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Lorsque le document est trop grand pour dtre reproduit en un seul cliche, il est film6 A partir de I'angle supdrieur gauche, de gauche d droite, et de haut en bas, en prenant le nombre d'imagos nicessaire. Les diagrammes suivants illustrent la mithode. ly errata 9d to nt ne pelure, ipon A 1 2 3 32X 1 2 3 4 5 6 f^tim-.s'^ ,r.r'^ -^ ^s >^ 1 J ^^yi, A , LrrUL^K^ « 9 ^ U n. £-• or s s* ??g &•£.»«» •-• m a. rj a ATI ar * DO ►;• I M. J. ^lagc ^ QTo. 3 educational §mte. t-^ THE ELEMENTS OF B^' If n • Ok «^ B 01 ? I Structural Botany WITH 81'ECIAL UEFEUENCK TO THE STUDY OF CANADIAN PLANTS; TO WHICH IS ADDED A SELECTION OF PiXAMINATIOX 1' A FEUS BY II. B. SPOTTON, M.A., F.L.S.. rinXCII'AI, OK IIAKMOHI) ST. COM.KCJ I ATK INSTITUTE. Authi>i'i~ri1 far use. in tlw. Srfinnls of Ontario. Autlidi'ized J'nr nsi' in the, Schtntls of (Quebec. Anth(n'i"i'(1 far nsi' in tin: ScIiikiIh of A'<'M> fli'uuitwivk. Anthin'izt'.d for use in the School i oj' Noru Scotia. Authorized for use in the Schools of Manitoba. W'viHcd Edition. With many Ilhistratinna hy the Author and others. w. .1. (i Ad 10 <*t, ('()^^I^\XY, rOKO.VTO. i '^Ts : ^ o oo - Take now a llower which has just opened. Beginning at the outside, you will find five little spreading leaves, somewhat yellowish Fig. 4. Fig. 4.— Radical leaf of Buttercup. Fig. 5.— Flower of Buttercup, from the back. ^&C large number of little yellow bodies, each at the top of a little thread-like stalk. Eat;li of these Ijodies, with its stalk, is called a stamen. The little body itself is the anther, and the stalk is its filament. Your magnifying glass will show you that each anther consists of two oblong sacs, united lengthwise, the filament being a continuation of the line of union (Fig. 7). ^ ' / If you look at a stamen of a flower which »^ /rrv »- has been open some time, you will find that each anther-cell has split open along its outer edge, and has thus allowed a fine yellowish dust to escape from it (Fig. 8). This dust is called ^mllen. A powerful )^ magnifier will show this pollen to consist of Fig. 7. Fig. 8. grains having a distinct form. As the stamens are many iij number, and free from each other, they are said to be p()ljUlot,ndjiQiis. 7. On removing the stamens there is still left a little raised mass (Fig. 9), which, with the aid ^ of your needle, you will be able to separate into a number of distinct pieces, all exactly alike, and looking something like unripe seeds. Fig. 10 shows one of them very much magnified, and cut through lengthwise. These little bodies, taken separately, are called car^U. Taken together, they form the pistil. They are hollow, a^^ Fig. 10. each of them contains, Fig. 9. as the figure sho a Fig. 6.— Section of a flower of Buttercup. Fig. 7. — Stamen of Buttercup. Fig. 8.--The same, allowing longitudinal opening of the anther. Fig. 9.— Head of carpels of Buttercup. Fig. 10.— A single carpel cut through lengthwise to show the r ^--fc. v> \ ^ f "^« "^ent poi„, and ha'MT ''"''^' ^* *"« *°P' > -^ '^ rough and n.ist, so that in 7' ''^^ '^ '"°- or "'hose anthers have burst on.n ^^'"■^ of pollen will bo fo"^ Tl ^ ''"'""'^ J This rough upper p! t of t'h "' ''^"- called the ,..i,Z I'll sh''""^'' '%,,... greatly magnified Tn ' ^ '"«■"* '"' ««gma is raised on a "taTk"";. ""'"'^ *'^ «- "• ^*-"^ - called a^.^ T.^X^^ "''''■ ^^^ ^ *f as to be al^st suppress!; T^" ^'^ '*^'' '"° ent.rely absent, the stig j^ ^1 t^r ""^ ^*^^« " hoUow part of the carpel is the o'^, *"- ^^"''«- The 111 our plant the r,;.ni • ^— ^' -«" the calyx, and is e Xul^^r^ '" ^"^ ^^ '«Pm«r, and, as the caroeT, ^ '^"' *° ^^ >«« or '•^e pistil is said to be ;:S;,r"°' --'ed together. ^ 8. Kenjove now all fi,« remains nc-thin„ hut .K """P^''' ^"'^ 'h«re peduncle. ThisLoHe .' '"'°"'" '"^ °f *he the flower. tI Hn h ^^ " '''^ '•"^^^^«* of o"P. all four ^arl e tV "f ^'^eBiHter. and pWra^e-ita^?^ V;^''^' «'-^^^^^ a" four of these parts it is^M to", " '"^ 9- Let us now return 1 '""'■^*''- v the structure of sta 1 "^ '*"*''"^"* ""at K F%:ii^^^;;::;;i:;zrz----: _^^he stame„ '''if-i'-S'^^I^T^l; ■ __j^a^ie stamen tt^^Xc k*t*- '-'.A < i ^ W^"*^diL I TANY. he lower end of lit condition, is at the top, > a '^ge is more or ^'^s. 11. *i'y. Such a he styJe is so the style is sessile. The m any way ' he free or d together, and there ^OP of the "^^Ptade of le Butter- stamens, 'ower has ' 9omj)lete. , oentthat V is only a ' stamen EXAMINATION OF A BUTTERCUP. V looks less like a leaf than any other part of the flower. Fig. 1"^ will, however, serve to show us tho plan upon which the botanist considers a stamen to be formed. The anther corresponds to the leaf-blade, and the filament to the petiole. The two cells of the anther correspond to the two halves of the leaf, and the cells burst open along what answers to the margin of the leaf. 10. In the case of apocarpous pistils, as that of the Buttercup, the botanist considers each carpel to be formed by a leaf-blade doubled lengthwise until the edges meet and unite, thus forming the ovary. Fig. 13 will make this clear. 11. Tliere are many facts which support this theory as to the nature of the different parts of the flower. Suffice it to mention here, that in the white Water-Lily, in which there are several circles of sepals and petals, it is difficult to say where the sepals end and the petals begin, on account of the gradual change from one set to the other. And not only Fig. 13. is there a gradual transition from sepals to petals, but there is likewise a similar transition from petals to stamens, some parts occurring which are neither altogether petals, nor altogether stamens, but a mixture of both, being imperfect petals with imperfect anthers at their summits. We can thus trace ordinary leaf-fcrms. by gi'adual changes, to stamens. *' We shall then distinguish the leaves of plants as foliage-leaves and Jfoiver-leaves^ giving the latter name exclusively to the parts which make up the flower, and the former to the ordinary leaves which grow upon the stem and its branches. Fig. 13.— Diagram to illustrate the Itiaf-struuture of the carpe/. #^^ fi 10 t\. 15. m /^ on,, t,,o head of „:.■:[; ^^^-S of the ovules, which have „o ' ' ""'*"» *° "'«^ «~-tJ' one of the carpels, and c Jf,, "" '"*• ^^'^'"°^« germinates. ^^""''^ ^^^^ ^Jie seed Kg. u, ^o'X:';r "^"' *''*'"' "-* «- p--* consists of (^)- The Rnnf Ti • ^■^ '.'ely destitute of buds "nil ""'' ^''^" °«'' '^'"J « ^2). The Stem t li "• bearsfoUage-leavesatin e ,r" "'""'"'' '' ^^--d- the axils of these, and bel" flll'""'" "^ '^™-''- ^om , (^)- The Leaves, 'rsea;":''^"^"^^-* "~-^^;;; _^^^^_formerare sub-divided f^itf. 16.