pop-corn, but the starch grains in the other cells are more or less rounded or slightly polygonal, and vary from 5 to 25 /i in diameter ; the central rarefied area is either wanting or usually not more than 2 /* in diameter. (3) Zea Mays saccharata yields the SUGAR CORNS. While the 472 A TEXT-BOOK OF BOTANY. grains are more or less translucent and horny, they have a wrinkled or shrivelled surface. The cells of the endosperm con- tain gum-like substances and a relatively small number of nearly spherical starch grains from 4 to io/x in diameter. BROOM CORN. (Andropogon arundinaceus vulgaris} is a plant which is cultivated for the panicles or seed heads, which are used in the manufacture of brooms. This plant differs from the other species of Andropogon in that the branches of the panicles are longer, straighter, and stronger, forming a so-called " brush." Quite a number of the grasses contain odorous principles, as Andropogon citratus, which yields lemon-grass oil ; A. Schccnan- thus, which yields! gingergrass or geranium-grass oil; A. squar- rosus, the rhizome of which is known as Vetiver. Coumarin is found in Vanilla grass (Anthoxanthum odoratum) and white or Dutch clover (Hierochlcc odorata}. Some species of Stipa are used in the manufacture of paper (Alfa or Esparto) in North Africa and Spain. b. CYPERACE;E OR SEDGE FAMILY.— These plants are all herbaceous, the majority being perennial (seldom annual). The rhizomes are mostly sympodial (being monopodial, however, in certain Carices), and the stems are mostly solid and triangular, without swollen nodes. The leaves are grass-like, generally arranged in three rows, and the sheath is closed, being mostly without ligules. The flowers may be hermaphrodite or unisexual, sometimes dioecious, and arranged in spikes or racemes. The perianth is wanting or only represented by 6 bristles, or by an indefinite number of hairs. The number of stamens is 3, with the anthers attached by their bases to the filament. The gynoecium consists of 2 to 3 carpels, with one style divided into 2 or 3 branches, and provided with papillae. The fruit is a nut, whose seed is generally united with the pericarp. The embryo is small and is centrally situated at the base of the seed, being surrounded by the endosperm. On germination, the cotyledon is freed from the seed. A number of the sedges yield food products, as the rhizomes of Cyperus esculentus and Eleocharis tuberosa, the latter of which is used in the manufacture of starch in China and India. Quite a number of species of Scirpus, Cyperus, Carex, etc., are used in CLASSIFICATION OF ANGIOSPERMS. 473 medicine. Various species of Cyperus (C. scariosus, of the East Indies, and C. pertenuis, of India) yield ethereal oils and are used in making perfumery. Cyperus Papyrus is used in medicine and also furnished the paper of the Ancients. IV. ORDER PRINCIPES. In this order is included that interesting group of tropical and sub-tropical plants the PALMS (Palmae). They are arbores- cent, having simple unbranched trunks which are terminated by clusters of leaves, in the axils of which flowers are produced. The leaves are pinnate (Feather Palms) or palmate (Fan Palms) and often very large. The petiole is well developed, with an am- plexicaul, more or less fibrous sheath. The inflorescence is usually lateral, in some cases forming a large spadix with a woody, boat- shaped spathe. In comparison the individual flowers are very small. The fruit is either a berry, as in the Date palm, or a drupe, as in the Cocoa-nut palm, generally i -seeded and with a large horny or bony endosperm, as in the Date palm (p. 135) and Phytelephas macrocarpa, the latter of which yields vegetable ivory, used in the making of buttons (Fig. 258). The fruit of the saw palmetto [Serenoa (Sabal) serrulata], one of the fan palms, is official. The saw palmetto is characterized by having a creeping, branching root-stock or rhizome, one end of which rises a short distance above ground, this portion being surmounted by a dense crown of leaves. The petioles are slender and spinose on the edges ; the blade is fan-shaped and consists of a number of palmate divisions which are slightly cleft at the apex. The inflorescence is densely tomentose and shorter than the leaves. The fruit is a i -seeded drupe. The palms yield a number of useful products. The Betel-nut palm (Areca Catechu) produces a seed having medicinal proper- ties (Fig. 259). The seeds, known as ARECA NUT, are 20 to 25 mm. long, conical, grayish-brown, with numerous spiral, reddish veins, heavy, hard, somewhat aromatic, astringent, and slightly acrid. They contain about o.i per cent, of an oily liquid alkaloid, arecoline, which chemically and in its physiological action resem- bles pelletierine ; 14 per cent, of tannin, resembling catechutannic acid; gallic acid; a red coloring principle; and 14 per cent, of a 474 A TEXT-BOOK OF BOTANY. fixed oil. They ako contain 3 other alkaloids: arecaine, arecai- dine, and guvacine, but these do not seem to give the drug its properties. CARNAUBA-WAX is obtained from the Carnauba-palni of Brazil (Copernicia cerifera). The wax exudes from the surface of the young leaves and is obtained by boiling them with water. DRAGON'S FIG. 258. Vegetable Ivory, the endosperm of the seeds of a Central American palm (Phytelephas macrocarpa). The fruits are produced near the ground, are nearly globular, measuring about I meter in circumference, and weigh about 14 pounds each. They are covered with a woody spinose wall (A), and enclose a number of drupes (B), each of which contains a single hard seed (C). The latter contains a hard, white, fine-grained endosperm (D); it is used in making small articles of turnery, as buttons, etc. — Reproduced by permis- sion of The Philadelphia Commercial Museum. BLOOD, a bright red resinous substance, is obtained from the juice of the fleshy fruit of Calamus Draco. It consists chiefly of resin, some tannin, and about 3 per cent, of benzoic acid. The Oil palm (Elocis guineemis) of equatorial West Africa yields a drupe with an oily sarcocarp, from which, by means of pressure or boiling with water, PALM OIL is obtained. The Cocoa- nut palm (Cocos nucif-era} yields the COCOA NUT of the market, CLASSIFICATION OF ANGIOSPERMS. 475 and is probably one of the most useful palms to the natives, fur- nishing, as it does, food, clothing, utensils of all kinds, building materials, etc. The Sago-palms (Metroxylon Rumphii and M. lave} yield SAGO, which is prepared by washing out the starch from the cut stems and subsequently heating it. A tree 15 years old yields from three to four hundred kilograms of sago starch. The Date palm (Phocni.v dactylifera) yields the DATES of the FIG. 250. A number of Areca-nut palms (Areca Catechu) growing in Ceylon. The stems are slender, attaining a height of 25 meters or_more, with a diameter of 3 to 4 dm. and bearing a cluster of leaves at the summit. The palm is also known as the Betel-nut palm, and is extensively cultivated throughout tropical India. — Reproduced by permission of The Philadelphia Commercial Museum. market, and it is interesting to note that since very early times the fruits produced by the growers in the Orient have been the result of artificial or hand-pollination. V. ORDER ARALES OR SPATHIFLOR^E. This order includes two families which are markedly different in their habits : ( i ) The Araceae, which are rather large herbs with an inflorescence known as a spadix and consisting of a fleshy 476 A TEXT-BOOK OF BOTANY. FIG. 260. Fruits and flowers of several of the palms. A, cluster of flowering spikes of the cocoanut palm (Cocos nucifera); B, number of the young fruits of the cocoanut palm; C, cluster of the ovoid fruits of the betel-nut palm (Areca Catechu); D, compound inflorescence of drooping spikes of the kittul (kittool) palm (Caryota urens); E, large clusters of deltoid fruits of kittul palm. — Reproduced by permission of the Philadelphia Commercial Museum. The cocoanut palm yields a larger number of economic products than any other tree in the world; the fruit is edible and yields the cocoanut oil, the sap produces an alcoholic beverage, the leaves are used for making useful articles, and the wood is employed in cabinet making. The Betel-nut palm yields a number of valuable products, the most important being the seed, which is not only used to stimulate digestion, but is used in many religious cere- monies, as well as in regulating the intercourse of the more polished classes of the East. The base of the leaf stalks of the kittul palm yield a fiber which Is elastic, shows considerable tenacity, and is used in the making of brushes for brewers' use. CLASSIFICATION OF ANGIOSPERMS. 477 FIG. 261. Jack-in-the-Pulpit, or Indian Turnip (Ariscema triphyllum) , a very common perennial herb growing in woods and thickets of the eastern and central parts of the United States and Canada, and characterized by I or 2 leaves which are divided into 3 elliptical- ovate, pointed leaflets and a characteristic spathe of a greenish color, frequently purple- striped and curving in a broad flap over the top of the club-shaped spadix. The plant produces a turnip-shaped corm with an intensely acrid juice. — After Troth. 478 A "TEXT-BOOK: OF BOTANY. spike, which is subtended or enclosed by a large bract known as a spathe, as in the Calla-lily, where it is large and white, and (2) the Lemnaceae or duckweed family, which is composed of minute, FlG. 262. Skunk Cabbage (Symplocar pus fcetidus), a perennial herb producing a very thick rhizome, from which arise in the early spring the flowers crowded on a spadix sur- rounded by a large, shell-like spathe which barely rises out of the ground and is striped or spotted with purple and yellowish-green. These are followed by a cluster of ovate, cordate leaves becoming 3 to 6 dm. long. In the illustration are shown 4 of the spathes, the one at the left being cut open to show the globular or ovoid spadix, and a single leaf unfolding. — After Troth. floating, thalloid plants that develop one or more flowers on the margin or upper surface of the thallus. ARACE^ OR ARUM FAMILY.— The plants belonging to this family are perennial herbs with tuberous or fleshy rhizomes CLASSIFICATION OF ANGIOSPERMS. 479 and simple or compound leaves which are usually long-petioled. The spadix is densely flowered, the staminate flowers being above and the pistillate below on the same axis, or the plants are wholly dioecious. The perianth when present consists of 4 to 6 scale-like segments. Frequently the spadix is subtended or enclosed by a more or less showy spathe. The fruit is usually a berry, some- times a utricle. FIG. 263. Water Arum (Calla paliislris), showing portion of rhizome, the broadly ovate and cordate leaves, and the inflorescence, which consists of a cylindrical spadix and an elliptical spreading spathe. A number of the plants of this family have medicinal proper- ties, and one of them yields the unofficial drug CALAMUS. The drug is derived from sweet flag (Acorus Calamus}, a plant common in swamps and along streams in the Eastern United States, and characterized by its long, narrow, linear, bilateral leaves, which are from 6 to 18 dm. in height and about 25 mm. in width. The inflorescence is a spike-like spadix having greenish-yellow flowers. Many of the Araceae possess an acrid juice. The acridity is 480 A TEXT-BOOK OF BOTANY. probably due either to saponin or an acrid volatile principle rather than to raphides of calcium oxalate. Frequently these principles are dissipated or destroyed on cooking, and the plants are then used as food, as the WATER ARUM (Calla palustris), which on account of its acrid principles is used as a remedy for snake bites when in the fresh condition, but which on drying loses its acridity and being rich in starch is used as a food (Fig. 263). To -this family also belong Jack-in-the-pulpit, or INDIAN TURNIP (Ari- scema trip hy Hum) , the acrid corm of which is used in medicine (Fig. 261) ; SKUNK CABBAGE (Symplocarpus fcctidus), the fetid rhizome of which has medicinal properties (Fig. 262). A number of plants of the Arum family are rich in starch, as the tubers of Xanthosoma edule of Surinam, which contain 62 per cent, of starch. VI. ORDER XYRIDEALES OR FARINOS^E. The plants are mostly perennial herbs of tropical and sub- tropical America. The order includes a number of families, among which is BROMELIACE/E, to which the pineapple (Ananas salivas) belongs. PINEAPPLE is a native of Brazil and is now cul- tivated in warm countries of the eastern and western hemispheres. The fruit contains a proteolytic enzyme resembling trypsin and also a milk-curdling ferment. The bast fibers of the leaves are used for textile purposes. Some of the Bromeliaceee are epi- phytic (air-plants), the best known member being probably the FLORIDA MO>S (Tillandsia usneoides), which is used in upholstery (Fig. 264). The family Commelinaceae is represented in the United States by Commelina or day-flower, some species of which have medic- inal properties. The roots of some tropical species contain saponin, as C. deficiens, of Brazil. The rhizomes of a number of species of Commelina contain notable quantities of starch and are edible. The spiderworts (Tradescantia) common in rich soil in the United States, and the Wandering Jew (Tradescantia Zebrina) commonly cultivated as an ornamental plant, also belong to this family. To the PONTEDERIACE^E belong several perennial aquatic or bog plants, whose leaves are usually thick or in some cases long and grass-like. The flowers are frequently arranged in Spikes subtended by leaf -like spathes (Fig. 265). CLASSIFICATION OF ANGIOSPERMS. 481 482 A TEXT-BOOK OF BOTANY. FIG. 265. Pickerel Weed (Pontederia cordata), a common aquatic herb growing along the margin of slow streams. It is a very hardy plant occurring far north and' grows best in water ten or twelve inches deep. It produces long-petioled leaves and a single stem bearing a spike of violet -blue, ephemeral flowers. — After Troth. CLASSIFICATION OF ANGIOSPERMS. 483 FIG. 266. Small Solomon's Seal, also commonly known as true Solomon's Seal (Poly- gonalum biflorum). It is a perennial herb with lance-oblong, sessile leaves, in the axils of which are usually two nodding greenish flowers. The plant grows in moist woods or wooded hillsides, and receives its common name from the creeping knotted rhizomes, on the upper surface of which are usually one or more prominent circular scars, formed upon the decay of the aerial shoots. — After Blown. 484 A TEXT-BOOK OF BOTANY. FIG. 267. False Solomon's Seal or False Spikenard (Smilacina racemose), a perennial herb with a somewhat stout stem, a number of alternate parallel-veined leaves and a terminal raceme of whitish, sometimes fragrant, flowers. It forms a horizontal knotted rhizome, on the upper surface of which are found circular scars. It may be found growing in under- brush in mo««it woods. — After Brown. CLASSIFICATION OF ANGIOSPERMS. 485 VII. ORDER LILIALES OR LILIIFLOR^E. The plants of this order are mostly perennial herbs with rhi- zomes, tubers, bulbs, or fibrous roots. The leaves are parallel- veined. a. LILIACE;E OR LILY FAMILY.— The plants are the most typical of the Monocotyledons. They are scape-like herbs with bulbs ; the flowers are symmetrical, and the perianth is parted into 6 more or less distinct segments (Fig. 123) ; the anthers are introrse. The ovary is free, 3-locular, with a single style, and the fruit is a 3-locular, loculicidally dehiscent capsule. The Liliacese is one of the most important families, containing about 2500 species, many of which are of great economic interest. Quite a number are cultivated on account of the beauty and fra- grance of their flowers. Among the latter are the hyacinth, lily, lily-of -the- valley, tuberose, tulip, and yucca. Of those yielding food products we have asparagus, being the young shoots of Asparagus officinalis. The edible bulbs include the onion (Alliuni Cepa}, garlic (Alliuni sativum), the leek or scullion (Allium Porrum), and chives (Alliuni Schocnoprasum). A number of the Liliaceae are among the common wild flowers, as swamp pink (Fig. 272), bell wort (Uvularia), lily (Lilium), dog's-tooth violet (Erythronium), Star of Bethlehem (Ornithogalum), False Solo- mon's Seal (Fig. 267), True Solomon's Seal (Fig. 266), Indian Cucumber- root (Medeola), colic-root (Fig. 271), cat brier (Smilax), etc. The following plants are of medicinal interest: Veratrum viride is a plant 2 to 8 feet high, which is charac- terized by the broad, clasping, strongly plicate leaves, and by hav- ing the flowers in large terminal panicles (Fig. 268). The plant is found in swamps and wet woods in the United States in spring and early summer. The rhizome is upright, and it with the roots is used in medicine. The plant, including the rhizome, closely resembles the Veratrum album of Europe. Colchicum autumnale. — This is the autumnal-flowering colchi- cum, a perennial herb but a few inches high which arises from a corm and bears proportionately large lilac-colored flowers. The fruit consists of 3 follicles containing numerous seeds. The corm and seeds of this and other species of Colchicum are used in 486 A TEXT-BOOK OF BOTANY. FIG. 268. Flowering specimen of Veralrum viride, showing the spreading, spike-like racemes and the. parallel-veined leaves. CLASSIFICATION OF ANGIOSPERMS. 487 medicine. Among the species yielding large corms and extensively cultivated is Colchicum B-urmanii (Fig. 269). Aloe species. — The stems are about a meter high and bear at the summit a cluster of thick, succulent leaves which are lance- olate and spinous-toothed (Fig. 270). The inflorescences are in long spikes which are quite showy and characteristic for the differ- ent species. Aloe Perryi, which yields the SOCOTRINE ALOES, possesses leaves with white spines and flowers that are orange-red or scarlet at the base, the stamens being unequal ; Aloe vera, which yields the BARBADOES or CURACAO ALOES, has leaves with yellow or reddish spines and yellow flowers in which the stamens are as long as the corolla ; Aloe ferox and some other African species, which yield CAPE and UGANDA ALOES, have flowers in close spikes, the petals being white and marked by green lines, and the stamens much longer than the corolla. The inspissated juice is official in all the pharmacopoeias. Urginca maritima, which yields the drug squill, is character- ized by its large, onion-like bulb, from which arise ten to twenty broadly lanceolate, grayish-green leaves ; and by having the in- florescence in long spikes consisting of whitish flowers which have a distinctly purple stripe on each division of the perianth. Convallaria majalis or Lily-of-the-valley is a plant which is well known. It produces a raceme of delicately odorous white flowers and beautiful oblong leaves with prominent parallel veins. The rhizome and roots are official. Smilax species. — The drug sarsaparilla is yielded by at least four different species of Smilax, These are mostly vines with woody or herbaceous, often prickly stems and leaves with petioles which have a pair of persistent tendril-like appendages. The flowers are small, mostly greenish, dioecious and in axillary umbels. The fruit is a globose berry. Not a great deal is known of the species which yield the drug, with the exception of Smilax medica, which yields the Mexican or Vera Cruz sarsaparilla. In Smilax medica the leaves vary from more or less cordate to auriculate- hastate; in Smilax officinalis, which yields the native Jamaica sarsaparilla, they are ovate, as they are also in Smilax papyracea, which yields Para sarsaparilla. The Jamaica Sarsaparilla, official in the British Pharmacopoeia, is obtained from plants of Smilax 488 A TEXT-BOOK OF BOTANY. ornata growing in Costa Rica and subsequently shipped to Jamaica. Nothing is known of the plant yielding Honduras sarsaparilla, although this drug has been in use for nearly four centuries. It FIG. 269. Floweiing plant of Colchicum Burmanii, a form producing very large corms and extensively cultivated in Holland. is said to be derived from Smilax officinalis. The sarsaparilla plants have short rhizomes which give rise to long roots, which are the part used in medicine. A DRAGON'S BLOOD, resembling that derived from Calamus CLASSIFICATION OF ANGIOSPERMS. 489 Draco, is obtained from Dracccna Draco, a tree growing in the Canary Islands. Some of the trees of this species are of historic interest, as the dragon tree of Orotava, which is 46 feet in circum- ference at the base. A number of the plants of this family contain saponin, as the species of Smilax. Some contain coniferin and vanillin, as Aspar- agus officinalis. Some of the group contain glucosidal principles which under the influence of ferments yield ethereal oils contain- FlG. 270. A field of Aloe plants, growing in the Riversdale District, Cape Colony. The stems are simple, with one or more clusters of leaves; the latter are from 3 to 6 dm. in length, fleshy and very thorny-prickly at the margin. — Reproduced by permission of the Philadelphia Commercial Museum. ing sulphur, as the various species of Allium. Garlic (Allium sativum) contains a glucoside, allisin, which on hydrolysis with an oxidase (allisin) forms the essential oil of garlic. A number also are quite poisonous when fresh but edible when cooked. b. AMARYLLIDACE^l OR AMARYLLUS FAMILY.— This group is of special interest because it includes the Agave .or Century plant. This is a characteristic genus of plants of the hot and arid regions of North America. The best known of these 490 A TEXT-BOOK OF BOTANY. is the CENTURY PLANT (Agave americana} , which is one of the most important economic plants of Mexico. The stem axis of the plant is very short and the thick, fleshy leaves form a tuft at FIG. 271. Plant of Aletris farincsa showing characteristic rosette of lanceolate leaves at the base and portion of long slender scape with numerous tubular flowers. The plant is common in dry coniferous woods in the eastern part of the United States. the summit. The leaves are lanceolate, with spinose margins, and furnished with stout terminal spines. The leaves as well as the' roots contain a large amount of mucilage which retains water and CLASSIFICATION OF ANGIOSPERMS. 491 FIG. 272. Swamp Pink (Helonias bullata) is a rather rare plant found only in certain localities, particularly in wet places, extending from southern New York to Virginia. It produces a tuberous root-stock, and the evergreen leaves are clustered near the base of a naked scape which bears in the early spring a short raceme of purplish flowers. This should not be confounded with the plant yielding the drug known as Helonias or false unicorn root, the latter being derived from Cham&lirium luteum, and at one time known as Helonias dioica. — After Troth. 492 A TEXT-BOOK OF BOTANY. thus helps to adapt the plants to these arid regions. The plants grow slowly and may flower when they are ten or twelve years old. The Agaves contain saponin and other principles of medicinal value. They yield a number of other products, as follows: PULQUE, a fermented drink of the Mexicans ; MEZCAL, a distilled drink resembling rum; various fibers, as SISAL HEMP, " Hene- quen " or " Sacci," etc. Other members of the Amaryllidacese likewise find use as medicines and as foods, many of them being cultivated as ornamental plants, as Narcissus, Hymenocallis, Crinum, and Amaryllis. c. DIOSCOREACE^: OR YAM FAMILY.— The plants be- longing to this family are twining shrubs or herbs with tubers either above or below ground. The general characters of the plants are shown in the wild yam-root (Dioscorea villosa) of the United States (Fig. 180). Several species, notably, D. Batatas, yield the YAMS or Chinese potatoes of commerce. Many of the species of Dioscorea, as well as other members of this family, contain active principles which, like those of the Araceae and Liliaceae, are destroyed on heating. The rhizome of Tamus communis contains saponin, and Rajania subamarata con- tains tannin. d. IRIDACE^: OR IRIS FAMILY.— The plants of this fam- ily are perennial herbs with mostly equitant (bilateral) leaves and horizontal rhizomes, or corms. The flowers are regular or irregular and with a petalloid stigma (Fig. 254, B). Iris versicolor is a flag-like plant, commonly known as the LARGER BLUE FLAG, and found abundantly in the marshes and wet meadows of the Eastern United States. It is distinguished by its tall stems and sword-shaped, somewhat glaucous leaves. The flowers are violet-blue. The rhizome somewhat resembles that of calamus, but is of a dark brown color and contains 25 per cent, of acrid resins, a volatile oil, starch, and tannin. Iris flofentina, which yields the ORRIS ROOT of commerce (Fig. 190), is a plant cultivated in Middle and Southern Europe, and closely resembles the above-mentioned species. The rhizome con- tains a volatile oil resembling that found in violets, and is used in perfumery. Orris root is also obtained from Iris germanica and /. pallida. The violet odor is developed on keeping the rhizome a year or two. CLASSIFICATION OF ANGIOSPERMS. 493 Crocus sativus, the orange-red stigmas of which have been used in medicine since ancient times, is an autumnal-flowering plant. The flowers are lilac-purple, somewhat like those of Colchicum, and occur at the summit of a scape rising 15 to 20 cm. above ground. The leaves are linear and rise directly from a more or less globular corm. The plant is cultivated in Spain and other parts of Europe and in the United States as well. The stigmas constitute the drug SAFFRON (Crocus), which was formerly official, and contain a coloring principle, i part of which will impart a distinct yellow color to 100,000 parts of water. Saffron contains a yellow glucoside, CROCIN, which is soluble in alcohol but not in water, and is colored blue by sulphuric acid. The drug also con- tains 7.5 to 10 per cent, of a volatile oil, which appears to be derived from a coloring principle that resembles carotin ; and the bitter principle picro-crocin. e. JUNCACE^E OR RUSH FAMILY.— These are grass-like marsh plants, which are distinguished by the fact that the flowers are small, with a 6-parted glumaceous perianth, and the fruit is a loculicidally dehiscent capsule. The stems are mostly solid, slen- der, usually arise in tufts from the rhizome, and are characterized by stellate parenchyma cells, among which are large, intercellular spaces, the latter also being characteristic of the leaves. The rushes are principally found in cold and temperate regions. Several species of Juncus and Luzula have been used in medi- cine, particularly in Europe. The seeds of Luzula compestris, a common wood rush of the United States naturalized from Europe, are edible. Soft rush (Juncus effusus} and Hard rush (/. conglomerate) are used in Japan in the manufacture of rush matting. In Holland the rush is grown on the embankments along the coast to prevent the action of the tides. VIII. ORDER SCITAMINALES OR SCITAMINE^. The plants of this order are mostly found in the Tropics and are perennial herbs with fleshy rhizomes. The leaves are large, more or less elliptical and pinnately veined. The leaf sheaths close tightly around each other and form a kind of false stem. The flowers are epigynous, unsymmetrical or zygomorphic, and fre- quently only one stamen is completely developed 494 A TEXT-BOOK OF BOTANY. a. THE ZINGIBERACE^: OR GINGER FAMILY is dis- tinguished from the other Scitaminese by the fact that the seeds have endosperm as well as perisperm. The plants are rich in volatile oils, and a number are used in medicine and perfumery. Zmgiber officinale yields the official ginger (Fig. 273). From a creeping, fleshy, branching and laterally compressed rhizome (Fig. 187) arises a stem about I M. high bearing numerous lanceo- late leaves. The flowering stalk arises directly from the rhizome, terminating in a spike which bears flowers having greenish-yellow petals with violet or purple stripes. Elettaria Cardamomum (E. repens) yields the cardamom of the several pharmacopoeias (Fig. 237). The plant has a leafy as well as floral stem which rises from a tuberous rhizome. The leaves are broadly lanceolate. The flowers are greenish-white, the labellum (consisting of two petal-like staminodes) being bluish. The fruit is a capsule, and the seeds are the part used in medicine. The so-called PARADISE GRAINS are the seeds of Amomuni Melegueta growing in Western Africa. They are about 3 mm. in diameter, dark brown, nearly smooth, friable, and contain a vola- tile oil. GALANGAL, which is used in perfumery, is the rhizome of Alpinia Galanga growing in the East Indies and cultivated in China and Bengal. It is frequently referred to as " Galangal major " to distinguish it from the rhizome of Alpinia officinarum growing in China near Hainan. Galangal occurs in short, branched pieces of a reddish-brown color, with numerous circular scars, and has an aromatic and pungent taste. It contains 0.5 per cent. of a volatile oil, the principal constituent of which is cineol ; a pungent principle, galangol ; an acrid, pungent resin ; 25 per cent, of starch ; and three crystalline principles. CURCUMA or TURMERIC is the rhizome of Curcuma longa, a reed-like plant which is largely cultivated in India and other tropical countries. In preparing the rhizome for market it is sub- jected to a scalding or parboiling process which agglutinates the starch in the cells. While turmeric is used as a condiment, it is also used on account of its color as an adulterant of mustard, rhubarb, and other articles, but is very easily detected. Several forms of curcuma are found in commerce, as " round curcuma," CLASSIFICATION OF ANGIOSPERMS. 495 consisting of the main rhizome, and "long curcuma," composed of the short branches. They occur in cylindrical or ovoid pieces, previous year s growin aner aecay or icai- ana nower-orancnes. /\, enure nower; a, sec- tion of flower showing beak-like appendage at the apex of the fertile stamen, which encloses the style; C, three-parted labellum or irregular segment of corolla showing 2 tooth- like staminodes (rudiments of stamens) at the base; D, the ovary with lower portion of style and two epigynous, filiform processes which secrete nectar; E, apex of funnel-shaped, fringed stigma. — -After Berg and Schmidt. 2 to 5 cm. long, of a yellowish-brown color externally, bright yel- low internally, and aromatic odor and taste. Curcuma contains 496 A TEXT-BOOK OF BOTANY. i per cent, of volatile oil containing phellandrene and turmerol ; 0.3 per cent, of a yellow crystalline principle, CURCUMIN, which is soluble in alcohol, sparingly soluble in water, forms reddish-brown solutions with alkalies and is converted into vanillin with weak oxidizing agents. It also contains considerable starch and a small quantity of an alkaloid. Other families of the Scitamineae are of great importance on account of the food-products obtained from them, as the Musa- cece, which contains the group of plants to which the BANANA (Musa paradisiaca and M. Sapientum) belongs. To the Canna- cecr belong the cultivated Cannas, one of them, Canna edulis, being grown extensively in the West Indies and Australia as a vegetable, and another, Canna coccinea, which grows in the West Indies and South America, furnishing " Tous les mois," the arrow-root starch of the English and French. To the Maranta- cece belongs Maranta arundinacea, which is cultivated in tropical America, and the rhizome of which yields the starch, MARANTA ARROWROOT (Fig. 88, J9), and is largely used in the preparation of infants' food. IX. ORDER ORCHIDALES OR MICROSPERM^. The most important family of this order is the ORCHIDACE^: or ORCHID FAMILY. The orchids are the most highly specialized of the Monocotyledons. They are perennial herbs with diverse habits, many tropical species being epiphytes, and of varying mor- phological structure, which is particularly evident in the zygo- morphic flowers. The perianth consists of 6 segments. The 3 outer correspond to sepals and are similar. Two segments of the inner circle correspond to petals and are alike, while the third, which is known as the LIP, is remarkably modified, being usually larger, often spurred, and frequently reversed, being turned for- wards and downwards by the twisting or torsion of the ovary. Only one of the stamens — the anterior of the external whorl — is developed and bears an anther. The other stamens are entirely wanting or present as staminodes (except in Cypripedium and the Apostasieae). The filament is united with the style to form a column, the so-called " stylar v >lumn," and the anther is thus placed on its apex, and behind the stigma. The 3 carpels form a unilocular ovary with 3 parietal, deeply bifid placentae. The fruit CLASSIFICATION OF ANGIOSPERMS. 497 is a pod or capsule, which dehisces mostly by means of 6 valves, and contains numerous minute seeds, which are without endo- sperm, and the embryo of which lacks frequently any trace of external organs. The seed-coat is membranous and loose. FIG. 274. A fruiting plant of Vanilla planifolia, an epiphytic orchid, which is indige- nous to Mexico and extensively cultivated in tropical countries, especially in Mexico and Java. The photograph is of a plant growing in Dominica, an island of the West Indies, and shows the long, elliptical leaves, also some of the long, slightly curved, slender pods. The latter are not fragrant, but develop their characteristic aroma by a process of slow curing. — Reproduced by permission of The Philadelphia Commercial Museum. Vanilla planifolia, which yields the official vanilla, is a high- climbing plant with long internodes and distinct nodes from which arise more or less oval or broadly lanceolate, somewhat fleshy leaves and also commonly a single aerial root. The long stem is terminated by a raceme, flowers also arising in the axils of the 3? 498 A TEXT-BOOK OF BOTANY. FIG. 275. Moccasin Flower or Pink Lady's Slipper (Cypripedium acaule), one of the commonest and most beautiful of the orchids, found growing in sandy and rocky woods from Newfoundland to North Carolina, and westward from Minnesota to Kentucky. The crimson pink flowers are solitary at the summit of long scapes; the lip is large inflated, slipper-shaped, drooping and with a fissure in front instead of a circular opening as in the other species. — After Troth. leaves for some distance back on the stem. The flowers are yel- lowish-green and the segments of the perianth are similar, and erect or spreading. The lip is united with the column, forming a CLASSIFICATION OF ANGIOSPERMS. 499 FIG. 276. Round-leaved Orchis (Habenaria orbiculata), an interesting orchid found growing in rich deep woods in the north temperate regions of the United States. It has a leafless scape, at the base of which are two orbicular or elliptical leaves spreading flat on the ground. The flowers are in a loose raceme, greenish-white, the lip being oblong linear and about the same length as the spur. — After Troth. 500 'A TEXT-BOOK OF BOTANY. FIG. 277. White Fringed Orchis (Habenaria blephariglottis), an attractive and rather common orchid growing in bogs and peaty lands throughout the eastern and centra! United States. The stems are from 4 to 6 dm. in length, terminated by many-flowered spike. The flowers are white, the lip being copiously fringed and the spur about 2 cm. in length. — After Troth. cylindrical body which is strongly concave on one side and spread- ing at the upper portion. The pollinia are granular. Pollination CLASSIFICATION OF ANGIOSPERMS. 501 may be effected by insects, but is usually brought about by arti- ficial means (hand-pollination). The fruits require several months to become fully grown, and an equal period of time is necessary for their maturity, which is indicated by their yellow color. They are then gathered and cured by alternately steaming and drying them, until they acquire the dark brown color and the odor of the commercial article. Vanilla is cultivated in all tropical countries where the temperature does not fall below 18° C., and the humidity is considerable. Usually vanilla culture is combined with that of Cacao. The plants begin to yield fruits the third year and continue bearing for thirty or forty years (Fig. 274). The yellow-flowering Cypripediums of the United States (C. pari'iflorum and C. parvifiorum pubcscens} yield the cypripedium which was formerly official. The plants are a foot or two high. The leaves are oval or elliptical (in the latter) or elliptical or lanceolate (C. parviflorum} . In C. pubescens the lip is pale yellow with purple veins, 25 to 50 millimeters long, and possesses a tuft of white, jointed hairs at the throat. In C. parvifiorum the lip is smaller and non-hairy. C. acaule is shown in Fig. 275. The root-stocks of a number of Orchids are rich in mucilage and yield the drug salep or a product resembling it. Salep occurs in the form of globular or somewhat flattened, more or less trans- lucent, light yellowish-brown tubers, 2 to 4 cm. long, of a horny texture and a mucilaginous taste. The principal constituent is mucilage, which originates in the cell-contents. It may contain in addition either starch or sugar. While the Orchidacese, which contains about 6,000 species, ranks second in numbers to the Compositse, there is probably no family which exceeds it in interest. The plants are extensively cultivated, and some of their flowers are the highest priced known in the commercial world. There are few localities in which there are not some orchids to be found, illustrations of several of which are here shown (Figs. 275 to 279). B. CLASS DICOTYLEDONE^E. The following are some of the prominent features of the Dicotyledons: (i) The leaves are reticulately (open) veined and usually with an irregular margin, being sometimes deeply lobed; 502 A TEXT-BOOK OF BOTANY. FIG. 278. Arethusa bulbosa, an Orchid growing in bogs from Newfoundland to South Carolina, and west to Minnesota. It produces a solitary magenta-crimson flower on a long, .slender scape, in the sheaths of which a solitary linear leaf arises and protrudes after the flower opens. In the illustration are shown a number of plants, some of which show the small bulbs at the base. — After Troth. (2) the parts of the flower are usually in circles of 2 to 5 each; (3) the stems and roots generally increase in thickness by means of a cambium, and the vascular bundles are open, varying from CLASSIFICATION OF ANGIOSPERMS. 503 FIG. 279. Rattlesnake Plantain, a rather common orchid, variously known as Epi- factis, Peramium, or Goodyera pubescens. It is generally found growing in coniferous woods and characterized by the dark-green basal leaves with their prominent nerves and numerous white reticulating veins. The flowers are greenish-white, numerous and crowded on the erect scapes. — After Troth. simple collateral to bi-collateral ; annular rings are formed in the perennial stems; (4) the germinating plant usually has two coty- ledons which are opposite each other. The Dicotyledons are divided into two series or sub-classes, depending upon whether 504 A TEXT-BOOK OF BOTANY. the parts of the corolla are distinct or are united, namely, the Archichlamydeae and Metachlamydese. ARCHICHLAMYDE.E OR CHORIPETAL^E. The Archichlamydeae or Choripetalae comprise those dicoty- ledonous plants in which the petals are separate and distinct from one another, or are entirely wanting. I. ORDER PIPERALES. The plants of this order are mostly tropical herbs and shrubs and possess very small flowers which have neither petals nor sepals. The leaves are simple and without stipules, the most important family medicinally, as well as in other ways, being the PIPERACE^E, to which the following medicinal plants belong. Piper nigrum is a woody climber that has leathery, grayish- green, ovate-elliptical leaves (Figs. 281, 282), with three prominent middle nerves and two side nerves ; the flowers are perfect, sessile and form an elongated fleshy spike ; the fruit is a berry which is yellowish-red when ripe. The unripe fruit constitutes the BLACK PEPPER of commerce. WHITE PEPPER is the ripe berry of Piper nigrum from which the epicarp is removed, while " LONG PEPPER " is obtained from Piper longmn, an entirely different plant, and consists of the entire spikes with immature fruits. Piper Cubeba is a climbing perennial, with leathery elliptical- ovate or long elliptical leaves ; the flowers are dioecious and arranged in spikes ; the fruit is a berry, the pedicel becoming much elongated after fertilization. The unripe fruit is the part used in medicine and is official as cubeb. Piper angustifolium yields MATICO, formerly official. The plant is a shrub growing in Central and South America and is characterized by its long, oblong-lanceolate, deeply reticulate, very hairy leaves. The flowers and fruits are very small and arranged in long, slender spikes, which are frequently found in the drug. Matico contains 2 to 3 per cent, of a volatile oil, containing a stearoptene matico camphor, which appears to be the most im- portant constituent. It also contains an acrid resin, a bitter prin- ciple, and a crystalline principle, artanthic acid. Other related CLASSIFICATION OF ANGIOSPERMS. 505 FIG. 280. Diagrams of cross sections of the flowers of a number of families of dicoty- ledonous plants showing the number and position of the parts with reference to each other: t, stem of plant; f, foliage leaf; b, bracts or leaves on the flower-stalk; s, sepals; p, petals; a, stamens; c, ovary; per, perianth. A, Linaceae; B, Cruciferas; C, genus Citrus; D, Rosaceae; E, Berberidaceas, showing nectaries (k) on the petals; F, Lauraceae, showing staminodes (g); G, epigynous flower of Rubiaceae; H, Ericaceae; I, Labiatae, showing position of other flowers (sv) in the cymes; J, Violacea? showing spurred stamens; K, Campanulaceas, showing bracts (a, /3) the relation of the sepals (i, 2, 3, 4 and 5), and two pos- terior hairy stamens; L, Leguminosae, showing the large posterior petal (p) known as the vexillum or standard, the two lateral petals (v) situated under the standard known as ake or wings, and the two anterior petals which are covered by the wings and partly cohering to form a prow-shaped body called the carina or keel (k). — Adapted from Warming. So6 A TEXT-BOOK OF BOTANY. FIG. 281. Black pepper (Piper nigrum), a climbing shrub growing in Botanic Gardens, Port of Spain, Trinidad. The illustration shows the ovate-elliptical leaves, opposite which are the fruiting spikes, which when ripe are of a yellowish-red color. The plant has been introduced into many tropical countries and is not infrequently seen in botanic gardens throughout the civilized world. — Reproduced by permission of The Philadelphia Commercial Museum. species of Piper are used in tropical America similarly to Piper angustifolium. The leaves of a number of species of Piper (known as " betel CLASSIFICATION OF ANGIOSPERMS. 507 5o8 A TEXT-BOOK OF BOTANY. leaves ") are mixed with the Areca nut and lime and constitute what is known as " BETEL," which compound is used for chewing, in India and other countries, chiefly on account of its astringency. The root of Piper methysticum is also chewed, and when mixed with the milk of the Cocoanut yields an intoxicating drink which is used by the inhabitants of the Sandwich Islands. The dried root has been used in medicine under the name of METHYSTICUM or KAVA-KAVA. It consists of large, branching, soft, spongy, dark brown pieces, which are tough, fibrous, and with a pungent, somewhat bitter taste. Kava-kava contains 3 resins, one of which has marked anaesthetic properties ; an alkaloid, kavaine ; a neutral body, methysticin ; and about 50 per cent, of starch. The drug is free from calcium oxalate crystals, these being usually wanting in the Piperaceae. II. ORDER SALICALES. This order comprises but a single family, namely, the SALI- CACE^: or Willow Family, to which belong the willows and pop- lars. The plants are dioecious shrubs and trees; the flowers being in aments or catkins and without petals or sepals. The fruit is a capsule containing many seeds which are small and with long, silky hairs at the base. The barks of a number of the members of this group contain glucosides, as salicin, which is found in Salix alba, the white willow of Europe and the United States, and the brittle willow Salix fra- gilis; and populin, which is found in the white or silver-leaf poplar (Populus alba) of Europe, Asia, and the United States and Populus pyramidalis of Italy. These principles are also found in other species of willow and poplar. A number of the barks con- tain a yellow coloring principle allied to quercitrin, as Salix daph- noides of Europe and Salix alba. Tannin is a common constituent in both the willows and poplars. The buds of many of the poplars contain in addition a volatile oil which is in the nature of a di- terpene, as those of Populus pyramidalis. Populus balsamifera, the tacamahac or balsam poplar of the United States and Canada, furnishes the BALM OF GILEAD buds which are coated with an oleo-resin that gives them their aromatic properties. Populus CLASSIFICATION OF ANGIOSPERMS. 