- .Section of seed sho • ''eea showing the small embrvo a„ ^°- '^" "^"ch magnified. v>-. (r ANY. Jttercup whoso ■'^^'•ly, Jeavin "■P^'^s on the pf>is will have ^'''^ wiJl now ^•^1 more dis- Slower which ^^ie grow til ^'* He move through the •^^ed almost nee "/..^'W ^-^-^^^c^,,.. ^^.^..j^ > ;^.V^U.c.. FUNCTIONS OF THE ORGANS OF THE FLOWKIl. 11 into radical and cauline, and the latter make up the [lower, the parts of which are four in number, viz.: calyx, corolla, stamens, and pistil. It is of great importance that you should make your- selves thoroughly familiar with the different parts of the plant, as just described, before going further, and to that end it will be desirable for you to review the pre-' sent chaptnsr carefully, giving special attention to those parts which v/ere not perfectlj'^ plain to you on your first reading. In the next chapter, we shall give a very brief account of the uses of the different parts of the flower. If found too ditlicult, the study of it may l)e deferred until further progress has been made in plant-examination. onsists of avoiding ^es, from ff, and is oioured, es from snd divided ignified. CHAPTER II. FUNCTIONS OF THE ORGANS OF THE FLOWER. 1 4. The chief use of the calyx and corolla, or floral envelopes^ as they are collectively called, is to protect the other parts of the flower. They enclose the stamens and pistil in the bud, and they usually wither away and dis- appear shortly after the anthers have shed their pollen, that is, as we shall presently see, as soon as their services as protectors are no longer requireJ. 15. The corollas of flowers p.ie usually bright-coloured, and frequently sweet-scented. There is little doubt that these qualities serve to attract insects, which, in search i^ of ^ '"^CTURAL BOTANY. °f the anthers, detach Td ZT' "'"^ '''<' "P^" cells Hien, some of .^ j, ^t T , ^ """^^ ''"'"'«««» of visited. *''« «a«e lend, subsequently 16. The essential nart ^e tu . »^ the p„,.pose of Zol^: f""'" '^ '"^^ -*-, -•"eh. as you have al e Jv I . '"'°'^'"'' *''« P-< ""-^ns, having a de/ini e s fu ?''" ' r™^ °^ ">■"»*« - -"all, alil^e in plants ftW "T ""'^ «-- furnished With t«o coats n " '""''• They are and the outer one ,:„!:, "'"^'-- -'--ely thin "'terior of the pollen.,3„ ■ t^ ^ """'"'^'^"- Th When a poUen-in f ^1 ^n Sll,"'!' '"^"■^ -««-• '" ^-^ ^-n a curious „,anue' (^t m T" '* '^^^'"^ H Pi'sljos its way through tf" -^^ ^^ ""''"' ""at *^^ ^^^^kpointintLS, /"'•"■ ""'' ^' «»«« of a slender tube. Th i? '°'-'""'« ^^^ "eginning . «">' then extends itreS^:'^'""'^'^^'«« the stign,^" ^te.n.Hyle, until it comes In th"'"" """""Sh the Ti'c liquid contents of thTnn > ''"'^ °^ '^^ "vary through this tubcwheh/emal^r" ''^^ «--d do^ and the body of the grain „T T^ "' "^ '°^« end, ;'- ovary contain: o'wj'f- "'""=" ^^^^^• end to the wall of the ova v Tb '' "''"'''^ "^^ °"« ^'sts of a kernel called It ^ "''"'« <=°n- "^ally surrour,dcd bvtw -^^ "'"""^ - of which there is a 11! """''' "'"""'' ''o'" Fiff 18. F«.18-&e«„7™7j^l<>Pi"gatube. " e- ■■•r, oecj Oau .A ANY. bringing their t^e open ceJJs quantities of ^^ upon the subsequently ^ the anther, ® the pollen, ts of minute JittJe grains • They are 'emelj thin, ^'^son. The "id matter, ^la it ^e^?;?^. 3 inner coat '> at Some ' beginning the stigma, ^'0"gh the 'he ovary, 'ied down >wer end, away, d by one . FUNCTIONS OF THE ORGANS OF THE FLOWER. 13 w Fiff 18. ulways to be found at that end of tlio ovule whicli is not attached to the ovary. (Fig. 18, ni.) About tlio time the anthers discharge their pollen, a little cavity, called the emh^jjij^nar, a[)pears inside tlio nucleus, near the micropyle. The pollen-tube, with its liquid contents, enters the ovary, passes through the micropyle, penetrates the nucleus, and attaches itself to the outer surface of the embryo-sac. Presently the tube becomes empty, and then withers away, and, in the mean- while, a minute body, which in time developes into the embryo, makes its appearance in the embryo-sac, and from that time the ovule may properly be called a seed. 17. In order that ovules may become seeds, it is always essential that they should be fertilized in the manner just described. If we prevent pollen from reaching the stigma — by destroying the stamens, for instance — the ovules simply shrivel up and come to nothing. .*v. Now it is the business of the flower to produce seed, and we have seen that the production of seed depends mainly upon the stamens and the pistil. These organs may conse(|uently be called the essential orggus of the flower. As the calyx and corolla do not play any direct part in the production of seed, but only protect the essential organs, and perhaps attract insects, we can under- stand how it is that they, as a rule, disappear early. Their work is done when fertilization has been accom- plished. Having noticed thus briefly the part played by each set of floral organs, we shall now proceed to the exami- nation of two other plants, with a view to comparing their structure with that of the Buttercup. < i l4 ELEMENTS OF mnVCTftfAt r.^ CHAPTKK Iir ;''rr:;;cr™ "■"""■""--.-■ ^""" "'■"«-''"S AND TilAT OP UUTTEBCUP. HeplS^'^'f: J°; "-3^ P;ocure ^P-'«e-s of the -« -t ii„d it i,/fl„;: "^^ f .f^ -"d«. but you summer. It j^ very desirabj -I ''"'"'° "'"^ «"'y y acs.rab,e tl,at you sl.ouM I.avo the « » Fig. 19. plant itself, but for those v;hn «l--ens, the anne J e J^ J^ ^^^^^ ^o obtain substitute. engravings may serve as a \iI.^,JM^x \ vv. JOLD— itESEM- TIIAT OF ^ens of the ^s, but you ^rid early 1 iiavo the HEPATICA. 15 Beginning, then, at the root of our now plant, you see that it does not differ in any great measure from that of the Buttercup. It may, in like manner, he described as fihnms. The next point is the stem. You will remember that in the Buttercup the stem is that part of tlie plant from which the leaves spring. Examining our Hepa- tica in the light of this fact, and following the petioles of the leaves down to their insertion, we find that they and the roots appear to spring from tlie same place — that there is, apparently, no stem. Plants of this kind are therefore called acanlesreiji^ that is, steniless, hut it must be carefully borne in mind that the absence of the stem is only apparent. In reality there is a stem, but it is so short as to be almost indistinguishable. The leaves of the Hepatica are, of coui e, all radii' al. They will also be found to be net-vpinsd. 19. The Flowers of the Hepatica are all upon long peduncles, which, like the leaves, appear to spring from the root. Naked peduncles of this kind, rising from the ground or near it, are called scap_^. The flower-stalks of the Tulip and the Dandelion furnish other familiar examples. Let us now proceed to examine the flower itself. Just beneath the coloured leaves there are three leaflets, which you will be almost certain to regard, at first sight, as sepals, forming a calyx. It will not be difficult, however, to con- vince you that this conclusion would be incorrect. If, with the aid of your needle, you turn back these leaflets, you Avill readily discover, between them and the coloured portion of the flower, a very si tort hit of stem (Fig. 20), t-" upper end of which is the receptaolp. As these I: ir^rX'^^ yv^' ^-^ Wt Buttercup, after I^^XTt'" 7'"'^"^^''''°^ ^^ stamens are very nnme f ^^tf "™"^- ^^« -ptaele^ne carpels are aC^^^^^ tacle and i;e'"r T' "^ ''" ^^''^P- of the carp is (F f 1^:^'"^ °"^ ** "-titcontiinsising;:l rib J"^-" ^''- - ffluci, resembles that of the 7-' h "'"'' ''" '"""■'. so pr« to learn thati;';;,f;L:;';,:r^°-^"''» oi- family of ,,,,„ts, an,I y„„ „; ° '',"'« ■^''""^ 0''der --.nber s„ch ...mblani' J J :',:f, *" t"'^" """ your notice, when you set out to " ^"'""^^^ "> £__f:::^'^^*x,u,nno plants for your «--.-S,„((le carpel, cularjed. \-" '-'a- he r< <^ d •eceptacJe, sniaJi foliage le bovver, the ^wer, then, is ^11 this re- ercup. The ^ not bein<' is an under- ^ coroIJa are IS wan tin fr the flower ^'ij Jniisfc be lerefore, as ^hat is left ^ft of our 'o^ha. The 'cl on the ^hort, so will be « Order 'vo and "ght to I" your ged. MARSH-MARIGOLD. 17 selves, because it is only in this way, and by slow steps, that you can acquire a satisfactory knowledge of the reasons which lie at the foundation of the classification of plants. 22. Marsh-Marigold. This plant grows in wet places almost everywhere, and is in llower in early sumnier. Note tlie entire absence of hairs on the surface of the planu It is therefore glabrous. The root, like that of the Buttercup and of the Ile- patica, is fibrous. The stem is hollow and furrowed. The foliage-leaves are of two kinds, as in the Butter- cup. The radical leaves spring from the base of the stem, whilst the higher ones are cauline. The leaves are not lobed, as in the other two plants, but are in- dented on the edge. They are also net-veined. 23. Coming to the flower (Fig. 23) we find a circle, or whorl, of bright yellow leaves, looking a good deal like the petals of the Buttercup, but you will look in vain for the corres- ;: ponding sepals. In this case there;/: is no whorl of bracts to mislead you. V^ Are we to say, then, that there is no calyx? If we adhere to the under- standing mentioned when describing the Hepatica, we must suppose the corolla to be wanting, and then the briglit yellow leaves of our plant will bo the 8('j)ah, and will together constitute the calyx. As to the num])er of the sepals, you will find, as in the Fig-. 23.--Flower and leaf of Marsh-Mari-'olc!. Fig-. 23, •f I ■^ II •i| .1 ELEMENTS OF STRUCTURAL BOTANY. Hepatica, some variation. Whilst the normal number is five, some flowers will be found to have as many as nine. 24. The stamens are next to be examined, but you should first satisfy yourselves as to whether the calyx is jjolysepaious or otherwise, and wliether it is free from the other floral leaves or not. If your examination be properly made, it will show you that the calyx is free and poly- sepalous. The stamens are very much like those of the Buttercup and Hepatica. They are numerous, they have both anthers and filaments, and tliey shed their pollen throu^di slits on the outer edges of the anthers. They are all separate from each other ([)olyandrous), and are all inserted on the receptacle. On lliis latter account they are said to hyj^^HIl: nous (below tlie pistil). 25. Remove the stamens, and you have left, as before, a head of carj)cls (Fig. 24). Examine one : there is the lower broad part, which you recognize as the ovary, the very short style, and the sticky stigma. To all appearance the carpels are pretty much the same as those of the two plants already examined. It will not do, however, to trust altogether to appearances Fi/j. '24. in this case. Cut open a cari)cl and you find that, instead of a single ovule at the bottom of the ovary, there are several ovules in a row along that edge of the ovary which is turned towards the centre of the flower. The ovary is, in fact, a pod, and, when the seeds ripon, splits open along its inner edge. If you can find one whi(^h has split in tliis way, you can hardly fail to be stru(!k with the resembhuuie which it l)ears lo a common leaf. (Fig. 25.) Fijj^. 24.— Head of carpels of Marsli-Mariyold. Fig. 25.— Single carpel, opened to show the two rows of seeds. lo iii- l-«j^ 12,1 FLOWER-SCHEDUI.ES. 10 On the whole tlie resemblance between the structure of the IMarsh-Marigold and tliat of the Hepatica and Buttercup is sutticiently gr<\it to justify us in placing it in tlie same family with tlunn. 2G. Having now made yourselves familiar with the different parts of these three plants, you are to write out a tabular deserif)tion of them according to the following form ; and, in like manner, whenever you examine a new plant, do not consider your work done until you have written out such a description of it. BUTTERCUP. DRUAN OB I'AIir OF FLOWEK. Calyx. Sejjals. Cc^rolla. Petals. St.imens. Filaments Anthers. Pistil. Carpels. Ovary. NO. COIIfiSION. ahHes'iox IIKMAKKS. Polysepalous. Inferior. ^ ^ PolypetalouH O) ( I Polyandrous. Apocarpous. . • r. 'A./ ' Hypogynous HypogyiiDU- ">v4 Each Petal with a pit at the base inside Sujieriof. | (.'arpela 1 -seeded In the form the term c(jhesum relates to the union of liJce parts ; for example, of sepals with sepals, or petals with i)etals ; while the term wlheslgji relates to the union of unlike part>; ; for example, of stamens with corolla, or ovary with calyx. Neither cohesion nor adhesion takes place in any of the three flowers we have examined, and accordingly, under these headings in our schedule wo write down the terms polysepalous, polypetalous, Sz(i.^ to indicate this fact. Tl^^^J i.tA ^ ^ ^ ^ S* . Ck^^ f 1 20 ELRMKNTJH Op STnUOTURAL IJOTANY. V^ . HE H^PATICA. OUC.AN. NO. COHESION. ADHESION. IIKMAUKS. Calyx. Sepals. 7 12 rolyst'palous. Inferior. Coloured like a corolla. Corolla. Wanting, j";^ Petals. 00 ■^J fctfrxAyx Stamens. Polyandrous. HypogynouH. Filameyits. Anthers. Pistil. Apocarpous. Go.rpels. Ovary. X Superior. Carpels 1 seeded. MAESII-MARIGOLD. ORGAN. NO. COHESION. ADHESION. REMAllKS. Coloured like a corolla. Calyx. Sepals. 5-9 L'olysepalous. Inferior. Corolla. Petals. 1 AV an ting. (^ Stamens. Filaments. Anthers. 00 Polyandi'ouH. fbP"ffyno"s- Pistil. Carpels. Ovary. CO Apocarpous. * ,1 Superior. Carpels contain several seeds. . - ! CHARACTERS OP RANUNCDLACE^E. 21 The symbol oo means " iiRlefiiiite," or " numerous," and may be used when the parts of any organ exceed ten in number. Under the liead "Remarks" you may describe any- thing wortliy of notice, for which provision is not made elsewhere in the schedule. If you use the exercise-book which has been prepared to accompany the text-book, you will find also space for drmoing such parts as are not easy to describe in words. 