509 mgra yields a volatile oil, of which the important constituent is humulene. The charcoal used medicinally is prepared by burning the wood of the young shoots of the white and black willow, poplar, beech, or linden without access of air. III. ORDER MYRICALES. This group somewhat resembles the Salicales in that the flowers are in aments. The flowers are either pistillate or staminate, and mostly dioecious in our native species. The most important family is the MYRICACE^E or Bayberry Family. The genus Myrica is especially characterized by the fact that the outer layer of the drupe is waxy. This is particularly true of the following species : Myrica cerifera, the wax myrtle of the sandy swamps of the United States, contains a volatile oil. The fruit of sweet gale (M. Gale) yields a volatile oil containing a camphor. The sweet fern (Comp- tonia peregrina} found in the United States yields a volatile oil resembling that of cinnamon. The rhizome of this plant contains also tannin and possibly gallic and benzoic acids. IV. ORDER JUGLANDALES. The plants are trees with alternate, pinnately-compound leaves. The staminate flowers are in drooping aments, the pistillate being solitary or several together. The flowers are monoecious and have a more or less distinct perianth consisting of 3 to 6 lobes. The fruit is a kind of drupe formed by the union of the torus with the wall of the ovary. There is but one family in this order, namely, the JUGLANDACE.E (Walnut family), which includes the hickory (Hicoria) and walnut. The black walnut (Juglans nigra) of the United States yields a valuable timber and an edible nut; the white walnut or butternut (/. cinerea) of the United States yields the butternuts which are edible, and a bark which has medicinal properties and was formerly official under the name of JUGLANS. It contains about 7 per cent, of a yellow, crystalline acrid principle which is colored purple with alkalies ; 2 to 2.5 per cent, of a crystalline resin; volatile oil, tannin, sugar, and a fixed oil. The bark of the stems of the butternut tree is used in dyeing. The ripe fruits are edible, as also the green nuts when 5io A TEXT-BOOK OF BOTANY. pickled. The sap of the tree contains a sugar. The wood, though inferior to black walnut, is used in cabinet making. /. regia, native of Persia and cultivated in various parts of Europe and California, yields the edible ENGLISH WALNUT. The following species of hickory yield edible nuts : The shell- bark hickory, Carya (Hicoria) ovata; the pecan (C. illinoensis) common from Illinois southward; and the king nut (C. lacini- osa). The wood of these as well as C. glabra and other species of hickory is used where strength and elasticity are required. Coloring principles are found in the barks of a number of species and are used for technical purposes. The following con-, tain yellow coloring principles : Hicoria ovata, H. sulcata, and H. glabra (pig-nut hickory) ; green coloring principles are found in H. tomentosa, and yellowish-brown principles in Juglans nigra, J. cinerea, and /. regia. The fatty oils from the cotyledons (kernels) of both hickory- nuts and walnuts are articles of commerce, and they have been used in medicine. V. ORDER FAGALES. The plants are trees or shrubs with alternate, petiolate, simple, pinnately veined leaves. The flowers are in aments, monoecious, and with a more or less distinct perianth. The fruit is a nut which is subtended by the mature involucre (bur or cup) or samara, the seeds being without endosperm (Fig. 283). a. BETULACE^ OR BIRCH FAMILY.— The plants are aromatic trees or shrubs and are represented in the United States by such trees as hornbeam (Carpinus), iron wood (Ostrya), and birch (Betula) ; and by such shrubs as the hazelnut (Corylus) and alder (Alnus). The plants yield a volatile oil consisting largely of methyl salicylate. The bark of the sweet birch (Betula lenta} yields the oil of betula which is official and closely resembles the oil of wintergreen. The bark of a number of plants of this family yields tannin and yellow coloring principles. A number of species of Betula yield a sweet sap, as B. lenta, and B. Bhojpattra of Rus- sia. The nuts of some species are edible, as the filbert or hazelnut of Europe (Corylus Avellana), the hazelnut of the Orient (C. Colurna), the American hazelnut (C. americana). CLASSIFICATION OF ANGIOSPERMS. 511 b. FAGACE^ OR BEECH FAMILY.— This family includes some of our largest forest trees, these being rather characteristic of temperate regions. They are all highly valued for their timber, and yield other valuable products besides. One notable character- istic is that all of the chestnuts and oaks and some of the beeches FIG. 283. White oak A, characteristic, lobed leaf; B, young branch showing pistillate (p) and staminate (s) flowers; C. hairy bracts of a staminate flower; D, group of hairs from bract; E, stamen; F. pollen grains; G, cluster of pistillate flowers; H, acorn with cupule; I, starch grains from acorn, which vary from 10 to 25 n long: J. trans- verse section of bark showing cork (k). stone cells (st), bast fibers (b). crystal fibers (ca), medullary rays (m), parenchyma (p); K, longitudinal section of bark showing end of bast fiber (b) crystal fibers (ca) and parenchyma cells (t) containing tannin. contain tannin in the wood, bark, and leaves. The oaks are further notable in being prone to the attack of gall-producing insects (various species of Cynips) whereby the peculiar excrescences known as galls are formed on the leaves and young shoots. Among the oaks which yield galls rich in tannin are the following : Quercus infectoria of the Mediterranean, which yields the official Turkish 512 A TEXT-BOOK OF BOTANY. or Aleppo galls (pp. 206, 334) ; Quercus Robur, which is some- times divided into Q. pubescens and Q. pedunculata, yields a European gall; the live oak (Q. virginiana) of Texas; and Q. lobata of California. Various oaks of the Southern States also produce "ink balls " or " ink galls," as Q. coccinca and Q. imbri- caria. Several species of oak are used in the tanning industry, as that of white oak (Quercus alba), red oak (Q. rubra), Spanish oak (Q. digitata), and black oak (Q. vclutina), all of North America ; Q. pedunculata and scssiliflora of Germany, and Q. den- tata of Japan. The glucosidal coloring principle quercitrin is found in the bark of Quercitron or black oak (Q. velutina}. Q. coccifera of Southern Europe yields a red coloring principle which is used in dyeing. The wood of the American beech (Fagus americana) and of the European red beech (F. sylvatica) yields a tar from which on distillation the official CREOSOTE is obtained. The cork of commerce which is used for a variety of purposes is derived from the bark of several species of Quercus, namely, Q. Suber and Q. occidentalis, growing in Spain, Southern France, and Algiers. The cotyledons of the seeds of the Beech family are rich in proteins, starch, and oil, and some of the nuts are edible, as the Spanish CHESTNUTS obtained from Castanea vulgaris, American chestnut from C. dentata, and CHINQUAPIN from C. pumila (Fig. 202). VI. ORDER URTICALES. This order embraces three families which, while they agree in certain characters, are quite distinct in other ways. a, ULMACE^ OR ELM FAMILY.— The plants are trees or shrubs with alternate, simple, serrate, petiolate leaves. The flowers are monoecious or dioecious, with a 4- to 6-divided peri- anth. The fruit is a i -seeded drupe, samara, or nut. The typical group of this family is that of the elms, of which the American or white elm ( Ulmus amcricana} is the most prized for orna- mental purposes. The elms yield valuable timber, and the bark of Ulmus campestris of Europe is used for tanning and dyeing be- cause of the presence of tannin and a yellow coloring principle. CLASSIFICATION OF ANGIOSPERMS. The inner bark of the red or slippery elm (Ulmus fulva) is used in medicine on account of its mucilaginous character (see Fig. 119, C}. The tree has a gray, fragrant bark; leaves which are very rough above and become fragrant on drying, and the wood is reddish-brown. The samara is not hairy as in some of the other species. FIG. 284. View taken in Ceylon of a part of a grove of 4-year-old rubber trees (Ficus elastica). This tree is extensively cultivated in Ceylon and other portions of tropical Asia, and most all of the Asiatic rubber is produced by this tree. The trees may be tapped when 25 years old, and for so succeeding years yield 40 pounds caoutchouc every 3 years. — Reproduced by permission of The Philadelphia Commercial Museum. b. HORACES OR MULBERRY FAMILY.— The mem- bers of this family are herbs, shrubs, or trees, many of them con- taining a milk-juice or latex. There are many representatives in the tropical regions and some in temperate regions. The flowers are unisexual, with a 4- to 5-parted perianth, and occur in spikes or ament-like clusters. Cannabis saliva. — This .is the plant yielding hemp and also the 33 A TEXT-BOOK OF BOTANV. drug Cannabis indica. The plant is an annual branching herb from i to 3 M. high. The leaves are alternate above, opposite below, digitate with 5 to 1 1 linear-lanceolate, deeply serrate lobes. The flowers are dioecious, the staminate occurring in panicles and the pistillate in erect simple spikes (Figs. 409, 410, 412). From the inner bark of the stem, which is fibrous, the HEMP FIBER is prepared. PIG. 285. Several large rubber trees (Ficus elastica) growing in Java and showing the production of numerous aerial roots from the branches. It occurs in damp forests from the base of the Sikkim Himalaya eastward to Assam and Arracan. There are large government plantations in-Assam, and it is also being cultivated in other provinces. Kurz remarks that it is frequent in Upper Burma, and that whole forests of the species are said to exist in the valley of Hookhoom. — Reproduced by permission of The Philadelphia Com- mercial Museum. Humulus Lupulus or hop is a twining perennial plant, curving to the right, with opposite, palmately 3- to 7-lobed (or simply dentate above) rough leaves (Fig. 286). The flowers are dioecious, the staminate ones occurring in panicles and the pistillate in ament-like spikes. On the inner surface of each scale of the ament occur two flowers consisting of a membranous perianth CLASSIFICATION OF ANGIOSPERMS. 515 and a bicarpellary ovary with two long styles. After fertilization the aments become cone-like, and this compound fruit constitutes the hop of commerce. This fruit differs essentially from the true strobiles or. cones of the Gymnosperms in that the seed in the latter is replaced by an akene. " Hops " are extensively used ing coneu emoryo; o. sunace view 01 oraci snowing epidermis ana ecus conic oxalate; H, cystolith of leaf; I, cystolith of stem; J, glandular hairs (lupulin). in the manufacture of various beers and to a limited extent in medicine. Ficus Carica, which yields the edible fig, is a deciduous tree from 3 to 7 M. high, and with large, 5-lobed, petiolate leaves. The flowers are situated in a hollow torus the walls of which 516 A TEXT-BOOK OF BOTANY. after fertilization become thick and fleshy, constituting the fruit. The best figs come from Turkey, Italy, Spain, and Provence. A large number of the plants belonging to the Moraceae yield economic products, some of which, as the drug Cannabis indica obtained from Cannabis sativa, are powerful narcotics. HASH- ISH or BHANG is a preparation made from the dried leaves, stems, and flowers of the pistillate plants and is smoked either alone or with tobacco, or chewed in combination with other substances, or an intoxicating drink is made from it, it being extensively used by the inhabitants of Arabia, Persia, India, and other Oriental countries. The leaves of Ficus Ribes of the Philippine and Mo- lucca Islands are smoked like opium. The milk-juice of a number of plants belonging to the Moraceae is the-source of arrow poisons. The URARI POISON of Brazil is obtained from Ficus atro.v; the IPOH ARROW POISON of Java and Borneo is derived from the Upas- tree, Antiaris to.vlcaria. Many of the plants of the group contain emetic principles, as the COCILLANA BARK of Guarea Rusbyi, a tree of Bolivia. The milk-juice of quite a number of species of Ficus yields India-rubber or caoutchouc ( Fig. 128) , as Ficus elastica of the East Indies, F. toxicaria of South America, F. elliptica and F. prinoides of New Granada and several other species of Brazil, Brosimum spurium of Jamaica, Cecropia peltata of the West Indies and South America, and Castilloa elastica of Mexico and the West Indies. Ficus bengJialensis of India and tropical Africa, and Ficus Tsiela of India, yield gum-lac. Ficus altissima and F. religiosa of tropical Asia yield shellac on the puncture of the stems by a hemipterous insect (Coccus lacca). A yellow coloring principle is found in Cudrania javanensis of tropical Asia and Africa, Chlorophora tinctoria of Mexico, Madura aurantiaca (Toxylon pomiferum) or osage orange, a hedge plant of North America ; Ficus tinctoria of the Friendly Islands and F. asperrima of India. . A fixed oil is obtained from Artocarpus Blumei of Java. A large number of the plants of the Moraceae yield edible fruits besides the fig tree already described, as the BREAD-FRUIT trees (Artocarpus incisa) of the Sunda Islands and the JACK-TREE CLASSIFICATION OF ANGIOSPERMS. 517 (A. intcgrifolia} of the East Indies, the WHITE MULBERRY (Morus alba} and the BLACK MULBERRY (Morus nigra}. The leaves of the white mulberry (Morus alba), indigenous to China and cultivated since the twelfth century in Europe and now in cultivation to a limited extent in the United States, are the chief food of the silkworm. c. FAMILY URTICACE/E.— The plants belonging to the Urticaceae or Nettle family are chiefly herbs with mostly petiolate, stipulate, simple leaves. The flowers are small and with 2 to 5 distinct or more or less united sepals. The fruit is an achene; the embryo is straight and surrounded by an oily endosperm. The stems and leaves of several of the genera are characterized by stinging hairs, this being especially true of the sub-group to which the genus Urtica or stinging nettle belongs. Of the stinging nettles the following are used in medicine: Urtica dioica of Europe and naturalized in the United States, U. spatulata of Timor, Laportca crenulata of tropical Asia, L. moroides of Queensland, and Girardinia palmata of India. In the small nettle (Urtica urens) of Europe and the United States an alka- loid has been found, and Laportea stimulans has been used as a fish poison. Boehmeria cordata of Brazil is used as a substitute for Arnica. The fibers of a number of the Urticaceae have been found useful, of which the following may be mentioned : Urtica cannabina of Asia, U. dioica, U. urcns and Boehmeria nivea of the Sunda Islands and China, the latter of which yields RAMIE.. The akene of Debregeasia edulis of Japan and the rhizome of Pouzolzia tuberosa of China and Japan are edible. VII. ORDER PROTEALES. The members of this group are mostly shrubs and found prin- cipally in the Tropics and southern hemisphere, several species being cultivated in greenhouses for the sake of the beautifully colored flowers which are in crowded inflorescences. The order is represented by but a single family, namely, the Proteacese. The leaves are leathery and vary even on the same plant from sim- ple to compound. The glucoside proteacin and a bitter principle are found in Leucadendron argentewn and L, concinnum, both 5i8 A TEXT-BOOK OF BOTANY. of Africa. A gum-resin is found in Grevillea robusta of Aus- tralia, and a tannin in the bark of Lomatia obliqua of Chile. A golden-yellow coloring principle is obtained from the flowers of Persoonia saccata of Australia. The wood of Protca grandi- ftora of Abyssinia is used in wagon building, and Leucospermum conocarpum of Cape Colony yields a valuable red wood and a tan bark. Banskia (cmula of Australia and the sugar-bush (Protea melli- fera) of Australia and P. speciosa have a sugary cell-sap. The oily seeds of the Chilean hazelnut (Guevina Avellana) are highly prized as food by the inhabitants. The seeds of Brabeium stellati- folium or wild chestnut of Cape Colony are poisonous when fresh, but on roasting they become edible and are used as a substitute for coffee. VIII. ORDER SANTALALES. This order embraces a number of families which are quite distinct in several respects. a. LORANTHACEyE OR MISTLETOE FAMILY.— The plants are half-parasites with well-developed leaves containing chloroplastids. They live on trees by means of haustoria. To this family belongs the American mistletoe (Phoradendron fla- vescens), parasitic on oaks, elms, the tupelo (Nyssa), red maple and other deciduous trees. The white, globose berries of this plant are quite poisonous, as are also those of the European mistle- toe (Viscum album} and the oak mistletoe of Southern Europe (Loranthus europtrus). Viscum album contains a volatile alka- loid, VISCINE, a glucoside and a resinous principle. This sub- stance serves to attach the seeds to the barks of trees, where they germinate, and it is used in the manufacture of BIRD-LIME, which owing to its viscid character is used to catch small birds. b. SANTALACE^ OR SANDALWOOD FAMILY.— The plants are chlorophyllous herbs or shrubs which are common in warm countries, and many of which are parasitic on the roots of other plants. A number of them contain volatile oils, as the wood of various species of Santalum. The official oil of sandal is obtained from the scented wood of the white sandalwood (Santalum album}, a small tree growing wild and also cultivated in India and the CLASSIFICATION OF ANGIOSPERMS. 519 East Indian Archipelago. The wood from the East Indies is known as Macassar sandal wood and yields 1.6 to 3 per cent, of oil, while the Indian wood yields 3 to 5 per cent. The oil consists of 90 to 98 per cent, of santalol. Fiji oil of santal is obtained from S. Yasi; and Australian oil of santal from Fusanus acuminatus and F. spicatus. The Chinese oil is obtained from Santalum Freycinctianum and S. Preisci. c. FAMILY BALANOPHORACEyE.— The plants of this group are indigenous to tropical and sub-tropical regions. They are root-parasites and develop tuberous rhizomes and fleshy shoots which are yellow and without foliage leaves. Balanophora elon- gata of Java grows on the roots of Ficus and other plants, and contains a large quantity of wax and resin. Sarcophyte sanguined of Cape Colony, which lives on the roots of certain Acacias, con- tains a principle with the odor of scatol. Cynomorium coccineuvn, found in the countries bordering the Mediterranean, has a blood- red, astringent sap. The torus of the flower of Langsdorffia hypo- goca of tropical America is edible. The plant is also rich in wax, and in New Granada it is sold under the name of " Siejas " and burnt like a candle. IX. ORDER ARISTOLOCHIALES. This order includes two families which are very different in their general habits, a. The Rafflesiaceae are parasitic herbs that are almost devoid of chlorophyll. The reddish vegetative parts penetrate into the tissues of the host, and from these arise almost mushroom-like flowers which in the case of Rafflesia Arnoldii of Sumatra are I M. in diameter, being probably the largest flowers known. The plants of this family are rich in astringent substances. b. ARISTOLOCHIACE^: OR BIRTHWORT FAMILY. — The plants are non-parasitic herbs or shrubs, some of which are twining. The leaves are simple and in many of the plants more or less cordate and reniform. The flowers are perfect and the perianth is 3- to 6-lobed. While the flowers of our native species are rather small and insignificant, those of the tropical plants are extremely curious, being generally of some striking color and of various odd forms. Aristolochia reticulata is one of the plants that furnishes the 520 A TEXT-BOOK OF BOTANY. official drug serpentaria (see Vol. II). From a slender rhizome with numerous hair-like roots arise one or more short, leafy branches which are more or less simple, somewhat hairy, and bear oblong-cordate, prominent-reticulate, hairy leaves (Fig. 287). The flowers are borne on slender, scaly, basal branches ; the calyx tube is purplish and curved like the letter " s," being enlarged around the ovary and at its throat. The fruit is a capsule containing numerous flat or concave seeds. An allied species, Aristolochia Serpentaria, furnishes the drug Virginia snakeroot. .It is a more delicate plant, the leaves being ovate-lanceolate, acuminate; the flowers are solitary, and in some cases cleistogamous. This species is found growing in the United States, more especially east of the Mississippi, while Aristolochia reticulata is found west of the Mississippi from Arkansas to Texas. The plants of this genus contain volatile oils, and in addition to the two species mentioned 45 other species are used in medicine in various parts of the world. Asarum canadense (Canada snakeroot or wild ginger) is a plant common in the Northern United States and Canada (Fig. 288). The long and slender rhizomes are used in medicine. They are 5 to 15 cm. long, about 2 mm. thick, more or less bent and curved, purplish-brown externally ; whitish internally ; the bark is thick, wood with about 12 fibre vascular bundles, pith large ; the odor is aromatic ; the taste pungent and bitter. The drug con- tains 2 to 3 per cent, of a volatile oil containing a fragrant body, asarol ; a pungent, fragrant resin ; a yellow coloring principle which is colored dark green with ferric salts ; and starch. The volatile oil obtained from A. europccum contains a principle (asa- rone) which forms irritating vapors on heating. X. ORDER POLYGONALES. This order is represented by a single family, the POLYGONACE.E or Buckwheat family. The plants are mostly herbs, but include some twining vines and shrubs. The leaves are simple, mostly entire, and characterized by having a stipulate appendage (ocrea) which sheaths the stem. The flowers are small, perfect, and with a 2- to 6-parted perianth. The fruit is a 3- to 4-angled akene. The embryo is either straight or curved, and the endosperm is mealy. CLASSIFICATION OF ANGIOSPERMS. 521 FIG. 287. Southern serpentaria (Aristolochia reticulata) showing the cordate, reticu- lately-veined leaves, and the clusters of irregular flowers on the lower part of the stem. •—After Carson. A TEXT-BOOK OF BOTANY. RheuM officinale is the source of the " South China " rhubarb from Szechwan, Kanzu, and Shensi. The plant is a perennial herb resembling the garden rhubarb. The rhizome is vertical and gives rise to a leafy branch terminated by the inflorescence, which is a panicle. The leaves are large, with a sub-cylindrical petiole, FIG. 288. Wild Ginger (Asarum canadense), A, showing habit of plant, consisting of underground root-stock, the kidney-shaped leaves on long petioles, and the short peduncled, bell-shaped flower which develops close to the ground; B, longitudinal section of flower, and C, a transverse section of flower. — Bicknell, in Bulletin Torrey Bot. Club, Nov., 1897. a cordate or orbicular lamina which is either entire or coarsely and irregularly dentate. There are several nearly related species which also yield the drug. Rheum palmatum of Northern China has leaves which are lobed or deeply incised, which character is especially marked in the variety tanguticum. Rheum Rhaponti- cum, which yields English rhubarb, has leaves which are heart- CLASSIFICATION OF ANGIOSPERMS. 523 shaped at the base and with a more or less irregularly undulate margin. All of these species are more or less common in culti- vation in botanical gardens in Europe. FIG. 289. Curled dock (Rumex crispus) showing two of the lower, long-petioled, oblong- lanceolate and wavy-margined leaves, and a flowering branch, the upper leaves of which are narrowly-oblong and short-petioled. Rumex crispus or curled dock is a perennial herb growing in fields and waste places in the United States and parts of Canada. 524 A TEXT-BOOK OF BOTANY/ FIG. 290. Field or sheep sorrel (Rumc* Acetosella), a common weed containing a sour juice and growing in open fields; I to 3 dm. high, having narrow-lanceolate or halberd- shaped leaves, and somewhat reddish flowers in a panicled raceme. — After Brown. The leaves are oblong-lanceolate, with an undulate margin and rather long petiole. The flowers have a 6-parted, dark green perianth, and are perfect or polygamo-dicecious. The fruit is a CLASSIFICATION OF ANGIOSPERMS. 525 dark brown, cordate-winged, 3-angled akene. The dried root is somewhat fusiform, reddish-brown, and with a bitter, astringent . Polygonacese), one of about 30 species taste. It contains chrysophanic acid, tannin, calcium oxalate, and some of the other constituents found in rhubarb (Fig. 289). Rume.v Acetosella (field or sheep sorrel) is a slender annual herb with hastate leaves, having flowers in compound racemes. 526 A TEXT-BOOK OF BOTANY. The leaves contain oxalic acid, both free and in combination with calcium and potassium (Fig. 290). FIG. 292. Buckwheat (Fagopyrum esculentum): A, transverse section of grain showing pericarp (c), endosperm (n) and slender coiled embryo (e); B, transverse section of portion of grain showing epicarp (e), fibrous layer (f) , pigment layer (p) .outer epidermis of spermo- derm (o) , aleurone cells (a), endosperm cells containing starch (n); C, surface view of cells of epicarp; D, isolated fibers of pericarp; E. surface view of aleurone cells; F, isolated par- enchyma cells of endosperm filled with starch grains as seen in buckwheat flour; G, appear, ance of starch grains when mounted in oil and viewed with polarized light; H, swollen and altered starch grains which are two to three times the size of the normal grains. Tannin is obtained from a number of the plants belonging to the Polygonacese, as the root of Rumex hymenosepalus of Texas . CLASSIFICATION OF ANGIOSPERMS. 577 which is known as CANAIGRE; the rhizome of Polygonum Bistorta of Europe which yields the drug BISTORTA. Polygonum cuspidatum of the gardens contains emodin; poly- gonin, a glucoside yielding emodin ; and probably emodin methyl ether. Rumex ecklonianus of South Africa contains emodin, a volatile oil and a resin. The latter consists of emodin monomethyl ether; chrysophanic acid, physosterol (resembling rhamnol), etc. Polygonum Hydropiper and P. aviculare, both common in the United States, are poisonous to sheep. A number of the plants of this family yield food products. Buckwheat is the fruit of Fagopyrmn csculentum indigenous to Central Asia and cultivated in many parts of the world (Fig. 292). Some are also cultivated as ornamental plants, as the Prince's feather (Polygonum orientale}. XI. ORDER CHENOrODIALES OR CENTROSPERMJE. This order includes seven families, in all of which the embryo is curved or coiled, and the reserve consists chiefly of perisperm. a. CHENOPODIACEyE OR GOOSEFOOT FAMILY.— The plants are annual or perennial herbs with simple leaves and small perfect flowers, the fruit being a utricle. The fruits of a number of the group contain volatile oil, and are used in medi- cine, as the common wormseed (Chenopodium ambrosioides anthelminticum) , which is found in waste places in the United States. Most of the oil is distilled in Maryland and is known in commerce as " Baltimore oil." Chenopodium mexicanum yields saponin. Atriplex hortensis of Tartary yields indigo. The ash of very many species of Atriplex as well as genera of the Chenopodiaceae yields soda. The seeds of several species are edible, as of Chenopodium viride of Europe and Asia, C. Quinoa of Chile, etc. Seeds of Spinacia tetandra of the Orient are used in bread-making. A number of species are used as garden vegetables, as spinach (Spinacia oleracea) and beet (Beta vulgaris). The SUGAR BEET (Beta vulgaris Rapa}, which contains from 4 to 15 per cent, of cane sugar (sucrose), is largely cultivated in Germany, as well as to some extent in the United States, and is an important source of cane sugar. While the juice of the beet 528 A TEXT-BOOK OF BOTANY. contains a larger amount of nitrogenous substances than that of the sugar cane, it is practically free from invert sugar. b. AMARANTACE^E.— The plants are weed-like and much resemble the Chenopodiaceae. They yield anthelmintic principles, edible seeds, and the leaves of a number of species are used as vegetables. The ash yielded by some species contains potash, as Achyranthes aspera and Amaranthus ruber. Some are ornamental plants having a fasciated inflorescence, as the Cock's-comb (Celosia cristata). c. NYCTAGINACE^: OR FOUR-O'CLOCK FAMILY.— The plants are mostly herbs growing in America. The leaves are entire and simple, and the flowers are regular and in terminal, or axillary clusters. The perianth consists of a 4- to 5-lobed corolla- like calyx. The most common representative of this family is the Marvel-of-Peru or four-o'clock (Mirabilis Jalapa}. While this plant is an annual in the United States, in the Tropics the tuberous root is used as a substitute for jalap, and is sometimes sold for it. The seeds of this plant are edible, as are also the leaves of several species, as of Bocrhavia erecta, which are used as green vegetables. Some members of the group, as Bougainvillea spectabilis, are handsome plants with bright rose-colored bracts which envelop the small greenish flowers. d. PHYTOLACCACE^:.— The plants of this family are mostly tropical and are represented in this region by only one species, namely, the common poke (Phytolacca decandra), the root and fruit of which are used to some extent in medicine. This is a succulent, branching herb i to 4 M. high, having a large perennial root. The stem is hollow except for the thin, papery partitions. The leaves are simple, ovate-lanceolate, petiolate. The flowers are in racemes and characterized by having ten stamens. The fruit is a dark purple, juicy berry (Fig. 293). The roots of this species as well as others contain powerful drastic principles, as Pircunia littoralis and Anisomeria drastica of Chile. Phytolacca abyssinica contains saponin, and a red color- ing principle is found in the berries of Phytolacca decandra and Rivinia tinctoria of Venezuela. The leaves of some species of Phytolacca are used as greens. e. AIZOACEyE. — This is a group of mostly tropical plants, CLASSIFICATION OF ANGIOSPERMS. 529 FIG. 293. Poke weed (Phylolacca decandra). a common weed growing in low grounds and waste places. The plant is a perennial herb, usually sending up from a large, fleshy root a number of stout stalks, I to 3 M. high; the leaves are ovate-oblong, and opposite which may arise the racemes of whitish flowers. The roots are quite frequently mistaken for parsnips, and when eaten may cause serious illness. The young shoots and leaves are sometimes gathered in the spring and may be used for a table vegetable. The juice of the berries is said to have been used in Portugal to color Port wine. — After Brown. very many of them having fleshy leaves and adapted to arid re- gions. Many of the plants, particularly those belonging to the genus Mesembryanthemum, are much prized on account of thei1* 34 530 A TEXT-BOOK OF BOTANY. beautiful flowers, which expand only in the sunshine. The com- mon ice-plant of the gardens, so called because of the numerous glistening globules of water which cover the leaves, is M. crystal- FIG. 294. Soapwort, Bouncing Bet (Saponaria officinalis), a perennial herb growing to a height of 3 to 6 dm. and producing opposite, entire leaves, and cymose clusters of rose- colored flowers, commonly double. This plant has been more or less cultivated; it has, however, escaped from the garden, and, in spite of its beauty, has become a troublesome weed in some places. The jjlant contains saponin and therefore forms a lather with water. It has been used as a detergent. — After Brown. linum. This plant as well as other species of Mesembryanthemum are'used in medicine. The ashes yielded by the plants of this family also contain soda. The seeds of some species of fylesem- CLASSIFICATION OF ANGIOSPERMS. 531 bryanthemum as well as other members of this family are edible, and the leaves of some species are used as vegetables like lettuce. /. PORTULACACE^E.— The plants are fleshy or succulent herbs mostly indigenous to America. The two common represen- tatives are the spring beauty (Claytonia virginica), the tubers of which are rich in starch, and purslane (Portulaca oleracea), some- times used .as a green vegetable. The seeds of the latter plant as well as of other species of Portulaca are used in medicine. g. CARYOPHYLLACE^. — The plants are annual or peren- nial herbs, often swollen at the nodes, with opposite, entire leaves, and usually perfect regular flowers. The perianth has a distinct corolla of 4 or 5 petals. The fruit is a capsule and the seeds are half anatropous. The plants are most abundant in the northern hemisphere ; and some of them are quite showy, as the CARNATION (Dianthus caryophyllus} and pinks (Dianthus species) and the cultivated pink or Sweet William (D. barbatus). A number of the members of this group contain saponin, as Bouncing Bet (Saponaria officinalis} , which is naturalized in the United States (Fig. 294), Gypsophila Struthium of Spain and other species of this genus, as well as species of Lychnis and Her- niaria. The leaves of Paronychia argentea are used in Morocco as a substitute for tea. The roots of Scleranthus peren- nis of Eastern Europe are inhabited by an insect (Coccus polonica} which is used in the preparation of a red dye. The fleshy stitch-wort (Alsine crassifolia) of Europe and the United States is poisonous to horses. XII. ORDER RANALES. The plants are mostly herbs, but include some shrubs and trees, and comprise eight families of economic importance. a. NYMPH^ACE^: OR WATER LILY FAMILY.— These are aquatic perennial herbs with thick root-stocks and floating, peltate leaves. The flowers are perfect and have large petals. The seeds are enclosed in an aril, and the embryo has rieshy cotyledons. Nuphar luteum of Europe and Middle Asia contains the alka- loid nupharine and tannin, the latter of which splits into ellagic and gallic acids. The yellow pond lily (Nymphcea advena) of the 532 A TEXT-BOOK OF BOTANY. United States contains similar principles. The seeds and rhizomes are rich in starch and are used as food, in some cases starch being manufactured from them, as of various species of Nymphoca, Nelumbo (Lotus) and Victoria, and ILnryalc fcro.v. b. RANUNCULACE^: OR CROWFOOT FAMILY.— These are annual or perennial herbs with simple or compound leaves, regular or irregular flowers, and fruits which are achenes, follicles, or berries. FIG. 295. Fruiting top of Golden Seal (Hydrastis canadensis) , showing the two large palmate leaves, above one of which is a berry-like fruit which is bright red when ripe. Hydrastis canadcnsis yields the official drug hydrastis. From a short, thick, horizontal rhizome with numerous slender roots rises a short stalk with a few palmately lobed, reniform, petiolate, pubescent leaves. The flowers are small, solitary and greenish- white, and the fruit is a head of crimson berries somewhat resem- bling the raspberry (Fig. 295). Cimicifuga racemosa (black cohosh or black snakeroot) yields the official drug cimicifuga. This is a tall perennial herb with large knotty rhizome, large decompound leaves, and a long raceme of white flowers (Fig. 296). CLASSIFICATION OF ANGIOSPERMS. FIG. 296. A group of transplanted wild plants with a plant of Cimicifuga racemosa in the foreground, showing the characteristic, large, decompound leaves and long raceme of flowers. Aconiium Napellus yields the official drug aconite (Fig. 186). This is a perennial herbaceous plant indigenous to Europe and extensively cultivated. From a tuberous root arises a simple leafy 534 A TEXT-BOOK OF BOTANY. stem with palmately lobed or divided leaves, and large, irregular, blue flowers which form a rather loose panicle (Fig. 297). The sepals are 5 in number, the posterior upper one being large and FIG. 297. Acomtum Napellus . A, one of the long-pctiolate. divided leaves; B, epi- dermal cells of lower surface; c, an epidermal cell of the upper surface; D, transverse sec- tion through one of the principal veins showing two fibrovascular bundles, and strongly collencliymatic cells beneath the lower epidermis; E, one of the few hairs from the petiole; F, lignified bast fibers surrounding the sieve jn the petiole; G, longitudinal section through fibrovascular bundle showing spiral and reticulate tracheae (t), bast fibers (b) and some of the collenchyma cells (c), those at the left exhibiting longitudinal pores which give a crystal -like effect. helmet-shaped. The petals are 2 to 5 and rather small ; the two posterior or upper ones which are hooded and concealed in the helmet-shaped sepal are nectar-secreting (Fig. 223, £). The fruit is a follicle and contains numerous small seeds. CLASSIFICATION OF ANGIOSPERMS. 535 FIG. 298. Wood anemone, wind flower (Anemone qutngue folia) , one of the earliest flowering woodland plants. It is a low, slender plant with 3 trifoliate leaves forming an involucre, from the junction of which arises a peduncle, bearing a solitary flower. The sepals vary in number as well as in color; there are generally 5, which are usually whitish, or slightly tinged with purple. — After Brown. Delphinium Staphisagria, which yields the official staphisagria or stavesacre, is a handsome, tall, biennial larkspur, with dark green, palmate 5- or 7-lobed leaves and blue or purplish flowers in 536 A TEXT-BOOK OF BOTANY. FIG. 299. Wild Columbine (Aguilegia canadensis) , one of the most interesting plants of the Ranunculaceae. It grows in the crevices of rocks and in open woods, and is a very striking plant, with its 5 long-spurred, scarlet petals. A number of species of Aguilegia are cultivated, and their flowers show considerable variation in form and color. — After Brown. racemes. The flowers are zygomorphic and somewhat resemble those of Aconite. CLASSIFICATION OF ANGIOSPERMS. 537 PULSATILLA, which was formerly official, is obtained from sev- eral species of Anemone growing in Europe. These are perennial herbs (Fig. 206) with basal leaves which are deeply lobed or dissected, those of the stem forming a kind of involucre near the flower. The flowers are rather large and with numerous petaloid sepals. The fruit is a densely woolly achene in those species which are used in medicine. The entire plant is used and contains an acrid volatile oil, the principal constituent of which is an anemone camphor (anemonol). The latter is easily decomposed into anemonon, which on fusion becomes exceedingly acrid. Similar principles are found in other species of Anemone as well as in certain species of Ranunculus (buttercup) and Clematis Vitalba of Europe. Very many of the other Ranunculaceae contain active princi- ples. The glucoside helleborein, which resembles digitalin in its medicinal properties, is found in Helleborus niger, the BLACK HELLEBORE of Europe, and probably in other species of Helleborus, as well as in Actcea spicata, the baneberry of Europe, and Adonis vernalis, the false hellebore of Europe and Asia. c. BERBERIDACE^ OR BARBERRY FAMILY.— The plants of this family are herbs or shrubs with simple or compound leaves, and flowers either single or in racemes (Figs. 134, E; 81, T}. The fruit is a berry or capsule. g Berberis Aquifolium (trailing mahonia) yields tHe unofficial drug berberis. It is a low, trailing shrub with 3- to 7-compound, scattered leaves. The leaflets vary from oval to nearly orbicular, are obtuse at the apex, slightly cordate at the base, finely reticulate, and spinose-dentate. The flowers are yellow and in dense ter- minal racemes. The fruit is a blue or purplish berry. Caulophyllum thalictroides or blue cohosh of the Eastern United States is a perennial herb with a thick rhizome and large ternately compound leaves (Fig. 300). The flowers are small and greenish-purple. The fruit is peculiar in that it resembles a berry and consists only of blue, globular, naked seeds, the pericarp being ruptured and falling away soon after fertilization. The rhizome and roots were formerly official. It is a horizontal, much branched rhizome with broad, concave stem-scars, and numerous roots ; it is grayish-brown externally, sweetish, slightly bitter and 538 A TEXT-BOOK OF BOTANY. somewhat acrid. The drug contains an acrid, saponin-like gluco- side, leontin ; a crystalline alkaloid, caulophylline ; two resins ; and starch. For analysis of the seeds see Chem. News, 1908, p. 180. Podophyllum peltatum or May apple is the source of the official podophyllum. This is an early, herbaceous, low, perennial plant forming large patches by reason of its long dichotomously branch- FIG. 300. A group of transplanted plants, showing in the upper portion a fruiting plant of blue cohosh (Caulophyllum ikalictroides), ing rhizome (Fig. 182). It forms two kinds of branches, one bearing a single, peltate, 5- to 7-lobed leaf ; and another bearing in the axil of two similar leaves a white flower which gives rise to a large, yellowish, ovoid berry which is edible. d. MENISPERMACE^: OR MOONSEED FAMILY.— The plants are climbing or twining, herbaceous or woody vines with simple, entire or lobed leaves and small, greenish-white dice- CLASSIFICATION OF ANGIOSPERMS. 539 cious flowers. The fruit is a drupe and contains a characteristic crescent-shaped seed. Menispermum canadcnse or Canada moonseed yields the drug menispermum which was formerly official. It grows in the North- ern United States and Canada and is a high-climbing vine with broadly ovate, cordate and 3- to 7-lobed leaves (Fig. 180). The flowers are in panicles giving rise to a characteristic cluster of bluish-black berries. The rhizome occurs in pieces which are 5 to 7 dm. long and 2 to 5 mm. in diameter ; externally it is longitudinally wrinkled, of a yellowish-brown color and somewhat resembles Sarsaparilla. In transverse section, however, it is very distinct (Fig. 194). The drug has a bitter taste and contains a bitter alkaloid menispine, berberine and starch. In addition it contains the alkaloid oxyacan- thine which is also found in Berberis vulgaris of Europe and the West Indies. Jateorhiza palmata yields the official drug calumba (columbo). The plant is a herbaceous climber somewhat resembling Meni- spermum, the leaves being more decidedly lobed. The flowers form long racemes. Chondrodendron tomentosum, the source of the unofficial drug pareira, is a high woody twiner. The leaves are large, petiolate, broadly ovate or rounded, slightly cordate, and densely tomentose on the lower surface. Anamirta paniculata is a woody climber of the East Indies. The fruits, known as fishberries or COCCULUS, are used as a fish poison by the natives and contain the neutral principle picrotoxin. Very many other plants of the Menispermacese contain power- ful toxic principles and are used as fish poisons and as antidotes to snake poison. Several species of Abuta are used in the prepara- tion of curare poison. e. MAGNOLIACE^: OR MAGNOLIA FAMILY.— The plants are mostly trees or shrubs and are represented in the United States by the magnolias and tulip tree (Liriodendron Tulipifera). The latter is a magnificent tree with characteristic leaves (Fig. 204) and large, fragrant, orange-colored, tulip-like flowers. The plants of this family contain a variety of constituents. 540 A TEXT-BOOK OF BOTANY. Ethereal oils containing anethol and resembling those of anise are found in the fruit of Illicium anisatum (I. verum} or STAR ANISE, a small evergreen tree growing in the mountains of South- ern China. A volatile oil with a disagreeable odor is found in a closely related species /. religiosum (Shikimi) of Japan. The fruit of the latter plant is known as JAPANESE STAR ANISE and contains in addition a poisonous neutral principle. The fruits of both star anise (Illicium) and the Japanese star anise are made up of 6 to 8 radially arranged follicles, which are dark brown, dehis- cent on the upper (ventral) surface and each contains a single, brown, shiny seed. Star anise has an odor and taste resembling anise. Japanese star anise has a bitter taste and in addition is brownish-black, very woody and strongly beaked. Volatile oils are also found in the flowers of the various species of Magnolia and in Michelia Champaca found in the Malay Archi- pelago and cultivated in India and Brazil, and in M. nilagirica of India, the latter being used in perfumery. Winter's bark is derived from Drimys Winteri, a shrub of South America. It occurs in quills which are from 5 to 10 mm. thick ; externally it is grayish-brown and covered with numerous lichens ; the fracture is short, the broken surface being marked by stone cells and resin canals ; the odor is fragrant ; taste aro- matic, pungent and bitter. The drug contains a volatile oil which consists essentially of a hydrocarbon known as winterin ; it also contains a resin. A crystalline principle magnolin, a glucoside and a volatile oil are found in Magnolia macro phylla (or cucumber-tree of the Southern States) and M. tripetala or umbrella tree growing southward from Pennsylvania. A bitter principle liriodendrin, a volatile oil, an alkaloid, and a glucoside are found in the tulip poplar or tulip tree. The bitter and aromatic bark of Michelia montana of Java is used like cascarilla (Euphorbiacese). A bitter resin is found in the fruit of Talauma Pluniieri or the Antilles. A glucoside which dissolves the blood corpuscles is found in Talauma macrocarpa of Mexico. A red coloring principle soluble in water occurs in the leaves of Michelia Tsiampaca of Java. The fruits of Schisandra propinqua of Nepal and Kadsura Rox- CLASSIFICATION OF ANGIOSPERMS. 54i burghiana of Japan contain considerable mucilage and are edible. The latter plant is also used as a hair-restorer. From the ash of Schizandra chincnsis of China and Japan sodium chloride is obtained. The flowers of Magnolia Juglans are used to flavor tea and the FIG. 301. North American papaw (Asimina triloba): A, branch showing lateral nodding flower and the large, pinnately- veined, entire leaves: B, section of the oblong, 3-seeded berry; C, D, seeds, the one in longitudinal section. — After Baillon. leaves of Talauma ovata are used as a substitute for tea in Brazil. /. ANONACE^ OR CUSTARD-APPLE FAMILY.— These are shrubs or small trees chiefly inhabiting warm-temperate and tropical regions. They yield very many economic products. The fruit of Xylopia brasilensis is used as a substitute for cubeb. Some yield fruits having an aroma similar to that of nutmeg, as 542 A TEXT-BOOK OF BOTANY. Monocarpia Blancoi of Africa and Jamaica. The flowers of Cananga odorat'a of tropical countries are used in the preparation of a pomade from which the perfume YLANG-YLANG is made. Ethereal oils are also found in other species, as Unona ligularis of Ambyona, the seeds of which are used in perfumery. The bark of Popowia pisocarpa of Java contains an alkaloid. FIG. 302. Nutmeg trees growing in Singapore. The trees are handsome, evergreen shrubs, extensively cultivated in the East Indies, and to some extent in tropical America. — Reproduced by permission of The Philadelphia Commercial Museum. The seeds of Xylopia salicifolia of Trinidad and X. muricata of Jamaica are very bitter, as are also the wood and bark of X. glabra of the West Indies. The seeds of Asimina triloba, the North American papaw (Fig. 301), contains an emetic principle. This plant should not be confounded with Carica Papaya (Caricacese) which contains the ferment papain. Many of the Anonacese yield large succulent fruits, some of which are edible, as the sugar apple obtained from Anona squa- CLASSIFICATION OF ANGIOSPERMS. 543 mosa and CUSTARD APPLE from A. reticulata both abundant in the Tropics. The fruit of A. muricata sometimes weighs as much as two kilograms. g. MYRISTICACEyE OR NUTMEG FAMILY.— This family is represented by the single genus Myristica. Nutmeg FIG. 303. Young plant of Cinnamomum zeylanicum grown from cutting. (Fig. 302) and mace are obtained from Myristica fragrans, an evergreen tree with ovate, petiolate, coriaceous, entire and pinnately-veined leaves. The flowers are small, yellow and dioe- cious. The fruit is a berry having somewhat the shape and size of the green fruit of black' walnut. It has a line of dehiscence, and when ripe is yellow. The arillode of the seed constitutes MACE, 544 A TEXT-BOOK OF BOTANY. while the kernel is the NUTMEG, the pericarp of the fruit and coat of the seed being rejected. h. LAURACE^: OR LAUREL FAMILY.