27. The three plants upon which we have been en- gaged up to this point are representatives or types of a very large group, called by botanists RauuttculacetP, that is, UilM!!d!:£]ii(Mf-Ql!i^.2dS^^''^' -^^^ ^^^^ members of it, w^hilst they may ditfer in certain minor characteristics, agree in all the more important respects. The minor dilFerences, such as we have observed in our examination of the specimens, lead to the sub-division of the group into several smaller groups, but any plant exhibiting the peculiarities common to all three may be regarded as typical of the Order, which is the name given to the group as a whole. These common peculiarities may be summed up with sufficient accuracy for our present pur- pose, fis follows : 1. The circles of fower-leaves, that is to saf/, the sepals, petals,, stamens, and carpels^ are entirely distinct, and unconnected with earh other, 2. The several members of each circle are also entirely separate from each other. S. It may he added that the stamens are almost invari- ably numerous, and that the plants are acrid to the taste ^ tS^i.M^ll.xrX.J^ . ^H-^^/^xi t^<\ iCiU.-^i k< '" 22 "■ / n te ELKMENTS OF STllUOTUHAri MOTANY. CHAPrKR JV. s - EXAMINATION OF OTlIKli COMMON PLANTS WITH IIYP/^GY NOUS STAMENS SIIEIMIEUD's 1»UKSE — UOUND- liEAVED MALLOW. 28. Wo shall now proceed to examine some plants, the ilowers of which exhibit, in their structure, impor- tant variations from the I-Jutteicup, Hepatica, and Alarsh-Marigold. Shepherd's Purse. This plant (Fig. 20) is one of the commonest of weeds. As in the Buttonup, the foliage-leaves are of two kinds, radical and cauiine, the former being in a cluster around the base of the stem. The cauiine leaves are all sessile, and each of them, at its base, projects backward on each side of the stem, so that the leaf somewhat resembles the head cf an arrow. Such leaves are, in fact, said to be fiaf/iffatc, or arrow- shaped. The Ilowers grow in a cluster at the top of the stem, and, as the season advances, the peduncle gradu- ally elongates, until, at the close of the summer, it forms perhaps half of the entire length of the stem. You will observe in this plant, that each separate flower is raised on a little stalk of its own. Each of these little stalks is a fmiicel, and when pedicels are present, the term peduncle is applied to the por- tion of stem which supports the whole cluster. 29. The flowers (Fig. 27) are rather small, and so will require more than ordinary care in their examination. Tiie calyx is polysepalous, and of Figf. 27.--Flower of Shepherd's Purse, enlarged. EO ^/\rx in(;^ Y. SHKf'HEllI) 8 J-UUHii. 2? ITTI nvp/)QY iOUND- ome plants, burn, impor- patica, and ?<)) is one of torcup, the Jfuiline, the the stem. •f them, at e stem, so an arrow, or arrow- top of the le gradu- it forms You will is raised tie stalks present, the por- e whole r, er small, lary care !, and of / Fi^r. 2().--Shfi)lifr(l'H Purse. 1 »« 'I 4A^f- >:> ' H I ^S 5f* ELEMENT":. OP STRUCTURAL I50TANY. four sepals. The corolla is polypetalous, and of four petals. The stamens (Fig. 28) are six in number, and if you examine them attentively, you will see that two of them aie shorter than the other four The mill stamens are consequently said to he tetradynamous. But if there had been only four .jtamens, in two sets of two each, they would have been called Y\g. 28. didy;fiamou'^. The stamens are inserted on the receptacle (hypogynous). The pistil is separate from the other parts of the tlcwer (superior). 30. To examine the ovary, it will be better to elect a ripening pistil from the lower part of the peduncle. It is a fiat body, shaped sometliing like a heart (Fig. 29), and having the short style in the notch. A ridge divides it lengthwise on each side. Carefully cut or pull away the lobes, and this ridge will remain, pre- senting now the appearance 3": a narrow loop, with a very thin membranous parti- tion stretched across it. Arouna the edge, on both sides of the partition, seeds are suspended from slender stalks (Fig. 30). Fig. 29. Fig. 30. There are, then, two carpels united together, and the pistil is, therefore, simcarpous. 31. Shepherd's Purse is a type of a large and important Order, the GrucJfene, or Cress Family. Other common examples, which should be studied and compared with Shepherd's Purse, are the garden Stock {single flowers are best for examination), Water-Cress, the yellow Mustard Fig, 28. — The same, with calyx and corolla removca. Fig. 29. — Ripened jiistil of Shepherd's I'lirse. Fig. 30.— The same, with one side removed to ahov iheseedg. ■MlaMniMMa shepherd's PURdE. 25 of the wheat-fields, Eadisli, Sweet Alyssum of the gardens, &c. All these plants, while dilfering in unimportant par- ticulars, such as the colour and size of the petals and the shape of the pod, agree in presenting the following char- acters : / 1. The sepals and petals are each four in number. I 2. The stamens are tetradynainous (and hypogijnous). \ 3. The fruit is syncarpous^ and is 2-celled by reason of ) a thin partition stretched between the carpels. Jf. It may be added that the plants are generally pungent i to the taste, and the flowers are almost invariably in terminal clusters^ like that of Shepherd^ s Purse, % SHEPHERD'S PURS!]. 0kg AN. Calyx. Sepals. No. 4 Cohesion. Polysepalous. AUHKSION. Inferior. Remauks. Corolla. Petals. 4 6 Polypetalous. Hyp ogy nous. Hypogynous. Sui)eiiur. Stamens. Filaments. Anthers. Tetradyna- nious. Two sepals with a pair of long stamens opposite each ; the other two with one short stamen opp. each. Pisti). Carpels. OiHirij. Syncai'pons. The two colls of the ovary HH|)avatecl by a thin partition. i 26 ELEMENTS OF STRUCTURAL JJOTANY. 32. Mallow. Tlie round-leaved Mallow (Fig. 31) grows along every wayside, and is a very common weed in cultivat- ed grounds. Pro- cure, if possible, a plant which has ripened its seeds, as well as one in flower. The root , of this plant is of of a different kind f io:ii those of the three plants first examined. It consists of a stout tapering part, de- scending deep in- to the soil, from the surface of which fibres are given ofi irregularly. A stout root of this kind is called a tap-root. The carrot is another example. 33. The leaves are long-petioled, net-veined, and in dented on the edges. On each side of the petiole, at its junction with the stem, you will observe a little leaf -like attachment, to which the name stimile is given. The presence or absence of stipules is a point of some import- ance in plant-structure, and you will do well to notice it in your examinations. You have now made yourselves Fig. 31.— Round-loaved Mallow. Fig. S2.--SectioTi of the flower. Fig-. 33. — Flower with calyx and corolla removed. Fi^. 34.- A ripened pistil with the persistent calyx. OJ\ .f-6A> I ^^ti^'>n^x.4f I OjO ^^- / '*^- c c tcs, - acquiiinted with all the parts that any leaf has, viz., hlade^ petivlf^ and stipules. ' 34. Coming to the flower, ohserve first that the parts of the calyx are not entirely separate, as in the tlowers you have already examined. For about half their length they are united together so as to form a cup. Tlie upper half of each sepal, however, is perfectly distinct, and forms a tooth of the calyx ; and the fact that there are five of these teeth shows us unmistakably tliat the calyx is made up of five sepals. We therefore speak of it as a gainosepalous calyx, to indicate that the parts of it are coherent. As the calyx does not fall away when the other parts of the flower disappear, it is said to be persistent. Fig. 31, a, shows a persistent calyx. 35. At the base of the calyx there are three minute leaf-like teeth, looking almost like an outer calyx. A circle of bracts of this kind is called an involucre. The three bracts under the flower of the Hepatica also consti- tute an involucre. As the bracts in the Mallow grow on the calyx, some botanists speak of them as an ^picalyx. The corolla consists of five petals, separate from each other, but united with the stamens at their base. 36. The stamens are numerous, and as their filaments are united to form a tube, they are said to be monadelphous. This tube springs from the receptacle^ and the stamens are therefore hypoggnous. Fig. 32 will help you to an under- standing of the relation between the petals and stamens. Having removed the petals, split the tube of the stamens with the point of your needle. A little care will then enable you to remove the stamens without injuring the ; .^\ r rO Ajt-^'l » \J^ I: 28 ELEMENTS OF STRUCTURAL ROTANT. !*:■"; pistil. Tlio latter organ will then l)o found to consist of a ring of colnncnt carpels, a rather stout style, and num- erous Idtig stigmas (Fig. .'3.'^). If you take the trouble to connt the carpels and the stigmas, you will find the num- bers to correspond. As the seeds ripen, the carpels separate from each other (Fig. 34). MALLOW. Oroan. No. 5 5 00 Cohesion. Gamosepa- lous. Adesion. Calyx. Sepals. Inferior. Corolla. Petals. Stamens. Filavients. Anthers. Polypetalous. Hypogynous. Mouadelphous One-celled. Syncarpons. Hypogynons. Pistil. Carpels. Ovary. GC Superior. Eemauks. Three hratt- fifrc)wing(^ii tlif calyx. Carpels as many as the stigmas. 37. Compare now the structure of the Hollyhock (single flowers should be seleetea; with that of the Mallow, and write out a description. Musk-Mallow and Abutilon (a :^ommon green-house plant) may also be examined with advantage. 38. The Order (Malvacea>) of which Mallow is a type ^is very distinctly marked by the following characteristics : 1. The sppals are always placed edge to edge (valvate) in th'j hud J while the petals overlap and are rolled together {convolute). 2. The stamens ar<- numerous and. moiiadeljdious, and their anthers are 1-celled. AWiougli united at the TMJHf.T5iH!i.A!.tJ';^ d^SjX ei WVtA^OARDEN PEA. (>(;^;^,; ^ ^.29 j^\ base with the claais of tlie '^)ctaU.^ they are neverthe- less inserted on the I'ecrptacle {hypogynous). S. TJie carpch are almost ahrays united in a ring^ which hreaks up at maturity, 4. It may he added that the leaves are furnished with stijndes, and the Juice of fhej^lonts is mucilaginous. CHAPTER V. EXAMINATION OP COMMON PLANTS WITH PERIGYNOUS STAMENH — GARDEN PEA — GJiBAT WILLOW-HEUJJ. 39. Garden Pea. In tlie flower of tliis plant, the ealyx is coiiritructed on the .sain(3 i)lan as in the Mallow, riiere are five se[)als, coherent below, and spreading out into distinct teeth above (Fig. 35). The calyx is there- fore gamosepalous. p,.„, ^,3 Examine next the form of the corolla (Fig. 36). One diirerence between the corolla and those of the previous plants will strike you at once. In the flowers of the latter you will remember that each petal was precisely ^*o- ^'^' like its fellows in size and shape, and we therefore spoke ' f the corolla as rer(idp\ In the Pea, on the other hand. i -^ 0 Fig-. 35. - Flower of Garden Pea. Vig. 36.— Front view c." the same. Fig. 37. — Diadelphoiis stamens of tlie same. ^ Vlp;. 38.— The pistil. Fig. 39.— Tho same cut through lengthwise. 30 ELEMENTS OF STRUCTURAL BOTANT ■\-, I ' In 1 I ., : 11,1 ■ one of the petals is large, broad, and open, whilst two smaller ones, in the front of the flower, are united into a kind of hood. We shall speak of this corolla, then, and all others in which the petals are unlike each other in size or shape, as irTemdar, As the Pea blossom bears some resemblance to a butter- . fly, it is said to be pa2yilionaceous. 40. Remove now the calyx-teeth and the petals, being very careful not to inj ure the stamens and the pistil, en- veloped by those two which form the hood. Count the stamens, and notice their form (Fig. 37). You will find ten, one by itself, and the other nine with the lower halves • of their filaments joined together, or coherent. When stamens occur in this way, in two distinct groups, they iire said to be djgdelphous ; if in three groups, they would be triadelx)hnas ; if in several groups, polyadelphous. In ihe Mallow,~you will remember, they are united into one group, and therefore we described them as monadelphous. You will, perhaps, be a lit|,ic puzzled in trying tc determine to what part of the flower the stamens are attached. If you look closely, however, you will see that the attachment, or insertion, is not quite the same as in the Buttercup and the other flowers examined. In the present instance they are inserted upon the lower part of the calyx, and o they are described as perigynous, a term meaning "^roond thojDistil." 41. But the pistil (Figs. 38, 39) is not attached to the calyx. ' It is free, or supm'ior. If you cut the ovary across, you will observe there is but one cell, and if you examine the stigma, you will find that it shows no sign of division. You may therefore be certain that the pistil H M h a n 'VvvA/tv*^ M GARDEN PEA. 31 You are now prepared to fill up the schedule descrip- tive of this flower. GARDEN PEA. ORGAN. NO. COHESION. ADHESION. REMARKS. Calyx. Sepals. '■ Corolla. Petals. 5 Gamosepalous Inferior. 5 Papilionace- ous. Irregular. Perigynous. The two front petals united. Stamens. Filaments. Anthers. 10 Diadelphous. Perigynous. - Pistil. Carpels. Ovary. 1 Apocarpous. Superior. 