— The members of this family are chiefly shrubs and trees which are distributed mostly in the Tropics, although a few are found in the temperate zones (Fig. 280, F). Sassafras offtcinale. — This is a tree common in the eastern and central portion of the United States and is characterized by its rough bark and its i- to 3-lobed leaves, from whence it received its former name Sassafras variifolium (Fig. 203). The flowers are yellow, dioecious and appear in the spring before the leaves. The fruit is an oblong, blue drupe. Cinnamomum zeylanicum, which is the source of the Ceylon cinnamon (Fig. 304), is a small, handsome, evergreen tree with opposite, coriaceous, broadly lanceolate, 3- to 5-nerved leaves (Fig. 303). The flowers are yellowish-white, hermaphrodite, or both pistillate and staminate. The fruit is a black, ovoid berry. The oil of Ceylon cinnamon from the bark and branches is charac- terized by its content of cinnamic aldehyde; from the leaves by eugenol ; and from the root bark by camphor. C. Cassia which yields Cassia cinnamon is a tree growing in China, Sumatra, and cultivated in Java. It has long, oblong-lanceolate leaves which are pubescent on the lower surface. Cassia cinnamon (bark) is also obtained from Cassia Burmanni. Saigon cinnamon (see Vol. II) is derived apparently from wild trees growing in the mountainous regions of Anam, the botanical origin of which has not been determined. The volatile oils of the members of the Lauraceae vary con- siderably in composition. In addition to the oils of Sassafras and Cinnamon the following may be mentioned: A CINNEOL- containing oil is found in Cinnamomum Oliveri of Australia, Umbellularia calif ornica of Western North America and Laiirus nobilis the noble laurel of the Mediterranean and Mexico. A BOR- NEOL-containing oil is obtained from the root of Dicypellium caryophyllatum of Guiana, the wood of which is known in Cayenne as rose-wood. An oil containing a notable amount of METHYL SALICYLATE is obtained from the spice-bush (Lindera Benzoin} of the United States. CLASSIFICATION OF ANGIOSPERMS. 545 FIG. 304. Cutting cinnamon in Ceylon. Cinnamomum zeylanicum is a native of the forests of Ceylon and is extensively cultivated, not only on the western coast of that island but in other countries of tropical Asia. The manner of cultivation is such that a number of stems are allowed to grow from a single root. When of sufficient height these are cut down and the smaller branches removed, as shown in the illustration. The bark is then separated from the thicker portion of the stems, gathered into bundles and placed under mats until a slight fermentation takes place. After the corky layer is removed the product is ready for the market. — Reproduced by permission of The Philadelphia Commercial Museum. Cinnamomum Camphora, or the camphor tree, is indigenous to China, Japan and Formosa, and is now cultivated in many warm 35 \ 546 A TEXT-BOOK OF BOTANY. countries as a shade and ornamental tree, growing very well in Southern California and the Southeastern States. All parts of the tree contain a volatile oil which on oxidation yields camphor, which latter is obtained on distillation and sublimation. Camphor of poor quality is obtained from C. Parthenoxylon of Burmah, Malaya and China, and C. glanduliferum of the Himalayas. Cam- phor is also a constituent of other ethereal oils of this same family, as the Massoy bark oil obtained from the root bark of C. zeylanicum and C. Bunnanni of Java. A EUGENOL-containing volatile oil is obtained from Ravensara aroniatica of Madagascar, and Machilus Thunbergii of Japan. Eugenol is also found in oil of laurel leaves (L. nobilis), Massoy bark oil, the oil of the leaves of Ceylon cinnamon, and the oils obtained from Cinnamomum Culilawan of the Malay Peninsula and China, and C. Wightii of East India, and possibly is also found in Dicypellmm caryophyllatum. The wood and the bark of Nectandra or Beeberu (Nectandra Rodi&i) of Guiana and Brazil contain several alkaloids, one of which is known as beeberine and is supposed to be identical with the alkaloids in Buxus sewipervirens (Fam. Buxaceae) ; pelosine found in Pareira ; and paricine found in the bark of the cultivated cinchonas of Java. Coto bark, which is used in medicine, is obtained from an unknown tree in Northern Bolivia belonging to this family. The bark contains a volatile oil having a pungent taste, and a volatile alkaloid. Fatty oils are obtained from Ravensara aromatica of Mada- gascar, Litsea glauca of Japan and other species of Litsea found growing in Cochin China and India. A red sap with a very fetid odor is obtained from Ocotea fattens of tropical and sub-tropical America, and the stink-wood of South Africa (O. bullata). XIII. ORDER RHCEADALES OR PAPAVERALES. These are mostly herbaceous, seldom woody, plants. The flowers are perfect and the fruit capsular. This order includes two families of importance medicinally. a. PAPAVERACE^: OR POPPY FAMILY.— These are herbs with a milky or colored latex. Papaver somniferum or opium poppy is an annual herb i to 2 CLASSIFICATION OF AKGIOSPERMS. 547 M. high. The stem is sparingly branched, with alternate, deeply lobed, pubescent, clasping (by a cordate base), dull green leaves (Fig. 305, A}. The flowers in the variety album, from which opium is obtained, are white or silver-gray, and in many cultivated varieties are large and extremely showy. The two sepals drop away with the expansion of the corolla ; the ovary is smooth, more or less globular and subtends the radiate stigma; the fruit is a FIG. 305. A, Opium poppy (Papaver somnifzrum) ; B, California poppy (Eschs--hoit- aia califjrmca) showing flower (a), and capsules (b, c), one of which (c) is dehiscent. — After Schimper. capsule (Fig. 238), dehiscing by means of terminal pores, and contains a large number of extremely small white seeds, known as MAW-SEED, and which yield a fixed oil known as poppy-oil. The latex of this plant (Figs. 306, 307) yields opium. Other allied members of the Papaveraceae possess narcotic properties, but the alkaloid morphine has not been isolated from any of them, as the California poppy (Eschscholtzia californica) (Fig. 305, B) ; the Mexican poppy (Argemone mexicana) ; Hy- pecoum procumbenSy and Fumaria plicata, both of Southern 548 A TEXT-BOOK OF BOTANY. Europe. These latter plants probably contain also the alkaloid protopine which is apparently identical with fumarine. Satiguinaria canadcnsis or bloodroot, the rhizome of which is official. The plant is a small, herbaceous, perennial herb with a red latex. The rhizome is horizontal, short and thick, and gives rise to a single, petiolate, palmately 5- to 9-lobed leaf and a single white flower with a long peduncle (Fig. 308). The capsule is FlG. 306. Poppy fields in the meadows 8 miles northwest of Ping-li, Shensi, China, showing the plants with large terminal flowers. — Reproduced by permission of The Phila- delphia Commercial Museum. oblong, 2-valved, and contains a number of smooth but crested seeds. Chelidonium ma jus (celandine) is the source of the herb CHELIDONIUM which was formerly official. The plant is a delicate branching herb about 0.5 M. high ; with alternate, deeply pinnati- fid leaves ; yellow flowers ; slender elongated capsule resembling that of the mustards, and a yellow latex in every part. Celandine is indigenous to Europe and Asia and is common in waste places in the United States. The drug contains the following alkaloids : CLASSIFICATION OF ANGIOSPERMS. 549 FIG. 307. Poppy fields in Afionkarohissar, Turkish Empire. The capsules are ready to be Incised allowing the milky juice to exude, which is then collected and constitutes the opium of commerce. — Reproduced by permission of The Philadelphia Commercial Museum. 550 A TEXT-BOOK OF BOTANY. Chelidonine (identical with stylophorine), chelerythrine (which is fluorescent), and protopine (found also in opium and sangui- naria). It also contains a bitter neutral principle chelidoxanthin and several organic acids (Fig. 309). To this family belong a number of other plants which contain principles similar to or identical with those found in Sanguinaria and Chelidonium, and of these the following are common in the FIG. 308. A group of transplanted bloodroot plants (Sanguinaria canadensis) show- ing i-flowered scapes, and the palmately veined and lobed leaves. United States : Yellow or celandine poppy (Stylophorum diphyl- lum) and the Dutchman's breeches (Bicuculla Cucullaria). The alkaloid PROTOPINE (fumarine) is found in the following plants of this family: Sanguinaria canadensis; Chelidoniiim majus; Stylophoruin diphyllnin; Eschscholtzia californica; Glau- ciwn corniculatum of Middle Europe; Bicuculla Cucullaria; Ad- lumia fungosa, the climbing fumitory of the United States and Canada ; Fumaria officinalis, the fumitory of Europe, which is naturalized in the United States and Canada ; Bocconia cordata of China and Japan, and B. frutescens of the West Indies, Mexico CLASSIFICATION OF ANGIOSPERMS. 551 and Paraguay; Dicentra pusilla of Japan and several species of corydalis. The tubers of squirrel corn or corydalis (Bicuculla canadensis) contain the alkaloidal corydaline. FIG. 309. Celandine (Chelidonium majus),' a biennial herb, with pinnately divided leaves, and terminal clusters of small, yellow flowers. The plant has an orange-colored latex. — After Brown. b. CRUCIFEM: OR MUSTARD FAMILY.— These are herbaceous plants with characteristic flowers and fruits. The flowers have four deciduous sepals, four petals which are more or less spreading and clawed at the base, and six stamens which are tetradynamous (Fig. 280, B). The fruit is a 2-celled silique or 552 A TEXT-BOOK OF BOTANY. FIG. 310. Fruiting specimens of the two mustards, the one on the left White Mustard (Brassica alba), and the one on the right Black Mustard (Brassica nigra). — After Newcomb. CLASSIFICATION OF ANGIOSPERMS. 553 silicic, which varies in shape in the different genera (Fig. 310). Brassica alba (white mustard). — The plant is a slender, branching, more or less hispid (bristly hairy) annual or biennial herb usually less than 0.5 M. high, with deeply pinnatifid lower leaves and lanceolate, dentate upper leaves. The flowers are yellow, and the silique is densely hispid, constricted between the seeds and terminated by a long, flat, sword-like beak (Fig. 310). The seeds are official as white mustard (Sinapis alba) but are known in commerce as yellow mustard. Brassica nigra or black mustard, the seeds of which constitute the official black mustard (Sinapis nigra), is a larger, more branch- ing plant than Brassica alba, being from i to 3 M. high. The silique is erect, more cylindrical and with a slender, filiform beak (Fig. 310). Glucosides similar to those which occur in BRASSICA ALBA and BRASSICA NIGRA are also found in other species of BRASSICA, as well as in the following related plants, but the oils produced are not identical: Horseradish (Roripa Armoracia), the oil being similar to volatile oil of mustard; water cress (R. Nasturtium) ; garden radish (Raphanus sativus) ; Sisymbrium Alliaria of Eu- rope, and the hedge mustard (S. officinale} naturalized in the United States; TURNIP (Brassica Rapa) of Europe; field penny-cress (Thlaspi arvense) of Asia and found in waste places in the Eastern and Middle United States ; the narrow leaved pepper- grass (Lepidium ruderale) naturalized from Europe ; scurvy-grass (Cochlearia officinalis) of Northern and Middle Europe, the herb of which, known as HERBA COCHLEARIA, is used in medicine; "HONESTY" (Lunaria annua) common in cultivation on account of the ornamental use of the dry pods ; Parrya macrocarpa of Southern Europe; treacle mustard (Erysimum cheiranthoides) of Northern Europe and the United States, and garlic mustard (E. Alliaria). The seeds of most of the Cruciferae are also rich in fixed oils, and the commercial oils are obtained from the following species : Wild mustard or charlock (Brassica arvensis) naturalized in the United States from Europe ; Hesperis tristis of Southern Europe ; cabbage (Brassica oleracea). An iNDico-forming glucoside is found in I satis tinctoria of Europe and /. indigotica of China; 554 A TEXT-BOOK OF BOTANY. Neslia paniculata of Europe and the Orient ; and Lepidium ozvai- hiense of the Hawaiian Islands. Shepherd's purse (Capsella Bursa-pastoris) contains an alkaloid (bursine) and tannin. The leaves and roots of many of the Cruciferae are used as garden vegetable^, and some are cultivated as ornamental plants. The seeds of Lunaria biennis (or "honesty") contain an orange-red crystalline alkaloid, or possibly a mixture of alkaloids. c. There are several other" families of the Rhoeadales which yield economic products. The RESEDACE/E include the migno- nette (Reseda odorata), the flowers of which yield a fragrant vola- tile oil ; and R. Luteola of Europe, which contains a yellow coloring principle and also an anthelmintic principle. The MORINGACE^E comprise a single genus, Moringa. The root of M. oleifera of tropical and sub-tropical countries contains a volatile oil resem- bling the volatile oil of mustard, and the stem yields an astringent gum resembling that of Bombax malabaricum (Bombaceae). XIV. ORDER SARRACENIALES. This order includes several families which are of special inter- est because of the fact that the leaves are of peculiar construction and adapted to the catching and digestion of insects (Fig. 208). Probably all of the plants of this order produce proteolytic ferments resembling those in the pine-apple and are capable of acting upon and digesting animal substance. Some writers have supposed that the properties of these plants might be due to bac- teria present in the liquid contained in the pitchers of the leaves, but there seems to be no question that a distinct enzyme resem- bling trypsin is formed in those plants which have been studied. (a) The genus Sarracenia of the family SARRACENIACE^: or pitcher-plant family, is represented in the United States by a number of species. The rhizome of Sarracenia purpurea (Fig. 311) contains several alkaloids, one of which, sarracenine, seems to have some resemblance to veratrine. (&) The DROSERACE.E or sundew family includes the Droseras or sundew plants and Dion&a muscipula, the Venus's flytrap of North Carolina (Fig. 209). A number of species of Drosera contain a red coloring principle similar to that isolated from the rhizomes of D. Whittakerii of Australia and is a derivative of methylnaphthoquinone. Citric CLASSIFICATION OF ANGIOSPERMS. 555 FIG. 311. Pitcher Plant (Sarracenia furpurea). The plant grows in peat bogs, and the pitcher-shaped leaves are usually half filled with water and serve as a trap for insects, which are finally digested and furnish the plant with nitrogenous food. The flowers are single on a naked scape and of a deep purple color, the petals being arched over the style. Many species of Sarracenia are prized by horticulturists because of their odd trumpet- shaped leaves. — After Troth. acid has been found in D. longifolia, a sundew common in the United States as well as in Europe and Asia, (c) The family NEPENTHACE.E contains the single genus Nepenthes, several spe- 556 A TEXT-BOOK OF BOTANY. cies of which are extensively cultivated in greenhouses. The leaves and roots of N. Boschiana of Borneo contain an astringent principle. XV. ORDER ROSALES. The plants range from herbs to shrubs and trees and have complete flowers which are mostly perigynous. The carpels are solitary, or several either distinct or united. a. PODOSTEMACE^E OR RIVER-WEED FAMILY.— The plants are aquatic and more or less alga-like, and are repre- sented in the United States by the river-weed (Podostemon Cerato- phyllum), which is a densely tufted plant found in running water attached to stones. The ash of these plants contains a consider- able amount of sodium chloride, the ash of Mourera Weddelliana of Brazil containing 50 per cent, of salt and being used as a source of table salt. b. CRASSULACE^ OR ORPINE FAMILY.— The plants are chiefly succulent herbs and represented by such plants as houseleek (Sempcrrivum tectorum), which is cultivated largely as an ornamental plant, and the common sedums, of which there are numerous species in temperate regions. The common mossy stonecrop or wall-pepper (Sedum acre} naturalized in the North- ern United States contains a ferment capable of dissolving the membrane formed in diphtheria and croup ; Scmpervivwn balsa mi- ferum of the Canary Islands contains a substance resembling the riscine found in certain Loranthaceae. Ditch or Virginia stonecrop (Penthorum scdoidcs} contains tannin. c. SAXIFRAGACE;E OR SAXIFRAGE FAMILY.— The plants are mostly found in temperate regions and among the im- portant members are mitrewort (Mitella), false mitrewort (Tia- rella cordifolia], alum root (Heuchera americana), golden saxi- frage (Chrysosplenium}, grass of Parnassus (Parnassia), mock orange (Philadclphus coronarius') and the wild hydrangea (Hy- drangea arborescens) . The plants are rich in tannin, as the alum root of Eastern and Central North America, which contains 10 to 20 per cent, of tannin. A glucoside hydrangin, a volatile oil, and possibly also a saponin are found in "SEVEN BARKS" or wild hydrangea (H. CLASSIFICATION OF ANGIOSPERMS. FIG. 312. Early Saxifrage (Saxifrage virginiensis'/, a perennial herb with a whorl of root leaves from which arise the flower scapes bearing open and loosely panicled cymes. It grows in the clefts of rocks, and the name is derived from the Latin, meaning to break a rock. No doubt because of its habit, medicinal virtues were earlier ascribed to it, and it was used to cure stone in the bladder. — After Troth. arborescens) ; a glucoside is also found in the root of garden hydrangea (H. paniculata grandifiora). In this family are also included the gooseberries (Fig. 245) 558 A TEXT-BOOK OF BOTANY. and currants. The cultivated CURRANTS are varieties of Ribes rubrum: the cultivated GOOSEBERRIES are varieties of R. Uva- crispa. Both of these plants are natives of Europe and Asia and have escaped from cultivation in the United States and Canada. The fruits contain fruit-acids and fruit-sugars and are used in a variety of ways. The fetid currant (Ribes prostration ) has a very fetid odor and it is said that the flowers of the buffalo currant (Ribes aureum} contain hydrocyanic acid. e. HAMAMELIDACEyE OR WITCHHAZEL FAMILY.— The plants are shrubs or trees and are most abundant in sub- tropical countries. Hamamelis virginiana, or witchhazel, the leaves and bark of which are used in medicine, is a shrub which is especially characterized by its asymmetric, undulate leaves and by its produc- ing flowers in the autumn when the leaves are falling and the mature, but not ripe, capsules of the preceding year are still present (Fig. 313). The forked branches of the witchhazel, as also the twigs of the peach and other plants, are used in various parts of the United States for detecting the presence of underground water. These are operated somewhat as follows : The branched arms are held by the operator in a horizontal position and as the operator surveys the field, it is supposed the main stem will dip in the direction indicating either underground water, petroleum, etc. It is the honest belief of the operators that the working of the rod is influenced by agencies — usually regarded as electrical currents following underground springs of water — that are entirely inde- pendent of their own bodies, and many uneducated people have implicit faith in their ability to locate underground waters in this way. However, it is held by scientists that the operation of the divining rod is generally due to the unconscious movements of the body or muscles of the hand. Liquidambar Styra-ciflna or sweet gum-tree of the Atlantic coast of the United States and Mexico, is a tall tree with charac- teristic cork-wings on the branches ; 3- to 7~lobed, petiolate, finely serrate leaves ; monoecious flowers, and a spiny, globular, capsular fruit. The tree yields a balsam allied to the official styrax CLASSIFICATION OF ANGIOSPERMS. 559 (storax), which is obtained from a very similar tree (L. orientalis). f. PLATANACE^ OR PLANE TREE FAMILY.— This FIG. 313. Branch of Witchhazel (Hamamelis virgintdna) showing alternate, short- petiolate and pinnate-reticulately veined leaves, having a broadly oval or obovate out- line, round, acute, or slightly acuminate apex; slightly cordate, inequilateral base; and undulate or sinuous margin. family consists of but one genus, Platanus, of which there are 7 species. It includes the sycamore or button wood (Platanus occidentalis), one of our largest trees, easily recognized by its 560 A TEXT-BOOK OF BOTANY. mottled exfoliating bark. The leaves are palmately lobed and within the base of the petioles are formed the winter buds. The flowers are staminate and pistillate heads, borne on separate ped- uncles. The fruits are spherical heads about 2 cm. in diameter, composed of numerous achenes, and persist on the trees throughout the winter. The wood is not only used for building purposes, but also for butchers' blocks. FIG. 314. Cross-pollination through the agency of a bee, in flower of quince (Cy- donia vulgaris). A .flowering branch; B, flower showing bee extracting nectar, and masses of pollen adhering to its legs, some of which will fall upon the stigmas of other flowers when it visits them ; C, ripe inferior fleshy fruit (pome) of quince. — After Dodel-Port. /. ROSACES OR ROSE FAMILY.— The plants are herbs, shrubs or trees usually with alternate, stipulate, simple or com- pound leaves, and regular perfect flowers with or without petals, and numerous stamens (Fig. 280, D). The fruit is a pome (Fig. 314), drupe (Fig. 315), follicle or achene (Fig. 236). Prunus serotina or wild black cherry is a tree varying from 10 to 30 M. in height, with a more or less smooth bark marked by prominent transverse lenticels, and showing a tendency to peel off in semicircular pieces, which gives the older bark, which is more or less black, a roughened appearance. The leaves and inner CLASSIFICATION OF ANGIOSPERMS. 561 bark have an agreeable aromatic odor; the leaves are oval- or oblong-lanceolate, acute or acuminate, and serrate, the teeth being FIG. 315. Fruitfng branch of wild black cherry (Prunus seroiina). glandular; the flowers are white and in racemes; the fruit is a dark purple or blackish, globular drupe (Fig. 315). The nearly related species wild cherry or choke cherry (Prunus virginiana) 36 562 A TEXT-BOOK OF BOTANY. is a shrub or small tree with broadly oval, acuminate leaves, red or nearly black drupes, and flowers and fruits several weeks earlier than P. serotina. Primus Amygdalus is a small tree resembling somewhat the peach tree. The leaves are lanceolate, serrate ; the flowers are rose-colored, and the fruit is a dehiscent drupe in which the leathery sarcocarp separates from the endocarp, which latter, with the seed which it encloses, constitutes the edible almond of the market. The kernels of some of the seeds are quite bitter (bitter almonds), and some are bland and free from bitterness. By a process of selection plants yielding the latter are now extensively cultivated in sub-tropical and warm-temperate regions, and yield the sweet or Jordan almond of the market. In Turkestan some of the almonds have a smooth endocarp. A glucosidal substance having the properties of amygdalin is found in the buds, leaves, bark and seeds, more especially the latter, of some members of the following genera : Primus, Sorbus (mountain ash), Cotoneaster, Amelanchier, and Eriobotyra (E. japonica or Japanese medlar). Prunus domestica yields the French plum or prune of com- merce. The leaves are ovate or ovate-lanceolate, dentate, and pubescent on the lower surface. The flowers are greenish-white, with a hairy peduncle. The fruit is a drupe, with a black or bluish-black epicarp, a brownish sarcocarp, and a hard, oval, smooth and flattened endocarp. The endocarps of the members ol tne genus Prunus vary greatly. The endocarp in the apricot (P. Armeniaca} is quite smooth, as is also that of the cherry (P. Cerasus) ; in the peach (Prunus Per- sica) it is reticulate. The bark of Pyrus Toringo yields a yellow coloring principle known in Japan as " dzaini." It also contains a white, crystalline glucoside (toringin), and pyrus-quercitrin, the latter forming yellow needles and on hydrolysis yields quercetin and rhamnose. The bark is also used to adulterate licorice, gentian and other drugs in the powdered form. The apple (Pyrus Malus) , the pear (Pyrus communis}, and the quince (Cydonia vulgaris) are inferior fruits known as pomes, the fleshy part developing from the torus and persistent calyx, the core being composed of the united carpels. The edible fruits CLASSIFICATION OF ANGIOSPERMS. 563 of the Rosaceae contain a number of FRUIT-ACIDS, such as malic, citric, tartaric, and FRUIT-SUGARS, as dextrose and levulose. The acids vary from 0.20 per cent, in pears to 1.50 per cent, in plums ; and the sugars from 4.48 per cent, in peaches to 8.26 per cent, in pears. The carbohydrates mannit and sorbit are found in the fruit of Prunus Laurocerasus of Europe. In the unripe fruits there is more or less tannin and also a principle known as PECTOSE. This latter during the ripening of the fruit is converted into PECTIN, a viscid principle which is further changed into pectic and pectosic acids, the solutions of which gelatinize on cooling, so that these fruits are adapted to jelly making (see pp. 243, 255). Rubus nigrobaccus, or high bush-blackberry, is a branching shrub i to 2 M. high with reddish, prickly, erect or recurved stems. The leaves are 3- to 5-foliate, the leaflets being ovate, coarsely and unequally serrate, and midrib and petiolules with stout, re- curved prickles. The flowers are white, in terminal racemes and with hairy and prickly stalks. The fruit is broadly ovoid and consists of an aggregate of drupelets which ripen in August and September. Rubus villosus Ait. (Rubus canadensis L.} or low-blackberry (Northern dewberry) is a trailing, shrubby, prickly plant the leaves of which are 3- to 7-foliate, the leaflets being oval or ovate- lanceolate, serrate and nearly smooth. The flowers are in racemes and the fruit resembles that of R. nigrobaccus, but is smaller. Rubus cuneifolius or sand-blackberry of the Eastern and Southern States is a small shrub less than i M. high, much branched, and with straight or recurved, stout prickles. The leaflets are ovate or cuneate, and densely pubescent, as are also the young shoots. The inflorescence consists of two to five flowers, the petals of which are white or pinkish. The fruit is oblong, more or less cylindrical, and sometimes 20 mm. long. Rubus Idccus or the cultivated European red-raspberry is a shrub with a glaucous, bristly stem and with 3- to 7-foliate leaves. The flowers are white and the red fruit consists of a cap-like col- lection of hairy drupelets which is easily detached from the non- fleshy receptacle. The fruit is used in the preparation of syrup of raspberry which is used for flavoring. There are a number of varieties of this species of raspberry in cultivation, the fruits of 564 A TEXT-BOOK OF BOTANY. which vary in color from crimson, brown, or yellow to nearly white. The fine flavored but watery fruit of the wild red-rasp- berry (R. sti'igosus) is sometimes substituted for the fruit of Rubus Idccus (Fig. 243). Rosa gallica, which yields the red rose-petals, official in a num- ber of the pharmacopoeias, is a native of Southern Europe and is extensively cultivated. Rosa centifolia, which is now known only in cultivation, and of which there are a large number of varieties, is distinguished by its glandular leaflets, and its pale red or pink petals. The cone-like collection of petals of the flower-bud is the part which is used in medicine, but it is deficient in coloring principles and fragrance as compared to Rosa gallica. Rosa damascena, the petals of which yield the oil of rose or attar of rose, is extensively cultivated in Bulgaria and to some extent in France and Germany. It flowers very profusely, and the yield of oil is about 0.02 per cent. The oil consists of a crys- tallizable hydrocarbon known as rose-camphor which is odorless, and a liquid portion consisting of geraniol, 1-citronellol, 1-lina- lool, citral, n-nonyllic aldehyde and phenyl ethyl alcohol. Similar oils are obtained from other species of Rosa growing in Northern Africa, Abyssinia and Northern India, as R. moschata, and R, sempennrens. The fruits of wild brier (Rosa canina} naturalized from Europe, as well as of other species of Rosa (R. pomifera and R. rugosa), contain considerable malic and citric acids and fruit- sugars, and are made into a confection by boiling with syrup. In addition to the . fruit-ethers found in the common edible fruits of this family and the volatile oil of rose, it should be mentioned that oils containing salicylic acid are also present. A number of species of Spiraea contain salicylic aldehyde and methyl salicylate. Quillaja Saponaria is a large tree having a thick bark and hard wood. The leaves are oval, coriaceous, slightly dentate and evergreen (Fig. 316). The flowers are monoecious or dioecious, white, apetalous, and axillary in groups of one to four. The ovary consists of 4 to 5 carpels and on ripening forms a star-like, spreading group of follicles. The inner bark is the part used in medicine. CLASSIFICATION OF ANGIOSPERMS. 565 A spurious quillaja bark (Q. Pocppigii) differs from the official in being thinner, darker and in having the surface covered with a coarse network of whitish lines. Another bark, occurring in quilled pieces, from 8-15 cm. long, and 1-5 cm. wide, has also been found in commerce. Hagenia abyssinica is an ornamental tree with 7- to 13-foliate leaves. The flowers are monoecious and occur in panicles ; the staminate being greenish-yellow and with 20 stamens ; and the pistillate fragrant, bicarpellary, and with a reddish calyx (Fig. PIG. 316. Soap-bark fr/ee (Quillaja Saponaria): A, flowering branch; B, one of the hermaphrodite flowers; C, the latter in longitudinal section. — After Baillon. 317). The fruit is a nutlet. The pistillate flowers are official under the name of Cusso. Various species of Prunus yield GUMS, as cherry, peach, apricot, etc. MUCILAGE is found in the testa of certain seeds, as of quince. The manna of Luristan is obtained from Pyrus glabra of Persia. Tannin and gallic acid are found in TORMENTILLA rhizome which is obtained from Potentilla silvestris, a perennial herb of Europe, and other species of Potentilla. The fruit of the hawthorn (Cratagus Oxyacantha} contains quercitrin. A bitter principle and tannin are found in Purshia tridentata of the Rocky Mountains. Phloridzin is found in the root bark of a number of species. of Pyrus and Prunus. 566 A TEXT-BOOK OF BOTANY. $9>X/-x/ FIG. 317. Hagenia abyssinica: A, branch showing a large panicle of pistillate flowers and the stipulate, compound leaves; B, C, staminate flowers; D, E, pistillate flowers. — After Berg and Schmidt. In the genus Fragaria to which the strawberry belongs, the torus becomes large and fleshy and is the edible part of the fruit. The garden strawberry (F. chilocnsis} has a large fruit, the achenes being sunken in the periphery of the torus (Fig. 242). In CLASSIFICATION OF ANGIOSPERMS. 567 the wild strawberries the fruit is smaller, usually somewhat flesh- colored and the achenes are either embedded in the torus as in F. virginiana or borne on the surface as in F. vesca. The strawberry fruit contains about 87 per cent, of water; 6 per cent, of cane sugar; 5 per cent, of invert sugar (a mixture of dextrose and levulose) ; I per cent, of free fruit-acids; and about 2 per cent, of nitrogenous substances. g. LEGUMINOS^E OR PULSE FAMILY.— The plants are herbs, shrubs, trees, or vines with alternate, stipulate and usually compound leaves. The flowers are complete, and the corolla is either regular or irregular; the stamens are usually united, and the pistil is simple and free, becoming in fruit a legume. The plants are widely distributed, many of them being found in the Tropics. Three principal sub-groups, which have been ranked as families by some botanists, are recognized. 1. PAPILIONAT^:. — Those species with papilionaceous flowers are separated into a group called the Papilionatae. This sub-group has a number of representatives in the United States, as clover, locust, and Baptisia (Fig. 280, L). 2. CESALPINIOIDE.E include the sennas and have flowers which are nearly regular, or imperfectly, or not at all papilionaceous. 3. The MIMOSOIDE^: include the acacias and have flowers that are regular. Cassia acutifolia is a small shrub with leaves that are 8- to lo-foliate. The leaflets are official as Alexandria or Tripoli senna ; the flowers are yellowish and in axillary racemes ; the fruit is a smooth, flat, dehiscent pod, with 6 to 8 seeds. Cassia angustifolia is a shrub which is cultivated in Southern India and resembles Cassia acutifolia. The leaflets which consti- tute India senna or Tinnevelly senna are longer and narrow-lanceo- late, and the pods are longer, and slightly crescent-shaped, as compared to those of C. acutifolia. Cassia Fistula or purging cassia, the pods of which are used in medicine, is a tree about 15 M. high. The leaves are 10 to 12- f oliate ; the flowers golden-yellow and in racemes ; and the fruit is a very long, cylindrical, indehiscent legume. The leaves of quite a number of species of Cassia are used in medicine and the 568 A TEXT-BOOK OF BOTANY. following are the source of FOLIA MALABATHRI : C. Tamala of Assam and C. javanica. Glycyrrhiza glabra is a perennial herb, with 8- to 14-foliate FIG. 318. Spanish licorice (Glycyrrhiza glabra) plant grown from a cutting by the late Henry N. Rittenhouse of Philadelphia. leaves (Fig. 318), the leaflets being glandular in the variety glandulifera ; the flowers have a violet-colored, papilionaceous corolla, and the fruit is a flat, dehiscent legume. The rhizome and roots are the parts used in medicine. CLASSIFICATION OP ANGIOSPERMS. 569 Cytisus scoparius or green or Scotch broom is a shrub nat- uralized from Europe. The branches are numerous, slender, erect and grow close together, adapting them for use as brooms. The tops are used in medicine. Tamarindus indica is a tree attaining a height of 25 M. The leaves are pinnately compound, having numerous sessile, entire, FIG. 319. Tragacanth plant (Astragalus gummifer): A, flowering branch; B, modified, thorn-like leaf with stipules at the base; C, irregular (bilateral) flower; D, legume of A. aristatus, — After Taubert. oblong leaflets -, the flowers are in terminal racemes and the petals are yellow with reddish veins ; the fruit is a curved, indehiscent legume which has a thin epicarp and a pulpy sarcocarp with numerous fibers, and contains a number of flat, . quadrangular seeds. The pulp is the part used in medicine as a laxative and refrigerant. Astragalus gummifer is a tomentose shrub less than i M. high. The leaves are pinnately compound, the leaflets being narrow 570 A TEXT-BOOK OF BOTANY. and elliptical ; the flowers are pale yellow, sessile and axillary ; the fruit is a small, somewhat cylindrical, hairy pod or legume. The gummy exudation constitutes the Tragacanth of commerce. Acacia Senegal, which yields gum Arabic or acacia gum, is a small tree with bipinnate leaves which are subtended by curved spines ; the flowers are yellow and in dense spikes ; the fruit is a broad pod containing five or six seeds. Acacia Catechu is a small tree which resembles Acacia Senegal and furnishes Black Catechu. FIG. 320. Acacia Senegal: A, flowering branch: B, a single flower showing numerous stamens; C, part of legume showing attachment of seeds; D, E, sections of seeds.— After Taubert. Pterocarpus Marsnpium is a fine timber tree with spreading branches. The leaves are 5- to 7-foliate, the leaflets being cori- aceous, obovate, ^and emarginate ; the flowers are pale yellow, and the fruit is an indehiscent, orbicular pod with a single reniform seed. The official Kino is prepared from the juice. The trees yielding kino are under State control in Madras. According to v. Hohnel the kino is present in special cells in the bark, which are arranged in radial rows in the region of the lep- tome. The cells are from 50 to ioo/u. wide and from 100 to CLASSIFICATION OF ANGIOSPERMS. 571 500 yu, long, the walls consisting of cellulose. The term " kino " is applied to the red astringent juices obtained from a number of plants. " AMERICAN KINO " is a synonym sometimes applied to the extract of Geranium tnaculatum (Fam. Geraniacese). Pterocarpus santalinus is a small tree with trifoliate leaves, and flowers and fruits resembling those of P. Marsupium. The heart-wood is official. Hccmatoxylon campechianum is a small tree with irregular spinous branches. The leaves are 8- to lo-foliate, the leaflets being sessile and obcordate. The flowers are fragrant, have a purple calyx and yellow corolla, and are in racemes. The fruit is a slender, lanceolate, flat pod, which dehisces laterally instead of along the sutures. The heart-wood of this tree constitutes the commercial Logwood, of which about 200,000 pounds are con- sumed annually, its chief use being as a dye-wood. Krameria triandra is a shrub with a few, simple, ovate-lanceo- late, sessile, silver-white, glistening leaves. The flowers are com- plete, having two purple petals and three stamens. The fruit is a i-seeded, globular, prickly, indehiscent pod. K. Ixina, found growing from Mexico to Northern South America, and K. argen- tea of Northern Brazil, are distinguished by having flowers with three petals and four stamens. The root is the part used in medicine. Copaiba Langsdorffii is a small tree found growing in Brazil. The leaves are 6- to lo-foliate, the leaflets being ovate-lanceolate, glabrous, coriaceous, and glandular punctate. The flowers are apetalous, and the fruit is an ellipsoidal, coriaceous, 2-valved pod having a single glandular seed with an arillus. An oleo-resin collects in longitudinal cavities in the trunk of the tree, often amounting to many liters, and sometimes the pressure thus pro- duced is sufficient to burst the trunk in places. The oleo-resin is official as COPAIBA. The latter consists of 30 to 75 per cent, of a volatile oil from which the sesquiterpene caryophyllene has been isolated ; a bitter acrid resin and a bitter principle. A similar prod- uct is obtained from a number of other species of Copaiba growing in South America, as well as C. copallifera of Western Africa, and Hardwlckia Mannii of tropical Africa, and H. pinnata of India. An oleo-resin known by the natives in the province of Velasco 572 A TEXT-BOOK OF BOTANY. in Bolivia as " Copaiba " is obtained from Copaiba paupera. It is thick, like Maracaibo balsam, but lighter in color and resembles in odor and taste true copaiba. It is distinguished from the other specimens of American copaiba by its dextro-rotation [a]o -j- 36°. Oh the addition of one to two volumes of petroleum ether it forms a clear solution, giving a white precipitate on the addition of more ether. Toluifera Balsamum is a tree about 25 M. high, with a straight trunk, on which the branches first appear at a height of from 15 to 20 M., and is found growing in Northern South America. The leaves are compound and with seven to eleven alternate, oblong, acuminate, glandular-punctate leaflets ; the flowers are white and in simple axillary racemes ; the fruit is a winged, inde- hiscent, i -seeded legume. The plants yield a balsam (official in all the pharmacopoeias and known as BALSAM OF TOLU) which occurs in schizogenous cavities in the bark of young twigs, and is obtained by incising the bark, it being usually collected in gourds. The balsam consists of 75 to 80 per cent, of resin, which is a compound of tolu-resinotannol, cinnamic and benzoic acids ; 18 to 20 per cent, of free cinnamic acid ; 0.2 to i per cent, of a volatile oil; and 0.5 per cent, of vanillin. A good tolu balsam is also obtained from T. peruifera growing in the northeastern part of South America. Toluifera Pereircc is a tree about 15 M. high, which has a short trunk and begins to branch at a height of 2 or 3 M. It otherwise resembles T. Balsamum. It is found over the whole of Northern South America, extending through Central America to Mexico, and is cultivated in Singapore. The balsam, which is formed as a result of injury to the trunk, consists chiefly of esters of benzoic and cinnamic acids, some free cinnamic acid, and vanil- lin. A very fragrant vanilla-like balsam is obtained from the fruit of this same plant, and in San Salvador it is known as white Peru balsam to distinguish it from the black Peru balsam obtained from the trunk. Physostigma venenosum is a woody climber. The leaves are 3- foliate, the leaflets being ovate --acuminate ; the flowers are violet in color and in axillary racemes ; the fruit is a broadly linear, somewhat flattened, distinctly veined, dehiscent pod which tapers CLASSIFICATION OF ANGIOSPERMS. 573 at both ends, and usually contains two or three seeds. The seeds are official as Physostigma. FIG. 321. Wild Indigo (Baptisia tincloria), a perennial herb resembling a shrub, possessing nearly sessile, 3-foliate leaves, and having, at the ends of the branches, loose racemes of yellow flowers. A pale blue coloring principle has been obtained from the plant resembling indigo, though somewhat inferior. — After Brown. The blue coloring principle INDIGO is mostly obtained from the herbs Indigo j era tinctoria and /. Anil which are indigenous 574 A TEXT-BOOK OF BOTANY. to, and cultivated in, tropical and sub-tropical countries. It is prepared by extracting the leaves with water. The glucosidal principle indican (or mother-substance of indigo blue) undergoes oxidation and the insoluble indigo blue separates out. This is the commercial indigo. A similar principle is found in the wild indigo (Baptisia tinctoria} of the United States and Canada; the leaves of Robinia Pseud-acacia of North America ; several species of Psoralea and Amorpha, as well as some other Leguminosae. It is also found in other families, as in Polygonacese, Cruci ferae, Ascle- piadaceae, and Apocynaceae. A yellow coloring principle is found in the dyer's broom (Genista tinctoria) of Europe and Asia and naturalized in the New England States. G. ovata of Europe yields a similar dye. COPAL RESINS are derived from a number of the Leguminosse : American copal from Hymenaa Coubaril of the West Indies and South America; Brazilian copal from H. Martiana of Rio Negro; Zanzibar or Chakazzi-copal from Trachylobium mosambicense of Western Africa; Sierra Leone copal (yellow gum, red gum) from Copaiba Guibourtia of Sierra Leone; Inhambane copal from Co- paiba conjugata and C. Gorskiana of Singapore, Jamaica and Australia. A number of the LOCO-WEEDS containing principles poisonous to cattle belong to the Leguminosae. The word " loco," meaning crazy, is. of Spanish origin, and is applied in reference to the pecu- liar nervous symptoms manifested by the affected animals. The plants causing greater loss than all other poisonous plants -com- bined and regarded as loco-plants par excellence are Aragallus Lamberti and Astragalus inollissimus. Of these two Aragallus Lamberti, also commonly known as rattleweed or white loco, is the most poisonous and has a wide range, extending from Alaska on the north down through the whole grazing region of the Great Plains, where it is very abundant. Astragalus mollissimus, known as purple loco, woolly loco, or Texas loco, is more limited in its range. Among other plants causing heavy losses to stockmen on the grazing lands of the Great Plains east of the Rocky Mountains may be mentioned the following : Zygadenus elegans ( Earn. Lili- aceae), especially dangerous to sheep ; the larkspurs or Delphiniums (Earn. Ranunculaceae), causing losses among cattle; and lupines, CLASSIFICATfON OF ANGIOSPERMS. 575 causing losses especially among sheep. The water hemlock (Cicuta maculata, Fam. Umbelliferse) is poisonous to all higher animals, including man. Among other plants poisonous to cattle the following may be mentioned: California loco-weed (Astrag- alus Crotalaria), Texas or woolly loco-weed (A. mollissimus) , rattle-box (Crotalaria sagittalis) found in the Eastern United States and Canada. The poisonous action of some of these plants has been ascribed to the presence of barium salts, although this has not been substantiated in alj cases. Clitoria glycinoides of Brazil and Phaca ochroleuca of Chile are poisonous to horses and should probably be included with the loco-weeds. A large number of the plants belonging to the Leguminosae contain toxic principles and those which have not already been considered might be grouped according to the principles which they contain. 1. ARROW-POISON group, including the genera Erythrophloeum, Afzelia and Pithecolobium. 2. FISH-POISON group, including the genera Albizzia, Afzelia, Bauhinia, Barbiera, Enterolobium, Leucaena, Millettia, Tephrosia, Acacia, Abrus, Clitoria, Mundulea, Derris, Lonchocarpus, Pisci- dia (P. Erythrina or Jamaica dogwood, which contains a curare- like alkaloid). 3. SAPONiN-containing plants as the genera Acacia, Albizzia, Entada (E. scandens or the sea bean of the East and West Indies), Enterolobium, Gleditsia and Gymnocladus (G. dioica or Ken- tucky coffee-tree growing in the United States and Canada). 