42. The beginner will be very likely to think, from its appearance, that the largest of the petals is made up of two coherent ones, but the following considerations show clearly that this is not the case. In the Buttercup, and other flowers in whvih the number of sepals and petals is the same, the petals do not stand before the sepals, but before the spaces between them. In the Pea-blossom this rule holds good if the large petal is considered as one, but not otherwise. Again, the veining of this petal is similar to that of a common leaf, there being a central rib from which the veins spring on each side ; and lastly, there are some flowers of the Pea kind — Cassia, for example — in which this particular petal is of nearly the same size and shape as the other four. 43. The Pea is a type of a highly important group of plants — the Order Leguminosoi. To it belong many plants II II. 32 ELEMENTS OP 8TIIUCTUR.VL BOTANY. liflhriiig very wi(loly in oxtornal ;ii)})()ar!iiicc-— the Locust Tree and the CI'^vit, lor ('Xiuiii-lc — hut exhihitiiij^^ in tlu; structure of thch- ilowcrs so marked a siiiiihuity that their relationshi}) is hcyoiid (juestion. The characters ])y which the Order is distinguished are chietly these : 1. The corolla is more or les-< pajnliouaceoub', and u inserted on the base of the calyx {x'ervjynons). 2. The stamens, almost im:ariald)j tfii in number, are also perifjij nous, and nearly always diadelphous. 3. The pistil is nearly alicays a Icmuif, /hat is to say, it is a single carpel icliich splits into two pieces at maturity, like the pmd oftlie Pea or Bean. 4. The leaves have stipules, and are warly always com- 'fxmnd, that is, of several distinct leajiets. Plants wliich may ho, compared Avith the Pea are Red Clover, White Clover, Sweet Clover, Medick, Locust-Tree, Bean, Yetch, Lupine, Sweet Pea, &c. 44. Great Wiliow-lierb. This plant is extremely common in low grounds and newly-cleared land, and you may easily recognize it by its tall stem and bright purple lijwers. Observe the position of the (lowers. In the three plants iirst examined we found the ilowers at the end of the stem. In the Willow-herl), as in the Mallow, they spring fr^m the sides of the stem, and immediately btdow the point from which each llower Fij,^ lo. springs you will Ihul a small leaf or br.ict (Pig. 40). Flowers Fig. 40.— Flower of Groat Willow-herb. .' . ^ GREAT WILLOW-HERB. 31^ which arise from the axils of hracts are said to be axillaris whilst th(»se wliich are at the ends of stems an; calh^l JeDuinaJ^iUid you may remember that flowers can only be produced in the axils of leaves and at the ends of stems and branches. 45. Coming to the flower itself, direct your attention, first of all, to the position of the ovary. You will find it a))parently under the flower, in the form of a tube tinged with })ur[)le. It is not in reality under the flower, because its purplish covering is the calyx, or, more accurately, the calijx-tuhf'y which adheres to the whole surface of the ovary, and expands above into four long teeth. The ovary, therefore, is inferior^ and the calyx, of course, superior^ in this flower. As the sepals unite below to form the tube the calyx is gamosepalous. The corolla consists of four petals, free from each other, and is consequently polypetalous. It is also regular, the petals being alike in size and V shape. Each petal is narrowed Fig 42^ I I iJ^ " ^^ ^^^^ hviSQ. into what is called the daw of the petal, the broad part, as in the r^rdinary foliage- leaf, being the blade. The stamens are eight in number (octandrous), four short and four long, and are attached to the calyx (porigynous). 40. The pistil has its three Fig. 41. parts — ovary, style,and stigma — verj distinctly marked. The stigma consists of four long lobes, which curl outwards after the flower opens. The Fig. 41. -Uipeiied pistil of Willow-herb. Fij,'. 4-2.— Cross section of the same. / •••> ■'£•:£ i ^ HI. ' 31 . ELEMENTS OP STRUCTURAt noTAN'SV ^ style is long and slender. Tlie examination of the ovary requires mucliL care; yow will get the best idea of its structure by taking one which has just burst open and begun to discharge its seeds (Fig. 41). Tlie outside will then be seen to consist of four pieces (^calves)., whilst the centre is occupied by a slender four-winged column (Fig. 42), in the grooves of which the seeds are compactly arranged. The pistil thus consists of four carpels united together, and is therefore syncarpous. Every seed is furnished with a tuft of silky hairs, which greatly facili- tates its transportation by the wind. 47. The Willow-herb furnishes an excellent example of what is called symmetry. We have seen that the calyx and corolla are each made up of four parts ; the stamens are in two sets of four each ; the stigma is four-lobed, and the ovary has four seed-cells. A flower is symmetrieal when each set of floral leaves contains either the same number of parts or a 'multiple of the same immber. Observe that the leaves of our plant are net-veined. The schedule will be filled up as follows : GRP]AT WILLOW-HERB. 1 OUGAN. NO. com: SIGN. ADHESION. IIEMARKS. Calyx. Sepals. '1 Gamoaepalous Superior. Corolla. Fetals. 4 Polypetalous. Perigynous. Perigynous. Stamens. Filaments. Anthers. 8 Octaudrous. Four short and four long. Pistil. Carpels. Ovary. 4 Syncarpous. Inferior. Seeds provided with tufts of hair. ROSACEOUS PLANTS. 35 Flowers to compare Avith Great Willow-herb are Fuchsia and Evening Primrose. Eitlier of these will serve as the type if Willow-herb cannot be obtained. CHAPTER VI. EXAMINATION OFCdJIMON ROSACEOUS PLANTS — SWEET BRIER STRAWBERRY CHERRY CRAB-APPLE RASPBERRY. 48. Sweet Brier. Fig. 43. As in the flowers examined in the last chapter, the sepals of Sweet Brier are not en- tirely distinct ; their lower halves cohere to form a tube, and the calyx is therefoT-e gamo- sepalous. Tlie corolla con- sists of five sepa- rate petals of the same size and shape, and is there- fore both regular and polypetalous. The stamens are very numerous, and separate from each other. As in the Pea and the Willow-lierb, so in this flower thev will be l:t. Fig. 43.- Flower and leaves of Sweet Brier. I 36 ELEMENTS OF STRUCTURAL BOTANY. found to be uttached to the calyx. They are, therefore^ perigynous. 49. To understand the construction of the pistil, you must make a vertical section through the roundish green mass which you will find on the under side of the flower. You will then lun e presented to you some such appearance as that in Fitr. 44. Tlie green mass, you *Ci* will observe, is hollow. Its outer covering is simply the continua- tion of the calvx-tube. lite lin^ ing of this cahjxAube is the recep- ^'^- *^- tade of the /lower ; to it are at- tached tiie separate carpels which together constitute tlie pistil (Fig. 45), just as the carjjcls of the Buttercup are attached to the raised receptacle of that Hower. We must remind you again that whenever the ovary is enclosed in the calyx-tube, and the calyx appears to spring from the summit of the ovary, the latter is said to l)e inferior^ and the former superior. In the case of Sweet Brier and similar forms, where the pistil is strictly apocarpous, and tin; other parts cohere at their base so as to form a tube enclosing the really free carpels, the pistil may be described as half-inferior, and y\^. 