4. CvxisiNE-containing plants ; the alkaloid cytisine is found in Laburnum vulgar e and L. alpinum growing wild in Southern Europe and also cultivated, and in one or more species of the following genera: Anagyris, Baptisia, Coronilla, Crotalaria, Genista, and Ulex. Abrin, composed of a globulin and albumose and whose prop- erties are affected at a temperature of 50° C. or over, is found in the seeds of JEQUIRITY (Abrus precatorius} and Cassia hispidula of Mexico; two alkaloids (lupinine and lupinidine) and a bitter glucoside (lupinin) are found in the white lupine (Lupinus albus) of Europe and in other species of Lupinus ; a glucoside ( wistarin) and a poisonous resin are found in WISTARIA, species of Wisteria, 5/6 A TEXT-BOOK OF BOTANY. a common woody climber in cultivation as an ornamental plant ; the glucoside ononin is found in RADIX ONONIDIS, the root of Ononis spinosa of Europe; the glandular hairs on the pods of Mucuna pruriens and M. urcns growing in the Tropics of both hemispheres constitute the COWHAGE of medicine ; butyric acid is found in ST. JOHN'S BREAD, the fruit of Ceratonia Siliqua, which grows in European countries bordering the Mediterranean, and also in Eperua falcata of Guiana. A bitter principle, bondicine, known as poor man's quinine, is found in Ccesalpima, Bonducella and other species of Cccsalpinia growing in Sumatra, Borneo, New Zealand and Brazil ; the seeds of Phaseolus lunatus of the East Indies contain a principle from which hydrocyanic acid is derived. The seeds of many of the plants belonging to the Leguminosae are rich in starch and proteins and hence are used as foods. The protein LEGUMIN is characteristic of this family. The following are some of the important food, plants: the garden pea (Pisum sativum), the garden bean (Phaseolus vulgaris) ; lentil (Lens esculenta} , Japanese Soy bean (Glycinc hispida}. The peanut (Arachis hypogcra) indigenous to Brazil and extensively culti- vated in most of the Southern States and in Southern Europe, belongs to the group of plants which have geocarpic fruits, that is, fruits which penetrate the soil during their develppment and ripen under ground (Fig. 231). In peanuts the starch is re- placed by a fixed oil which is present to the extent of about 45 per cent, and which is an article of commerce. In addition to the seeds mentioned those of a number of other plants as well as some fruits, roots and leaves are used as foods in various parts of the world, particularly in the Tropics. The plants of a number of species are used as forage, as those of clover (Trifolium) ; some are cultivated as ornamental plants, as sweet pea (Lathy rus odoratus), and some yield valuable timber, as the locust (Robinia}. Soy Bean (Glycine hispida} is an important food plant and forage crop. The plant is an annual with trifoliate hairy leaves, rather inconspicuous pale or violet-colored flowers, and with broad pods containing 2 to 5 seeds. The seeds are more or less com- pressed, spherical or elliptical and vary in color from whitish- or yellowish-green to brownish-black. The yield of seed per CLASSIFICATION OF ANGIOSPERMS. 577 acre may run as high as 40 bushels. As a forage crop it yields as high as 2 to 3 tons of cured hay per acre. The seeds contain about 5 per cent, of starch and nearly 50 per cent, protein sub- stances. The seeds are therefore very nutritive and are exten- sively used in feeding of live stock. In Japan the seeds are known as " Soy," being derived from the Japanese word " Shoyu," in allusion to a preparation made from the seeds. In Europe it is also used to a limited extent as a food. In this country it is used to some extent as a food for persons suffering from diabetes. ALFALFA or Lucerne (Medicago sativa) is one of the most val- uable forage plants known to man. It is a perennial herb with obovate-oblong leaves, bluish purple flowers occurring in racemes, and twisted pods. Alfalfa is extensively cultivated in all parts of the United States. It is an exceptionally deep-rooted leguminous plant and under the best conditions is long lived, growing in the arid lands of the West as well as in the rich soils of the East. In many essentials and in feeding for stock alfalfa resembles the clover. The alfalfa is relatively somewhat richer in digestible protein than the clover but considerably lower in fat. VEGETABLE BEZOARS are concretions formed in the stomachs of ruminating animals. They consist of the hairs of crimson clover and the awns of oats, barley arid other cereal grains. They are spherical in shape, of a yellowish-brown color, with smooth, even surfaces, of a firm texture, and saturated with intestinal juices. The balls when dried shrink but little and vary from 10 to 12 cm. in diameter. Since the introduction into the United States of crimson clover as a forage plant or green manure, there have been numerous deaths reported among horses and other cattle due to their eating crimson clover, which leads to the formation of bezoars caused by the undigested hairs matting together. An examination of these bezoars shows that the hairs of which they are composed, lie with the broken or basal end toward the center of the ball, the sharp summit being directed toward the surface. XVI. ORDER GERANIALES. This order includes a number of families of economic impor- tance. The sepals are mostly distinct ; the stamens are few ; the carpels are united, and the ovules are pendulous (epitropous). 37 578 A TEXT-BOOK OF BOTANY. a. GERANIACE/E OR GERANIUM FAMILY.— The plants are herbs with alternate or opposite, usually stipulate leaves, regular and perfect flowers, and capsular fruit (Fig. 236, C). Geranium maculatutn is a perennial herb (Fig. 322) with a short, thick, horizontal rhizome, from which arises a simple, some- FIG. 322. Geranium maculatum showing typical dicotyledonous flowers and the s-parted, reticulately-veined leaves. what branching, hairy stem, with 3- to 5-parted, variously toothed and cleft, petiolate leaves, those on the upper part of the stem being opposite ; the flowers are regular and 5-merous, occurring singly or in twos in the axils of the leaves; the petals are rose- purple and hairy at the base ; the fruit is a dehiscent capsule ; the CLASSIFICATION OF ANGIOSPERMS. 579 five carpels when ripe separate and roll upwards, remaining attached to a central column by means of a slender carpophore, the individual carpels being in the nature of achenes. The rhizome is the portion used in medicine. The cultivated geraniums belong to the genus Pelargonium, and some of the species furnish oil of rose geranium, as P. odora- tissimum, P. capitatum and P. Radula, all of which are cultivated in France, Spain, Germany, Algiers and Reunion for the oil, which is largely used in perfumery. The oil contains geraniol, cit- ronellol, and various esters. The leaves of Pelargonium peltatum, growing in certain parts, of Africa and Australia, contain oxalic acid and acid oxalates. b. OXALIDACE^: OR WOOD-SORREL FAMILY.— To this family belongs the genus Oxalis, some species of which have leaves that are quite sensitive to light as well as mechanical stimuli, which applies especially to the cultivated forms of South Africa, and to the common wood-sorrel (Oxalis Acetosella} of the United States and Canada, as well. The leaves contain oxalic acid and acid oxalates. c. THE TROP^OLACE^: OR NASTURTIUM FAMILY comprises but a single genus, Tropaeolum. Some species are culti- vated for ornamental purposes and are the nasturtiums of the garden. The young shoots are succulent and taste like some of the cresses, hence they have received the name " Indian cress." They contain volatile constituents resembling those of the Cruci- ferae, and in the leaves of Tropccolum majus benzyl mustard-oil is found. The flower-buds and young fruits of this species are used for pickling like capers. . d. LINAGES OR FLAX FAMILY.— The most important plant of this family is the common flax (Linum usitatissimum) . This is an erect, slightly branching annual herb with alternate, lanceolate and 3-nerved leaves. The flowers are in terminal, leafy panicles, the pedicels being slender, the calyx non-glandular, and the petals blue (Fig. 280- A}. The fruit is a lo-locular, lo-seeded capsule. The seeds are official. There are a number of cultivated varieties and the seeds of the r.ar. humile contain a glucoside which yields, under the influence of ferments, hydrocyanic acid. A cathartic principle has been found in L. catharticum growing in 580 A TEXT-BOOK OF BOTANY. Europe. The bast fibers of Linum usitatissimum are used in the manufacture of linen. These fibers are distinguished from many other vegetable fibers in not containing lignin. e. ERYTHROXYLACE^E OR COCA FAMILY.— This family contains but two genera, one of which is Erythroxylon. FIG. 323. Flowering branch of Erythroxylon Coca showing the parallel lines on either side of the midrib, which are not true veins, but due to an extra development of hypodermal cells in this region. — After Reiche. The official coca leaves (Fig. 323) are obtained from Erythroxy- lon Coca. The plant is a shrub and requires a very humid atmos- phere and a comparatively high elevation. The leaves are alternate, petiolate and entire; the flowers are white and very small ; the fruit is a reddish drupe resembling that of dogwood. Coca leaves contain several alkaloids, including cocaine, cinna- CLASSIFICATION OF ANGIOSPERMS. 581 myl-cocaine, truxilline and ecgonine. Of these cocaine is the most important, the Bolivian leaves containing the greatest amount, or 0.5 to i per cent. ; the other alkaloids preponderate in the Peruvian leaves, which usually do not contain more than one-half or two- thirds as much cocaine as the Bolivian leaves ; the Java leaves also contain benzoyl-pseudotropine ; in addition, coca leaves contain a volatile aromatic principle ; and a tannin giving a green color with ferric salts. COCAINE (benzoyl-methyl-ecgonine) occurs in monoclinic prisms. The hydrochloride of cocaine with palladous chloride forms a characteristic crystalline double salt (Fig. 97). Other species of Erythroxylon also yield useful products. An aromatic oil is found in the wood of E. monogynum of Ceylon and India, and the wood is known as " bastard cedar " or " bastard santal." A brownish-red coloring principle is found in the red- wood (E. arolatum) of Jamaica and in E. subcrosum and E. tortuosum. Purgative and anthelrnintic principles are found in some species of this genus. /. ZYGOPHYLLACE^: OR CALTROP FAMILY.— The plants are mostly herbs and shrubs which are widely distributed in warm-tropical regions. The leaves are mostly opposite, pin- nate and stipulate. The genus Guaiacum is of interest on account of the wood containing considerable resin, which is used in medicine. • Guaiacum officinale is a small tree with 4- to 6-foliate leaves, the leaflets being ovate, entire and sessile ; the flowers are large, blue, and in axillary clusters ; and the fruit is a 2-valved capsule (Fig. 324). G. sanctum is a tree resembling G. ofUcinale, but is distinguished by having leaves which are 8-foliate and with smaller leaflets, and a 4- to 5-valved capsule. The resin of both species is official. "» A resin having an odor resembling that of creosote occurs in the CREOSOTE BUSH (Covillea tridentata) of Mexico and Texas. The juice of Peganum Harmala contains a yellow coloring principle used in dyeing. A number of the plants of this family contain powerful poisonous principles. g. RUTACE^E OR RUE FAMILY.— The plants are shrubs or trees, seldom herbs, with lysigenous oil-secretion cells. The A TEXT-BOOK OF BOTANY. leaves are usually alternate, simple or compound and glandular- punctate (Fig. 280, C). Xaniho.vylum americanum or northern prickly ash is a shrub or small tree with 5- to n-compound leaves, the leaflets being ovate and nearly sessile ; the flowers are dioecious, greenish, and in axillary cymes ; the fruit is a black, 2-valved capsule. X. Clava- Herculis or the southern prickly ash is a very prickly shrub, which FIG. 324. Guaiacum officinale: A, flowering and fruiting branch; B, gynaeciuti in longitudinal section showing the pendulous ovules; C, a seed; D, E, the fruit in longitudinal and transverse sections. — After Berg and Schmidt. is characterized by having cork-wings on the bark. The leaves are 5- to 17- foliate, the leaflets being ovate and crenulate; the flowers are in terminal racemes and have a calyx of 4 or 5 sepals, the calyx being wanting in X. americanum. The bark of these two species is official. PILOCARPUS. — To this genus belong a number of species which are shrubs or small trees and indigenous to tropical America. The leaves are mostly pinnately-compound, the leaflets being coriaceous and entire ; the flowers are small, greenish and in axillary or terminal racemes ; the fruit is a i-seeded, 2-valved CLASSIFICATION OF ANGIOSPERMS. 583 capsule. The leaves of three species are official as Pilocarpus or Jaborandi. BAROSMA. — The buchu leaves of medicine are obtained from several species of Barosma (see Vol. II). The plants are branch- ing shrubs with opposite, coriaceous, serrate or dentate leaves with glandular margins ; the flowers are white or reddish and occur, i to 3, in the axils of the leaves ; the fruit is a 5-valved capsule. The leaves contain a volatile oil, one of the constituents of which is diosphenol. CITRUS. — The fruits of a number of species of this genus are edible, and the plants are also valued for their volatile oils. They are aromatic, glandular, mostly thorny shrubs or small trees indigenous to tropical and sub-tropical Asia, and now extensively cultivated in tropical, sub-tropical and warm-temperate regions. The leaves are more or less winged-petiolate, glaucous, coria- ceous, mainly unifoliate (or trifoliate) ; the flowers are complete, with a 3- to 6-toothed gamosepalous calyx, and 4 to 8 glandular petals ; the stamens are 20 to 60, in groups of I to 9 ; the ovary is subtended by a cushion-shaped disk, and the fruit is a spher- ical, oblong or pear-shaped berry, having a coriaceous pericarp with numerous lysigenous oil-glands, a juicy pulp made up of peculiar hair-structures which arise from the endocarp, and in which are embedded white polyembryonic seeds (Fig. 280, C). Botanists have divided this genus into two sub-groups: (a) the Pseudo-yEgle group is represented by the trifoliate orange (Citrus trifoliata) , cultivated widely in the United States as a hedge. The leaves are trifoliate and deciduous, the petals spatu- late and the ovary and disk hairy, (b) In the Eucitrus group the leaves are unifoliate and evergreen, the petals oblong, and the ovary and disk glabrous. This latter group includes the two species which yield most of the edible Citrus fruits. Citrus Aurantium includes a number of sub-species and varie- ties. The plants are small trees with leaves having winged petioles ; fragrant, white flowers ; and a more or less globular fruit. The SWEET ORANGE (Malta, Portugal) is derived from the sub-species sinensis. The BITTER ORANGE (Seville, Curasao) is derived from the sub-species amara. The flowers of both the Sweet and Bitter Orange tree contain a volatile oil known as OIL 584 A TEXT-BOOK OF BOTANY. OF NEROLI, and composed of limonene, geraniol, linalool, etc. The oil from the rind of the fruit is known as OIL OF ORANGE PEEL, and is obtained chiefly from Italy and Sicily. It is composed of limonene, citral, citronellol, etc. The oil from the Bitter Orange peel has a superior flavor and is known as BIGARADIA OIL. The Bergamot Orange is the fruit of the sub-species Bergamia, culti- vated in Europe, but only rarely in the United States. The oil of the rind of the fruit is known as BERGAMOT OIL and consists largely of linalyl acetate. In the group of MANDARIN or Kid- glove orange (Citrus nobilis} the fruit is compressed, spherical, 5-6 cm. in diameter and with an orange-yellow, loose and easily removable rind. The SHADDOCK or grape-fruit is derived from the sub-species sinensis var. decumana, a tree indigenous to :the Malay Archipelago and extensively cultivated in India, Flor- ida, California and elsewhere. The fruits are quite large, some- times weighing several kilograms, and those which are round are the most valuable commercially, being known as Pomelos or GRAPE-FRUITS. The BLOOD ORANGE is the fruit of the sub-species sinensis var. sanguined. The OTAHEITE ORANGE, which is ex- tensively cultivated as a dwarf pot plant and the foliage and flowers of which resemble those of lemon, is probably a variety of the sub-species sinensis, or it may be a hybrid of lemon and orange. The NAVEL ORANGE is a sweet orange in which an additional compound ovary is developed within the fruit. LEMON and LIME fruits are derived from sub-species of Citrus tnedica, which are mostly shrubs with simple, petiolate leaves, reddish twigs and flowers, and more or less ellipsoidal fruits. Lemons are derived from the sub-species Limonum. The rind of the fruit yields the OIL OF LEMON, which consists of limonene, citral, etc. Most of the commercial article comes from Sicily and Calabria. Lime fruits or limes are derived from the sub-species acida, a shrub cultivated in the West Indies and Florida. The CITRON fruit, the rind of which is used in the making of preserves and confections, is derived from the sub-species genuina. The fruit is large and lemon-like but with a thick rind, the plant being cultivated to some extent in Florida and California. The KUMQUAT ORANGE is obtained from Citrus japonica, a thornless tree with spreading dwarf habit extensively cultivated CLASSIFICATION OF ANGIOSPERMS. 585 in China and Japan and very hardy even in Northern Florida. The fruit is round or oblong, from 3 to 5 cm. long and 2 to 3 cm. in diameter, and of an orange-yellow color; the rind is sweet, while the pulp is acid, and usually free from seeds, although from i to 4 slightly beaked seeds may be present. The inner white portion of the rind of the Citrus fruits con- tains a crystalline, tasteless glucoside known as hesperidin (see pp. 151-154). Those which are bitter contain in addition several bitter glucosides, namely, aurantiamarin and naringin. (See Aurantii Amari Cortex, and Aurantii Dulcis Cortex, in Vol. II.) Volatile oils are also found in other members of the Rutaceae. The garden rue (Ruta graveolens), the leaves of which are used in medicine, contains a volatile oil consisting of several ketones. It also contains a glucoside known as rutin which resembles the barosmin of buchu ; and quercetin, which is said to be derived from rutin. The Hop tree (Ptelea trifoliate.) of Eastern North Amer- ica contains besides a volatile oil, a resin and an alkaloid. The volatile oil of pepper-moor (Zanthoxylum piperitum) of China and Japan is known as Japanese oil of pepper. ANGUSTURA BARK obtained from Cusparia trifoliata or C. officinalis, plants growing in the region of the Orinoco River, con- tains a volatile oil, resin, a bitter principle and four alkaloids. The wood of Amyris balsamifera of Guiana and Jamaica, yields on distillation a volatile oil resembling Oleum Rhodii. h. SIMARUBACE^E OR AILANTHUS FAMILY.— The plants are chiefly shrubs or trees with alternate and pinnately- compound leaves. The flowers are regular, dioecious or polyg- amous and in axillary racemes. The plants are natives of tropical Countries and are distinguished from the Rutaceae, which they somewhat resemble by the absence of oil secretory cavities. They are widely employed particularly in the tropics, on account of their bitter principles, and are considered valuable tonics, febrifuges and remedies for dysentery. Picrasma excelsa is a small tree with 9- to 17- foliate leaves, the leaflets being ovate and more or less tomentose, particularly in the bud ; the flowers are yellow, polygamous and in axillary panicles ; the fruit is a large, spherical drupe. The, wood of the plant constitutes Jamaica quassia. 586 A TEXT-BOOK OF BOTANY. Quassia amara is a small tree or shrub with 4- to 5-foliate leaves; the leaflets are narrow, obovate and acuminate, and the rachis and petiole or stalk are winged ; the flowers are her- maphrodite, with 10 stamens, bright red corolla, and in terminal racemes; the fruit is a 5-valved indehiscent pod or nutlet. The wood constitutes Surinam quassia. A red coloring principle is found in Samadera indica of India, Ceylon and Java. The alkaloid cedronin is found in the seeds of Simaba Cedron of New Granada, the seeds being used as an anti- dote for the bites of poisonous animals. A similar principle may exist in the bark of Simaruba versicolor of Brazil, the plant being used for a similar purpose. The alkaloid brucamarine is found in the fruit of Brucca sumatrana. A tragacanth-like gum is obtained from Ailanthus excelsa of India. DIKA or GABUN CHOC- OLATE is obtained from the seeds of Irvingia gabonensis of trop- ical West Africa. Cay-Cay-Butter is obtained from the seeds of Irvingia Oliveri and /. malayana of Malacca and Cochin China. A gum resembling acacia is also obtained from the bark, peti- oles and seeds of the species of Irvingia. i. BURSERACE^: OR MYRRH FAMILY.— The plants are shrubs or trees, the latter being sometimes quite large, with resin-canals in the bark, and alternate compound leaves; the flowers are small, occurring in racemes. The members of this family are found in tropical countries. CommiphQra abyssinica is a shrub 10 M. high, the branches being modified to thorns ; the leaves are trifoliate, the leaflets being oblong, dentate, sessile and the terminal one much larger than the other two ; the flowers are dioecious, and the fruit is a drupe with a fleshy, resinous sarcocarp. The official Myrrh is probably obtained from this plant as well as other species of Commiphora. A number of other resinous products are yielded by plants of this family. West India ELEMI resin or Elemi Occidentale (Anime) is obtained from the stems of Protium Icicariba of Brazil. The resin is greenish-yellow, soft, with a bitter taste and dill-like odor. Manila Elemi is a soft, granular, lemon-yellow or grayish-white resin derived from Canarium commune of the Philippine Islands. Bengal Elemi is derived from Commiphora Agallocha of the East Indies and Madagascar. The TACAMAHAC CLASSIFICATION OF ANGIOSPERMS. 587 RESINS are balsamic resins, of which there are several commercial varieties : Mauritius tacamahaca is obtained from Protium hepta- phyllum of Columbia, and Mexican or West Indian tacamahaca from Bursera tomentosa of Mexico, West Indies, and South America. INDIA BDELLIUM is a resin obtained from the bark of Commiphora Roxburghiana of Northwestern India and Belu- FIG. 325. Myrrh plant (Commiphora abyssinica): A, young branch showing tri- foliate leaves; B, flowering and fruiting stem with thorn-like branches; C.leaf axis in which occur a fruit and staminate and pistillate flowers; D, staminate flower in longitudinal section; E, longitudinal section of pistillate flower; F, longitudinal section of fruit showing arillus-like mesocarp and the easily dehiscent endocarp. — After Engler. chistan. CoFAL-like resins are obtained from Canarium ben- galense (East Indian Copal) and possibly several species of Bur- sera. BLACK DAMMAR resin is obtained from Canarium ros- tratum of the Molucca Islands. OLIBANUM or Frankincense is a gum-resin obtained from several species of Boszvellia of Asia and Somaliland. AMERICAN OLIBANUM or Soft Resin of Cayenne exudes spontaneously from the stems of Protium heptaphyllum and P. guianense. GILEAD BALSAM is obtained from Protium 588 A TEXT-BOOK OF BOTANY. altissimum and P. Carana of Guiana and Brazil. MEXICAN LIN- ALCE OIL is obtained from Bursera graveolens, and several species of Bursera of Mexico are used as a substitute for Aloe wood. ;. MELIACE.E OR MAHOGANY FAMILY.— This is a large family of tropical trees and shrubs with mostly alternate, compound and exstipulate leaves, the leaflets being entire, with secretion cells, but not glandular-punctate (Fig. 326). The flowers PIG. 326. Pride of China (Melia Azedarach): A, flowering branch; B, a part of the inflorescence. — After Harms. are complete, the filaments being united into a tube ; and they occur in axillary clusters or racemes ; the fruit is a capsule, berry or drupe ; the seeds are sometimes winged and with fleshy or leaf- like cotyledons. The bitter principle mangrovin is found in the bark of the China Tree or Pride of China (Melia Asedarach) indigenous to Asia, and extensively cultivated in tropical and warm-temperate regions, and naturalized in the southern part of the United States (Fig. 326). A similar principle is found in other plants of this family. CLASSIFICATION OF ANGIOSPERMS. 589 Carapa Oil, which has a characteristic odor and bitter taste and is toxic to insects, is obtained from the seeds of Carapa pro- cera and C. guianensig, of tropical West Africa and tropical America, and also from Swietenia Mahagoni (Mahogany Tree). Cedar- wood oil ("Oleum Cedrelae ") is obtained from several species of Cedrela growing in tropical America. The most impor- tant constituent of the oils is cadinine. Oils with a garlic-like odor are found in the seeds of Melia Asedarach, the bark of Cedrela australis of Australia and the fruit of Dysoxylum binec- tariferum of Java. Besides the Mahogany tree there are other trees of this family which yield valuable woods. Cigar boxes and sugar boxes are made from the wood of Cedrela odorata of the West Indies and Guiana, and from other species of Cedrela. k. MALPIGHIACE^ is a rather large family of shrubs, small trees, or lianes with anomalous stem-structure, found in the Tropics, principally in South America. The leaves are usually opposite, the sepals are glandular, and the fruit is a winged samara somewhat like that of maple (Acer). The plants contain a notable amount of tannin and the woods of some species contain a red coloring principle. /. POLYGALACEyE OR MILKWORT FAMILY.— The members of this family are herbs or shrubs, occurring in all parts of the world except in the. Arctic regions. Polygala Senega is a perennial herb about ]/$ M. high. It has a fleshy root, producing at the crown a large number of buds and giving rise to a cluster of overground stems or so-called plants. The leaves are alternate, lanceolate or oblong-lanceolate and ses- sile ; the flowers are faintly greenish-white and in cylindrical spikes ; the capsule is loculicidally dehiscent, and the seed is hairy and slightly longer than the lobes of the caruncle. The root is official. Polygala alba or White Milkwort yields the White or Texas Senega. The stems are numerous and taller than those of P. Sen- ega; the leaves are narrow-lanceolate or linear with revolute mar- gin ; the flowers are white and in elongated conic spikes ; the caruncle lobes are about half as long as the seed. The plant is found west of the Mississippi River, extending as far south as Texas and Mexico and west as far as Arizona and New Mexico. 590 A TEXT-BOOK OF BOTANY. m. EUPHORBIACE^ OR SPURGE FAMILY.— The plants are herbs, shrubs or trees with acrid and often milky latex. The fruit is mostly a trilocular, dehiscent capsule ; the seeds are anatropous and have an oily endosperm. FIG. 327. Stillingia sylvatica: showing the more or less closely arranged leaves and the terminal spike of flowers. — After Bentley and Trimen. Stillingia sylvatica or Queen's-Root yields the official Stillingia (Fig. 327). The plant is a perennial herb about I M. high and diffusely branched. The leaves are obovate, short-petiolate, with glandular-serrate margin ; the flowers are in terminal spikes, light yellow, monoecious, the staminate being above and the pistillate below, the latter solitary in the axils of the lower bractlets. CLASSIFICATION OF ANGIOSPERMS. 591 Ricinus communis or Castor-Oil Plant is an annual herb in the temperate regions but is shrub-like and perennial in tropical and sub-tropical countries. In temperate regions the plant is from I to 5 M. high ; the leaves are peltate and 6- to I i-palmately-lobed ; the flowers are greenish, apetalous, monoecious and in racemes, the pistillate being above the staminate on the flower-axis ; the fruit is a 3-locular, oval, spinous capsule, which dehisces septi- cidally (Fig. 237, B). The seeds are anatropous, somewhat flat- tened-oblong ; 10 to 16 mm. long and 4 to 8 mm. in diameter; smooth, mottled grayish-brown or yellowish-red, with a promi- nent caruncle ; hard but brittle testa, thin white tegmen, large oily endosperm, and thin foliaceous cotyledons at the center. The seeds contain 45 to 50 per cent, of oil which constitutes the Castor Oil of medicine and a large amount of proteins in the form of aleurone grains (Fig. 250, D}. The cake from which the oil is expressed contains a poisonous principle known as ricin which is apparently poisonous to cattle, but not to poultry. Croton Tiglium is a shrub or small tree indigenous to tropical Asia and extensively cultivated in tropical countries ; the leaves are alternate, oblong-lanceolate with petioles which are glandular at the base, but wanting in the star-shaped hairs so characteristic of other species of this genus ; the flowers are small, monoecious and in terminal racemes, the pistillate being above and the stam- inate below ; the fruit is a 3-locular, septicidally dehiscent capsule. The seeds resemble those of Ricinus in size and structure, except that they are less smooth, more brownish in color and the caruncle is quite small. They contain a fixed oil which is obtained by expression and which is poisonous and a powerful cathartic. The seeds of a number of the other members of the Euphorbiaceae contain fixed oils resembling those of Croton and Ricinus, as CURCAS, the seeds of Jatropha Curcas of tropical America. MEXICAN CROTON OIL is obtained from the seeds of Euphorbia calyculata. The seeds of the Caper Spurge or Wild Caper (Euphorbia Lathyris), nat- uralized in the United States from Europe, also contain a fixed oil resembling that of Croton. The seeds of Joannesia Princeps of the maritime provinces of Brazil are also powerful purgatives. Malfotus philippinensis is a shrub or small tree found in trop- 592 A TEXT-BOOK OF BOTANY. ical countries of the Eastern Hemisphere. The leaves are alter- nate, petiolate, ovate, acuminate, coriaceous and evergreen ; the flowers are small, dioecious, and in racemes ; the fruit is a 3-loc.ular, glandular-hairy capsule. The hairs of the capsule are official in a number of pharmacopoeias under the name of KAMALA and occur as a reddish-brown, granular powder, consisting of two kinds of hairs, the one colorless and occurring in branching clusters (Fig. 151) and the other with yellowish-red, multicellular, glandular heads. The important constituent is about 80 per cent, of a dark brownish-red resin composed of a crystalline principle rottlerin, isorottlerin, two reddish-yellow resins, a coloring principle and wax. It-also contains a trace of volatile oil, starch, sugar, tannin, oxalic and citric acids. A red coloring principle is found in the bark of Aleurites triloba of the Polynesian Islands, Euphorbia parviflora of Ceylon, E. pulcherrima of Mexico and Brazil and the other species of Euphorbia. CASCARILLA BARK is obtained from Croton Eluteria and other species of Croton growing in the Bahama Islands and other parts of the West Indies and Florida. Cascarilla bark is official in a number of pharmacopoeias. It occurs in small curved pieces or quills, i to 3 mm. thick, externally brownish-gray ; inner surface is reddish-brown, the fracture short, resinous ; odor aromatic ; partic- ularly on burning; taste aromatic and bitter. Cascarilla contains i to 1.5 per cent, of a volatile oil, containing eugenol, limonene, an oxygenated portion, and some other constituents; 15 per cent, of resin ; a bitter principle, cascarillin ; tannin and vanillin. COPALCHI BARK or Quina blanca which is derived from Croton niveus of Mexico contains a bitter principle, copalchin, which is also found in other species of Croton. Malambo bark is derived from Croton Malambo of Venezuela, the latter two barks being sometimes substituted for Cascarilla bark. ELASTICA or India Rubber (Caoutchouc) is the prepared milk- juice obtained from one or more species of the following genera: Hevea, Mabea, Euphorbia, etc. (see pp. 238-241). The fresh latex of a number of species is a powerful irritant, as that of the Sand-box tree (Hura crepitans} of tropical America, which con- tains a highly toxic albuminoid; the Blinding-tree (Excaecaria CLASSIFICATION OF ANGIOSPERMS. 593 Agallocha) of Southern Asia and Australia, the juice of which produces blindness. The gum-resin EUPHORBIUM is obtained from Euphorbia res- inifera, a cactus-like plant of Morocco, and is also found in other species of Euphorbia. It contains, among other constituents, 38 per cent, of an acrid resin, and 22 per cent, of a crystalline prin- ciple euphorbon. The milk-juice of several species of Euphorbia is used in the preparation of arrow poisons in Brazil. One or more species of tne following genera are used as fish poisons : Flueggea, Phyl- lanthus, Bridelia, Exccecaria and Euphorbia. A number of plants are used as remedies for the bites of serpents, as the bark of Phyllanthus mollis of Java and Euphorbia pilulifera of South America and India. Euphorbia pilulifera, common in tropical countries, contains an alkaloid, a wax-like substance, several resins and tannin. (Ph. Jour.. 29, July 31, 1909, p. 141.) A camphor-containing oil is found in the bark of Pentalo- stigma quadrilocularc of Australia ; the aromatic wood of Col- liguaya odorifera of Chile is used as a substitute for santal and on burning emits a rose-like odor ; the leaf of Croton mentho- dorus of Peru contains an oil with an odor of mentha; a balsam resembling Copaiba is derived from the bark of Croton origani- folius of the West Indies; methylamine is found in Mercurialis annua of Europe and other species of Mercurialis. Tannin is found in the following genera: Macaranga, Phyllanthus and Bridelia; Brazil kino is obtained from a species of Croton (C. erythrceus?} of Brazil. A gum-lac is formed on the stems of Aleurites laccifera of the Antilles and Ceylon as a result of the sting of an insect, and contains among other substances a large amount of methyl- and ceryl-alcohols, and a substance resembling abietic acid. The sap of Euphorbia Cyparissias of Europe yields a resin which is sometimes substituted for scammony. A reddish resinous substance resembling dragon's blood is obtained from Croton erythrema of Brazil ; a yellow coloring principle is found in the seed of Croton tinctorius of Mexico ; poncetin, a violet coloring principle, occurs in Euphorbia hetero- phylla of .Brazil ; a blue coloring principle is found in Chrozo- phora tinctoria of Southern Europe and Africa and in Argitham- 38 594 A TEXT-BOOK OF BOTANY. nia tricuspidata lanceolata of Chile; an indigo-like principle is obtained from Mercurialis perennis of Europe. The fresh latex of Euphorbia phosphorea of Brazil is phosphorescent. Quite a number of the seeds of this family contain fatty oils. The Chinese Tallow tree (Sapium sebiferum} yields a fat which is used for burning and for technical purposes ; a similar fat is obtained from the seeds of several species of Aleurites and Euphorbia. TAPIOCA starch is derived from the tuberous roots of Manihot utilissima, extensively cultivated in tropical countries ; other spe- cies of Manihot also yield starchy food products. Edible fruits are obtained from the following genera : Phyl- lanthus, Baccaurea and Antidesma ; the seeds of Hevea brasiliensis are edible ; a sweet sap is found in Baccaurea ramifiora of Cochin China and Brazil; a peptone-like ferment is found in Euphorbia heterodoxa of South America and other species of Euphorbia. XVII. ORDER SAPINDALES. The plants of this order are chiefly trees and shrubs. The flowers are mostly regular and the seeds usually without endo- sperm. The order has a number of representatives in both tropical and temperate regions. a. BUXACE^: OR BOX TREE FAMILY.— The plants are shrubs with alternate or opposite, evergreen leaves, and usually axillary monoecious or dioecious flowers. The most important plant of this family is the Box tree (Buxus sempervirens} , which is extensively cultivated. The wood is used for making musical instruments and for other purposes, and the twigs have been used in medicine. The latter contain several alkaloids, the most impor- tant being buxine, which resembles beberine; a volatile oil con- taining butyric acid and a wax containing myricyl alcohol and myricin. b. FAMILY CORIARACE^E.— This family is represented by but a single genus, Coriaria. The plants are shrubs found in Europe, Asia and South America, and yield several important economic products. The leaves and bark of C. myrtifolia of Southern Europe and Northern Africa are rich in tannin and used in dyeing. This plant also contains a narcotic principle, resem- CLASSIFICATION OF ANGIOSPERMS. 595 blmg picrotoxin, known as coriamyrtin, which is also found prob- ably in C. atropurpurea of Mexico. The leaves of Coriaria myrti- folia or TANNER'S SUMAC are coriaceous, distinctly 3-nerved, astringent and bitter and were at one time substituted for senna leaves. A black dye is obtained from C. ruscifolia of New Zealand and Chile. While the fruits of some species are quite poisonous, the sap of the fleshy leaves is used in New Zealand in making an intoxicating drink. c. ANACARDIACE^E OR SUMAC FAMILY.— The plants are trees or shrubs with an acrid, resinous or milky latex, and alternate leaves. Rhus Toxicodendron, POISON IVY or Poison Oak, is a woody vine, climbing by means of aerial roots and sometimes becoming quite shrub-like, which is common along roadsides in the United States. The leaves are 3-foliate, the leaflets being ovate, acumi- nate, nearly entire, inequilateral and with short stalks ; the flowers are green and in loose axillary panicles ; the fruit is a globular, glabrous, grayish drupe (Fig. 328). The nature of the poisonous constituents of Poison Ivy is not definitely known. It was orig- inally considered to be in the nature of a volatile principle. Pfaff and his pupils seemed to show that the poisonous principle was a non-volatile brownish-red resin which is soluble in alcohol and called toxicodendrol. Schwalbe, on the other hand, states that the poisonous substance is of a volatile nature, being formed in the laticiferous vessels and by osmosis is transferred to the hairs. The poison may be transmitted either by direct contact with the hairs, much as in the same manner with the nettles, or by volatiliza- tion of the oil when the hairs are broken. The experience of most plant collectors would seem to indicate that in Poison Ivy there is a volatile toxic constituent (Amer. Jour. Pharm., March, 1914). On the other hand, Rost and Gilg were unable to find a volatile poison in either the hairs or pollen of Poison Ivy. In some ex- periments conducted by Warren on pollen grains, similar negative results were obtained (Amer. Jour. Pharm., Dec., 1913). The poisonous principle occurring in several species of Rhus is an amber-red, non-volatile liquid. It is of a resinous nature, com- bining with the alkali hydroxides to form nigrescent compounds, and otherwise behaves like certain phenolic compounds. The toxic 596 A TEXT-BOOK OF BOTANY. resin exists in the plant in the form of an emulsion which readily blackens with the alkali hydroxides. So delicate is this reaction that minute amounts of the substance may be detected by means FIG. 328. Leaves and fruit of the poison ivy (Rhus radicans). This is a 3-follate com- pound leaf , the leaflets being ovate and having veins which bifurcate and end free. of the microscope if the plant tissues are mounted in an alcoholic solution of potassium hydroxide. A vesicating principle CARDOL is found in the CASHEW NUT. The latter is the fruit of Anacardium CLASSIFICATION OF ANGIOSPERMS. 597 occidentale, a shrub growing in tropical America. A principle resembling cardol is found in the East India Marking tree or Ink tree(Semecarpus Anacardium)and Holigarna ferruginea of India. The POISON SUMAC or Poison Elder (Rhus Vernix} is a shrub or small tree found in swamps in the United States and Canada. The leaves are 7- to 13- foliate, with obovate or oval, acuminate, entire leaflets ; the flowers are small, green, and in axillary pani- cles; the fruit resembles that of R. radicans (Fig. 328). The plant is poisonous like R. Toxicodendron and probably contains the same principle. Other species of Rhus are also poisonous, as the western Poison Oak (R. diversiloba} of the Pacific Coast, and the Japanese Lacquer or Varnish tree (R. vernicifera and R. succedanea}. The lacquer trees grow wild in both China and Japan, where they are also cultivated. The lac is obtained by incising the bark and removing it with a pointed spatula. The grayish-white emulsion is strained and on exposure to air it changes to brown, becoming finally black. This change is due to the oxidizing enzyme laccase. The natural lac ( Kiurushi) contains a non-volatile poisonous resin-like principle and is closely associ- ated with other resinous substances. Japanese lac is thinned with camphor, or mixed with linseed oil, and on drying in a moist atmos- phere forms the most indestructible varnish known. Various pig- ments are used, as vermilion, gamboge, acetate of iron and other substances. The best glossy black colors are obtained by the addition of iron. Rhus ylabra or the Scarlet Sumac is a smooth shrub. The leaves are u-to 31 -foliate, the leaflets being lanceolate, acuminate, sharply serrate, dark green above and lower face glaucous ; the flowers are greenish, polygamous1 and in terminal panicles ; the fruits of this plant and of R. typhina (Fig. 329) are used in medicine. CHINESE GALLS are excrescences produced on Rhus semialata as a result of the stings of an Aphis. JAPANESE GALLS are similar formations occurring on Rhus japonica. (See pp. 206, 334.) Pistacia Lentiscus is a shrub or tree, which is found growing in the Grecian Archipelago. The leaves are pinnately compound and with winged axis, the leaflets being alternate, oblong, entire, sessile ; the flowers are small, dioecious, and in axillary clusters. In the bark of this plant there are large cavities which contain 598 A TEXT-BOOK OF BOTANY. FIG. 329. Fruiting branch with leaves of Rhus typhina. Reproduced from Sargent's "Silva of North America." Rhus typhina is commonly known as the " staghorn sumac" in allusion to the soft brown pubescence covering the twigs and branches. It is also known as the " vinegar tree" and " Virginia sumac." It may attain the height of a tree, and is usually found growing in uplands in good soil, ocasionally being found like Rhus glabra on barren gravelly banks. It is very abundant in the eastern United States and apparently sparingly distributed west of the Appalachian Mountains. CLASSIFICATION OF ANGIOSPERMS. 599 an oleo-resin that is official as Mastic in a number of pharmaco- poeias (see Vol. II). The wood of Schinopsis Lorentzii and S. Balanscc, growing in Argentine and Paraguay, is known in com- merce as QUEBRACHO COLORADO. It is red, very hard and contains tannin, gallic and ellagic acids. The PISTACIO nuts or Pistacia almonds are obtained from Pistacia vera indigenous to Syria and Mesopotamia and exten- sively cultivated in the countries bordering the Mediterranean. The kernels are used extensively in confectionery. The nuts are FIG. 330. Gallic acid: long orthorhombic crystals obtained from an aqueous solution. about 20 mm. long, somewhat quadrangular in cross section, and the seed consists of two fleshy, green cotyledons. The seeds of 'Buchanania lati folia and other species of Buchanania are used in India much like almonds. Gums are found in several species of Anacardium and Sclero- carya. ACAJOU GUM is obtained from Anacardium occidentale. Considerable sugar and citric acid are found in MANGOS, the fruit of Mangifera indica native of Farther India and Ceylon and cultivated in the Tropics. A fruit used like lemons is obtained from Dracontomelon mangiferum of Malacca and the Sunda Islands. 600 A TEXT-BOOK OF BOTANY. d. AQUIFOLIACE;E (ILICACE^:) OR HOLLY FAM- ILY.— The plants are mostly shrubs or trees with alternate, petio- late, simple leaves and small, white, regular flowers. The fruit is a berry-like drupe containing several nutlets. The most im- portant genus of this family is Ilex, a number of species of which are found in the United States. The European holly (Ilex Aquifolium) contains a bitter gluco- sidal principle, ilicin, which is found in the bark as well as the drupes. The drupes contain a principle which is a homologue of benzyl alcohol, and a glutinous substance which renders them useful in the manufacture of bird lime. The American holly (7. opaca} growing in the Eastern United States probably contains similar constituents to the European holly. This is the plant which furnishes the CHRISTMAS HOLLY. MATE, Paraguay or Brazilian tea, consists of the leaves of Ilex paraguariensis (Fig. 331) found in Brazil, Argentine and Paraguay. They contain about 2 per cent, of caffeine, n per cent, of tannin and some volatile oil, and are used like tea in the making of a beverage. Cassine or Appalachian tea consists of the leaves of the Dahoon holly (Ilex Cassine) growing in the Southern United States. These leaves contain about half as much caffeine and tannin as Mate. e. CELASTRACEyE OR STAFF-TREE FAMILY.— These are shrubs, as Euonymus, or woody climbers, as the climbing bit- tersweet (Celastrus scandens}. The plants are especially charac- terized by their dehiscent fruits and scarlet or reddish arilled seeds. Euonymus atropurpureus (Wahoo or Burning Bush) is a shrub or small tree. The twigs have four distinct cork-wings, making them somewhat 4-angled. The leaves are opposite, petio- late, ovate-oblong, acuminate, crenulate-serrulate and hairy be- neath. The flowers are purplish and in axillary cymes. The fruifi is a 3- to 4-lobed, persistent, loculicidally dehiscent capsule with 6 to 8 scarlet seeds. The bark of the root is official. The leaves of Cat ha edulis growing in Arabia and Abyssinia are chewed and also used like tea. They contain the alkaloids cathine and celastrine which are supposed to have similar proper- ties to cocaine, as well as tannin and an ethereal oil. A yellow coloring principle is found in the bark of Euonymus ting ens of CLASSIFICATION OF ANGIOSPERMS. 601 FIG. 331. Yerba Mate trees (Ilex paraguariensis) growing in Pereira Continho and Almeido, Santos, Brazil. The plants are shrubs or small trees, with ovate or nearly spatu- late, dentate and slightly coriaceous leaves. The latter are used, under the name of Para- guay tea, in the preparation of a tea-like beverage. The trees are extensively cultivated in South America, and large quantities of Mat6 are consumed annually. The young branches are gathered between December and August, dried over a fire, the leaves being separated, and are then ready for market. — Reproduced by permission of The Philadelphia Com- mercial Museum. 602 A TEXT-BOOK OF BOTANY. the East Indies. The yellow coloring principle in the arils of the seeds of Celastrus and Euonymus appears to closely resemble carotin. The seeds of a number of plants of this family contain a considerable quantity of fixed oil, as Celastrus macrocarpus of Peru, and Maytenus Boaria of Chile. /. ACERACE^: OR MAPLE FAMILY.— The plants of this family are trees or shrubs, the most widely distributed repre- sentative of which is the maple (Acer). The most distinguishing character of this family is the fruit, which is a double samara. The sap of a number of species of Acer contains cane sugar or sucrose, and the sap of the sugar maple (Acer saccharinum) which grows in the United States and Canada contains from 3 to 4 per cent. The making of maple syrup and maple sugar is quite an industry in some localities. Maple sugar is also obtained from the black sugar maple (Acer nigruni) and the ash-leaved maple (A. Negundo). The bark of the latter species is used to some extent in medicine. Valuable timber is yielded by the maple trees. g. HIPPOCASTANACE;E OR BUCKEYE FAMILY.