45. the calyx consequently as half-superior. 50. Strawberry. So far as calyx, corolla, and sta- mens are concerned, the flower of Strawberry very nearly rc^sembles that of Sweet Brier. Alternating with the live calyx-lobes, however, will be found five bractlets, Fig. 44. — Vertical section tbrocigh he y'&iW. Fig. 46.— Vertical section tl iiigh r.pt Irulfc of Swee*- Brier. I I'l I \ 4*. ROSACEOUS PLANTS. '67 Fig. 4G. fhich constitute, as in Mallow, an eincahjx. The pistil must be carefully examined. In this case there will h(> found a conical elevation in the centre of the- flower, on the surface of which are inserted many separate carpels, much in the same way as in Buttercup. At maturity this elevated receptacle will have become greatly enlarged and pulpy, with the real fruit, the ripened carpels, dotted over its surface (Fig. 46). 51. Cherry or Plum. Here also the calyx, corolla, and stamens are all adherent, and a hollow cup is formed, in the bottom of which (but entirely free from these parts) the pistil is developed (Fig. 47). It ', consists of a single carpel, ""^ in which there are at first two ovules, though gen- erally but one seed is ripened. The fruit is called a drupe^ the seed being surround(Ml by three distinct layers: (1) a hard shell (the^/^y 54. Raspberry. Calyx, corolla, and stanuuis have the saino arrangement as in StrawbcuTy, and tlic ^jistil is likewi.so a})Ocar}ious, tlie nu)n(!rous carpels coverin^V////^o/^.s'. In tli(j (Mnitro of tlio llovver arc two short styles projecting above the disk, and ;i, vertical section tlirough the ovary (Fig. 53) shows it to 1k^ two-celled, with a .single seed sn^;pended from the top ot eacli coll. V/ATER-PARSNIP. on '.;.■.:•:. NO. COHESION. ADHKr-iio:^ i«:m rwKs. Calyx. Sepals. 5 5 o Gamosepalous Superior. Calyx-tfeth al- most obsolete.! Corolla. Petals. Pol3-sepalous. Epigyuous. Petals in- curved. Stamens. Pentandrous. Epigynous. Pistil. Carpels, j 1 Syiicarpous. Infex'ior. 59. The Water- Parsnip is a type of the large Order Umbel li/ene, whicli is well marked by the following -characters : ^Ov 1. The jioioers are clustered in umbels, and these are \S fieneralltj conqwicnd. ^ r2. - The calyx is perfectly adherent to the ovary, so that almost none of it projects above. 3. The petals and stamens {jive each) are epigyuous. Jf. The ovary is ttvo-celled, and is surmounted by two styles. At maturity the pistil separates into two dry carpels. cL ig ^^^'^N^^^'^-^^zi A COMPOSITE FLOWER. 43 i\ EXAiMIiNATlON OF dOMMOX PLANTS WITH KPIPETALOUS STA MENS — DANDELION — CATNIP. Fig. 54. are all radic:',!. 60. Dandelion. Tlio examination of this flower will be somewhat more difficult tiian that of any we have yet undertaken. Provide yourselves with specimens in flower and in seed. The r(jot of the plant, like that of tho Mallow, is a tap-root. The stem is almost suppressed, and, as in the case of the Hepatica, the leaves They are also net- veined. The flowers are raised on scapes, which are hollow. At first fright the flower appears to have a calyx of many sepals, and a corolla of many petals. Both of these ap- pearances, however, are contrary to facts. Witli a sharp knife cut the flower through the middle fi-om top to bottom (Fig. 54). It will then appear that the flower, or rather fiower-head, is made up of a large number of distinct pieces. With the point of your Jieedle detach one of these pieces. At the lower end of it you have a small body resembling an unripe seed (Fig. 55). It is, in fact, an ovary. Just above this there is a short bit of stalk, sur- mounted by a circle of silky hairs, and above this a yellow tube with one side greatly prolonged. This yellow tube is a corolla, and a close examination of tht; extremity of Fig. .^4.— Vertical section of Dandelion flower. k f ; f Fig. 65— Single floret. Fig. 55. i M ^^'wU nux -- ^ AX^o-jjxU, ^Cv pci n hi i 44 ELEMENTS OF STRUCTURAL BOTANY. its long side will show the existence of five minute points, nv teeth, from which we infer that the tube is made up of five coherent petals. As the corolla is on the ovary, it is said to be Epigumms. Out of the corolla protrudes the long style, divided at its summit into two stigmas. To discern the sVamens will require the greatest nicety of observation. Fig. 5G will help you in your task. The stamens are five in number. They are inserted on the tube of the corolla {epipetalous) and Fig.f>c. tlieir anthers cohere (Fig. 57), and form a ring about the style. When the authers are united in tiiis way, the stamens are said to ])e ^ungenesioufi. 61. It appears, then, tliat the Dandelion, instead uf being a single flower, is in reality a compound of a great many flowers upon a common recej)tacle, and <'<>\\\,tli/'/'.- ' ^"^^^'^^ seemed at first to be a calyx is, in ■ '"" reality, an mvolucrc}^ made up of many Fig.57. bracts. ^^^^s But liave the .single flowers, or jlorets, as they are propeily called, no calyx ? The theory is that they have one, but that it is adherent to the surface of the ovary, and thp.t the tuft of silky ht^irs which we noticed is a prolongation of it. Fig. 68. j^^^^y |_m,,j ^Q y(^^p specimen having the seeds ready to blow away. The seeds are all single ; the little bit of stalk at the top has grown into a long slender thread, and the tuft of hairs has spread out like the rays of an um])rella (Fig. TiS). Ihit thougli the seeds are Fig. 56.— Corolla laid open to show epipetalous stamens. Fig. 67,~Syngenesiou8 anthers of Diindelioi). Fig. 58.— Fruit of Dandelion. A COMPOSITE FLOWER. 45 invariiibly single, it is inferred from the two-lobed stigma that there are two carpeh. The following is the schedule: DANDELION. ORGAN. No. COHKSION'. AmiEsioN. Kemarks. Calyx. Sepals. 5 Gamosepaloiis Superior. The number of He})alH is in- ferred from analog?/ to be five. Corolla. Petals. 6 Gamopetalous Syngenesious. Epigynous. Stamens. 5 Epipctaloiis. Pistil. Carpels. 