— The plants are shrubs or trees with opposite, petiolate, and 3- to 9-digitately-foliate leaves. The flowers are in terminal panicles and the fruit is a 3-lobed capsule, which usually contains one large, shiny seed. The horse-chestnut (JEsculus Hippocastanum') contains in the bark two fluorescent .bitter principles, aesculin and paviin, the former of which is in the nature of a glucoside ; and in the bark, leaves and flowers the coloring principle, quercitrin is present; ! in the seed-coat saponin is supposed to occur, and the glucoside aesculin as well. The cotyledons contain considerable starch, some proteins and sugar, a small quantity of a fixed oil, and argyresin, •to which the antihemorrhoidal action appears to be due. A narcotic principle is present in the bark, twigs and leaves of the red buckeye (Aisculus Pavia) of the Southern United States. h. SAPINDACE;E OR SOAPBERRY FAMILY.— The plants are mostly trees or shrubs indigenous to the Tropics. In some genera they are herbaceous or woody vines (lianes). The plants of this family usually have either a milky sap or contain saponin, and it seems strange that a plant yielding caffeine, namely, CLASSIFICATION OF ANGIOSPERMS. 603 Paullinia Cupana, which furnishes the official Guarana, should belong to this group. The fruit shells of Nephelium lappaceum contain a toxic sapo- nin (Ph. Weekblad., 45, i, 156, 1908). Four or five per cent. FlG. 332. Flowering and fruiting branch of Brazilian cocoa (Paullinia Cupana) yielding the Guarana used in medicine. — After Radlkofer. of SAPONIN is found in the fruit of Sapindus trifoliatus of India. A principle related to saponin is found in Sapindus Saponaria of tropical America. Saponin is also found in the fruits of other species of Sapindus, the bark of Pometia pinnata of the Sunda 604 A TEXT-BOOK OF. BOTANY. and South Sea Islands, and the kernels of the seeds of the two species of Magonia indigenous to Brazil. The latter plants also yield a poisonous nectar and the root-bark is used in the poison- ing of fish. A shellac is obtained from Schleichera trijuga of India and the seeds of this plant yield " marcassa oil." Paullinia Cupana is a woody climber indigenous to and culti- vated in Northern and Western Brazil. The leaves are alternate and 5-foliate, the leaflets being oblong, acuminate, coarsely, irreg- ularly dentate, and with short stalks ; the flowers are yellow and in axillary panicles ; the fruit is a 3-locular, 3-seeded sub-drupose capsule (Fig. 332). i. BALSAMINACE^E OR JEWEL-WEED FAMILY.— The plants are succulent herbs with alternate, petiolate leaves and conspicuous axillary flowers; the fruit is a capsule which at maturity breaks into five valves, discharging the seeds with con- siderable force. The balsam of the gardens (Impatient Balsamina), which flowers all summer, belongs to this family. Other species of Impatiens are also cultivated. The stem sap as well as that of the flowers of a number of species of Impatiens is used on account of its red and yellow coloring matters, to color the skin of the hands and feet as also the nails by the people of India, Tartary and Japan. The seeds of some species of Impatiens yield an oil which is used for burning. XVIII. ORDER RHAMNALES. This order includes two large families which are characterized by having 4 or 5 stamens which are either alternate with the sepals or opposite the petals when the latter are present. The ovules are atropous. a. RHAMNACE^: OR BUCKTHORN FAMILY.— The plants are woody climbers, shrubs or small trees. Rhatnnus Purshianus is a large shrub or small tree. The leaves are petiolate, oblong, elliptical, acuminate, finely serrate and pubes- cent beneath ; the flowers are small and in axillary umbellate cymes, and the fruit is 3-lobed, black, ovoid, and drupaceous. The bark constitutes the official Cascara sagrada (Fig. 333). Rhammis Frangula or Alder Buckthorn is a shrub the botan- CLASSIFICATION OF ANGIOSPERMS. 605 ical characters of which closely resemble those of R. Purshianus. The bark of this plant is also official. FIG. 333. A Cascara tree on University of Washington campus. — After Johnson and Hindman, Amer. Jour. Pharm., 1914, p. 389. The leaves of the shrub known as New Jersey Tea (Ceanothus americanus) are said to have been used as a substitute for tea during the Revolutionary times. This plant is found in the East- 6o6 A TEXT-BOOK OF BOTANY. ern United States and Canada and the root, which contains con- siderable tannin and possibly an alkaloid, has been used in medi- cine. The leaves of Sageretia theezans of Asia have also been used as a substitute for tea. A number of plants of this family have been SUBSTITUTED FOR HOPS in the fermentation industry, as Ceanothus reclinatus of the West Indies ; Colubrina fermcnta of Guiana, and Gouania domingensis of Martinique and Hayti. Saponin is found in the bark of Gouania tomcntosa of Mexico. A crystalline bitter principle, colletin, occurs in the wood of Col- letia spinosa of South America. The bark of Discaria febrifuga of Brazil has been used as a substitute for cinchona. A number of genera furnish fish poisons, as Zizyphus, Tapura, and Gouania. Gum-lac is formed on the twigs of Zizyphus Jujuba of Asia as the result of the sting of an insect (Coccus lacca}. The fruits of several species of Zizyphus, thorny shrubs found growing in South America, are edible and enter into the French or Spanish confection known as JUJUBE-PASTE. b. VITACE^: OR GRAPE FAMILY.— The plants of this family are woody climbers or erect shrubs with alternate, petiolate leaves, and small, greenish, regular flowers, the fruit being a berry. The most important genus, economically, is Vitis, to which belong the cultivated grapes, the fruits of which furnish raisins, wine and brandy. The GRAPE-VINE indigenous to Europe (Vitis vinifera} is cultivated in all temperate and sub-tropical countries, and the variety silvestris which is found distributed in the Medi- terranean countries as far east as the Caucasus Mountains is sup- posed to have furnished the cultivated wine grape. The CONCORD and CATAWBA GRAPES are cultivated varieties of the northern Fox- or Plum-grape (Vitis Labrusca) indigenous to the Northern United States east of Minnesota. The DELAWARE GRAPES are cul- tivated varieties of the frost-grape (V. cordifolia} and the sweet- scented grape (V. vulpina} of the Eastern United States. The pulpy part of the grape contains from 9 to 18 per cent, of grape- sugar and 0.5 to 1.36 per cent, of tartaric acid. In unfavorable seasons the tartaric acid is replaced in part by malic acid. The soil has a marked influence on the quality of grapes, a sandy soil CLASSIFICATION OF ANGIOSPERMS. 607 producing a light colored wine, a soil rich in calcium a -sweet wine, and a clay soil a fine bouquet, etc. WINES are made by fermenting the grape juice, and contain from 5 to 20 per cent, of alcohol, from i or 2 to 12 per cent, of sugar, about 0.5 per cent, of tartaric, acetic and other fruit-acids, tannin and coloring matter from a trace to 0.3 per cent., and various compound ethers, giving them their characteristic flavors or bouquets. WHITE WINES are made from the juice of the pulp of the white or colored grapes after separation from the epicarp and seeds. In the manufacture of RED WINE no care is taken to separate the seeds and skins of colored grapes or even the stems on which the fruits are borne. PORT WINE is made from a grape grown in Portugal, the wine being chiefly exported from Oporto. The term CLARET is applied to a red wine containing a small amount of alcohol. BRANDY is obtained by the distillation of the fermented juice of the grape. CHAMPAGNE is a product obtained by fermenting grape juice to which other substances have been added, and contains about 10 per cent, of alcohol and 67 per cent, of carbon dioxide. RAISINS are obtained from a variety of Vitis vinifera containing a high percentage of sugar. In the prepara- tion of raisins the ripe grapes are dried either by exposure to the sun or artificial heat. In grape preserves in addition to the indis- tinguishable cells of sarcocarp, raphides of calcium oxalate occur. A principle resembling toxicodendrol is found in Vitis incon- stans of Japan. A greenish-blue coloring principle occurs in Vitis sicyoides of South America. The leaves and twigs of VIRGINIA CREEPER or American ivy (Psedera quinque folia) contain tartaric acid, glycollic acid, catechin and inosit. XIX. ORDER MALVALES. This order includes several families having rather diversified characters. The stamens are numerous, the sepals are valvate and the placentas are axillary. a. FAMILY EL^OCARPACE^.— The members of this family are shrubs or trees mostly indigenous to the Tropics. They are distinguished from the plants of the other families of this order in not containing lysigenous mucilage canals. A prin- ciple yielding hydrocyanic acid is found in Echinocarpus Sigun 6o8 A TEXT-BOOK OF BOTANY. FIG. 334. American Linden, Basswood or Lime tree (Tilia americana). A, flowering branch showing the obliquely heart-shaped, serrate leaves with conspicuous midrib and primary veins, and cymose clusters of yellowish-white fragrant flowers, which are at- tached to the midvein of an oblong, leaf-like bract. B, several of the ovoid or spherical, nut-like fruits about the size of peas. — From Bulletin 26. U. S. Department of Agriculture. of Java. A yellow coloring principle is found in the leaves of Vallea cordifolia of Peru. A fatty oil is found in the seeds of several species of Elceocarpus. A number of fruits of this family CLASSIFICATION OF ANGIOSPERMS. 609 are .edible. Maqui Fruit is obtained from Aristotelia Maqui of Chile and is used to color wine. The seeds of Sloanea dentata are eaten like chestnuts in Guiana. b. TILIACE^ OR LINDEN FAMILY.— The plants are shrubs or trees with alternate, simple leaves, and with white flowers in cymes or panicles. In the Linden or Basswood ( Tilia) the peduncles are partly adnate with the long, leaf-like bracts. The fruits are dry drupes (Fig. 334). The flowers of the European Linden (Tilia europcea} contain a fragrant volatile oil and are used in medicine. The flowers of other species of Tilia also contain volatile oils, and the flowers of Tilia toment'osa of Southern Europe are used to flavor champagne. The leaves of Tilia europcea contain the glucoside tiliacin. Sev- eral species of Grewia are used as fish poisons. A purgative principle is found in the seeds of Corchorus olitorius of Southern Asia, Africa and South America. A bitter principle occurs in the seeds of Corchorus tridens of Arabia, India and Egypt. A reddish-colored, fatty oil known as APEIBA OIL is obtained from the seeds of Apeiba Tibourbon of Guiana. The root of Grewia scabrophylla is used as a substitute for Althaea in India. Mucilage is found in the flowers and fruits of a number of genera. The leaves of Corchorus siliquosus are used in Panama as a substitute for tea. A number of the fruits of this family are edible, as of Muytingia and Apeiba. The bast fibers of several species of Cor- chorus, particularly C. capsularis of China and India, constitute jute, which is used in the making of cordage. The fiber is sep- arated by cold retting in stagnant water. c. MALVACE;E OR MALLOW FAMILY.— The plants are mostly herbs or shrubs with alternate, simple leaves, and regular, perfect, large flowers, with the stamens united into a column which encloses the styles (Fig. 222, £), and a capsular fruit. The culti- vated ornamental Hollyhock and Althaea belong to this family. Althcea oMcinalis or marshmallow is a perennial herb about i M. high with broadly ovate, petiolate, acute, dentate and lobed, pubescent leaves ; the flowers are 2 to 4 in number in the axils of the leaves and have rose-colored petals. The bractlets are linear and the fruit consists of 15 to 20 indehiscent carpels. The root is used in medicine as a demulcent. 39 A TEXT-BOOK OF BOTANY. GOSSYPIUM species. — The plants are herbs or shrubs with 3- to 5-lobed leaves, and large axillary flowers ; the fruit is a 5-locular, dehiscent capsule or pod; the seeds are spherical or somewhat angular and covered with long i -celled hairs, which latter constitute cotton (Fig. 139). PIG. 335. Indian mallow, velvet leaf (Abutilon Theophrasti). A common plant grow- ing in waste places, with velvety, heart-shaped leaves; yellow flowers; and characteristic fruits, consisting of 12 to 15 beaked carpels. — After Brown. There are three important cultivated species. ( i ) SEA ISLAND COTTON is obtained from Gossypium barbadense, a plant which is principally cultivated in the Southern United States and also in Northern Africa, Brazil, Peru and Queensland. This species is distinguished by the fact that after removal of the hairs from CLASSIFICATION OF ANGIOSPERMS. 611 the seeds they are smooth. (2) G. arboreum has purplish-red flowers, yields a particularly white cotton, and is cultivated in Egypt, Arabia and India. (3) G. herbaceum is distinguished by its broadly lobed leaves and yellowish flowers. This plant has been cultivated for over 26 centuries in Arabia and the East Indies, and since 1774 in the United States. Of this latter species there are a number of cultivated varieties. The bark of the root constitutes the cotton-root bark of medicine. The seeds of the genus Gossypium contain a large percentage of fixed oil, which is obtained by expression and is official as COTTON SEED OIL. The residue is known as cotton seed oil-cake, and contains a considerable amount of proteins with a small quan- tity of fixed oil and a poisonous principle, gossypol. The acetate of gossypol is toxic in the dose of 0.24 Gm. per kilo of weight of live rabbit (Withers and Carruth, Jour. Agric. Research, 1915, V.,p. 261). The flowers of some of the members of the Malvaceae contain coloring principles, and have been used for dyeing, as Hollyhock (Althcca rosea) and Mallow (Malva sylvestris). MUSK SEED or Amber seed, which is used in perfumery as a substitute for musk, is obtained from Abelmoschus moschatus indigenous to the East Indies and now cultivated in other tropical countries. Malva inos- 'chata also has the odor of musk, and is found in Middle and Southern Europe. Saponin is found in the roots of Sida jamaicensis and Hibiscus Sabdariffa of the East and West Indies; Sida paniculata of Peru is used as an anthelmintic and the action is supposed to be due to the glandular hairs. The seeds of several members of this family are used as substitutes for coffee, as Abutilon muticum of Egypt, and Okra or Gumbo (Hibiscus esculentus). The leaves of Sida canariensis and 5\ retusa, the latter of India, have been substituted for tea leaves. The fruits of several of the members of this family are edible, as Hibiscus esculentus, which yields the vegetable okra, and H. ficulneus of Ceylon and Egypt, which are used like beans. Fibers are obtained from a number of the other members of this family, as the bast fibers of Hibiscus tiliaceus of the Tropics, H. cannabinus of the East Indies, Urena lobata, Abutilon indicum, A TEXT-BOOK OF BOTANY. Sida retusa, and Napcea lavis, all cultivated more or less in tropical countries. d. FAMILY BOMBACE^:.— This is a group of tropical trees yielding a variety of useful products. A gum is obtained from Bombax malabaricum, and mucilage is contained in the genus Ochroma and several species of Bombax. The root of Bombax malabaricum contains tannin in addition. The bast fibers of a number of the plants of this family are used like cotton in making fabrics, as species of Bombax, Chorisia and Adansonia. The fruits of several of the Bombaceae contain tartaric acid, as the Sour Cucumber tree or CREAM-OF-TARTAR TREE (Adansonia Greg- om) of Northern Australia; and the MONKEY-BREAD TREE or BAOBAB (Adansonia digitata} of India and South America, which attains a diameter of 9 M. The green fruit of Matisia cordata of the Andes region is edible. The seeds of Bombax insigne and Matisia Castailo of South America yield a product on roasting which is used like cacao bean. The seeds of Cavanillesia umbel- lata of Peru are edible and contain a considerable quantity of fixed oil. e. STERCULIACE^E OR COLA FAMILY.— The plants are herbs, shrubs or trees, sometimes lianes, with mostly simple, petiolate, alternate leaves ; the flowers are small and form a rather complex inflorescence. Theobroma Cacao is a small tree 5 to 10 M. high, with cori- aoeous, glaucous, entire leaves, and clusters of brownish 5-mer- ous flowers arising from the older branches or stem ; the fruit is large, fleshy, ovoid, 10- furrowed longitudinally, yellow or reddish, and contains five rows of seeds, 10 or 12 in each row (Fig. 336). The seeds are ovoid, somewhat flattened, and with large, convo- luted cotyledons which break up into more or less angular frag- ments on drying. The seeds contain 35 to 50 per cent, of a fixed oil known as CACAO BUTTER and official as Oleum Theobromatis ; 15 per cent, of starch; 15 per cent, of proteins; i to 4 per cent, of theobromine; 0.07 to 0.36 per cent, of caffeine, about 0.5 per cent of sugar, and also a small amount of tannin. The red color of the seed is due to a principle known as cacao-red which is formed by the action of a ferment on a glucoside. The Cacao tree is indigenous to the countries bordering the Gulf of Mexico and is now cultivated in many tropical countries. CLASSIFICATION OF ANGIOSPERMS. 613 FIG. 336. Cacao tree (Theobroma Cacao), growing in Rio Hondo. Costa Rica. In the illustration is shown the peculiar habit of this tree in producing large, ovoid, fleshy fruits on the main axis or trunk, as well as on the older branches. When Cortez conquered Mexico he found the Aztecs using Cacao seeds to make a beverage; this was later introduced into Europe, previous to either coffee or tea. — Reproduced by permission of The Phila- delphia Commercial Museum. 614 A TEXT-BOOK OF BOTANY. . 337. A flowering branch of the Kola nut tree (Cola acuminata) , growing in Trini- dad. The leaves are obovate or lanceolate, acuminate, and in the axils are borne small clusters of purplish flowers. The tree is indigenous to Africa and is extensively cultivated in the West Indies and Brazil, in which countries it has become naturalized. — Reproduced by permission of The Philadelphia Commercial Museum. CLASSIFICATION OF ANGIOSPERMS. 615 Most of the cacao of the market is obtained from Ecuador (the Guayaquil variety being especially valued), Curaqao, Mexico, Trinidad, and the Philippine Islands. The seeds of the wild plants contain a bitter principle, the quantity of which is found to be greatly reduced in the plants when under cultivation. The bitter principles in the raw product are more or less destroyed by the process of fermentation to which the seeds are subjected in preparing them for use, which at the same time develops the aroma. Cola acuminate is a tree with lanceolate or obovate, acuminate, entire, petiolate leaves. The flowers are purplish, unisexual, and in small axillary clusters, frequently arising from the old wood ; the fruit consists of five follicles, each containing 4 to 8 seeds. The seed is made up of two large, fleshy cotyledons. They have much the same constituents as Cacao, but the proportions of these differ (Fig. 337). The leaves of Waltheria glomerata are used as a hemostatic in Panama like matico, as are also the leaves of Pterospennum acerifolium. The inner bark of Fremontia calif ornica is used for purposes similar to those of elm bark. Mucilage is also found in the following genera : Pentapetes, Wal- theria, Guazuma, Helicteres, and Sterculia. Tannin is found in the bark of Guazuma ulniifolia of South America. An oil is manu- factured from the seeds of Sterculia fcetida of the East' Indies and Cochin China. The seeds of a number of species of Sterculia are edible. Abroma angusta of India yields a fiber which has been suggested as a substitute for silk. XIX. ORDER PARIETALES. This is a group of plants of rather wide distribution, and includes perennial herbs like the violets ; evergreen shrubs, such as the Tea Plant ; and vines like the Passion flower. As the name indicates, the plants of this order are characterized by the flowers having, for the most part, ovaries with parietal placentas. a. FAMILY DILLENIACE^E — The plants are mostly trop- ical trees which yield valuable timber. The wood of a species of Dillenia growing in the East Indies also contains red coloring substances. The fruits of Dillenia indica contain citric acid and are used like lemons. The leaves of Curatella americana contain considerable silicon and are used to polish wood. Dillenia speciosa 6i6 A TEXT-BOOK OF BOTANY. FIG. 338. Leaves, flowers, and fruits of the Tea plant (Thea sinenis, or Camellia viridis). The plant is a shrub or small tree bearing lanceolate, evergreen leaves, and in the axils occur the rather large, white, fragrant flowers. The fruits are small, globular capsules. — Reproduced by permission of The Philadelphia Commercial Museum. of India contains a large percentage of tannin. Some species of Dillenia are cultivated and the foliage and flowers combine to make the plants the most beautiful in the plant kingdom. £. MARCGRAVIACEJE,— The members of this family are CLASSIFICATION OF ANGIOSPERMS. 617 partly epiphytic, and have dimorphic leaves, the smaller ones being pitcher-like. The plant which is cultivated in greenhouses, M arc- gravia umbellata, is used in the Antilles in medicine. c. THEACE^E OR TEA FAMILY.— The plants are shrubs or trees with alternate, evergreen leaves, and perfect, regular FIG. 339- Picking tea on a plantation in Japan, the wall at the left probably being the ruins of an ancient temple. While the plant ordinarily is a shrub, it is kept trimmed and is a bush from 2 to 5 feet high. The plants begin to bear in the third year, and continue to yield a commercial article from 3 to 7 years thereafter. The number of crops per year is determined by the geographical location. In the tropical fields of Ceylon, India, and Japan lea,ves are picked frequently, while in northern Japan they secure only one crop a year.— Reproduced by permission of The Philadelphia Commercial Museum. flowers with numerous stamens, occurring one or more in the axils of the leaves. The fruit is a 3- to 5-locular, dehiscent capsule. The most important member of this family is Thea sinensis, the two varieties viridis and Bohea furnishing the leaves known as TEA. The Tea tree is indigenous to Eastern Asia, and is now extensively cultivated in China, Japan, India, Java, Brazil, Sicily, Portugal and France, and to some extent in the Southern United States (Figs. 338, 339). 618 A TEXT-BOOK OF BOTANY. The fresh leaves of Thea do not have the properties which characterize the commercial article, the aroma and other qualities being developed after special treatment. Two general classes of tea are found in commerce, these depending on the mode of treat- ment. Those which are rapidly dried by means of artificial heat constitute GREEN TEA. The leaves which are slowly dried, per- mitting fermentation to set in, furnish BLACK TEA. Tea leaves contain 1.5 to 3.5 per cent, of caffeine; theobromine and the- ophylline (an isomer of theobromine) ; 10 to 20 per cent, of gallo- tannic acid ; quercitrin, and a volatile oil containing, among other components, methyl salicylate. The seeds contain about 30 per cent, of fixed oil, I per cent, of caffeine, and saponin. The leaves furnish one of the sources of the official caffeine. Saponin is found in the seeds of Thea Sasanqua of China and Japan. Two saponin-like substances (assamin and assaminic acid) are found in the seeds of Thea assamica. The flowers of T, Sasanqua are used in China and Japan to flavor teas. The flowers and leaves of Thea Kissi are used as an insecticide. The red colored sap of Laplacea Hcematoxylon of New Granada is used in medicine. d. GUTTIFER^: OR GAMBOGE FAMILY.— The plants are principally shrubs and trees of the Tropics, that is, if we exclude the Hypericaceae which are now put in a group by them- selves. Garcinia Hanburyi is a tree with ovate, petiolate, coriaceous, opposite leaves. The flowers are small, yellow, dioecious, occur- ring in small clusters in the axils of the leaves. The fruit is a pome-like berry, with a papery endocarp and an oily sarcocarp, and 3 or 4 seeds, i in each loculus (Fig. 340). The trees are chiefly valued on account of the gum- resin known as gamboge which they contain. A resin used in making plasters is obtained from Calophyllum brasiliense of Brazil. Balsams resembling Copaiba have been obtained from Calophyllum Calaba of the West Indies. Balsams known as TACAMAHAC are also derived from the following plants : Bourbon Tacamahac from Calophyllum Tacamahaca, India Taca- mahac from C. apetahim and Brazilian Tacamahac from Rheedia Madruno. Balsams are also obtained from Caraipa grandiflora CLASSIFICATION OF ANGIOSPERMS. 619 of Brazil, and Rhecdia acumlnata of Peru. Resins and balsams are obtained from a number of species of Clusia. A yellow coloring principle, mangostin, is obtained from the bark and fruit of Mangosteen (Garcinia Mangostana} of the East Indies. Yellow coloring principles are found in Ochrocarpos FIG. 340. Gamboge plant (Garcinia Hanburyi). A branch showing the • axillary pistillate flowers and pome-like fruits. — After Baillon. longifolius of India and Vismia acuminata of South America. Tannin occurs in Mahurea palustris of Brazil, Mesua ferrea of the East Indies, that flower-buds of Ochrocarpos longifolius of India, and several species of Cratoxylum of China and Java. A butter-like fat is obtained from the seeds of Garcinia indica. A fixed oil known as LAUREL-NUT OIL is derived from the seeds of Calophyllum Inophyllum and other species of Calophyllum 620 A TEXT-BOOK OF BOTANY. growing in the East Indies, Cochin China and Brazil, as well as the seeds of Symphonic, fasciculata of Brazil. The bark of Clusia pseudochina is used in Peru as a substi- tute for cinchona. An alkaloid is found in Vismia robusta of Java. A gum is obtained from Calophyllum tomentosum of India and Vismia acuminata, that of the latter being purgative. The flower buds of the India Suringi (Ochrocarpos longifolius) have an aromatic odor resembling cloves. Aromatic principles are also found in other plants of this family. Edible fruits are yielded by the following plants : MANGO FRUIT from Garcinia Mangostana and other species of Garcinia; MAMMEI APPLE or Apricot of St. Domingo from Maminea amer- icana of tropical America, the latter being used in the prepara- tion of Mammey wine or " Toddy " and a liquor known as " Eau de Creole." The seeds of Platonia insignis are used like almonds in Brazil and Paraguay ; the fruit of the latter plant is quite acid and is eaten with sugar. e. HYPERICACE^: OR ST. JOHN'S-WORT FAMILY.— The plants are herbs or shrubs of the temperate regions, and are represented in the United States by the Hypericums, which are quite common. The flowers are characterized by the numerous stamens which are united into distinct groups or clusters. The flowers of Hypericum perforation or Common St. John's-wort contain yellow and red coloring principles. Yellow coloring prin- ciples have also been isolated from Hypericum laricifolium of Ecuador and H. elodes of Northern Europe. The entire plant of H. perforation is used in medicine and contains considerable resin, and a small amount of volatile oil. /. FAMILY DIPTEROCARPACE^:.— The plants of this family are principally trees and indigenous to tropical Asia. The family derives its name from the winged fruits of the principal genus Dipterocarpus. A number of economic products are fur- nished by this group of plants. BORNEO CAMPHOR is obtained from Dryobalanops aromatica. The camphor separates in canals in the older parts of the wood and between the wood and bark, and is obtained by felling the trees, splitting the wood, and then removing the camphor by hand. Owing to the fact that some of the trees do not contain camphor, it is sometimes necessary to fell CLASSIFICATION OF ANGIOSPERMS. 621 a hundred trees in order to obtain 6 or 8 K. of the product. The young twigs of this plant as well as the older wood yield a volatile oil known as Oil of Borneo camphor. GURJUN BALSAM or Wood oil is obtained from a number of species of Dipterocarpus growing in the East Indies by incising the stems as in the collection of turpentine. The balsam is used as a substitute for copaiba and contains an ethereal oil which consists chiefly of a sesquiterpene, an indifferent resin, and gur- junic acid. SINDOR BALSAM is obtained from Dipterocarpus mar- ginatus of Borneo. A resin known as " PINEY RESIN," which is used as a substitute for Dammar, is obtained from a number of species of Valeria growing in India. CHAIA RESIN is obtained from Shorea rubifolia of Cochin China. The bark. of Shorea robusta of Northern India contains 32. per cent, of tannin. The seeds of species of Shorea, Pinanga, Gysbertsiana and Isoptera yield the fatty oil known in Java as TANGKAWANG. The seeds of a number of plants of this family contain considerable starch, as Vateria, Vatica and Doona. The woods of the following genera are extensively used : Vatica, Shorea, and Hopea. g. FAMILY TAMARICACE^E.— The plants are halophytic shrubs found in the desert regions of Central Asia and Mediter- ranean countries and one genus (Fouquieria) is found in Mexico. Fouquieria splendens is cultivated to some extent, and is known as Ocotilla or Coach-whip Cactus. The bark contains gum, resin and wax; the latter is known as OCOTILLA WAX and resembles beeswax. The twigs of Myricaria germanica of Europe are used as a substitute for hops. A manna-like sugar is formed on the stems of Tamarix mannifera growing in Egypt, Arabia and Afghanistan, as the result of the sting of an insect (Coccus manni- parus). Tannin is found in a number of species of Tamarix as well as in the galls formed on the plants, the tannin being used for dyeing. A table salt is prepared from the ash of several species of Reaumuria found in Northern Africa and the East Mediterranean region. h. FAMILY BIXACE^E.— These are shrubs or trees found in the Tropics, and are of interest chiefly on account of the seeds of Bixa Orellana which furnish the coloring matter known as ANNATTO (Orlean, Arnotta). The plant is found in tropical 622 A TEXT-BOOK OF BOTANY. America and also in Polynesia and Madagascar. The seeds are covered with a fleshy arillus from which the coloring matter is prepared by means of water. The insoluble matter is collected, made into cakes and chiefly used for dyeing and coloring. Annatto contains a red crystalline principle, bixin, a yellow coloring prin- ciple, orellin, and an ethereal oil. The root of this plant also con- tains some coloring matter. A yellow coloring principle is found in Cochlospermum tinctorium of Senegambia and an aromatic resin is obtained from Cochlospermum Gossypium of Ceylon and Malabar. i. FAMILY CANELLACE^ OR WINTERANACE^E.- These are trees with aromatic barks having an odor of cinnamon ; pellucid-punctate leaves ; and golden-yellow flowers. The most important member of this family is IVinterania Canella growing in the Antilles and in Southern Florida, which furnishes the CANELLA BARK or False Winter's bark used in medicine. The bark occurs in large quills or broken pieces, from 3 to 10 mm. thick, with the periderm nearly entirely removed, the outer surface yellowish or orange-red with transversely elongated patches of cork and shal- low, whitish depressions ; the fracture is short with numerous resin canals ; the odor aromatic ; taste aromatic, bitter and pungent. It contains mannitol, resin and 0.5 to 1.28 per cent, of a volatile oil containing eugenol, cineol, caryophyllene and pinene. The bark of one or more species of Cinnamodendron of tropical America is sometimes substituted for Canella bark, but it is distinguished by containing tannin, which constituent is not found in Canella. j. VIOLACE^E OR VIOLET FAMILY.— The plants are herbs or shrubs with basal or alternate leaves, perfect, irregular flowers, and 3-valved dehiscent capsules (Fig. 280, /). The best known representatives of this group are the cultivated species of the genus Viola, including the English or sweet violet ( Viola odor- ata), which produces a volatile oil containing ionon ; and the varie- ties of Viola tricolor vulgaris which furnish the pansies of the garden. The entire herb of Viola tricolor has been used in medi- cine and contains the yellow coloring principle viola-quercitrin, salicylic acid and methyl salicylate (Figs. 201, 232). k. FAMILY FLACOURTIACE^:. — These are tropical shrubs and trees, and are chiefly of interest because of their valu- able woods 'and acid, juicy fruits. A number of them are of CLASSIFICATION OF ANGIOSPERMS. 623 medicinal interest. CHAULMUGRA OIL is said to be obtained from the seeds of Gynocardia odorata of Farther India. The seeds also contain gynocardic acid and hydrocyanic acid. The latter is also present in the seeds of Hydnocarpus venenata of Southern India and Ceylon and the leaves of Kiggelaria africana. A number of species of Lcetia growing in Cuba yield a resin resembling sandarac. The Coccos oil which is used in perfumery is obtained from several species of Myroxylon growing in Poly- nesia. The fixed oils from the seeds of Gynocardia odorata and of several species of Pangium are used in cooking. A bitter principle occurs in the bark of Casearia adstringens of Brazil. A purgative principle is found in C. esculenta of tropical Asia and Australia. The root of Homalium racemosum of Guiana contains an astrin- gent principle. /. FAMILY TURNERACE^:.— These plants are herbs, shrubs and trees mostly found in tropical America, and are of interest on account of the leaves of Turnera diffusa, particularly the variety aphrodisiaca, which yield the DAMIANA of medicine esteemed as a tonic laxative like Rhamnus Purshianus. The drug usually consists of leaves, although the reddish stems, yellowish flowers and globular capsules may be present. The leaves are about 25 mm. long, varying from oblanceolate to obovate; the margin is serrate-dentate; the color, .light-green (older leaves somewhat coriaceous and pubescent); the odor aromatic; taste aromatic and bitter. Damiana contains a volatile oil, resin, and the bitter principle damianin. Ethereal oils are found in other species of Turnera, and T. angustifolia of Mexico contains con- siderable mucilage. m. PASSIFLORACE^ OR PASSION-FLOWER FAM- ILY.— The plants are mostly herbaceous or woody vines climbing by means of tendrils, with alternate, palmately-lobed, petiolate leaves and solitary, perfect, regular flowers. The flowers are peculiar in that between the corolla and stamens there are numer- ous, frequently petaloid, colored, sterile, filamentous bodies which are known collectively as the " corona." The fruit is a berry or dehiscent capsule. The genus Passiflora is known as the Passion- flower because the flowers are considered to be emblematic of the Crucifixion, the corona representing the crown of thorns, the 624 A TEXT-BOOK OF BOTANY. stamens the nails, and the gynaecium with its three styles, the three thieves. The rhizomes of the Passion-flowers of the South- ern States (Passiflora incarnata and P. lutea) have been used in medicine. Not much is known with regard to the active principles of these two plants or of the thirty other species of Passiflora which are used in medicine. The fruits of several species of Passi- flora are edible, and a number of them are cultivated on account of their beautiful as well as odorous flowers. n. CARICACE^: OR PAPAW FAMILY.— This family is composed of two genera of latex-containing trees growing in trop- ical America, the best known of which is the genus Carica. The Papaw or Melon tree (Carica Papaya} is a small tree with a straight, slender, usually unbranched trunk which bears at the summit a cluster of long-petiolate, deeply-lobed leaves. The flowers are dioecious, and the fruit is a large, melon-like berry. The green fruits as well as the leaves contain a milk-juice which is obtained by incising them. The material is dried and is used in medicine on account of its containing a proteolytic ferment, papain or papayotin, which is active in the presence of both acids and alkalies. The leaves and fruit also contain the alkaloid car- paine, and in addition the leaves contain the glucoside carposid. The root contains a glucoside somewhat resembling potassium myronate and a ferment which has a decomposing action upon it. A proteolytic ferment is also present in the leaves of Carica quer- cifolia of Argentina. The melon tree is cultivated on account of the fruits, which are edible. o. BEGONIACE^E. — This is a family of tropical plants which are extensively cultivated. They are herbs or shrubs frequently with tuberous rhizomes and with characteristic, asymmetric, varie- gated leaves. They are easily propagated by cuttings, providing they have sufficient moisture, even the leaves giving rise to new plants. The roots of Begonia anemonoides of South America and B. gracilis of Mexico contain purgative principles. Calcium oxal- ate and acid oxalates are found in the leaves of probably all of the species of Begonia. The roots of a number of species of this genus are astringent. p. DATISCACE/E. — The plants are trees or shrubs found principally in the Tropics. A bitter principle is found in the CLASSIFICATION OF ANGIOSPERMS. 625 Yellow hemp (Datisca cannabina) of Southern Europe and the Orient. The root contains a yellow coloring principle, datiscin, which is used in the dyeing of silk. The wood of Octomeles and Tetrameles is used in the making of tea-chests. XXI. ORDER OPUNTIALES. The plants of this order are succulent,- with much reduced leaves, and with flowers characterized by having a perianth with numerous segments and an inferior ovary. a. CACTACE^ OR CACTUS FAMILY.— This is a remark- able family of succulent plants growing largely in the arid regions of Mexico, Brazil and other parts of America. The stems are more or less flattened, terete or tuberculated, in some cases becom- ing branched and woody. The leaves are reduced to scales, but are sometimes larger, more or less cylindrical or dorsiventral, and usually drop off sooner or later. In the axils of the leaves or leaf-scars there are usually groups of hairs and spines. The flowers are mostly solitary, sessile, perfect, regular and conspic- uous. The fruit is usually a fleshy berry, the fruits of a number of species being edible. Quite a number of the Cacti have been used in medicine, the one most commonly employed being the NIGHT-BLOOMING CEREUS (Cereus grandiflorus), which is extensively cultivated on account of its flowers. The flowers and fresh stems are the parts used. They contain several acrid principles, including probably an alka- loid and a glucoside, the drug resembling in its action digitalis. MESCAL BUTTONS (Anhalonium) are the dried tops of several species of Lophophora growing in Northern Mexico. The main axis of the plant is under the ground and produces at certain points small aerial shoots which are more or less button-shaped or disk-like, being about 20 to 50 mm. in diameter. In the center of the disk occur tufts of hairs which vary in the different species, and among which are usually found one or more pinkish flowers. The drug has been used like Night-blooming Cereus, and con- tains several alkaloids, namely, anhalonine (similar to pellotine), mescaline, anhalonidine and lophophorine. Alkaloidal principles are also found in other members of this family. The sap of several species of Cereus of the Antilles has anthel- 40 626 A TEXT-BOOK OF BOTANY. FIG. 341. Prickly Pear or Indian Fig (Opuntia vulgaris), a prostrate, more or less spreading cactus, composed of flattened stems bearing very small, awl-shaped and decidu- ous leaves and short, yellowish-green bristles and occasionally solitary spines. The flowers are pale yellow, opening in the sunshine. The fruit is a succulent berry about 2.5 cm. long. Various of these cacti are used as food by the cattle, which often eat them with the bristles. Frequently the spines are burnt off by the cattlemen with the use of gasolene torches, so as to prevent the accumulation of spines in the stomachs of the cattle in the form of phyto-bezoars, which are globular accumulations of vegetable tissues. (See p. 577.)— After Troth. CLASSIFICATION OF ANGIOSPERMS. 627 mintic properties, as also that of certain species of Rhipsalis and Opuntia. A caoutchouc-like exudation is obtained from Opuntia. vulgaris and other species of Opuntia growing in the West Indies. An astringent principle is found in the root and bark of Opuntia Karwinskiana of Mexico. A tragacanth-like gum is found in Peireskia Guacainaclio of Venezuela, Opuntia rubescens of Brazil and O. Tuna of the West Indies, Mexico and South America. An alcoholic beverage is made by the Indians of Sonora from the fruit- juice of Ccreus Thunbergii. A number of species of Opuntia yield edible fruits. The PRICKLY PEAR is the fruit of Opuntia Tuna growing in the West Indies and tropical America ; INDIAN FIG is derived from Opuntia Ficus-Indica growing in Southern Europe, particularly Sicily; a fruit also known as Prickly pear or Indian fig is derived from Opuntia vulgaris, a common Cactus growing in sandy soil in the Eastern United States. The COCHINEAL INSECT which is official under the name of coccus in a number of pharmacopoeias (Coccus Cacti) feeds upon various of the Cactacecc, more especially the Xopal plant, Nopalea (Opuntia} coccinellifera, a native of Mex- ico and Peru. (See Kraemer, Amcr. Jour. Pharm., 1913, p. 344.) XXII. ORDER MYRTALES OR MYRTIFLOR^E. The plants are herbs or shrubs with complete flowers, rarely apetalous, producing one or more ovules in each loculus. a. THYMEL^ACE^: OR MEZEREUM FAMILY.— The characters of this family are illustrated by the Spurge laurel or Mezereon (Daphne Alesercum'), which is a small shrub about i M. high, with oblong-lanceolate, acute, entire, sessile leaves, and small groups of fragrant flowers, the perianth tube of which is purplish- red or white. The fruit is an ovoid, reddish drupe. The bark of Daphne Mezereum and other species of Daphne is used in medicine. The bark of Funifera utilis of Brazil contains a vesicating principle. A principle with similar properties is found in the bark of Leather wood (Dirca palustris) of the Eastern United States and Canada. The fruit and leaves of Gnidia carinata of Cape Colony contain emetic and drastic principles. A poisonous principle is found in Pimelca trichostachya of Australia. A 628 A TEXT-BOOK OF BOTANY. yellow coloring principle is found in several species of Daphne and Thymelcea. The wood of Aquilaria Agallocha of India and China is aromatic and resembles the " Aloe wood." A balsam is obtained from the wood of Pimelea oleosa of Cochin China. The bast fibers of quite a number of plants are used in the making of paper, as of Daphne in India, Gnidia of Madagascar, Lagetta (L. lintearia or Lace-tree) of Jamaica and St. Domingo, Thymelaa of the Mediterranean countries and Linodendron of Cuba. The fibers of Leather wood (Dirca palustris) of the Eastern United States and Canada are said to be used in a similar manner. b. FAMILY EL^AGNACE^:.— This is a small family represented in the United States by several genera, among which is the Buffalo berry (Lepargyrcra argentea}, a thorny shrub found in the western part of the United States and the Northwest Terri- tory. The fruit is a reddish drupe-like berry which contains a small amount of citric and malic acids, 5 per cent, of sugar, and in composition is much like the currant. It is eaten by the Indians, and used to a great extent in the Western States in the making of jellies. The leaves and flowers of a number of species of Elaeagnus are used in medicine. c. LYTHRACE^: OR LOOSESTRIFE FAMILY.— The members of this family are herbs, shrubs and trees usually with opposite, entire leaves. The flowers are in racemes and the fruit is a capsule. Quite a number of the plants yield valuable woods and a number are cultivated as ornamental plants. The flowers of Woodfordia floribunda of India contain a red coloring principle, and the bark and leaves of Lafocnsia Pacari of Brazil contain a yellow coloring principle. Considerable tannin is found in the root of the Purple loosestrife (Lythrum Salicaria} of the Northern United States and Canada, and widely distrib- uted in the Old World ; and also in the fruit of Woodfordia flori- bunda, a plant which is extensively cultivated in greenhouses. A bitter principle, nessin, is found in the leaves of Nescca syphilitica of Mexico and probably other species of this genus. Cuphea viscosissima of Mexico is said to resemble digitalis in its physiologi- cal action. A vesicating principle, resembling cantharidin in its action, is obtained from the fresh leaves of Ammannia baccifera of India. A narcotic principle is found in the seeds of Lager- CLASSIFICATION OF ANGIOSPERMS. 629 strcemia Flos-regince of India. The flowers of Lawsonia inermis, native to and cultivated in the Orient, have an odor resembling that of the Tea rose. The shrub is also cultivated to some extent in the West Indies and is known in the Orient as the HENNA PLANT. The leaves are used in the preparation of the cosmetic Hinna. They contain an orange or brownish-yellow dye which is used in the dyeing of the skin and hair. d. PUNICACE;E OR POMEGRANATE FAMILY includes a single genus of two species. The Pomegranate (Punica Grana- tum) indigenous to the Levant and now extensively cultivated is of chief interest. The plants are small trees, the young twigs of which are 4-angled and frequently thorn-like. The leaves are opposite, ovate-lanceolate, entire and short-petiolate. The torus, calyx and corolla are scarlet, and the gynaecium consists of two whorls of carpels. The fruit is an inferior edible berry with a hard pericarp or rind. The pulpy portion is formed from the outer layer of the seed-coat. The bark of the root and stem is used in medicine (see Granatum, Vol. II). The rind of the fruit is used as an astringent because of the tannin which it contains. It does not appear, however, to contain the alkaloids found in the official bark. e. FAMILY LECYTHIDACE^.— The plants are mostly shrubs and trees indigenous to the Tropics. They are of chief interest on account of the BRAZIL-NUT (Fig. 342) obtained from Bertholletia excelsa, and the Sapucaya-nut obtained from the Monkey-pot tree (one or more species of Lecythis), both genera of South America. The seeds (so-called nuts) are rich in oil and proteins and are edible. The fruit of Careya arborea is drupa- ceous and is also edible, the seeds being considered, however, to be poisonous. Bitter narcotic or poisonous principles are also found in the fruit of Planchonia valida of the Molucca Islands and the seeds of a number of species of Lecythis. The fruits and roots of a number of species of Barringtonia are used in China and Java to stupefy fish. The pericarp of the fruit of Fcetida moschata of Guiana contains considerable quantities of an ethereal oil. The flowers of Grias cauliflora of the Antilles are used like tea. A cooling drink is made from the sarcocarp of Couroupita guianensis of the West Indies and Guiana 630 A TEXT-BOOK OF BOTANY. /. RHIZOPHORACE^: OR MANGROVE FAMILY.— These are tropical shrubs or small trees with evergreen, cori- aceous leaves, small cymose and axillary flowers, and seeds which germinate while the fruit is still attached to the plant. The best FIG. 342. Brazil-nut (also known as Para nut, cream nut, and nigger-toe), the seeds of Bertholletia excelsa, a Brazilian tree belonging to the Fam. Myrtaceae. In the illustration is shown a portion of the fruiting branch with some of the long, leathery leaves. The fruits terminating the branches are woody, vary from 10 to 15 cm. in diameter, and are in the nature of a pyxis, — i.e., opening by means of a lid. It encloses about 20 brownish-gray, 3-sided seeds, which are largely exported from Para. — Reproduced by permission of The Philadelphia Commercial Museum. known genus of this family is Rhizophora (Mangrove tree), of which there are three species, the AMERICAN MANGROVE being R. Mangle. This tree produces aerial roots on the stems and branches, and leaves which are characterized by a number of layers of CLASSIFICATION OF ANGIOSPERMS. 631 water-containing cells. The plants grow in muddy swamps, or along the sea-coast where the water is brackish, a number together forming the so-called " Mangrove swamps " (Fig. 165). The root and bark of the Mangrove, as well as other species of Rhizophora and several species of Bruguiera, contain a large quantity of tannin which resembles catechu. The aerial roots of Rhizophora are used by the natives of Polynesia in the making of bows, and the woods of several genera are used in carpentry. g. MYRTACE^ OR MYRTLE FAMILY.— This is a group chiefly, of shrubs and trees, some, as of species of Eucalyptus, being the loftiest trees known, attaining a height in some instances of 105 M. The plants are indigenous to Australia and tropical America and some are extensively cultivated. EUCALYPTUS species. — The leaves frequently vary in shape and in arrangement on the young and older branches of the same plant. On the young branches they may be, as in Eucalyptus Globulus, ovate or broadly elliptical, opposite and sessile, while on older branches they are scythe-shaped, glandular-punctate, glabrous, petiolate and alternate. In the latter case the petioles are twisted and the leaves stand edgewise so that both surfaces are equally exposed to the light and hence of similar structure. The flowers are solitary, or in cymes or umbels, occurring in the axils of the leaves. Petals are wanting and the whitish stamens, which are numerous and inflexed in the bud, are covered by an oper- culum or lid which is considered to be formed by the union of the sepals, and which dehisces on the maturing of the stamens, this being one of the most characteristic features of the genus. The fruit is a 3- to 6-locular truncated capsule or pyxis. This is a very important genus from an economic point of view, among the products being the volatile oil (oil of eucalyptus), and eucalyptol, both of which are official, and the tannin or so-called " gum," known as Eucalyptus kino. Jambosa Caryophyllus (-Eugenia caryophyllata). — This is a small tree indigenous to the Molucca Islands and now extensively cultivated in the Tropics. The leaves are opposite, ovate-lance- olate, acuminate, petiolate, entire and evergreen. The flowers are rose-colored and in cymes; the fruit is berry-like and constitutes the Anthophylli or MOTHER-CLOVE. The unexpanded flower-buds 632 A TEXT-BOOK OF BOTANY. constitute the drug or spice known as Cloves. (See Vol. II.) Pimento, officinalis is a tree with opposite, lanceolate, acute, petiolate, pellucid-punctate and evergreen leaves. The flowers are small, white and in axillary racemes. The fruit, known as " All- spice," is used for flavoring. Not only are ethereal oils obtained from the genera Euca- lyptus, Jambosa and Pimenta already described, but also from other members of the Myrtacege. OIL OF BAY or oil of Myrcia is distilled from the leaves of Pimenta acris of the West Indies. The oil consists largely of eugenol, methyl-eugenol, chavicol, methyl-chavicol, citral, phellandrene and myrcene, and is used in the preparation of BAY RUM. The fruits of P. acris yield 3.3 per cent, of an oil resembling the leaf oil. Cheken leaves are obtained from Eugenia Chekan. They are about 25 mm. long, ovate or rectangular, with entire, somewhat revolute margin, light green, pellucid-punctate, aromatic, astrin- gent and bitter. Cheken leaves yield about i per cent, of a volatile oil containing cineol and pinene ; 4 per cent, of tannin ; a volatile alkaloid and a glucoside. Oil of Cajeput is obtained from the leaves and twigs of Mela- leuca Leucadendron, particularly the varieties Cajeputi and minor of the East Indies. The principal constituents of this oil are cineol, terpineol, pinene, and a number of aldehydes and acid esters. An oil resembling Cajeput oil is obtained from the leaves and flowers of Myrceugenia camphorata of Chile. The leaves of Myrtus communis, a plant extensively cultivated in the Mediterranean countries of Europe, yield a distillate with water known as EAU D'ANGE and used as a toilet article. The leaves of the following plants are used as substitutes for tea leaves : Myrtus Molina of Chile, Melaleuca genistifolia of Australia, and Leptospermum scoparium and other species of this genus growing in New Zealand. The seeds of Eugenia disticha are known in the Antilles as Wild coffee. Quite a number of the genera of this family yield edible fruits. GUAVA or Guayava fruit is obtained from Psidium Guajava of tropical America. ROSE APPLE is the fruit of Jambosa malaccensis, growing in the East Indies and Oceanica. JAMBUSE BERRIES are derived from Jambosa vulgaris which is extensively cultivated in the Tropics. The CLASSIFICATION OF ANGIOSPERMS. 633 lemon-like fruit of Myrcia coriacea is used in medicine, the bark in tanning, and the wood in dyeing. The fibrous bark of Eugenia ligustrina is used like oakum. h. FAMILY COMBRETACESE.— The members of this fam- ily are shrubs or trees, sometimes climbing; with usually alternate, petiolate, simple leaves ; sessile flowers in racemes ; somewhat fleshy, winged, I -seeded fruits, and are mostly found in the Tropics. Like the Fagaceae the plants of this family contain a tannin, similar to gallotannic acid, in nearly all parts of the plant. The MYROBALANS of the East Indies are the young fruits of Terminalia Chebula. The pericarp contains from 5 to 45 per cent, of tannin, the latter amount being found in the fruits known as Long or Chebula Myrobalans. The fruits also contain ellagic and chebu- linic acids. The fruits of Terminalia Bellerica constitute the Bel- eric Myrobalans. The galls of Terminalia macroptera of Africa and other species of Terminalia as well as of Bucida Buceras of tropical America are particularly rich in tannin. A yellow coloring principle is found in Terminalia Brownii of Africa and is used in dyeing leather. The bark of T. Catappa of Asia and Africa is used to dye leather black. A gum-resin with cathartic properties is obtained from Termi- nalia fagifolia of Brazil. An aromatic resin is found in Ter- minalia angustifolia of the East Indies. The fruits of one or more of the Combretacese are said to be used in the preparation of the arrow-poison of the Negritos. The seeds of Terminalia Catappa and Combretum butyrosum contain about 50 per cent, of fixed oil. These seeds as well as those of other species of Terminalia and Quisqualis indica of Farther India and tropical Africa are edible. The seeds of the latter plant when unripe are said to be used like mustard. The woods of a number of the plants of the Combretacese are valuable for building purposes, and some of the genera furnish ornamental plants which are cultivated in greenhouses. i. FAMILY MELASTOMATACE^:.— This is a large family of herbs, shrubs, and trees with opposite, 3- to 9-nerved leaves and regular, perfect, often showy flowers. They are chiefly found in South America and are represented in temperate regions by 634 A TEXT-BOOK OF BOTANY the Meadow beauty (Rhexia). Quite a number of the plants are cultivated and a large number yield edible fruits. The fruits, barks and leaves frequently contain COLORING PRINCIPLES. A yel- low coloring principle is found in the leaves of a number of species of Memecylon of the East Indies and Africa, which resembles that of saffron and curcuma. Red coloring principles are found in the berries of a number of species of Blakea of South America. A black coloring principle is obtained from the fruit of several species of Tamonea of tropical America, Melastoma malabathri- cum of the East Indies and Tococa guianensis ^f Northern South America and Tibouchina Maximiliana of Braz«. Tannin is found in considerable quantity in the bark? of Tibouchina, Dissotis and Rhynchanthera. The leaves of Tamonea thecezans are used in Peru as a sub- stitute for tea. A mucilage is found in the bark of Medinilla crispata of the Molucca Islands. The flowers of the latter plant as well as of M. macrocarpa are used as a remedy for the bite of poisonous serpents. ;. ONAGRACE^: OR EVENING PRIMROSE FAMILY. — These are mostly annual or perennial herbs with usually entire or toothed, simple leaves. The flowers are perfect, regular or irregular, epigynous, variously colored, solitary in the axils of the leaves or in somewhat leafy spikes. The fruit is a dehiscent capsule, berry, drupe, or nut. This family is represented in tem- perate regions by such plants as the Willow herb (Epilobium), Evening primrose (CEnothera), on which de Vries has carried on his famous mutation experiments, and Enchanter's nightshade (Circsea). The cultivated FUCHSIA also belongs to this family. A yellow coloring principle is obtained from the herb and unripe fruits of Jussieua pilosa of Brazil. The roots of CEnothera bien- nus, O. muricata and other species of this genus are edible. This family also includes the group of aquatic plants, repre- sented by a single genus and one of which, Trapa natans or Water chestnut, is naturalized to some extent in the ponds of Massachu- setts and New York. The fruit is coriaceous, 2- to 4-spinose, and i -seeded. The cotyledons are unequal, rich in starch, and are edible, sometimes being ground and made into bread by the people of Europe and Northern Asia. CLASSIFICATION OF ANGIOSPERMS. 635 FIG. 343. Evening Primrose (CEnothera biennis), a simple, sometimes more or less branching herb growing to a height of 3 to 15 dm. The leaves are lanceolate or oblong- lanceolate; the flowers are symmetrical, with yellow petals; and the capsules are narrow and 4-valved. This plant is one of the commonest of the CEnotheras, growing in open places. It is a biennial like the other species, but it is possible for horticulturists to develop its life history in one year. — After_Brown. 636 A TEXT-BOOK OF BOTANY. XXIII. ORDER UMBELLALES OR UMCELLIFLOR^. The plants of this order are widely distributed .in northern temperate regions, although there are some representatives in the Tropics. The flowers are small, 4- or 5-merous and epigynous. a. ARALIACE^: OR GINSENG FAMILY.— The plants are mostly trees or shrubs with alternate, petiolate, simple or 3- to /-compound leaves. The flowers are either in umbels or panicles. The fruit is a drupe or berry. The best known representatives of this family are the English ivy (Hedera Helix} of Europe, and Ginseng (Panax quinque folium} (Fig. 345) growing in the East- ern and Central United States. This plant is the source of the ginseng root of commerce, considerable quantities of which are exported to China, where it is used like the root of Panax Ginseng, a plant growing wild in Manchuria and Korea. Both plants are also cultivated in the United States, the roots from the wild plants being preferred. The root contains a volatile oil, and considerable starch. Several species of Aralia are used in medicine (Fig. 344). The leaves of the English ivy contain the glucoside helixin, and a carbohydrate, inosit. They also contain formic, oxalic, malic, tannic and hederic acids, besides the yellow principle carotin. The fruits of the ivy contain a purplish-red coloring substance and are said to be poisonous. The Chinese RICE PAPER is made from the pith of Tetrapanax papyriferum, which grows wild in Formosa and is extensively cultivated in China. The pith is cut spirally into thin strips, which are spread out flat and then cut into pieces varying from 15 to 30 cm. long and 10 to 12 cm. broad. This paper differs from other papers in that it is a natural product. The rhizome of Panax repens, growing in Japan, contains 20.8 per cent, of a non-toxic saponin with hemolytic properties. b. UMBELLIFERyE OR CARROT FAMILY.— The plants are herbs, frequently with hollow stems ; alternate, simple or com- pound leaves, the base of the petiole often forming an inflated sheath ; and small white, yellowish, greenish or somewhat purplish flowers occurring in simple or compound umbels. The fruit is a cremocarp, having characters which are of important taxonomic CLASSIFICATION OF ANGIOSPERMS. value, as the presence or absence of secondary ribs, number and position of the vittae, etc. FIG. 344. Wild Sarsaparilla (Aralia nudicaulis). The plant produces a long, cylin- drical rhizome at or near the surface of the ground, and sends out at various points a single, long-stalked compound leaf, and a shorter, naked scape bearing 2 to 7 umbels of greenish- white flowers. The rhizome is sold as American Sarsaparilla, but it has none of the con- stituents of the true Sarsaparilla. — After Brown. Coriandrum sat hum is an annual herb the fruits of which are official. The compound leaves are bi- or tri-pinnate, the leaflets 638 A TEXT-BOOK OF BOTANY. being narrow linear-lanceolate ; and the flowers are white or rose- colored. FIG. 345. Panax quinquefolium (Ginseng): A, upper portion of plant showing pal- mately-compound leaves with long-stalked leaflets and the berry-like drupes; B, fusiform root; C, roots showing characteristic stem scars at the upper portion. — From a photograph by Wyss. (See also Fig. 166, p. 305.) Conium maculatum or Poison Hemlock is a tall, erect, branch- ing, biennial plant, with purplish spotted stems, large pinnately CLASSIFICATION OF ANGIOSPERMS. 639 decompound leaves and small, white flowers (Figs. 346, 347). The fruit as well as the leaves is used in medicine. Carum Carvi (Caraway) is a biennial herb with bi- or tri- pinnate, deeply incised leaves, and white flowers. The fruit is official and the leaves are also used in medicine. Pimpinella Anisum is a small, hairy, annual herb. The leaves are variable, the lower being somewhat cordate and serrate, the middle distinctly lobed, and the upper ones trifid ; the flowers are white. The fruit is official and is also used for flavoring. Focniculum vulgare is an annual or perennial, glabrous herb with very finely dissected leaves, the divisions being narrow-linear. The flowers are yellow, and the involucre and involucels are wanting. The fruit is official. Ferula foctida is a stout, perennial herb with few, ternately compound leaves and small, polygamous, light yellow flowers. The root is rather large and yields the gum-resin asafetida. Asafetida is also derived from other species of Ferula. Ferula Sumbul is a tall perennial herb with purplish latex- containing stems. The basal leaves are ternately compound and with amplexicaul base. The leaves decrease in size from the base upward, becoming bract-like near the inflorescence. The flowers are polygamous, resembling those of F. foctida. The root is official and is probably also obtained from other closely related species of Ferula. A large number of the plants belonging to the Umbelli ferae contain essential oils, resins, gum-resins and related substances. The gum-resin AMMONIAC is an exudation found on the stem and branches of Dorema Ammoniacum and other species of Dorema as a result of the sting of an insect. The plant is found in Western Asia. The gum-resin occurs in yellowish-brown, globular, or somewhat flattened tears which are brittle, milky-white internally, with a distinct balsamic odor and bitter, acrid, nauseous taste. It contains a small quantity of volatile oil having the odor of Angelica. AFRICAN AMMONIAC is obtained from Ferula tingitana growing in Northern Africa and Western Asia. The gum-resin GALBANUM is obtained by incising the root of Ferula galbaniflua and other species of Ferula growing in the Levant. Galbanum occurs in pale yellowish-brown agglutinated A TEXT-BOOK OF BOTANY FIG. 346.— Poison Hemlock (Conium maculatum), showing the spreading habit of the plant and the prominent large compound umbels of flowers. — After Bornemann. CLASSIFICATION OF ANGIOSPERMS. 641 FIG. 347.- Conium maculatum, showing the large decompound leaves with pinnatifid leaflets, and the compound umbels of flowers, with detached, enlarged views of umbels and a compound umbel. — From Bulletin No. 26, U. S. Department of Agriculture. The fresh juice of Conium maculatum was used in the preparation of the famous hemlock potion which was employed by the Greeks in putting their criminals to death. This is not the same plant under the name of Conium which is referred to in Roman and mediaeval Latin literature, the latter being Cicuta virosa, which does not grow in Greece and in Southern Europe. 41 642 A TEXT-BOOK OF BOTANY. FIG. 348. Cicuta maculata (Water Hemlock): A, upper part of stem with leaves and compound umbels; B, base of the stem and the thick tuberous roots; C, cross-section of stem showing part of a mestome-strand and the pith with secretory cells (a), vessels (v), libriform (St), pith (p); D, a flower showing petals with long inflexed summit and the five stamens inserted on the disk that crowns the ovary; E, the fruit; F, fruit in longitudinal section showing the two ovules; G, cross-section of a mericarp showing the six vittae or oil- tubes. — After Holm. tears, forming a more or less hard mass, which is brittle when cold but soft and sticky at 37° C. ; the odor is distinct, balsamic ; the taste bitter and acrid. It contains from 10 to 20 per cent, of a volatile oil composed of d-pinene, cadinene, and other principles. CLASSIFICATION OF ANGIOSPERMS. 643 A volatile oil, known as AJOWAN OIL, and containing thymol, is obtained from the fruit of Carum Ajowan of Europe, Asia and Africa. A volatile oil containing APIOL is found in the fruit and leaves of the garden parsley (Petroselinum sativum). DILL OIL is obtained from the garden Dill (Anethum graveolens). The fruit of Sweet cicely (W 'ashingtonia longistylis} yields a volatile oil known as sweet anise oil, which contains anethol. The oil of water fennel (CEnanthe Phellandrium) contains about 80 per cent, of phellandrene. CUMIN OIL is obtained from Cuminum Cyminum of Turkestan and Egypt, and contains cymene. The roots of a number of the plants of this family contain volatile oils, as Lovage (Levisticum officinale) of Southern Europe; European angelica or garden angelica (Angelica Arch- angelica] ; American angelica or the purple-stemmed angelica (A. atropurpurea} found in the Northern and Eastern United States and Canada; Wild angelica (A. sylvestris) of Europe. c. CORNACE^E OR DOGWOOD FAMILY.— The plants are shrubs or trees with simple, opposite leaves, and flowers in cymes or heads, which in the case of the Flowering dogwood (Cornus florida) are subtended by four large, petal-like, white, or pinkish bracts. The fruit is a i- or 2-seeded drupe. The bark of Cornus florida, a shrub or small tree growing in the United States, contains a bitter principle, cornin ; and a small quantity of gallic and tannic acids. Aucuba japonica, a plant indigenous to the Himalayas, China and Japan and extensively cultivated on account of its crimson berries, contains a glucoside aucubin. It is found in the different varieties and varies in amount from 0.31 to 1.96 per cent. METACHLAMYDE.E OR SYMPETAL^. This is the highest group of plants and is marked by the follow- ing characters : The corolla is sympetalous ; the flowers are mostly perigynous or epigynous and both the corolla and stamens are borne on the perianth tube. The number of parts is definite, there being 5 sepals, 5 petals, 5 or 10 stamens and 2 or 5 carpels. This sub-class includes but six orders, to which, however, belong a large number of medicinal and economic plants. 644 A TEXT-BOOK" OF BOTANY. I. ORDER ERICALES. The plants of this order are distinguished by the fact that the stamens are mostly free from the perianth tube. a. PIROLACE^E. — The plants are small, mostly evergreen perennials, and are represented in the United States by several genera. Chimaphila innbellata (Prince's pine or Pipsissewa) is a small trailing or creeping plant producing distinct flower- and leaf- branches. The leaves are used in medicine. The flowers are in small corymbs and the petals are white or pinkish. In Chimaphila maculata the leaves are lanceolate, mottled with white along the veins and the flowers are considerably larger. With the Pirolaceae are sometimes grouped the saprophytic plants of the genus Monotropa. There are two representatives of this genus which are common in the United States, namely, Indian pipe (Monotropa uniflora) and false beech-drops (M. Hypopitys*). The latter contains a glucoside or an ester of methyl salicylate, and a ferment gaultherase (Fig. 349). b. ERICACEAE OR HEATH FAMILY.— This is a large family and the plants are widely distributed, especially in the northern mountainous parts of both the Eastern and Western Con- tinents. They vary from perennial herbs to trees. The flowers are usually regular, the stamens being mostly 2-spurred (Fig. 221, S), and the fruit is either a superior or inferior drupe or berry (Fig. 280, //). Arctostaphylos Uva-Ursi is a low branching shrub which trails or spreads on the ground. The leaves are used in medicine (Fig. 355). The flowers are small, white or pink, few and in short racemes. The fruit is a red, globular drupe. Trailing arbutus (Epigcca rcpens) is a trailing, shrubby, hairy plant with broadly elliptical or ovate, coriaceous, evergreen leaves and white or rose-colored, fragrant flowers which are either per- fect, with styles and filaments of varying length, or dioecious. The leaves contain similar constituents to those in Uva-Ursi and Chimaphila (Fig. 353). The leaves of wintergreen (Gaultheria procumbens} are the cource of true oil of wintergreen, which consists almost entirely CLASSIFICATION OF ANGIOSPERMS. 645 FIG. 349. Indian Pipe (Monotropa unifiora), a saprophytic plant of the Ericaceae growing on decaying roots of various plants and on decomposing vegetable matter. The stems are white or yellowish-red, furnished with scales or bracts in place of leaves, and surmounted usually with a single nodding flower becoming in fruit erect. — After Troth. 646 A TEXT-BOOK OF BOTANY. FIG. 350. Purple Azalea or Pinkster Flower (Rhododendron nudiflorum), showing the upright lower stalk surmounted by several spreading branches, each bearing a number of showy tubular flowers at its extremity. The flowers of this plant often appear before the leaves. CLASSIFICATION OF ANGIOSPERMS. 647 of methyl salicylate. It contains a small quantity of an alcohol and an ester giving the characteristic odor. The same principles FIG. 351. Great Laurel or Rose Bay (Rhododendron maximum), an evergreen shrub found in low woods and along streams, chiefly in the mountains of the eastern United States, often forming impenetrable thickets. It is one of the most beautiful of the flowering shrubs, producing from scaly, cone-like buds numerous corymbose clusters of flowers varying from pale rose to white. — After Troth. probably also occur in several other species of Gaultheria (Fig. 354). 648 A TEXT-BOOK OF BOTANY. FIG. 352. Mountain Laurel (Kalmia latifolia). This is a handsome evergreen shrub growing on rocky hills and in damp soils in the eastern United States. The foliage is bright green, and the showy flowers occur in terminal corymbs, being either of a whitish or pink color. The leaves of many species of Kalmia are said to be poisonous to animals, which is especially true of the Sheep Laurel, known as Lambkill (Kalmia angustifolia) , which is not infrequent on hillsides and pastures. — After Troth. The poisonous principle andromedotoxin is found in a number of species of Rhododendron, Leucothce, and Pieris. This principle is a powerful emetic and one of the most toxic principles known. CLASSIFICATION OF ANGIOSPERMS. 649 FIG. 353. Trailing Arbutus or Mayflower (Epigcea ripens). This is one of the first of the early spring flowering plants. It is a prostrate woody plant, usually more or less covered up with the autumn leaves and with rounded and heart-shaped evergreen leaves. The flowers occur in small axillary clusters, are of a rose-red color, dimorphic as to styles and stamens, and are very fragrant. They are transplanted with difficulty, and require an acid soil, as do many other Ericaceae. — After Troth. 650 A TEXT-BOOK OF BOTANY. FIG. 354. Wintergreen, teaberry (Gaultheria procumbent), a low shrub producing slender stems lying at or beneath the surface of the earth and having ascending flowering branches rising to a height of 7 to 12 cm. The leaves are evergreen, obovate or oval, and very spar- ingly toothed; the flowers are whitish, urn-shaped and axillary. The fruit is capsular, sur- rounded by the fleshy calyx, which forms the reddish aromatic globular berries. — Bureau of Plant Industry, U. S. Department of Agriculture. CLASSIFICATION OF ANGIOSPERMS. 651 trailing, shrubby plant with thick y (Arctostaphylos Uva-ursi), a t aves and whitish flowers in terrain 652 A TEXT-BOOK OF BOTANY. FIG. 356. Black or High-bush Huckleberry (Gaylussacia baccata or G. resinosa). An erect shrub with straggling branches, having leaves and flowers that are densely covered with resinous dots; the leaves vary from oval to oblong; the flowers are reddish-yellow, clustered in short racemes on terminal and axillary branches; the fruit is a sweet, blackish, berry-like drupe. In some varieties it is smooth and shiny, in others it is bluish and covered with a bloom. — After Brown. CLASSIFICATION OF ANGIOSPERMS. 653 It probably occurs in the nectar of the flowers of Kalmia and Rhododendron, being the cause of the poisonous properties of the honey from this source. The leaves of several species of laurel FIG. 357. Dwarf Blueberry or Early Sweet Blueberry (Vaccinium pennsylvanicum) . A low shrub growing to a height of 2 to 6 dm. The leaves are lanceolate or oblong, of a bright green color and minutely serrate with bristle-pointed teeth; the flowers are few, in short racemes, the corolla being whitish and cylindrical; the berries are bluish, covered with a bloom, and ripen during July and August. — After Brown. (Kalmia) contain considerable quantities of this principle, and are poisonous to cattle. The plants of the genus Gaylusaccia are small shrubs distin- guished by having an inferior, berry-like drupe with ten loculi. To this genus belong the huckleberries, as black huckleberry 654 A TEXT-BOOK OF BOTANY. (G. baccata) ; blue huckleberry (G. frondosa) ; and dwarf huckle- berry (G. duitiosa). The latter plant grows in sandy swamps in both the United States and Canada and the fruit ripens in May and June. The fruits of the other two species ripen in July and August (Fig. 356). FIG. 358. Low Blueberry or Blue Huckleberry (Vaccinium vacillans). A small shrub with yellowish-green branchlets having nearly entire, narrow, obovate leaves. The flowers are in racemose clusters, appearing before the leaves are half grown, as shown in the illustration; the corolla is pinkish-white, oblong-cylindrical, and somewhat constricted at the throat. The berries are blue, covered with a bloom, and ripen in August and Sep- tember.— After Brown. The plants belonging to the genus Vaccinium vary from very small shrubs to tree-like shrubs and the fruit is an inferior, 5-locular berry with numerous seeds. The blueberries or bilberries (whortleberries) are the fruits of several species of Vaccinium. CLASSIFICATION OF ANGIOSPERMS. 655 The low-bush blueberry (V. pennsylvanicum} yields the berries which ripen in June and July, while the high-bush blueberry ( V. corymbosum} furnishes the fruits which are found in the market in July and August (Figs. 357, 358). FIG. 359. Small Cranberry (Vaccinium Oxycoccos). A trailing evergreen shrub, which produces slender erect or ascending branches with oblong revolute leaves, rose-colored nodding flowers, and a 4-locular,' reddish, acid fruit. The berry of the American Cranberry (V . macrocarpon) is much larger and furnishes the fruit of the market. There are many varieties in cultivation. — After Brown. The bilberry of Europe, Vaccinium Myrtillus, a plant growing in Northern Europe and Asia and the Western United States and Canada, is said to destroy -Bacillus typhosus and B. Coli, an infusion of the dried berries being used for this purpose. The leaves of this plant contain ericolin and kinic acid. 656 A TEXT-BOOK OF BOTANY. Cranberry is the fruit of several species of Vaccinium which are sometimes grouped in a separate genus, Oxycoccos. There are two principal species : The large or American Cranberry ( V . macrocarpon} in which the berries are ovoid or oblong and the small or European Cranberry ( V. Oxycoccos} in which the berries are globose. The berries contain from 1.4 to 2.8 per cent, of citric acid; and a bitter glucoside, oxycoccin (Fig. 359). Many attempts have been made to cultivate the blueberry, trailing arbutus, and other plants of the Ericaceae. For some years a number of the agricultural experiment stations in the United States have attempted to grow the blueberry as a fruit, but none of these attempts has resulted in the commercial success of blueberry culture, and the experimental results have been chiefly of a negative character. The reason for this has been due, as pointed out by Coville (Bull. No. 193, Bureau of Plant Industry, U. S. Department of Agriculture), to a misunderstanding of the soil requirements for this' plant. Plants will thrive only in soil having the following properties : I. The soil must have a distinctly acid reaction, such as is found in peat bogs or on the surface of the ground in sandy, oak, or pine woods. 2. Aeration of the soil is necessary. The rootlets of the swamp blueberry are remarkable in having no root hairs whatsoever, so that their absorptive surface is only about one-tenth that of other plants having root hairs. The growth of the rootlet of the blueberry is much less than that of other plants, being about at the rate of only I mm. per day under favorable conditions. The rootlets of healthy blueberry plants are inhabited further by a mycorrhizal fungus which apparently has the property of assimilating nitrogen. II. ORDER PRIMULALES. Of the three families belonging to this order, there are two which are to some extent represented in temperate regions. a. PRIMULACE^ OR PRIMROSE FAMILY.— The plants are mostly perennial herbs with perfect regular flowers, and capsu- lar fruits. The family is chiefly of horticultural interest, as it contains the genera Primula and Cyclamen. There are several species of Primula cultivated, and they are among the most popular and beautiful of the florist's flowers (Fig. 360). Several of the CLASSIFICATION OF ANGIOSPERMS. 657" FIG. 360. Primula (Primula obconica), one of several species of Primula which are cultivated in greenhouses and as house plants. The leaves are circular heart-shaped, long petiolate, and very hairy; the flowers are pinkish or lilac color and occur in umbels. The hairs of this plant are very irritating, and cause a dermatitis similar to that produced by poison ivy.' — After Guernsey. species are found in Northern United States and Canada. Dur- ing recent years it has been reported that the wild primrose (P. farinosa) and also the cultivated species (P. obconica) possess 42 658 A TEXT-BOOK OF BOTANY. hairs which are very irritating and cause a dermatitis similar to that produced by poison ivy. A number of the primulas have been examined chemically. The subterranean parts of Primula officinalis contain two crystal- line glucosides, primeverin and primulaverin, which by the action of the ferment, primeverase, produce an anise-like odor. The odors of the other species of Primula are probably due to distinct glucosides: (a) one producing an anise-like odor, as in P. offici- nalis, P. capltata, and P. denticulata; (b) one producing the odor of methyl salicylate, as in P. longiHora, P. elatior, and P. vulgaris; (c} one producing the odor of coriander, as in P. auricula, P. panonica, and P. Palinuri. The flowers of a number of species are light in color and somewhat luminous in the dark. b. PLUMBAGINACE^E OR LEADWORT FAMILY.— Perennial, mostly acaulescent herbs, growing in saline locations. Sea lavender or marsh rosemary (Limonium carolinianum} is found in the salt meadows from Labrador to Texas. The plant is reported to contain tannin and has been used in medicine. III. ORDER EBENALES. This order includes three families which are chiefly indig- enous to the Tropics. The leaves are alternate, and the flowers vary in the different families, the fruit being a berry or drupe. a. SAPOTACE^: OR SAPODILLA FAMILY.— The plants usually have a milky latex, and many of them yield GUTTA-PERCHA, of which the following may be mentioned : Palaquium Gutta, P. oblongifolium, P. borneense and P. Treubii, all growing in the East Indies. The latex is obtained by incising the trees and collect- ing the exuding juice in suitable vessels. It soon coagulates and forms grayish or reddish-yellow hard masses, which are plastic at 65° to 70° C. Owing to the fact that the material is plastic when heated and firm and tenacious when cold, it is used for a variety of purposes, as in the manufacture of surgical instruments and as a material for filling teeth. Gutta-percha as it exudes from the tree is supposed to consist of a terpene-like hydrocarbon, which on coagulation is oxidized, forming a number of resinous compounds. The plants of other genera of this family also yield CLASSIFICATION OF ANGIOSPERMS. 659 gutta-percha, as Mimusops Balata, M. Elengi, and about fifteen species of Payena growing in the East Indies. GUM BALATA is obtained from Mimusops Balata, a tree of Guiana. The gum is more resinous and flexible than gutta-percha. It contains /?-amyrin acetate and probably lupeol acetate. A gum resembling gutta-percha is obtained from the Sabodilla tree (Achras Sapota}. This gum is known in commerce as GUM CHICLE and is obtained from Yucatan. It is whitish, brittle, and yet somewhat elastic, aromatic, and contains 45 per cent, of a colorless crystallizable resin, soluble in alcohol and ether ; and 18 per cent, of caoutchouc. It is used in large quantities in the making of chewing gum. The seeds of Illipe butyracea yield a fixed oil which is known as VEGETABLE BUTTER. A fixed oil is also obtained from other species of Illipe as well as various species of Bassia, Argania, and Butyrospermum, that from the latter being known as " shea butter." The family is notable on account of the hard woods, known as IRONWOODS, which it furnishes, these being yielded by Mimusops Kauki of Farther India and tropical Australia and Argania Side- roxylon of Southwestern Morocco. A number of species also yield highly prized edible fruits, as the SAPOTILLA yielded by Achras Sapota indigenous to the Antil- les and cultivated in tropical countries, and STAR APPLE yielded by Chrysophyllum Cainito of tropical America. b. EBENACEyE OR EBONY FAMILY.— The plants differ from those of the preceding family in not containing a latex. The flowers are monrecious or dioecious and they usually have from two to eight styles. The chief interest is in the genus Diospyros, which yields the wood known as EBONY. Black ebony is obtained from various species of Diospyros growing in tropical Africa, and Asia, and the Philippine Islands. White ebony is obtained from several species of Diospyros growing in the Philippines. A red ebony is obtained from D. rubra of Mauritius, a green ebony from D. Chloroxylon of Farther India, and a striped ebony from several species growing in the Philippines. PERSIMMON fruit is obtained from Diospyros virginiana, a tree growing from Rhode Island south to Texas. The astrin- 660 A TEXT-BOOK OF BOTANY. gency of the unripe fruit is due to the tannin which it contains. When it is ripe, which is not until after the appearance of frost, it is palatable and contains considerable malic acid and sugars. The Japanese persimmon is a cultivated variety of D. Kaki and produces a large orange-colored fruit which is not uncommon in the fruit markets in many parts of the world. At the present time the plant is cultivated in California. The bark of our native persimmon is used in medicine. It contains considerable tannin which resembles gallotannic acid, and a crystalline resinous principle with a peculiar odor and slightly astringent taste. c. STYRACACE^: OR STORAX FAMILY.— The flowers of this family somewhat resemble those of the Ebenaceae, but the filaments of the stamens are united in a single series, and there is a single slender style. Styrax Benzoin is a medium-sized tree with long, ovate, acu- minate leaves which are very hairy on the under surface. The flowers occur in terminal racemes, and are silvery white on the outer surface and reddish-brown on the inner surface. The bal- samic resin yielded by this plant is official as benzoin. IV. ORDER GENTIANALES OR CONTORTS. The plants of this order have opposite leaves, the flowers are regular and the gynaecium consists of two separate carpels. The order includes five families, all of which furnish medicinal plants. a. OLEACEyE OR OLIVE FAMILY.— This family is chiefly of interest because of the olive and manna trees. The olive tree (Olea europcea} is indigenous to the Orient and is now cultivated extensively in Southern Europe, Northern Africa, the islands of the Mediterranean, tropical America, includ- ing the Southern United States, and in California. The leaves are narrow-lanceolate, entire, coriaceous and evergreen. The flowers are small, white, diandrous and in axillary racemes. The fruit is a drupe, the sarcocarp of which is rich in a fixed oil known as olive oil. The oil is obtained by expression, and is official. Depending upon the character of the fruits and the amount of oil which they yield, over forty varieties are recognized. CLASSIFICATION OF ANGIOSPERMS. 661 The fresh green olives contain a glucoside oleuropein, which disappears on the maturation of the fruit. Fraxinus Ornus is a tree resembling the ash, with /-foliate leaves, and polygamous flowers occurring in compound racemes. The fruit is a flat samara with the wing at the apex. The sac- charine exudation from this plant is official as manna. The white ash (Fraxinus americana) is a valuable tree on account of the timber which it yields. The bark contains a bitter glucoside, f raxin, the solutions of which are fluorescent ; a bitter substance, f raxetin ; an ethereal oil of a butter-like consistency, and tannin. Some of these principles are also found in other species of Fraxinus growing in the United States and Europe. The bark of the fringe tree (Chionanthus virginica) of the Southern United States contains an intensely bitter glucosidal principle, chionanthin, and possibly also saponin. The leaves of the garden lilac (Syringa vulgaris} contain a crystalline glucoside, syringin, and syringopicrin, both of which are probably also found in other species of Syringa as well as the bark and leaves of privet (Ligustrum vulgare), which latter plant is extensively used for hedges. b. LOGANIACE^E OR LOGANIA FAMILY.— The plants are variable in character, being herbs, shrubs, trees or vines. Yellow jessamine (Gelsemium sempervirens) is a twining woody vine, sometimes trailing on the ground for a considerable distance. The leaves are oblong-lanceolate and evergreen. The flowers are bright yellow and dimorphic. The fruit is a septi- cidally dehiscent capsule. The rhizome and roots are official. Carolina pink (Spigelia marilandica) is a perennial herb with ovate-lanceolate, more or less actite and nearly sessile leaves. The flowers are yellow on the inner and scarlet on the outer surface, and occur in a i-sided spike or scorpioid cyme. The fruit is a loculicidal, few-seeded, 2-valved capsule (Fig. 361). The rhizome and roots are official. Strychnos Nux-vomica is a small tree with broadly elliptical, 3- to 5-nerved, reticulately-veined, somewhat acuminate, cori- aceous leaves. The flowers are whitish and in terminal cymes. The fruit is a berry of varying size and contains several seeds, the seeds being official. 662 A TEXT-BOOK OF BOTANY. CURARE, which is used by the Indians of South America as an arrow-poison, is supposed to be made from the bark of Strych- nos to.vifcra growing in Guiana, and probably other species of FIG. 361. Carolina pink (Spigelia marilandica) showing the rhizome bearing two branches with opposite leaves and flowers in terminal scorpioid cymes. this genus. The active principle of this poison is' the alkaloid curarine, which when administered hypodermically has a powerful action resembling that of digitalis. CLASSIFICATION OF ANGIOSPERMS. 663 FIG. 362. Closed Gentian (Gentiana Andrewsii), probably one of the most abundant of the fall-flowering Gentians. It is a perennial, forming stout, leafy stems, terminated by sessile clusters of blue flowers. The corolla is closed, and hence this Gentian is sometimes ' called "Bottle Gentian." It grows in moist grojind throughout most of the eastern United States and Canada. — After a photograph by Troth. c. GENTIANACEyE OR GENTIAN FAMILY.— The plants are mostly herbs with regular, perfect, showy flowers occurring usually in small cymes or racemes (Fig. 362). Yellow gentian (Gentiana lutea) is a large, perennial herb 664 A TEXT-BOOK OF BOTANY. (see Vol. II) with large, 5- to 7-nerved, broadly elliptical leaves. The flowers are yellow and occur in axillary cymes. The fruit is a 2-valved, ovoid capsule. The rhizome and roots are official. Many of the gentians are among the most highly prized of the wild flowers, some of them, as the fringed gentian (Gentiana crinita), being one of the most beautiful. The closed gentian (Fig. 357), so called because the flowers remain closed, is quite abundant in moist grounds throughout most of the United States and Canada. The roots of a number of species of American gentian have medicinal properties resembling that of G. lute a. Menyanthes, the yellowish-white horizontal rhizome of Men- yanthes trifoliata (Fig. 363), contains an amorphous glucoside which is slightly soluble in water, soluble in alcohol, and is precipi- tated with tannin. Upon hydrolysis menyanthin yields a volatile oil possessing an odor reminding one of bitter almonds. Swertia Chirata. — The entire plant is official. HERBA CENTAURII MINORIS, the entire plant of Erythrcea Cen- taurium of Europe, contains a glucoside, erytaurin, which forms small colorless prismatic and bitter crystals and is slowly hydro- lyzed by emulsin. Sabbatia Elliottii, occurring in the pine barrens of the Southern States, is known as the " quinine herb." d. APOCYNACE/E OR DOGBANE FAMILY.— The plants vary from perennial herbs to shrubs and trees, contain an acrid latex, and have flowers with the stigmas and styles united and the stamens distinct. They are mostly found in the Tropics. Apocynum cannabinum is a perennial herb with erect or ascend- ing branches. The leaves are oblong-lanceolate, opposite, nearly sessile or with short petioles (Figs. 226, 251). The flowers are greenish-white, the lobes of the corolla being nearly erect and the tube about as long as the calyx. The fruit is a slender, terete follicle containing numerous seeds tipped at the micropylar end with a tuft of hairs. The root is official. The root of a closely related species, namely, spreading dog- bane (Apocynum androscemifolium}, is sometimes substituted for the official drug. The plant is distinguished by being more spreading in its habit. The leaves are ovate (Figs. 226, 364), the flowers are pinkish, the lobes being revolute, and the tube several times as long as the calyx. CLASSIFICATION OF ANGIOSPERMS. 665 FIG. 363. Buckbean or Bogbean (Menyanthes trifoliata), a perennial herb with a fleshy horizontal rhizome, producing erect stems, bearing three oval or oblong leaflets, and a raceme with numerous, white or rose-colored, fringed flowers. The plant grows in bogs and shallow water in northern United States and Canada. — Bureau of Plant Industry, U. S. Department of Agriculture. 666 A TEXT-BOOK OF BOTANY. FIG. 364. Spreading Dogbane (Apocynum androscemifolium), a perennial, branching herb, with ovate-oblong, opposite leaves, and small, pinkish fragrant flowers occurring in terminal cymes. All parts of the plants contain a white acrid latex. — After Brown. Strophanthus Kotnbe. — The plant is a woody climber with elliptical-acuminate, hairy leaves. The flowers are few, charac- terized by long styles, and occur in axillary racemes. The fruit consists of two long follicles containing numerous awned seeds, CLASSIFICATION OF ANGIOSPERMS. 667 which are official. In the closely related plant S. hispidus the flowers are numerous and occur in terminal cymes. FIG. 365. Butterfly-weed or Pleurisy-root (Asdepias tuberose), showing the sessile, oblong- ovate leaves and the simple, many-flowered umbels. QUEBRACHO or ASPIDOSPERMA is the bark of Aspidosperma Quebracho-bianco, a tree growing in Argentine. It contains a number of alkaloids and is used to some extent in medicine. 668 A TEXT-BOOK OF BOTANY. The leaves and bark of the cultivated oleander (Nerium Olean- der) contain the glucoside oleandrin, resembling digitalin in its action ; a .fluorescent principle, and probably several other principles. The common periwinkle ( Vinca minor) contains the principle vincin, which is supposed to be a glucoside and which probably occurs in other species of Vinca. e. ASCLEPIADACE^ OR MILKWEED FAMILY.— The plants somewhat resemble those of the Apocynacese. The flower, however, is distinguished by having distinct styles, a 5-lobed corona connecting the corolla and stamens, which latter are mostly monadelphous, and pollen grains that are coherent, forming char- acteristic pairs of pollinia. Few of the plants are of any economic importance. The latex oi the stems and the hairs of the seeds are deserving of attention. PLEURISY ROOT, which was formerly offi- cial, is obtained from Asclepias tuberosa, a plant growing in the Eastern United States and one of the two members of this genus that have orange-colored flowers (Fig. 365). CONDURANGO is the bark of Marsdenia Cundurango, a liane of Ecuador and Colombia. It occurs in quilled pieces, the bark being from 2 to 6 mm. thick. Externally it is brownish-gray and with a more or less scaly cork. The taste is bitter, acrid, and aromatic. The drug contains an amorphous glucoside ; an unsatu- rated alcohol occurring in large prisms; and a volatile oil (0.3 per cent.). ' V. ORDER POLEMONIALES OR TUBIFLORyE. This is a large order of plants, which are mostly herbaceous. The leaves are either opposite or alternate ; the flowers are regular or irregular, the stamens being usually adnate to the corolla. a. CONVOLVULACE^ OR MORNING-GLORY FAM- ILY.— The plants are mostly herbs or shrubs, frequently twining (to the left). They are found mostly in the Tropics, but quite a number of genera occur in temperate regions (Fig. 366). Exogonium Purga is a perennial twining herb with distinctly veined, cordate leaves ; purple flowers with the stamens exserted. and occurring in cymes. The fruit is a 2-locular capsule. The CLASSIFICATION OF ANGIOSPERMS. 669 plants produce slender rhizomes with tuber-like roots, these being used in medicine. Convolvulus Scammonia is a perennial twining herb, with a large .tap root, containing a resinous latex, and is the source of the official scammony root. The leaves are sagittate ; the flowers are large, yellowish- white and funnel- form, as in the morning- FIG. 366. Great bind weed (Convolvulus sepium) showing trailing or twining habit, the hastate leaves and funnel-shaped corolla. The plant is very resistant to noxious fumes and is usually found in smelter regions. glory, and occur in the axils of the leaves, either solitary or in clusters. The fruit is a 4-seeded, 4-locular, dehiscent capsule. A number of the plants of the Convolvulaceae are cultivated, probably the most important of which is the SWEET POTATO vine (Ipomcca Batatas), a plant extensively cultivated in tropical and sub-tropical countries on account of the edible tuberous roots. The roots contain from 3 to 10 per cent, of sugar and 9 to 15 per cent, of starch, which occurs in larger proportion in plants grown 670 A TEXT-BOOK OF BOTANY. in sub-tropical countries. The starch is a commercial product and is known as sweet-potato starch or BRAZILIAN ARROW-ROOT. The grains are more or less bell-shaped and 2- or 3-compound, about the size of wheat-starch grains, and in other ways resemble those of tapioca. To this family also belongs rather an interesting group of parasitic plants, namely, dodder (Cuscuta). They contain the principle cuscutin, and quite a number have been used in medicine. b. POLEMONIACE^: OR POLEMONIUM FAMILY.— A family mostly of herbs and chiefly of horticultural interest. It contains the genus Phlox, which is indigenous exclusively to North America. A number of the species are cultivated and are included among the most valuable hardy, herbaceous perennials. The flowers are among the most beautiful and persistent of our garden plants. Another interesting genus belonging to this family is Polemonium, a number of species of which have been long under cultivation as border plants. Polemonium reptans is rather com- mon in the woods of the Northern United States (Fig. 367). c. HYDROPHYLLACE;E OR WATERLEAF FAMILY.— The plants are herbs or shrubs which are indigenous to Western North America. Very few of the plants of this family are of use medicinally, although quite a number are ornamental plants. Eriodictyon calif ornicum (E. glutinosuni} or Yerba Santa is a shrub growing in Northern Mexico and California. The leaves are official (Fig. 368). The flowers are funnel-form, white or purple, occurring in cymes. The fruit is a dehiscent capsule and the seeds are small and few. d. BORAGINACE^: OR BORAGE FAMILY.— The plants are mostly herbs with regular blue flowers, occurring in scorpioid inflorescence. The best examples of the group are the forget-me-not (Myosotis), the roots of several species of which have been used in medicine ; and the garden heliotrope (Heliotropum peruvianum) , the fragrance of the flowers being due to a volatile oil. • This plant, as well as other species of Heliotropum, contains a poisonous volatile alkaloid. At one time there was considerable interest inALKANET^the root of Alkanna tinctoria of Southern Europe and Asia, on account of the red coloring principle alkannin, which is soluble in alcohol, CLASSIFICATION OF ANGIOSPERMS. 671 FIG. 367. Greek Valerian (Polemonium reptans), a perennial, 2 to 4 dm. in height, having . alternate pinnate leaves and light blue flowers in corymbs. — After Brown. ether, fixed and ethereal oils, but insoluble in water. COMFREY or SYMPHYTUM is the root of Symphytum officinale and other species of this genus naturalized from Europe in waste places in the United States. It occurs on the market in small, purplish- 672 A TEXT-BOOK OF BOTANY. FIG. 368. Yerba Santa (Eriodictyon cali form cum), a low, evergreen, aromatic sjirub, the leaves and stems being covered with a resinous exudation. The leaves are lanceolate, irregularly serrate or nearly entire, and woolly hairy beneath; the flowers are violet or purple in color, and occur in cymose panicles. — Bureau of Plant Industry, U. S. Depart- ment of Agriculture. CLASSIFICATION OF ANGIOSPERMS, 673 black, more or less curved pieces, which are quite mucilaginous and astringent to the taste. The drug contains a gluco-alkaloid, consoliclin, and an alkaloid, cynoglossine. It also contains a small amount of amylo-dextrin, i.e., starch which is not colored blue with iodine, and tannin. The root and herb of HOUND'S TONGUE (Cynoglossum officinale) are both used in medicine. The drug contains the powerful alkaloid cynoglossine, which resembles cura- rine in its action ; and the gluco-alkaloid, consolidin. e. VERBENACE^ OR VERVAIN FAMILY.— The plants are chiefly herbs or shrubs with usually opposite or verticillate leaves and more or less irregular flowers (Fig. 369). To this family belongs the group of verbenas, some ,of which are used in medicine, as blue vervain (Verbena hastata), which resembles eupatorium in its medicinal properties ; nettle-leaved vervain (V '. urticifolia], which contains a bitter glucoside. The drug LIPPIA MEXICANA consists of the leaves of Lippia dulcis mexicana, and contains a volatile oil, the camphor lippiol, tannin, and quercetin. Lippia citriodora, found growing in the central part of South America, contains a volatile oil, of which citral is a constituent. TEAK-WOOD, which is one of the hardest and most valuable of woods, is derived from the teak tree (Teciona grandis), a large tree indigenous to Farther India and the East Indies. /. LABIATyE OR MINT FAMILY.— The plants are mostly aromatic herbs or shrubs, with square stems, simple, opposite leaves, bilabiate flowers, and a fruit consisting of four nutlets. The calyx is persistent, regular or 2-lipped and mostly nerved. The corolla is mostly 2-lipped, the upper lip being 2-lobed or entire, and the lower mostly 3-lobed. The stamens are adnate to the corolla tube, and are either 4 and didynamous, or 2 per- fect and 2 aborted. The ovary is deeply 4-lobed (Fig. 280, /). The Labiate are especially distinguished on account of the volatile oils which they yield, and a few contain bitter or glucosidal principles. i. The following PLANTS ARE USED IN MEDICINE: Scutellaria lateriflora (skullcap). The plant is a perennial herb producing slender stolons somewhat resembling those of 43 674 A TEXT-BOOK OF BOTANY. i*lG. 369. Blue Vervain (Verbena hastata), a tall, perennial herb, with oblong-lanceolate leaves, and numerous terminal spikes of violet-blue flowers. — After Brown. CLASSIFICATION OF ANGIOSPERMS. 675 peppermint and spearmint. The stems are erect or ascending, commonly branching and from 22 to 55 cm. high (Fig. 370). 676 A TEXT-BOOK OF BOTANY. Marrubium vulgar e (white hoarhound) is a perennial woolly herb with ascending branches; the leaves and flowering tops are used in medicine. Salvia officinalis or garden sage is a perennial, somewhat shrubby, pubescent herb. The leaves are ovate, crenulate. The flowers are bluish, somewhat variegated, the calyx and corolla both being deeply bilabiate. Only the two anterior stamens are fertile (bear anthers) ; the connective is transverse, the upper end bearing a perfect pollen-sac, and the lower a somewhat enlarged rudimentary pollen-sac (Fig. 223, F}. Hedeoma pulegioides (American pennyroyal) (Fig. 371). MENTHA species. — The plants are nearly glabrous, diffusely branching herbs, which form leafy stolons that are perennial (Fig. 184). The leaves and flowering tops of both Mentha piperita (Fig. 372) and Mentha spicata are official. 2. VOLATILE OILS of the following plants are official : Rosmarinus officinalis is a shrub growing in the Mediterranean countries. The plant has linear, coriaceous leaves, and bluish, bila- biate flowers, the middle lobe of the lower lip of the corolla being large, concave, and toothed on the margin. The flowering tops yield from i to 1.5 per cent, of oil which is composed of 15 to 18 per cent, of borneol ; about 5 per cent, of bornyl acetate ; and pinene, camphene, camphor, and cineol. There are two commer- cial varieties of the oil, the Italian and French, the latter having the finer odor. Lavandula officinalis (garden lavender) is a shrub growing in the Northern Mediterranean countries, as well as in England. The leaves are linear, coriaceous ; the flowers are small, light blue, bilabiate, with a tubular calyx, and occur in opposite cymes (verticillasters). The oil is derived from the fresh flowering tops, the flowers yielding about 0.5 per cent. Two kinds of oil are on the market, namely, French and English. The French oil contains 30 to 45 per cent, of 1-linalyl acetate; linalool ; geraniol, both of which latter constituents occur free and as esters. The English oil con- tains about 5 to 10 per cent, of linalyl acetate and a slight amount of cineol. Spike lavender (Lavandula Spica} is sometimes dis- tilled with true lavender (see p. 679). CLASSIFICATION QF ANGIOSPERMS. 677 Agriculture. Thymus vulgaris (garden thyme) is a small shrub having linear or linear-lanceolate leaves, and pale blue flowers with 6;8 A TEXT-BOOK OF BOTANY. strongly bilabiate, hairy calyx, and occur in axillary cymes. The plant grows in the mountains of Southern France. The herb FIG. 372. Peppermint (Mentha piperita): B, portion of shoot showing petiolate leaves; C, transverse section of leaf showing several forms of glandular hairs on lower surface, loose parenchyma (m) and palisade cells (p); D, lower surface of leaf showing stoma (s) and glandular hair (g). Spearmint (M entha spicatq.) : A. portion of shoot showing flowers and nearly sessile leaves; E, flower; F, outspread corolla showing cleft posterior lobe (p) and the four adnate, included stamens; G, H, hairs from calyx; I, sphere crystals (sphsrites) of a carbohydrate found in the corolla and style; J, pollen grains. contains from 0.3 to 0.9 per cent, of volatile oil, which is of a dark reddish-brown color, and contains from 20 to 25 per cent, of thymol ; and cymene, 1-pinene, borneol and linalool. The Spanish CLASSIFICATION OF ANGIOSPERMS. 679 oil of thyme contains from 50 to 70 per cent, of carvacrol, but no thymol. 3. OF OTHER PLANTS OF THE LABIATE which are of interest, the following may be mentioned : Lavandula Spica yields oil of spike, which has an odor of lavender and rosemary. The oil contains camphor, borneol, cineol, linalool, and camphene. Origanum Majorana (Sweet marjoram) is an annual culti- vated herb that has more or less oval, entire leaves, white flowers, and an aromatic odor and taste. It produces a volatile oil which contains terpinene and d-terpineol. Origanum vulgar e (Wild marjoram) grows in fields and waste places in the Eastern United States and Canada. The calyx is equally 5-toothed and the corolla varies from white to pink or purple. It contains a volatile oil having an odor somewhat like that of the oil of 0. Majorana. Origanum hirtum and O. Onites yield an origanum oil containing carvacrol and cymene. The oils obtained from Cretian Origanum are the source of commercial carvacrol. Pogostemon Patchouli, a plant cultivated in Southern China and the East and West Indies, furnishes the oil of PATCHOULI used in perfumery. Patchouly camphor and cadinene have been isolated from the oil, but nothing, however, appears to be known of the nature of the odorous principle. Hyssopus officinalis (Garden hyssop) contains about 0.5 per cent, of volatile oil to which the characteristic odor of the plant is due. Satureia hortensis (summer savory) yields a volatile oil containing carvacrol, cymene and terpene. Ocimum Basilicum (Sweet basil) is an herb growing in Europe, and yields an oil which is used in the preparation of Chartreuse and similar liquors. The oil contains methyl chavicol, linalool, cineol, camphor, pinene, and terpin hydrate. Melissa officinalis (Sweet balm) is a perennial herb indigenous to Europe and Asia and also cultivated. The leaves are ovate, dentate, and the flowers are bilabiate, the calyx being bell-shaped and 13-nerved. The taste is bitter, this being due to a bitter principle. The fresh leaves are quite aromatic and produce from o.i to 0.25 per cent, of a volatile oil containing a stearoptene. Several species of Monarda known as HORSEMINT or wild 68o A TEXT-BOOK OF BOTANY. FIG. 373. Cat Mint or Catnip (Nepeta Cataria), a. hardy perennial herb with heart- shaped, oblong, deeply crenate, velvety, whitish green leaves, bearing in the axils dense whorls of light purplish flowers. It is a common weed and derives its common name from the fact that cats are fond of it, eating it and rubbing themselves upon it. — Bureau of Plant Industry, U. S. Department of Agriculture. bergamot are used in medicine. The oil was at one time official. The oil of Monarda punctata, a perennial herb found growing CLASSIFICATION OF ANGIOSPERMS. 681 from New York to Texas, contains thymol, thymoquinone, hydro- thymoquinone, carvacrol, cymene, and limonene. Nepeta Cataria (catnip) is a perennial herb naturalized in the United States from Europe (Fig. 373). It contains a bitter FIG. 374. (b) A mass of Ground Ivy {Nefeta hederacea) growing on an embankment, with (a) Spring Beauty (Claytonia virginica). principle, tannin, and an oxygenated volatile oil. Nepeta hede- racea or GROUND IVY is a creeping perennial herb with blue bilabi- ate flowers and reniform leaves (Fig. 374). It contains a bitter principle and volatile oil. Cunila origanoides, or American DIT- 682 A TEXT-BOOK OF BOTANY. TANY, is a small perennial herb growing from New York to Florida, and characterized by its pungent aromatic properties. Leonurus Cardiaca or MOTHERWORT is a perennial herb nat- uralized in the United States and Canada from Europe. The FIG. 375. Flowering tops of Datura fastuosa flava, a variety of a plant growing in the East Indies, the Malay Archipelago, and tropical Africa, containing much the same con- stituents as Datura Stramonium. — After Newcomb. leaves are 3-lobed; the calyx is 5-nerved and with 5 prickly teeth ; the corolla varies from white to pink or purple. The plant contains a volatile oil of rather an unpleasant odor ; a bitter prin- ciple; two resins and several organic acids, namely, malic, citric and tartaric. CLASSIFICATION OF ANGIOSPERMS. 683 /. SOLANACE^ OR POTATO FAMILY.— The family includes herbs, shrubs, trees, and vines, which are most abundant in tropical regions. The leaves are alternate and vary from entire FIG. 376. Atropa Belladonna shoeing the alternate, petiolate, ovate, entire leaves, in the axils of which are the solitray fruits or flowers with large, leafy bracts. to dissected. The flowers are mostly regular, except in hyos- cyamus. The stamens are adnate to the corolla tube, the anthers connivent, and the pollen-sacs apically or longitudinally dehiscent. The fruit is a berry or capsule in which the sepals mostly persist 684 A TEXT-BOOK OF BOTANY. and sometimes become enlarged or inflated. The seeds have a large reserve layer, and the embryo is frequently curved. Datura Stramonium (Jimson weed, thorn apple) is a large, annual, branching herb, found in waste places in the United States and parts of Canada, being naturalized from Asia. The leaves and flowering tops are official. The large, spiny capsule is shown in Fig. 236, B. D. fastuosa (Fig. 375) has similar medicinal properties. Atropa Belladonna (Deadly nightshade) is a perennial herb producing a large, fleshy root, which is used in medicine (Fig. 376), as are also the leaves and flowering tops. Scopolia carniolica is a perennial herb with nearly entire or somewhat irregularly toothed leaves. The flowers are campan- ulate and dark purple. The fruit is a globular, transversely dehis- cent capsule (pyxidium). Hyoscyamus niger or henbane is a biennial herb (Fig. 377), the leaves and flowering tops of which are official. Pichi is the dried leafy twigs of Fabiana imbricata, a shrub with small, scale-like leaves, indigenous to Chile. It contains a volatile oil; o.i per cent, of a bitter alkaloid; a glucoside resem- bling sesculin ; and a bitter resin. Solanum Dulcamara (Bitter sweet) is a perennial, climbing herbaceous plant, indigenous to Europe and Asia and naturalized in the Northern United States. The branches which have begun to develop periderm are collected, and were formerly official as DULCAMARA. They are cut into pieces 10 to 20 mm. long which are greenish-brown, hollow, with a sweetish, bitter taste and contain a glucoside, dulcamarin, and the gluco-alkaloid solanine (Fig. 378). Solanum carolinense (Horse nettle) is a perennial herb having numerous yellow prickles on the branches and leaves. The leaves are oblong or ovate, irregularly lobed (Fig. 379). The flowers are white or light blue and occur in lateral cymes. The fruit is an orange-yellow, glabrous berry. The plant is common in waste places in Canada and the United States east of the Mississippi. The root and berries are used in- medicine. The root is simple and quite long, 5 to 10 mm. in diameter, yellowish-brown, the bark readily separating from the wood. It has a narcotic odor CLASSIFICATION OF ANGIOSPERMS. 685 FIG. 377. Flowering branch of Hyoscyamus niger annuus, showing sessile, acutely lobed leaves and two of the funnel-form flowers. — After Newcomb. and a sweetish, bitter, somewhat acrid taste. Both the root and berries contain the gluco-alkaloid solanine, which varies from 0.15 (in the root) to 0.8 per cent (in the berries). 686 A TEXT-BOOK OF BOTANY. FIG. 378. Bittersweet (Solarium Dulcamara), a perennial, climbing or twining shrub, with several types of leaves, varying from ovate heart-shaped. The flowers are blue or purplish and hang in loose cymose clusters. The fruit is an ovoid, reddish berry and very poisonous. It is sometimes eaten by children, producing fatal effects. — After Brown. CLASSIFICATION OF ANGIOSPERMS. 687 Capsicum fastigiatum (Cayenne pepper,) is a perennial, smooth, herbaceous, or somewhat shrubby plant, with ovate, acuminate, petiolate, entire leaves ; the flowers are greenish-white, and solitary FIG. 379. Horse netrle (Solatium carolinense) : A, portion of shoot showing flowers and fruits and spines on leaves and stem; B, longitudinal section of spine (s) and portion of stem showing glandular (g) and non-glandular (h) hairs, and cells containing small sphenoidal crystals (ca) ; C, thick-walled, strongly lignified cells of spine; D, portion of fibrovascular bundle showing small sphenoidal crystals (ca) of calcium oxalate in the cells accompanying the sieve; E, stellate, non-glandular hair; F, stoma of stem; G, diagram of cross section of flower showing sepals (s), petals (p), stamens (a), ovary (c) ; H, longitudinal section of flower; I, stamen showing terminal pores; J, cross section of 2-locular berry; K, pollen grains, 30 f* in diameter. in the axils of the leaves. The fruit is official and is known in commerce as African or Cayenne pepper. This plant and a num- ber of other species of Capsicum are indigenous to tropical 688 A TEXT-BOOK OF BOTANY. America, where they ar,e extensively cultivated, as also in Africa and India. Nicotiana Tabacum (Virginia Tobacco plant) is a tall annual herb indigenous to tropical America and widely cultivated. The stem is simple, giving rise to large, pubescent, ovate, entire, decur- rent leaves, the veins of which are prominent and more or less hairy. The flowers are long, tubular, pink or reddish, and occur in terminal spreading cymes. The various forms of tobacco are made from the leaves, which are hung in barns, whereby they undergo a slow drying or process of curing. Other species of Nicotiana are also cultivated, as N. persica, which yields Persian tobacco ; and N. rustica, the source of Turkey tobacco. Tobacco leaves contain from 0.6 to 9 per cent, of the alkaloid nicotine ; an aromatic principle nicotianin or tobacco camphor, to which the characteristic flavor is due and which is formed during the curing of the leaves. The dried leaves yield from 14 to 15 per cent, of ash, consisting in large part of potassium nitrate. Solatium tuberosum (Potato plant) is indigenous to the Andes region of South America and is extensively cultivated on account of the edible tubers. The tubers (potatoes) contain about 75 per cent, of water, 20 per cent, of starch, and nearly 2 per cent, of proteins in the form of large protein crystalloids. The fruits and young shoots contain the gluco-alkaloid solanine and the alkaloid solanidine. The tubers contain a small amount of solanine, which is increased when they are attacked by certain fungi or exposed to light. (Consult pp. 142, 148, 194, and 198.) Besides the potato plant, several other plants belonging to the Solanacese yield vegetables, as the Tomato plant (Solatium Lyco- persicum) and the Egg plant (Solatium Melongena}. Various cultivated species of Capsicum annuum furnish the common red peppers of the market. g. SCROPHULARIACEuE OR FIGWORT FAMILY.— The plants are herbs, shrubs or trees with opposite or alternate leaves and perfect, mostly complete and irregular flowers. The corolla and stamens show some resemblance to those of the Labi- atae in that the corolla is frequently more or less 2-lipped and the stamens are didynamous. The fruit is a dehiscent capsule and CLASSIFICATION OF ANGIOSPRRMS. 689 the seeds have a reserve layer and a straight or slightly curved embryo. FIG. 380. Culver's-root (Leptandra virginica) showing the verticillate leaves and the long spike-like terminal racemer. Leptandra virginica (Veronica virginica}, or Culver's root, is a perennial herb with leaves in whorls of 3 to 9, those on the upper part of the stem being opposite. They are lanceolate, serrate, 44 690 A TEXT-BOOK OF BOTANY. and pinnately veined ; the flowers are white or bluish, tubular, and in dense racemes. The rhizome and roots are official (Fig. 380). FIG. 381. Foxglove (Digitalis purpurea): The terminal i-sided raceme with slightly irregular, declined, tubular flowers, and a leaf of the first year's plant with long, winged or laminate petiole. Digitalis purpurea (Foxglove) is a tall, biennial, pubescent herb, producing the first year a large number of basal leaves (rig. 381), and the second, a long raceme of drooping, tubular, CLASSIFICATION OF ANGIOSPERMS. 691 slightly irregular, purplish flowers ; the inner surface of the corolla is spotted, the stamens are didynamous, and the upper calyx segment is narrower than the others. The leaves are official in all the pharmacopoeias. The Scrophulariaceae are well represented in the United States, and a number of the plants have medicinal properties. The com- mon MULLEIN (Verbascum Thapsus)' contains a volatile oil, two resins, and a bitter principle. The flowers of mullein contain the same principles and in addition a yellow coloring principle. Other species of Verbascum are used in medicine in different parts of the world. BUTTER-AND-EGGS (Linaria vulgaris} contains a crystalline principle, linariin, antirrhinic acid, a volatile oil, resin, and tannin. Several species of Scrophularia, as,S. nodosa of Europe and 5. marilandica of the Eastern United States, contain a pungent resin and a trace of an alkaloid. TURTLE-HEAD (Chclone glabra) (Fig. 382) contains a bitter principle and gallic acid. The plant of HYSSOP (Gratiola officinalis) of Europe contains gratiolin, a bitter glucoside, and gratiosolin. The leaves of Curanga amara of the East Indies contain a glucoside, curanjiin, which resembles digi- talin in its action. h. BIGNONIACE^: OR TRUMPET-CREEPER FAM- ILY.— The plants are shrubs, trees or woody vines, and are repre- sented in the United States by the catalpa tree (Catalpa bigno- moides) and the trumpet creeper (Tecoma radicans). The bark, pods, and seeds of CATALPA have been used in medicine and con- tain a bitter principle, catalpin, a glucoside, and several crystalline principles. The TRUMPET CREEPER contains narcotic poisonous principles. The leaflets of CAROBA (Jacaranda Co paid) and other species of Jacaranda contain the alkaloid carobine, an aromatic resin, carobone, and a principle having the odor of coumarin. i. PEDALIACE^E. — The plants are herbs indigenous to the Tropics of the Old World, some of which are now cultivated in the Tropics of both hemispheres. Benne oil (oil of sesame) is obtained from the seeds of Sesamum indicum by expression. It consists chiefly of a glycerite of oleic acid, a glycerite of linoleic acid, and myristin, palmitin. and stearin. It is a bland, non-drying oil and is used like olive oil. 692 A TEXT-BOOK OF BOTANY. FIG. 382. Turtle-head (Ckelone glabra), a perennial herb with lanceolate, serrate, opposite leaves and short, terminal spikes of whitish or purplish flowers. The corolla is bilabiate, the mouth slightly open, the upper lip broad and arched, suggesting the head of a turtle or snake, hence the origin of the common name. — Bureau of Plant Industry, U. S. Department of Agriculture. CLASSIFICATION OF ANGIOSPERMS. 693 FIG. 383. Purple Gerardia (Gerardia purpurea, Fam. Scrophulariaceae), a branching herb with linear leaves; and large, bright purplish -pink, bilabiate flowers. — After Bsown. 694 A TEXT-BOOK OF BOTANY. /. ACANTHACE^ OR ACANTHUS FAMILY.— The plants are mostly tropical perennial herbs, or shrubs with opposite FIG. 384. Common Plantain (Plantago major). A very familiar weed found along waysides and in poorly kept lawns. The leaves are clustered, lying near the ground, broadly elliptical and with prominent parallel veins. The flowers occur in long, dense spikes which give rise to small, capsular fruits, being sometimes employed as a green bird food. — After Brown. leaves ; in the mesophyll or epidermal cells and parenchyma of the axis occur cystoliths. Several genera are represented in the United States, one of which, Ruellia (Ruellia ciliosa), is the source CLASSIFICATION OF ANGIOSPERMS. 695 FIG. 385. Squaw-root, also known as Cancer-root (Conopholis americana), one of the Orobanchacece or root parasites. It is shown here growing on the roots of another plant. The flowering plants are from I to 2 dm. high, and consist of a cone-like stalk with fleshy scales surmounted by a spike of more or less yellowish flowers. — After Troth. 696 A TEXT-BOOK OF BOTANY. of the spurious spigelia which has been on the market for some years past. Rucllia ciliosa is a perennial herb which is distinguished from the other species of the genus Ruellia by the leaves, stems, and calyx being distinctly pubescent. The leaves are ovate-lanceolate, nearly sessile and entire ; the flowers are blue, sessile, solitary, or two or three in a cluster, in the axils of the leaves ; the stamens are 4, and exserted. The fruit is an oblong, terete capsule con- taining from 6 to 20 orbicular seeds. The plant is found from New Jersey and Pennsylvania to Michigan and as far south as Florida and Louisiana. Long cystoliths are found in some of the epidermal cells of both surfaces of the leaf. Quite a number of the plants of the Acanthaceae are used in the Tropics in medicine. One of these, Adhatoda Vasica of trop- ical Asia, contains the alkaloid vasicine, and is said to have the property of destroying algae which grow in the rice swamps. k. PLANTAGINACE^E OR PLANTAIN FAMILY.— The plants are annual or perennial herbs, represented by but few genera, but numerous species. The principal genus is Plantago, which includes 200 species that are widely distributed. Several species of Plantago are used in medicine. The common plantain (Plantago major) contains a glucoside, acubin ; emulsin; and invertin, and the short rhizome, considerable starch. The seed- coat has an outer mucilaginous layer, and the mucilage of the seeds of Plantago Psyllium, P. arenaria (both of Europe), and P. Ispaghula (of the East Indies) is used as a sizing material. The seeds of a number of the species of Plantago are used as bird food, particularly for canaries. /. QROBANCHACE^ OR BROOM-RAPE FAMILY.— This very interesting family is made up of plants which are parasitic upon the roots of other plants and are consequently rather light in color, as they develop no chlorophyll. Squaw-root or Cancer-root (Conopholis americana) has the flowers arranged in the form of a spike looking like an elongated cone, especially after the flowers have begun to turn brown (Fig. 385). Another little olant, also more or less white or yellow in color, is Beech- drops (Epifagus), which develops upon the roots of the beech. CLASSIFICATION OF ANGIOSPERMS. 697 VI. ORDER RUBIALES. The plants of this order are distinguished from all of the preceding Sympetalae by having flowers which are distinctly epigy- nous. The leaves are opposite or verticillate. a. RUBIACE^: OR MADDER FAMILY.— The plants are herbs, shrubs, or trees, and of the representatives found in the United States the following may be mentioned: Bluets (Hons- FIG. 386. Cinchona Ledgeriana: A, flowering branch; B, bud and open flower; C, fruiting branch. — After Schumann. tonia species), Partridge-berry (Mitchella repens), and Bedstraw (Galium species). In. Mitchella and Houstonia the flowers are dimorphic. CINCHONA species. — The plants are mostly trees, or rarely shrubs, with elliptical or lanceolate, entire, evergreen, petiolate, opposite leaves (Fig. 386). The flowers are tubular, rose-colored or yellowish-white, and occur in terminal racemes. The fruit is a capsule, which dehisces into two valves from below upward, the valves being held above by the persistent calyx. The seeds 698 A TEXT-BOOK OF BOTANY. CLASSIFICATION OF ANGIOSPERMS. 699 are numerous and winged. There are from 30 to 40 species of Cinchona found growing in the Andes of South America at an elevation above 800 M. in a restricted area about 500 miles in length extending from Venezuela to Bolivia. The plants are £ FIG. 388. Ipecac plant [Cephaelis (Uragoga) Ipecacuanha]: A, flowering shoot; B, flower in longitudinal section; C, fruit; D, fruit in transverse section; E, seed; F, annulate root. — Aftei Schumann. cultivated in Java, Ceylon, New Zealand, and Australia, as well as in Jamaica (Fig. 387). There are two species which furnish the Cinchona bark of medicine: (i) Cinchona Ledgeriana (C. Calisaya Ledgeriana}, which has small, elliptical, coriaceous leaves, the under surface o! which is reddish ; small, yellowish, inodorous flowers, and a 700 A TEXT-BOOK OF BOTANY. short capsule; (2) C. succirubra, which has large, thin, broadly- elliptical leaves, purplish-red calyx, rose-colored petals, and a very long capsule. While C. Ledgeriana yields barks containing the highest amount of alkaloids, C. succirubra is most cultivated. Uragoga (Ccphaclis} Ipecacuanha. — The plants are perennial herbs 10 to 20 cm. high, with a creeping, woody, hypogeous stem. The roots are official in all of the pharmacopoeias (see Vol. II). The leaves are elliptical, entire, short-petiolate, and with divided stipules (Fig. 386). The flowers are white and form small ter- minal heads. The fruit is a blue berry, with characteristic spiral arrangement of the carpels. Coffea arabica is a small evergreen tree or shrub with lanceo- late, acuminate, entire, slightly coriaceous, dark green, short- petiolate leaves, which are partly united with the short inter- petiolar stipules at the base. The flowers are white, fragrant, and occur in axillary clusters. The fruit is a small, spherical or ellip- soidal drupe with two locules, each containing one seed, or COFFEE GRAIN. The coffee plant is indigenous to Abyssinia and other parts of Eastern Africa, and is cultivated (Fig. 389) in tropical countries, notably in Java, Sumatra, Ceylon, and Central and South America, particularly Brazil, over 600,000 tons being produced annually in the latter country. The yield of one tree is between i and 12 pounds. There are two methods of freeing the seeds from the parchment-like endocarp : In the one case the fruits are allowed to dry and are then broken ; in the other case, which is known as the wet method, the sarcocarp is removed by means of a machine, and the two seeds with the parchment-like endocarp are allowed to dry in such a manner as to undergo a fermentation, and after drying the endocarp is removed. Coffee seeds contain from i to 2 per cent, of CAFFEINE ; from 3 to 5 per cent, of tannin ; about 15 per cent, of glucose and dextrin ; 10 to 13 per cent, of a fatty oil consisting chiefly of olein and palmitin ; 10 to 13 per cent, of proteins ; and yield 4 to 7 per cent, of ash. The official caffeine is derived in part from coffee seeds. In the ROASTING of coffee there is a change in the physical character of the seeds, as well as a change in some of -the constit- uents. The AROMA is supposed to be due to an oil known as coffeol, which is said to be a methyl ether of saligenin. CLASSIFICATION OF ANGIOSPERMS. 701 FIG. 389. Coffee tree growing in Costa Rica. An evergreen shrub, with elliptical leaves resembling somewhat those of the laurel. The flowers are white, fragrant, and are formed in clusters among the branches, being followed by the berry-like fruits, which when ripe are about the size of and resemble the cranberry. Each fruit contains two elliptical plano-convex seeds, which on being separated constitute the so-called coffee bean of com- merce.— Reproduced by permission of The Philadelphia Commercial Museum. 7O2 A TEXT-BOOK OF BOTANY. YOHIMBI (Yohimbihi) bark is obtained from Corynanthe Yo- himbe, a tree growing in the Cameroon region of Africa. The pieces of bark are 25 cm. or more in length, 5 to 8 mm. thick, externally dark brown or grayish-brown, and somewhat bitter. Numerous bast fibers are present, but no sclerotic cells. It yields 4 alkaloids (0.3 to 1.5 per cent.), the principal one being yohim- bine (corymbine or corynine), which forms white prismatic FIG. 390. Picking coffee in Brazil. The coffee shrub is cultivated in plantations, and when the berries are ripe they are collected either by shaking the tree and allowing the berries to fall upon a cloth or they are picked by hand directly from the branches, and removed from the field by oxen teams. More than half of the coffee of the world is grown in Brazil, the remainder being obtained in various parts of tropical America and East India. — Reproduced by permission of The Philadelphia Commercial Museum. needles, soluble in alcohol and almost insoluble in water, and on treatment with nitric acid becomes first deep green and then yellowish, changing to a cherry-red if followed with an alcoholic solution of potassium hydroxide (distinction from cocaine). A number of the Rubiaceae contain valuable coloring prin- ciples, as the madder plant (Rubia tinctorum}, which is a peren- nial herb occurring wild in Southern Europe and formerly culti- vated in France and Germany on account of the coloring principle CLASSIFICATION OF ANGIOSPERMS. 703 FIG. 391. Buttonbush (Cephalanlhus occidentalis) , a small shrub growing in swamps and along streams throughout the United States. The leaves are opposite or whorled in threes. The flowers are white and densely aggregated in spherical peduncled heads; they secrete large quantities of nectar, and are sought to such a degree by the bees that the bush is often called "Honey balls." — After Troth. in its roots, ^he root is known commercially as MADDER, and con- . tains when fresh a yellow coloring principle, which on the drying of the root breaks up into several glucosides, one of which on further decomposition yields ALIZARIN, the principle to which the 704 . A TEXT-BOOK OF BOTANY. red color of the dried root is due. At present alizarin is made artificially from anthracene, a coal-tar derivative. Morinda citrifolia, a shrub widely distributed in tropical coun- tries, contains a red coloring principle in the flowers and a yellow coloring principle in the roots, the latter being known as morindin and resembling the color principle in madder. The pulp of the fruit of Cape jasmine (Gardenia jasminoides) contains a yellow coloring principle resembling crocin, found in Crocus. The stem and root barks of Button-bush (Cephalanthus occi- dentalis*), common in swampy regions in the United States, are used in medicine (Fig. 391 ) . The barks contain a bitter glucoside, cephalanthin, and a tasteless glucoside which is fluorescent in solu- tion. Mitchella repcns contains a saponin-like body in the fruit and a tannin and bitter principle in the leaves. Quite a number of species of Galium (bedstraw) are used in medicine and for other purposes. A principle resembling glycyrrhizin is found in wild licorice (Galium circ&sans}, a perennial herb growing in dry woods in the United States, and also in Galium lanceolatum, which is found from Virginia northward to Ontario. The yellow bed- straw (Galium verum}, naturalized from Europe, contains a milk- curdling ferment. b. CAPRI FOLIAGES OR HONEYSUCKLE FAMILY.— The plants are perennial herbs, shrubs, trees, or woody climbers with opposite, simple or pinnately compound leaves. The flowers are perfect, epigynous, regular, or bilabiate, and arranged in corymbs. The fruit is a berry, drupe, or capsule. They are mostly indigenous to the northern hemisphere. Viburnum pruni folium (Black haw) is a shrub or small tree 25 cm. in diameter. The winter buds are acute and reddish- pubescent ; the leaves are ovate, elliptical, obtuse or acute at the apex, somewhat rounded at the base, finely serrulate, glabrous, and short-petiolate (Fig. 392) ; the flowers are white and in nearly sessile cymes ; the fruit is a small, oval, bluish-black, glaucous, inferior drupe. The ro6t-bark is official. Viburnum O.pulus (Wild guelder-rose or cranberry-tree) is a shrub about half the height of V. prunifolium, with broadly ovate, deeply 3-lobed and coarsely dentate pubescent leaves. The CLASSIFICATION OF ANGIOSPERMS. 705 flowers are white and in compound cymes, the outer being sterile and large and showy. The fruit is a reddish, globular, very acid drupe, clinging to the branches all winter. The Snow-ball or guelder-rose of the gardens is a sterile variety of this species. Another variety (edule) is also cultivated on account of its edible fruits, particularly in Canada and the Northern United States. FIG. 392. Fruiting branch of Viburnum prunifolium. A number of species of Viburnum are rather common in various parts of the United States, as the Maple-leaved arrow- wood (V . acerifolium), which is a small shrub with deeply 3-lobed, coarsely dentate leaves and small, nearly black drupes ; Arrow-wood (V '. dentatum), with broadly ovate, coarsely den- tate leaves and blue drupes, which become nearly black when 45 706 A TEXT-BOOK OF BOTANY. ripe; Soft-leaved arrow-wood (V , molle}, which somewhat re- sembles V . dentatum, but has larger leaves that are crenate or dentate and stellate-pubescent on the lower surface ; Larger withe- rod (V . nudum), having nearly entire leaves and a pink drupe, which becomes dark blue. Sambucus canadensis (American elder) is a shrub growing in moist places in the United States as far west as Arizona and in Canada. The leaves are 5- to /-foliate, the leaflets being ovate, elliptical, acuminate, sharply serrate, and with a short stalk; the flowers are small, white, and in convex cymes. The fruit is a deep purple or black berry-like drupe. The dried flowers are used in medicine. They are about 5 rrrrn. broad, with a 5-toothed, turbinate calyx, and a 5-lobed, rotate corolla, to which the 5 sta- mens are adnate. The odor is peculiar and the taste is muci- laginous and somewhat aromatic and bitter. The active principles have not been determined, but are prob- ably similar to those of S. nigra. The inner bark is also used in medicine and contains a volatile oil, a crystallizable resin, and valerianic acid. It does not appear to contain either tannin or starch. The roots of elder contain a volatile principle somewhat resembling coniine. The pith consists chiefly of cellulose, is deli- cate in texture and has a variety of uses (Fig. 132). The Black elder (Sambucus nigra), which is a shrub com- mon in Europe, is characterized by narrower leaflets, a 3-locular ovary, and black berries. The flowers are official in some of the European pharmacopoeias. They contain about 0.4 per cent, of a greenish-yellow, semi-solid volatile oil, which when diluted has the odor of the flowers. They also contain an acrid resin. The Red-berried elder or mountain elder (S. pubens} some- what resembles the common elder, but the stems are woody, and the younger branches have a reddish pith. The flowers are in paniculate cymes, and the fruits are scarlet or red. Other plants of the Capri foliaceae are also used in medicine. Horse gentian (Triosteum perfoliatum) , a perennial herb with connate-perfoliate leaves and small, orange-red, globular drupes, growing in Canada and the United States as far west as Kansas, furnishes the drug (rhizome) known as WILD IPECAC or Trios- teum. The rhizome is yellowish-brown, somewhat branched, CLASSIFICATION OF ANGIOSPERMS. 707 cylindrical, 10 to 20 cm. long, 10 to 15 mm. in diameter, with numerous cup-shaped stem-scars, and coarse, spreading roots ; it is rather hard and tough, and has a bitter, nauseous taste. Triosteum contains an emetic alkaloid, triosteine, and considerable starch. The seeds of Triosteum perfoliatum are sometimes roasted and employed like coffee, the plant being known as Wild coffee. The roots and stems of the following plants are sometimes employed: The Snowberry (Symphoricarpos racemosus), the Bush honeysuckle (Diervilla Lonicera}, and various species of Lonicera, these being also known as honeysuckles. VII. ORDER VALERIANALES OR AGGREGATE. The plants are mostly herbs with an inferior ovary, which is either unilocular with a single pendulous ovule, or tri-locular with frequently but a single anatropous ovule. a. VALERIANACE^E OR VALERIAN FAMILY.— The plants are herbs with opposite, exstipulate leaves, small, perfect, or polygamo-dicecious flowers, occurring in corymbs. The fruit is dry, indehiscent, and achene-like. The calyx is persistent, be- coming elongated and plumose, and resembling the pappus in the Compositae. Valeriana officinalis (Garden or Wild valerian) is a tall, peren- nial herb, more or less pubescent at the nodes. The leaves are mostly basal, pinnately parted into seven or more segments, which are lanceolate, entire, or dentate. The flowers are white or pink and arranged in corymbed cymes. The calyx is much reduced, consisting of 5 to 15 pinnately branched teeth (pappus) ; the corolla is tubular, somewhat sac-like on one side, but not spurred as in other members of this family ; the stamens are 3 in number and adnate to the corolla tube ; the stigma is 3-lobed. The fruit is ovoid, glabrous, and with a conspicuous plumose pappus. The rhizome and roots are official. The young leaves of several species of Valerianella are used as a salad and are cultivated like spinach, as the European corn- salad (V. olitoria), which is also cultivated to some extent in the United States. b. DIPSACACE^: OR TEASEL FAMILY.— The plants are annual or perennial herbs, chiefly indigenous to the Old World. ;o8 A TEXT-BOOK OF BOTANY. The flowers are arranged in heads on a common torus, resem- bling in some cases those of the Compositse. Some of the plants are used in medicine, as the roots, leaves, flowers, and seeds of Fuller's teasel (Dipsacus fullonum), the roots of Succisa pratensis of Europe, and several species of Scabi- osa and Cephalaria. The seeds of Cephalaria syriaca when admixed with cereals give a bread that is dark in color and bitter. This family is, however, chiefly of interest on account of Fuller's teasel, which is a cultivated form of Dipsacus ferox, indigenous to Southwestern Asia, the plant being cultivated in Europe and New York State. The elongated, globular heads, with their firm, spiny, and hooked bracts, are used in the fulling of cloth. VIII. ORDER CAMPANULA1]^. This order differs from the two preceding by having the anthers united into a tube (syngenesious). It includes three prin- cipal families, which are distinguished by differences in the char- acter of the androecium: (a) Cucurbitacese, in which there are three stamens, having not only the anthers united but the fila- ments also (monadelphous) ; (&) Campanulaceae, in which there are five stamens, both the filaments and anthers being united into a tube; (c) Compositse, in which there are five stamens, but the anthers only are united, the filaments being separate (Fig. 82, A). a, CUCURBITACE^ OR GOURD FAMILY.— The plants are mostly annual, tendril-climbing or trailing herbs (Fig. 66), mainly indigenous to tropical regions. The leaves are alternate, being opposite the tendrils, petiolate, and entire, palmately lobed or dissected. The flowers are epigynous ; the petals are borne on the calyx tube and frequently are united (campanulate) ; the ovary is i- to 3-locular and with few or many anatropous ovules. The fruit is a pepo, which is indehiscent but may burst somewhat irregularly. Citrullus Colocynthis is a trailing herb with deeply lobed leaves. The flowers are yellow, axillary, and monoecious, the staminate being with short filaments and glandular pistillodes (aborted pistils), and the pistillate having a 3-locular, globose ovary and three short staminodes. The fruit is globular, 5 to 10 CLASSIFICATION OF ANGIOSPERMS. 709 cm. in diameter, smooth, greenish, and mottled. The fruit de- prived of the epicarp is official. Cucurbita Pepo (pumpkin-vine) is an extensively trailing hispid vine, with large, nearly entire, cordate leaves having long petioles. The tendrils are branching. The flowers are large, deep yellow, and monoecious ; the staminate ones being in groups and the pistillate single. The fruit is a large, yellowish berry, sometimes weighing from 10 to 72 K. The seeds are numerous and are official as Pepo. Ecballium Elaterium (Squirting cucumber) is a bristly-hairy, trailing perennial herb with thick, rough-hairy, cordate, some- what undulate leaves. The flowers are yellow, monoecious. The fruit is ellipsoidal, about 4 cm. long, rough-hairy or prickly, pend- ulous, and at maturity separates from the stalk, when the seeds are discharged upward through a basal pore. The plant is indig- enous to the European countries bordering the Mediterranean, the Caucasus region, Northern Africa and the Azores. The juice of the fruit yields the drug ELATERIUM, which is official in the British Pharmacopoeia. Elaterium yields 30 per cent, of the ELATERIN of the Pharmacopoeias. From the latter by fractional crystallization from 60 to 80 per cent, of a-elaterin, a laevo-rota- tory crystalline substance is separated, which is completely devoid of purgative action ; and varying amounts of /3-elaterin, a dextro- rotatory crystalline compound which possesses a very high degree of physiological activity (Power and Moore, Ph. Jour., 29, Oct. 23, 1909, p. 501 ; and Proc. Chem. Soc., No. 362, 1909, p. 1985). Bryonia or BRYONY is the dried root of Bryonia alba (White bryony), a climbing herb indigenous to Southern Sweden, East- ern and Central Europe, including Southern Russia, and Northern Persia (Fig. 181). The root contains two bitter glucosides, bryonin and bryonidin ; two resinous principles and considerable starch. Bryonia dioica (Red bryony) also has medicinal proper- ties and is a source of the drug. B. dioica has red berries, while the fruit of B. alba is black. The latter plant is sometimes known as Black bryony, but this plant should not be confounded with Tamus communis (Fam. Dioscoreaceae), of Southern Europe, the rhizome of which is known commercially as Black bryony. The fruits and seeds of various members of the Cucurbitaceae ;io A TEXT-BOOK OF BOTANY. contain powerful drastic and anthelmintic principles. A number of the plants, however, are cultivated on account of the fruits, which are used as food, as the pumpkin already mentioned, the WATER MELON (Citrullns vulgaris) , indigenous to Southern Africa and cultivated in Egypt and the Orient since very early times ; CANTALOUPE or musk-melon, derived from cultivated varieties of Cucumis Melo, indigenous to tropical Africa and Asia, also culti- vated since early times. The common CUCUMBER is obtained from Cucumis sativus, which is probably indigenous to the East Indies. These fruits contain from 90 to 95 per cent, of water, and the water melon contains 3.75 per cent, of dextrose, 5.34 per cent, of saccharose, and yields 0.9 per cent, of ash. Luffa cylindrica is an annual plant indigenous to the Tropics of the Old World. It is cultivated to some extent in America, but especially in the Mediterranean region. The fruit is more or less cylindrical and 20 cm. or more long. The pulp is edible and the fibrovascular tissue forms a tough network, which, when the seeds, epicarp, and pulpy matter are removed, constitutes the LUFFA-SPONGE. The fruits of Luffa operculata and L. echinata, both found in Brazil, contain a bitter principle resembling colocynthin. b. CAMPANULACE;E OR BELL-FLOWER FAMILY.- The plants are mostly annual or perennial herbs, but are some- times shrubby, with an acrid juice containing powerful alkaloids. The rhizomes and roots of about twelve of the genera contain inulin. The leaves are alternate ; the corolla is regular, cam- panulate and rotate, or irregular, as in Lobelia. The fruit is a capsule or berry containing numerous small seeds. Lobelia inflata (Indian or Wild tobacco) is an annual, pubes- cent, branching herb (Fig. 224), the dried leaves and tops of which are official (see Vol. II). About 15 different species of Lobelia are used in medicine. The most important of those grow- ing in the United States is the Cardinal flower or Red lobelia (Lobelia cardinalis), a plant found in moist soil from Canada to Texas, and characterized by its long, compound racemes of bright scarlet or red flowers. The Blue cardinal flower or Blue lobelia (L. syphilitica) is a plant of nearly the same habit and same gen- CLASSIFICATION OF ANGIOSPERMS. 711 eral character, except that the flowers are of a bright dark blue color or occasionally white. c. FAMILY COMPOSITE— This is a large group of plants, which are annual, biennial, or perennial herbs, under-shrubs, shrubs, trees and twiners or even climbers, a few being aquatic. They contain inulin, a constituent peculiar to this group of plants. The most distinguishing character is the inflorescence, which is a head or capitulum (Fig. 228), consisting of one or two kinds of flowers, arranged on a common torus, and subtended by a number of bracts, forming an involucre. The flowers are epigy- nous and the fruit is an achene, usually surmounted by the per- sistent calyx, which consists of hairs, bristles, teeth or scales, which are known collectively as the PAPPUS (Fig. 227). The individual flowers are called florets (Figs. 241, 242), and may be hermaphrodite or pistillate, monoecious, dioecious, or neutral. Depending upon the shape of the corolla, two kinds of flowers are recognized, one in which the corolla forms a tube, which is 5-lobed or 5-cleft, known as TUBULAR FLOWERS (Figs. 227, 228, C) ; and one in which the petals are united into a short tube, with an upper part that forms a large, strap-shaped, usually 5-toothed limb, known as LIGULATE FLOWERS (Figs. 227, 228, D). In some of the plants of the Composite the head consists of ligulate flowers only, but in the larger number of plants the head is composed of both tubular and ligulate flowers or tubular flowers alone and accordingly two main groups or sub-families are dis- tinguished. The sub-family in which all of the flowers are lig- ulate is known as LIGULIFLOR.E, or CICHORIACETE, by those who give the group the rank of a family. This group includes plants like dandelion, chicory, lettuce, and Hieracium. The group or sub- family in which the flowers are all tubular or ligulate on the margin only is kno.wn as the TUBULIFLOR^E. When the head consists only of tubular flowers it is called DISCOID, but when ligulate flowers are also present it is called RADIATE. When the heads are radiate, as in the common daisy, the tubular flowers are spoken of as DISK-FLOWERS, and the ligulate flowers as RAY- FLOWERS. The disk-flowers are usually perfect, while the ray- flowers are pistillate or neutral (without either stamens or pistils). By some systematists the Tubuliflorse are divided into groups ;i2 A TEXT-BOOK OF BOTANY. which have been given the rank of families. This division is based especially on the characters of the stamens. In a small group represented by the ragweed and known as the AMBROSI- ACE^E, the anthers, while close together (connivent) , are not united, and the corolla in the marginal or pistillate flowers is reduced to a short tube or ring. In a large group, which includes probably 10,000 species and which is considered to be the COMPOSITE proper, the stamens in the tubular flowers are syngenesious and the marginal or ray-flowers are distinctly ligulate. This group includes the daisy, sunflower, golden-rod, aster, thistle, and most of the plants which yield official drugs. It may also be added that the Compositse is considered to be the highest and youngest group of plants. Taraxacum officinale (Dandelion) is a perennial, acaulescent herb with milky latex ; oblong-spatulate, pinnatifid or runcinate, decurrent leaves, and with a i -headed scape, the stalk of which is hollow. The flowers are ligulate, golden-yellow and numerous ; the involucre consists of two series of bracts, the inner one of which closes over the head while the fruit is maturing, afterward becoming reflexed. The fruit consists of a loose, globular head of achenes, each one of which is oblong-ovate and with a slender beak at the apex which is prolonged into a stalk bearing a radiate tuft of silky hairs, which constitute the pappus. The root is fusi- form and usually bears at the crown a number of branches 2 to 5 cm. long, having a small pith and other characters- of a rhizome. The root is official. Lactuca virosa (Poison lettuce) is a biennial prickly herb, with milky latex and oblong-obovate, spinose-toothed, runcinate basal leaves and with alternate, somewhat sessile or auriculate, scattered stem leaves, the apex and margin being spinose. The flowers are pale yellow and occur in heads forming terminal pani- cles. The involucre is cylindrical and consists of several series of bracts. The flowers are all ligulate and the anthers are sagit- tate at the base. The achenes are flattish-oblong, and the pappus, which is raised on a stalk, is soft-capillary, as in Taraxacum. The prepared milk-juice is official as Lactucarium. Eupatorium perfoliatum (Boneset or Common thorough wort). •• — The leaves and flowers are used in medicine. CLASSIFICATION OF ANGIOSPERMS. 713 Eupatorium sebandianum, which is added to Mate as a sweet- ening agent, contains two sweet glucosides ; eupatorin and reban- din; a bitter principle, and a resin. GRINDELIA species. — The plants are perennial, greenish-yellow, resinous herbs, sometimes being under-shrubs, with alternate, sessile or clasping, oblong to lanceolate, spinulose-dentate leaves, and large, terminal, yellowish heads, consisting of both ligulate and tubular flowers. The leaves and flowering tops of Grindelia camporiim, G. cuneifolia and G. squarrosa are official. Erigeron canadetisis or Leptilon canadense (Canada fleabane) is an annual or biennial, hispid-pubescent herb found growing in fields and waste places in nearly all parts of the world. The stems are simple, with numerous crowded leaves and numerous flowers occurring in terminal panicles. The plants are sometimes branched and i to 3 M. high. The leaves are linear, nearly entire, of a pale green color, the lower and. basal ones being spatulate, petiolate and dentate or incised. The flowers are white and the heads are composed of both ligulate and tubular florets, the former being pistillate and not longer than the diameter of the disk. The pappus consists of numerous capillary bristles and the involucre, which is campanulate, consists of five or six series of narrow, erect bracts. The fresh flowering herb contains 0.3 to 0.4 per cent, of a volatile oil which is official, tannin, and a small amount of gallic acid. The oil is obtained by distillation and consists chiefly of d-limonene. The genus Erigeron includes a number of species which have medicinal properties. E. annuus (Sweet scabious or Daisy flea- bane) is a low, branching, annual herb, characterized by its linear- lanceolate or ovate-lanceolate leaves and its conspicuous flowers, which resemble those of the common daisy, the ray-flowers often being tinged with purple (Fig. 393). It contains a volatile oil resembling that of Canada fleabane, and tannin. The Philadel- phia fleabane (Erigeron philadelphicus} is a perennial herb pro- ducing stolons, and has clasping or cordate leaves, the basal being spatulate, and is further distinguished by its light purplish-red ray-flowers. nobilis (Roman chamomile) is an annual or peren- A TEXT-BOOK OF BOTANY. nial, procumbent, branched herb, with numerous 2- to 3-pinnately divided leaves, the ultimate segments being narrow-linear. The flowers occur in terminal heads with long peduncles, a conical torus and few white pistillate ray-flowers. The flowers of culti- FlG. 393. Daisy-fleabane (Erigeron annuus). vated plants are official (see Vol. II), the heads consisting mostly of ligulate flowers, forming so-called " double flowers," as in the cultivated chrysanthemums. Anacyclus Pyrethrum (Pellitory) is a perennial herb resem- bling Anthemis nobilis in its general characters. The ray-flowers, CLASSIFICATION OF ANGIOSPERMS. however, are white or purplish, and the pappus consists of a ring or scale. The root is official. Matricaria Chanwnrilla (German chamomile) is an annual, diffusely branched herb, with pinnately divided leaves, consisting of few, linear segments. The flowers are official (Figs. 228, 394). * ' \- *<* '•*: \ ••• FIG. 394. A single plant of Matricaria Chamomilla, showing finely divided leaves and numerous composite flowers. — After Newcomb. Arnica montana is a perennial herb with small rhizome; nearly simple stem ; opposite, somewhat connate, entire, spatulate, hairy leaves, and yellow flowers in large heads with long peduncles. The flowers are official. Arctium Lappa (Burdock) is a coarse, branched, biennial or A TEXT-BOOK OF BOTANY. FIG. 395. Chicory or Succory (Cichorium Intybus), a branching perennial herb with oblong or lanceolate, more or less clasping leaves and axillary clusters of violet-blue flowers. The plant is cultivated as a pot herb and salad, and the young roots are used like carrots. The plant is more widely grown for its roots, which are used in the preparation of a substi- tute of coSee. — After Brown. CLASSIFICATION OF ANGIOSPERMS. 717 perennial herb, with alternate, broadly ovate, repand, entire, tomen- tose, mostly cordate leaves, the basal ones being from 30 to 45 cm. long. The flowers are purplish-red or white, tubular and form rather large corymbose heads ; the involucre consists of numerous lanceolate, rigid, nearly glabrous bracts, which are tipped with FIG. 396. Burdock (Arctium Lap pa), a biennial herb with large, mostly cordate leaves crowded at the base of the stems, and bearing small clusters of purplish flowers in the shorter branches above. It is a common roadside weed, and well known because of the burr-like fruits, consisting of the hooked tips of the bracts of the involucre. — After Brown. hooked, spreading bristles. The achenes are oblong and some- what 3-angled, and the pappus consists of numerous short bristles (Fig. 396). The root is used in medicine. The common burdock (Arctium minus} resembles A. Lap pa, but is a smaller plant and is more common in the United States. The heads are smaller and the inner bracts are shorter than the 7i8 A TEXT-BOOK OF BOTANY. tubular flowers, the bristles of this series being erect and with the outer spreading. Calendula officinalis (Marigold) is an annual herb with alter- nate, spatulate, oblanceolate, entire or serrate leaves. The flowers are yellow and form solitary heads, consisting of both ray and tubular florets. In the cultivated varieties most of the tubular florets are changed to ligulate, the latter being official (Fig. 227). While the Compositae include a large number of genera and species, the plants do not yield many important drugs, although a number are used in medicine and for other purposes. The so-called INSECT FLOWERS (Pyrethri F lores) are the partly expanded flower-heads of several species of Chrysanthe- mum, and are used in the preparation of a powder which is a powerful insecticide. The plants are perennial herbs resembling in their habits the common white daisy (C. Lcucanthemum) . The DALMATIAN Insect Flowers are obtained from C. cineraria: folium, growing in Dalmatia, and cultivated in Northern Africa, Cali- fornia and New York. The heads as they occur in the market are about 12 mm. broad, light yellowish-brown and have a slightly rounded or conical torus, which is about 12 mm. in diameter and consists of 2 or 3 series of lanceolate involucral scales. The ray- florets are pistillate, the corolla varying'in length from I to 2 cm. and having numerous delicate veins and 3 short, obtuse or rounded teeth. The tubular flowers are perfect and about 6 mm. long. The ovary is 5-ribbed and the pappus forms a short, toothed crown. The odor is distinct and the taste bitter. PERSIAN Insect Flowers are derived from C. roseum and C. Marschallii, growing in the Caucasus region, Armenia and North- ern Persia. The heads are about the size of those of C. cineraria- folium; the torus is dark brown ; the involucral scales and ray- florets are purplish-red ; the ovary is ic-ribbed. Insect flowers contain from a trace to 0.5 per cent, of a vola- tile oil, the Persian flowers containing the larger proportion, and the amount decreasing with the maturing of the flowers. They also contain two resins, varying from 4 to 7 per cent., the larger amount being found in the Dalmatian flowers ; a small quantity of a gluco«ide and a volatile acid. The principle toxic to insects is PYRETHRON, an amber-yellow, CLASSIFICATION OF ANGIOSPERMS. 719 syrupy substance which is the ester of certain unidentified acids, and on saponification yields the alcohol pyrethrol which crystal- lizes in fine needles. The acids combined in the ester pyrethron do not give crystalline salts. WORMWOOD or Absinthium consists of the dried leaves and flowering tops of Artemisia Absinthium, a perennial, somewhat woody, branching herb, indigenous to Europe and Northern Africa, cultivated in New York, Michigan, Nebraska and Wis- consin and naturalized in the United States from plants that have escaped from cultivation. The leaves are grayish-green, gland- ular-hairy, I- to 3~pinnately divided, the segments being obovate, entire, or lobed ; the flowers are yellowish-green, the heads being about 4 mm. broad and occurring in raceme-like panicles; the torus is hemispherical and the involucre consists of several series of linear bracts, the inner being scale-like ; the florets are all tubular, the outer ones sometimes being neutral. The herb is aromatic and very bitter. The fresh drug contains about 0.5 per cent, of a VOLATILE OIL which is of a dark green or blue color, has a bitter, persistent taste but not the pleasant odor of the plant, and consists of d-thujone (absinthol), thujyl alcohol free and combined with acetic, iso- valerianic and palmitic acids, phellandrene and cadinene. The other constituents oi the drug include a bitter glucosidal principle, ABSINTHIIN, which forms white prisms and yields on hydrolysis a volatile oil ; a resin ; starch ; tannin ; succinic acid, potassium succinate, and about 7 per cent, of ash. The plant is used in the preparation of the French liquor known as ABSINTHE. Artemisia Cina yields the official Santonin. Other species of Absinthium also yield volatile oils, as the COMMON MUGWORT (Artemisia vulgaris}, which yields from Q.I to 0.2 per cent, of an oil containing cineol ; Artemisia Barrelieri, which contains an oil consisting almost entirely of thujone, and said to be used in the preparation of Algerian absinthe. SAFFLOWER consists of the dried florets of Carthamus tinc- torius, an annual herb which is known only in cultivation. The florets are tubular, yellowish-red, the corolla tube being about 2 cm. long and with 5 small, linear lobes ; the stamens are exserted. The ovary with the long, slender style is usually not present in 720 A TEXT-BOOK OF BOTANY. the drug (Fig. 227, C). Safflower contains a small percentage of a yellow coloring principle -(safflower-yellow), which is soluble in water, and 0.3 to 0.6 per cent, of a red coloring principle (car- thamin or carthamic acid), which is insoluble in water but soluble in alcohol, the solution having a purplish-red color. A volatile oil is also present. Carthamin is used in conjunction with French chalk in the preparation of a rouge. TANSY, the dried leaves and tops of Tanacetnm vnlgare and var. crispnm, perennial, aromatic herbs indigenous to Furope, extensively cultivated and naturalized in the United States. The leaves are large and pinnately divided, and the flowers, both tubu- lar and ligulate, are yellow, the heads being in terminal corymbs. The plant yields from o.i to 0.3 per cent, of a volatile oil, consisting of thujone, borneol and camphor; and 3 resins. ELECAMPANE (Inula Helenium} is a large, perennial, densely pubescent herb with alternate leaves and large, solitary terminal heads, consisting of yellow tubular and ligulate florets (Fig. 227). The plant is indigenous to Central Europe and Asia, and natural- ized in North America from Canada to North Carolina. The root is used in medicine and was formerly official as INULA. The root of Polymnia Uvedalia, a plant closely related to Inula, but indigenous to the United States east of the Mississippi, contains a volatile oil, a glucoside, tannin, and a resinous sub- stance consisting of two resins, one of which is pale yellow and soft, the other dark brown and hard. The following Composite, while not of very great importance, are used in some localities: YARROW (Achillea Mille folium} is a common weed naturalized from Europe (Fig. 397), and contains about o.i per cent, of a dark blue volatile oil with a strongly aromatic odor and a small amount of a bitter alkaloid, achilleine. The roots of yarrow, on the other hand, y. Id a volatile oil with a valerian-like odor. Achillea nobilis of Eurc^£ contains an oil resembling that of yarrow, but it is of finer quality and has a spice-like taste. Achillea moschata, an alpine plant of Europe, yields three alkaloids and a volatile oil containing cineol, and is used in Italy in the preparation of the liquor, "Esprit d' Iva." Achillea tanacetifolia yields a blue volatile oil having the odor of tansy. 'CLASSIFICATION OF ANGIOSPERMS. 721 5 £ — . J- ' ftl'^f ~~. . FIG. 397. Yarrow or Milfoil (Achillea Millefolium), a perennial herb, b iching only at the top and bearing deeply pinnatifid leaves, the segments being very narrow. The flowers are small, white, occasionally crimson and arranged in large, terminal corymbs, — Bureau of Plant Industry, U. S. Department of Agriculture. The HIGH GOLDEN-ROD (Solidago canadensis) yields 0.63 per cent, of a volatile oil, consisting chiefly of pinene, with some phcl- 46 722 A TEXT-BOOK OF BOTANY. landrene and dipentene, and containing about 9 per cent, of borneol, 3 per cent, of bornyl acetate and some cadinene. The True or ANISE-SCENTED GOLDEN-ROD (Solidago odora) yields an aromatic volatile oil and a small amount of tannin. FIG. 398. Method of gathering the pollen of Golden-rod (Solidago Shortii) for immuniz- ing the hay-fever horses. The plant is gathered just about the time that the pollen-sacs are ready to open, then taken to a sunny room — free from draft and air disturbances — placed slanting in a basin filled with water, the blossoms drooping over the sides of the vessel, with clean, smooth paper spread underneath them. The following morning the pollen will be on the paper and can readily be gathered with a feather-top or a quill. — After Schimmel & Co. The rhizome of the large Button-snakeroot (Lacinaria scari- osa), growing in the eastern and central portion of the United States and Canada, contains o.i per cent, of volatile oil, about 5 per cent, of resin, and 2 per cent, of a caoutchouc-like substance. CLASSIFICATION OF ANGIOSPERMS. 723 COLTSFOOT (Tussilago Farfara] is a plant indigenous to Europe and naturalized in the Northern United States and Can- ada. It is an acaulescent herb with a slender rhizome 30 to 40 cm. long ; nearly orbicular, somewhat lobed and tomentose leaves, and large, solitary, yellow flowers appearing before the leaves. The plant contains an acrid volatile oil, a bitter glucoside, resin and tannin. ECHINACEA is the root of Brauneria (Rudbeckia) purpurea, a plant growing in rich soil from Virginia to Illinois and south- ward, and of B. angustifolia, growing from the Northwest Terri- tory to Texas (Fig. 399). The drug contains an alkaloid and 0.5 to i per cent, of an acrid resinous substance to which the medical properties are due. ROSIN WEED or COMPASS PLANT (Silphium laciniatum) , found growing from Ohio to South Dakota and south to Texas, produces an oleo-resin which exudes either spontaneously or from the punctures of insects, and contains about 19 per cent, of vola- tile oil, and 37 per cent, of acid resin. The THISTLE (Cnicus benedictus) contains a crystalline bitter principle, cnicin, which is colored red with sulphuric acid. The Mexican drug PIPITZAIIOAC is the rhizome of Perezia Wrightii, P. nana and P. adnata, plants found in Southwestern Texas and Mexico. It contains about 3.6 per cent, of a golden- yellow crystalline principle, pipitzahoic acid, which appears to be related to oxythymoquinone and is colored an intense purple with alkalies and alkaline earths. LION'S FOOT, the root of Prenanthes Serpentaria, P. alba and other species of Nabalus growing in the United States, contains bitter principles, resin and tannin. Mio Mio (Baccharis cordi- folia), of South America, is poisonous to sheep and cattle and contains an alkaloid, baccharine, and a bitter principle. SPINY CLOTBUR (Xanthium spinosum) contains a bitter resin and possi- bly a volatile alkaloid. The fruit of Xanthium spinosum, a common weed naturalized from Europe, contains an amorphous, non-glucosidal substance, xanthostrumarin, which forms precip- itates with a number of the alkaloidal reagents. SNEEZE-WEED (Helenium autumnale) contains a volatile oil, a bitter glucoside and tannin. Helenium temdfolium, of the Southern United States, 724 A TEXT-BOOK OF BOTANY. FIG. 399. A flowering specimen of the Purple Cone-flower (Brauneria angustifolia), showing the 3-nerved lanceolate leaves and 2 of the flower heads with the characteristic long spreading rays. — After Newcomb. is a narcotic poison. PARA CRESS (Spilanthes oleracea), of trop- ical America, contains a soft pungent resin and a crystallizable principle, spilanthin. The common white daisy (Chrysanthemum CLASSIFICATION OF ANGIOSPERMS. 725 Leucanthemum) yields about 0.15 per cent, of a greenish volatile oil with the odor of chamomile and mint. CHICORY, the root of Cichorium Intybus, a perennial herb with blue or purplish ligulate florets, indigenous to and cultivated in Europe and naturalized in the United States (Fig. 395), is used in medicine as well as in the preparation of a coffee substitute. The root is spindle-shaped, somewhat resembling Taraxacum, but is of a light brown color and the laticiferous vessels are arranged in radial rows in the somewhat thinner bark. It contains a bitter principle and a large amount of inulin. In the preparation of a coffee substitute the root is cut into rather large, equal pieces and roasted, after which it is ground to a yellowish-brown, coarse powder. The grains are heavier than water, imparting to it a yellowish-brown color. Under the microscope it is distinguished by the branching latex-tubes and rather short, oblique tracheae with rather large, simple pores. The SUNFLOWER (Helianthus annuus} is an annual herb indig- enous to tropical America and extensively cultivated. The plant is grown on a large scale in Russia, Hungary, Italy and India for its fruits, which yield a fixed oil resembling that of cotton seed. The achenes (so-called seeds) are obovate, flattened, externally black or with alternate white and black stripes, the pappus con- sisting of two deciduous, chaffy scales. Sunflower seed-cake is readily distinguished by a few of the fragments of the epicarp, with the characteristic twin, unicellular, non-glandular hairs and large, oblique, but rather short, sclerenchymatous fibers. Besides 40 per cent, of a fixed oil, the seeds contain a peculiar glucosidal tannin, helianthic acid, which is colored deep green with ferric chloride and yellow with alkalies. The root contains inulin; the shoot asparagin, and the fresh pith about 1.5 per cent, of potas- sium nitrate. The pith has been used in the preparation of MOXA, a combustible vegetable material which burns without fus- ing and is used by the Portuguese to destroy any deep-seated inflammation. The pith of various species of Artemisia, which also contains considerable potassium nitrate, furnishes the Chinese Moxa. JERUSALEM ARTICHOKE (Helianthus tuberosus) is a large, coarse, pubescent herb with yellow ray-florets, which is indigenous 726 A TEXT-BOOK OF BOTANY. to the Middle United States and sometimes cultivated. The tubers, which resemble artichokes, are more or less elongated or pear-shaped, reddish-brown, somewhat annulate, and internally white or reddish. They have been used as a substitute for pota- toes and contain about 16 per cent, of the following carbohydrates : Inulin, pseudo-inulin, inulenin, saccharose, helianthenin, and syn- antherin. In early spring with the development of the tubers there is formed a small quantity of dextrose and levulose. The Globe artichoke of the gardens (Cynara Scolymus) is a hardy perennial and is valued on account of the fleshy involucral scales and torus, which are edible. The POLLEN of a number of plants of the Composite, as rag- weed (Ambrosia), golden-rod (Solidago), aster and chrysanthe- mum, is said to be responsible for the autumnal cold, known as HAY FEVER. A similar disease is produced in spring and early summer by the pollen of certain grasses. It has been found that the pollen grains of these plants contain a highly toxic substance, belonging to the toxalbumins, which is the cause of the disease. By inoculation of rabbits, goats and horses with this toxalbumin a serum containing an antitoxin is obtained which neutralizes the pollen toxin and protects those who are susceptible to hay fever from its attacks. In practice the serum is prepared by injecting the toxalbumin subcutaneously into horses, the serum being known in commerce as POLLANTIN (Fig. 398). The pollen of the following plants is toxic: aster, barley, chrysanthemum, convallaria, corn-flower, golden-rod, grasses, honeysuckle, oats, oenothera, ragweed, rice, rye, spinach, wheat, and zea. The constituents of rye pollen are 86.4 per cent, of organic matter, 10.2 of water, and 3.4 of ash. The organic matter consists of 40 per cent, of toxic substances, 3 of fixed oil, 25 of carbohydrates, and 18 of a non-albuminous substance. The num- ber of pollen grains per gram varies in different plants : from Indian corn being 7,000,000, of rye 20,000,000, of golden-rod 80,000,000, and of ragweed 90,000,000. The flowers of the Japanese chrysanthemum " Riuno-kiku " (Chrysanthemum sinense faponicum) yield 0.8 per cent, of a volatile oil containing an optically inactive crystalline iso-camphor. CHAPTER VI. CULTIVATION OF MEDICINAL PLANTS. WHEN the forests and woods were full of wild medicinal plants that could be easily gathered, there was hardly an incentive to consider the farming of them. Now that they are becoming scarcer, the need is especially apparent. Our interest in the culti- vation of medicinal plants, however, is not primarily because there is a growing scarcity of the sources of supply, but in order that drugs of uniform quality and increased value may be had. For- tunately, there is a tendency on the part of some manufacturing pharmacists to concentrate their efforts upon a few plants yielding drugs and to study them in relation to their active principles throughout different periods of the season. In addition to these actual experiments, there are numerous inquiries made regarding the possibilities of the successful farming of medicinal plants. These inquiries come from various people who, for one reason or other, would like to get into country life and have some definite work to do. Many of them have never had any practical experi- ence in growing plants other than taking care of a garden plot. Nearly all know nothing of the commerce of drugs and have no idea of the problems connected with the disposition and marketing of them. Fortunately, some experiments have been conducted and there is some general information as to how one should proceed in the work. However, it must be said at the outset, no one can grow medicinal plants without having some training and special education for it ; and unless one is familiar with the prac- tical conditions of trade, that is in regard to the markets and prices paid for drugs, even though successful in raising a good crop, one may not be able to dispose of it. It is very difficult to lay down any one rule that can be invariably followed on this sub- ject. In fact, very little work has been done to enable us to draw other than very broad conclusions. The first thing to be consid- ered is locality. Of course, tropical plants would not grow in the temperate zone, nor mountainous plants at the seaside, although even here there are exceptions that only experiments can show 727 728 A TEXT-BOOK OF BOTANY. Then again, there are plants which grow only in the rich woodland soil, while others grow in barren soil in open places. Some plants- require special kinds of soil, as Atropa Belladonna and Cannabis sativa, which do not seem to reach a high state of cultivation except in a calcareous soil. On the other hand, the plants of the Ericaceae are peculiar in that they require an acid soil (pp. 250, 656). In beginning this work in a new locality it is very important to make a rather careful survey of the plants growing wild, or those which have become naturalized. It would be safe to say that within certain limits, if there are a number of genera of any family well represented that has some of the habits of the plant with which one desires to experiment with, there is a probability that it may be grown successfully. This can be ascertained to some extent by the nature of the plants that are brought under cultiva- tion. For instance, digitalis might be grown very successfully in localities where it is cultivated and has become naturalized. By a priori reasoning, in the cultivation of licorice, the ideal location for growing the plant would be in the West and North- west where the wild licorice, Glycyrrhisa, lepidota, is indigenous. In addition, it is necessary to study the best ways of propagating the plant one wishes to grow. Sometimes this is by means of seeds, as in belladonna and digitalis ; at other times it is by propa- gation of rhizomes, as hydrastis and glycyrrhiza ; or again by root-stocks or prostrate stems, as in the mints. Sometimes both seeds and cuttings may be used, as in the case of hydrastis. PLANTS GROWN FROM SEEDS. — A large number of plants can be grown from seeds, and when they are grown in this manner, espe- cially in a temperate climate, where the growing season is rather short, it is necessary to begin the germination of the seed early in the spring. This must be done in the house or under conditions where there is some protection. They may be sown either in small boxes or seed pans, in which the soil is quite sandy o) ; while in the case of an oil-globule or starch grain the reverse is true, i.e., it is lightest when the focus is above (Fig. MICROSCOPIC TECHNIQUE AND REAGENTS. 753 • 416, £) and darker when the focus is lowered (Fig. 416, F). To obviate as much as possible the formation of air-bubbles, the edge of the cover-glass should first be applied to the liquid on one side and then allowed to drop upon it. When particular care is required, a pair of forceps may be used for holding the cover and lowering it gradually. FIG. 416. Diagrams showing the difference between an air-bubble and an oil-globule in different foci: When the focus is above, as at A, the air-bubble (C) is dark gray and the oil-globule (E) tight gray. When the focus is at the lower portion, as at B, the air- bubble (D) is light in the center and the oil-globule (F) dark gray. The same optical effects as are obtained with oil-globules are observed with cell walls, starch grains and crystals. Frequently also simple pores in the cell-walls are mistaken for cell-contents, and sometimes even the lumen of the cell has been mistaken for a prism of calcium oxalate. The beginner will therefore find it an advantage to study the simple pores in the pith cells of elder or sassafras (Fig. 132). In sections show- ing either the upper or lower wall of the cells, the pores appear as circular or elliptical markings, which may be mistaken for cell- 48 754 A TEXT-BOOK OF BOTANY. contents, but which in focussing upon them are seen to be optical or microscopical sections of the pores. MICROMETRY OR MICROSCOPIC MEASUREMENT. — In the micro- scopic study of any substance a knowl- edge of the comparative size of the elements is often of much help in deter- mining the identity of material under examination, and for this reason the student should early learn to measure the characteristic elements, or those showing a variation in size in different plants, as starch grains, calcium oxalate crystals, diameter of cells, thickness of cell-walls, etc. The method best adapted for this work is that involving the use of a micro- metric scale which is placed in the eye- piece and known as the ocular micrometer. But to determine the value of the ocular micrometer it is necessary 'to use another scale known as the stage micrometer. The stage micrometer, as its name indi- cates, is used on the stage, and when placed in juxtaposition to an object indi- cates its size. However, it is obviously impracticable always to place an object alongside of the scale, and hence in prac- <£HUj^ _...* tice the ocular micrometer is used, the . 1 value of the divisions of which are c?pe'sfen|Thi0?e?ltk,nrof determined by comparison with those of SaAsthe stage micrometer (Fig. 417). The Su^a! value of the divisions of the ocular scale . varies for different objectives, eye-pieces ffi>toafrSta»lU?£j$: and tube lengths, hence it is necessary to on whld? thi™ci"aremi:CTom- ascertain the value of the divisions for the different optical combinations and tube lengths employed. The stage micrometer is usually divided into tenths and hundredths of a millimeter, and the millimeter being equivalent to 1000 microns (the micron being indicated by the MICROSCOPIC TECHNIQUE AND REAGENTS. 755 Greek letter //,), the smaller divisions are equivalent to 10 microns (io/x). For example, suppose, using a low-power objective, that 10 divisions of the ocular scale equal 20 of the smaller divisions of the stage micrometer. Thus, 20 divisions of the stage micrometer are equivalent to 20 times lOju, , or 200 ju; then, since 10 divisions of the ocular scale equal 20 divisions of the stage micrometer, one division of the ocular scale is equivalent to i/io of 200 fi, or 20 fi. Or, using the high-power objective, we may suppose that 80 divisions of the ocular scale equal 24 divisions of the stage micrometer. Thus, I division of the ocular micrometer is equivalent to 1/80 of 240^, or 3 /x. Then, if an object has a diameter covering 3 divisions of the ocular micrometer, its diame- ter is equivalent to 3 times 3 p (the value of one division), or 9 /i. REAGENTS. — The reagents that have been recommended for microscopical work are quite numerous, and, while nearly all of them may have more or less special merit, the number of reagents actually required in practice is fortunately quite small. It is important that .the student recognize the necessity for a thorough understanding of the structure of the material under examination rather than place too much dependence upon the effects produced by reagents ; in other words, the study of struc- ture should precede the use of reagents, particularly stains, when it will often be found that the latter can be dispensed with entirely. The chemicals that are employed in microscopical work, either as reagents or for other purposes, may be classified as follows: (i) Preservatives, (2) Fixing and Killing Agents, (3) Harden- ing and Dehydrating Agents, (4) Clearing Agents, (5) Stains, and (6) Special Reagents. PRESERVATIVES are substances used to preserve material which is to be examined. The most important of these are alcohol ( from 40 to 95 per cent.) and formalin [2 to 6 per cent, aqueous or alcoholic (60 per cent, alcohol) solution], the latter of which is considered advantageous in the preservation of specimens contain- ing coloring substances, as leaves, flowers, etc. Almost any anti- septic of the proper strength may be used as a preservative. FIXING or KILLING AGENTS are more especially employed in the study of the protoplasmic cell-contents, where by their use the life-processes of the cell are brought to a sudden termination, 756 . A TEXT-BOOK OF BOTANY. the object being to fix the contents in a condition approaching as nearly as possible the normal living state. In order to carry out this operation successfully, the living specimen must be placed in the fixing or killing agent as soon as collected, and if the specimen is large it should be cut into small pieces. The following are some of the common fixing agents: Chromic acid in 0.5 to i per cent, aqueous solution ; osmic acid in i to 2 per cent, aqueous solution ; Flemming's mixture, which is an aqueous solution of chromic acid (0.25 per cent.) containing o.i per cent, of osmic acid and o.i per cent, of acetic acid; picric acid in concentrated aqueous or alcoholic solution ; picric-sulphuric acid, a concentrated aqueous solution of picric acid containing 2 per cent, by volume of sulphuric acid; and mercuric chloride (corrosive sublimate) used in o.i to i per cent, aqueous or alcoholic solution. HARDENING or DEHYDRATING AGENTS are those substances which are employed for the purpose of hardening the specimen so as to facilitate sectioning and for removing the water, which would interfere with its examination. Alcohol is to be regarded as the principal hardening or dehydrating agent, and considerable care is necessary in its use; the specimen is treated successively with alcoholic solutions of gradually increasing strength, begin- ning with a 35 per cent, solution, in which the specimen is kept for twenty- four hours ; then it is placed in 50 per cent, alcohol for' from six to twenty-four hours, and then in 70 per cent, alcohol, in which it may be kept until ready for use. In order to avoid shrinking of the material at this stage, it may be kept in a solu- tion of alcohol and glycerin, or oil of bergamot, or a mixture of xylol and paraffin. When the material is to be examined it should be removed to 85 per cent, alcohol for from six to twenty- four hours, then to 95 per cent, alcohol and absolute alcohol suc- cessively for the same length of time. Of the other dehydrating agents the most important are anhydrous glycerin, pure carbolic acid, and anhydrous sulphuric acid, the latter being used in a desiccator and not applied directly to the specimen. CLEARING AGENTS. — Most dehydrating agents are also clear- ing agents, because of the fact that the air and water in the speci- men are replaced by a medium having greater refractive proper- ties. Some clearing agents act chemically on the tissues and cell- MICROSCOPIC TECHNIQUE AND REAGENTS. 757 contents. Among the clearing agents most frequently employed are: Chloral in saturated aqueous solution, and chloral-glycerin solution (a solution of equal parts of glycerin and water saturated with chloral). Essential oils, as clove, turpentine, cedar, mar- joram, etc., are also useful for this purpose, particularly when the specimen is to be mounted in Canada balsam. STAINING AGENTS are those that produce more or less defi- nitely colored compounds with the cell-contents or -walls. They include: (i) the Aniline Dyes and (2) Non-aniline Stains. The aniline stains may be used in aqueous solutions, weak alcoholic solutions or strong alcoholic solutions, containing from i to 3 per cent, of the dye. The following are the aniline stains most frequently employed : Aniline blue, Bismarck brown, fuchsin, gentian violet, methylene blue, methyl violet and safranin. In addition to these, aniline hydrochloride or sulphate is used in what is known as Wiesner's Reagent, which is a 25 per cent, solution of alcohol containing 5 per cent, of either of these salts, a drop of either hydrochloric or sulphuric acid being used with a drop of the solution, according as the hydrochloride or sulphate has been used. LOFFLER'S METHYLENE BLUE. — This reagent is prepared by adding 30 c.c. of a concentrated alcoholic solution of methylene blue to 100 c.c. of water containing 10 milligrams of potassium hydrate. ZIEHL'S CARBOL-FUCHSIN. — This solution is prepared by add- ing 15 c.c. of a concentrated alcoholic solution of fuchsin to 100 c.c. of water containing 5 grams of carbolic acid. ANILINE DYES are usually employed in concentrated aqueous solution, but owing to the difference in solubility of the dyes the solutions vary in strength. Saturated solutions of eosin or gen- tian violet may be prepared by dissolving i gram of the dye in 100 c.c. of water, while to make a saturated solution of methylene blue requires 0.400 Gm. of the dye to 100 c.c. of water. Some •investigators prefer to replace the distilled water with aniline water, which is prepared by adding about 3 grams of anilin oil to 100 c.c. of distilled water. • REAGENT BOTTLE FOR STERILE SOLUTIONS. — The solutions of the aniline dyes as ordinarily prepared deteriorate more or less rapidly and are usually made up fresh each time they are required 758 A TEXT-BOOK OF BOTANY. for use. These solutions, as well as other reagents that are prone to decomposition, may, however, be kept for months or even years by preparing them with care and keeping them in a special kind of bottle (Fig. 418). An ordinary bottle may be used, and is fitted with a rubber stopper perforated so as to allow the intro- duction of two glass tubes. These tubes are bent twice at right angles and the free ends directed downwards. One of the tubes is connected with an atomizer bulb and serves for forcing out the FIG. 418. Reagent bottle for sterile solutions. liquid. A small plug of absorbent cotton is placed in the tube at the point C, so as to filter the air. This may be improved by blowing a bulb in the tube for holding the cotton. The bottle should be sterilized before placing the solution in it, and the solu- tion should be made by adding the dye to sterile water contained in the bottle. The solution may be afterwards further sterilized by means of steam if this should be found necessary, as in this way only a perfectly sterile solution could be produced. MICROSCOPIC TECHNIQUE AND REAGENTS. 759 if if li -jEi i! JO I »*i* § S a2-§ s o ° § ? § °^"s § 2. ^ g[ I O o ° D* T* 2J O* nc«. o-^ g 2,5 g £,£ g. w o §•£. ajto^'i-^' <"*£"' §" "* <" S'D*-"' a"-"3 ^s? Si §P 3 O ft n-f-r* O ;— !(D rf 3 (p 3 ^ f6 rt- ^ ft O « 2. - £T|5 ET Q. £j <§ ?3- ~ rf ^ ^ ^ 0Q £ w P ^ *«S OQ £ w P _ ^. 3 Q Calcium Oxalate Crystals 10 ' n ' w gtgijjn ?H ^^.^ ? H gi'S^Q CO t-lsllii M if 1 1 ffs ftf'll rt n^^o^S o-— ff , 3 t — o " ^ O 2. «• «• o^-o a — s- «tOS'Sp-9 5!'5i-3 C»-5«*Sa<'1<^ w &i 3-35 5*31? •< 3 re CJ 2*5 ?fi*S8r l-ft L»S • s s.g^ Ego, "KOSP 1-T 3™^ 3"^' O'0'- S-3 ^ ^g&'rr3 ^< a § ~£. i — £. ^3.5" • 3 P. E-^^S^rt- '"a 3|? 3|B! Ig- 1"? ^Afrl'^ Tracheae «• c» 3 •o3q - ^ i?II98 i3? iiE^?1 Isf? BO!^ ff o EL1"1 Sfo*o s 3*(?^ 5*°*^^^ w'o^^ *ic"3 w& < «5* ^ Ow^— S> 2^— I" 33 O3^ "^*2.3lU CO ^"ri- n* t1"1 ft 3 jSrtOt— ^O^± fiO fi fe* • "^O^ ^ £* 3. p" (6 3 D- i 30- JD *o ^ "-"G. 5? SA ^ ft O " 2*0 ^ u r^S- p p a 5- ||1^ 1*5*1 2 «-in>E: g.5" H? tt- p 3' o) CT30Q (» p. o B- 1 P < p , a *— I ^ ^ n HJ i§ III!' la*- it MB! f!l — ™ T w g,S v CS li 5= 3 ^ rt Cork and Cutin 0 vg ^5-85-^ J^rr ^o o^i2 ^ip-CL^-3 S,^ -^ 2g" : S! ? rlfll! j | O ^^ I! *<"<^ * ;T