2 Syncarpoiis. Inferior. Number of carpels infer- red from num- ber of stigmas. G2. Flowers constructed on the plan of the Dandelion are called Cornytdte flowers. The Order (Compositie) comprises an immense number of common plants, in <^ome of which all the corollas in the head are, as in the D.nidelion, of one sort, namely, with one side prolonged into a strap, and hence called strap-shaped or /{y^^/fy/^' — In most cases, however, the ligulate corollas form a circle round the mai'gin of the head only, as in Sunflower, while the central di><]: is tilled up with small regular gamopetalous corollas with a tive-toothed border. Or it may happen, as in Thistle, that all the flowers are regu- lar, ligulate corollas being absent. These, however, are minor points, and, while serving to distinguisli subor- dinate groups, do not interfere with the great and salient characters which mark the Order as a whole. So, also, 1/ ■ ' :! I n 46 ELEMENTS OP STRUCTURAL POTANY. instead of the tuft of silky hairs (technically called the liappus) which surmounts tlie ovary, there may be, as in Sunflower, a, few teeth-like projections, ov scaler, or a mere rim hardly to be distinguished at all. 63. The Order is easily recognized by the following characters : 1. The floioers, or florets^ are in heads on a common re- ceptacle, and siirrou7uled hy an involucre. 2. The stamens are inserted on the corolla, and are united hij their anthers {syrujenesious ). 3. The style is 2-lob('d at the apex. 64. Representatives of this Family are so numerous that it is needless to give a list. Specimens exhibicing all the vaiiations in regard to the corollas, pappus, ^c, should be gathered and notes made of their structure. In Part II. will be found a very full account of all the sp(^cies likely to be met with, and the exercise book has a number of blank schedules specially arranged for Com- posites. 65. Oatnip. Note carefully the appearance of the stem. It is s([uare. The flowers are in axillary clusters. The calyx is a tube (Fig. 59), terminating in live sharp teeth, and you may observe that the tube is a little longer on the upper side (that is, the side tc'imrds the stem) than on the lower. The corolla is somewhat peculiar. It has somewhat the appearance of a wide-open mouth, and is known as a labiate or two-lipped Fig. 59. corolla. The upper lip is erect and notched at the apex. Fig. 59.— Flower of Catnip. A LABIATE FLOWER. 47 The lower lip spreads outward, and consists of a large central lobe and two small lateral ones. Altogether, therefore, there are jive lobes constituting the gamopetal- ous corolla. Pull out the corolla, and with the point of your needle split its tube in front. On laying it open, the stamens will be found to be inserted upon it (epipet- alous). They are four in number, two of them longer thun the other two. Hence they are described as didynamous. The anthers are peculiar in not having their lobes parallel (Fig. 60), these being wide apart at the base, in con- sequence of the expansion of the connedhv^, the Fig. 60. name given to that part of the anther which unites its two lobes or cells. The pistil consists of a two-lolicd stigma, a long stylo, and an ovary v/hich seems at first as if made up of four distinct carpels (Fig. Gl). But the two-lobed stigma will warn you o^gainst this supposition. The ovary really consists of two carpels, each of two deep lobes, and, as the seeds ripen, these Fig. 62. lobes form four little nutlets (Fig. 62), each containing a single seed. 66. The Catnip is a type of the Order Lahiatca (Mint Family), so called because the corollas are usually labiate. It is marked by the following characters : 1. The stem is square, d the leaves are opposite and generallii aromatic. 2. The corolla is itmri' or less labiate. S. The stamens are mostlp didi/namour. «;^/ Fig. 01. Fig. 00.- -Front view of the aaiiio. Fig. 01.— Pistil of Uatiiip. Fig. 62.— Ripo ovary of four separate nutlets. I J I i 48 ELEMENTS OF STRUCTURAL BOTANY. 4 Tke ovary is four-lohed, and at iiiaturifii breaks up into four nutlets. Other types are the various Mints, Sage, Thyme, Summer Savory, Pennyroyal, Bergamot, Sel'"!-heal, Horehound, &c., many o£ which are of very common occurrence. CATNIP. Organ. No. Cohesion. Adiiksion. Ek.makks. Calyx. Sepals. 5 Gamosepalous Inferior. Calyx- tube nerved. ('orolla. Petals. Stamens. Anthers. 5 Grauiopetalous HypogynouB. Two-lipped. Upper lip of two, and lower of threo, lobes. •I 2 Didynamous. EpipetaloUH. Superior. 1 Lobes of an- thers not par- allel. Pi«Ul. Ccrpels. Syiicarpous. The ripe ovary of f our nutlets. CHAPTER TX. EXAMINATION OF PLANTS WFTK MONrECIOUS FLOWERS — CUCUMHl'Ml— OAK. 67. OuCUmber. You can liardly liave failed to notice that only a small proportion of the blossoms on a Cucumber vine produce cucumljers. A great many 'I r-w MONCECIOUS FLOWERS. 19 wither away and are apparently of no use. An atten- tive inspection will show tliat some of the blossoms have oblong fleshy protuber- ances beneath them, whilst (v\ others are destitute of these il attachments. Select a flower '*^ of each kind, and examine first the one with the protuberance (Fig. 63), which latter, from its appearance, you will pro- bably have rightly guessed to be the ovary. The situation of the ovary here, indeed, is the same as in the Willow-herb. The ^i, calyx-tube adheres to its surface, and is prolonged to some little distance above it, expanding finally into five teeth. The corolla is gamopetalous, and is adherent to the calyx. Remove now the calyx and the adherent corolla, and there is left in the centre of the flower a short column, terminating in three stigmas, each two. lobed. Thc7'e are no stamens. 68. IS'ow examine the other blossom (Fig. 64). Calyx and corolla have almost cxactlv the same appearance as bcfo'^Ci. Remove them, and you have left three stamens growing on the calyx-tube, and slightly united by their anthers (syngenesioiis). Fig. 04. Tlwri' ?'.s' )i() fHstil. m fii' Fig'. 03. - ristillntc flower of rncnnihcr. Fijf. 64.— Stamiiiatc flower ol Cuounibor, 50 ELEMKNTS OF STRUCTURAL BOTANYc m You see now why some blossoms produce cucumbers and others do not. Most of tlie blossoms have no pistil, and are termed staminafe or sfenle ficnvers, whilst the others are indillate or fertih'. Flowers in wliich either stamens or pistils are wanting are also called imperfect. When staminate and pistil hite flowers grow on the same plant, as they do in the case of the Cucumber, they are said to be mona'cious. 69. In plants of this kind the pollen of oiie kind of blossom is conveyed to the stigmas of the other kind, chiefly by insects, which visit the flowers indiscrimin- ately in search of honey. The pollen dust clings to their hairy legs and bodies, and is presently rubbed off' upon the stigma of some fertile flower. 70. In order to describe monoecious flowers, our schedule will require a slight modification. As given below, the symbol ^ stands for "staminate flower," and the symbol ^ for "pistillate flower." CUCUMBEE. Organ. No. 5 5 3 Cohesion. Adhesion. Eemakks. Calyx. Sepals. Gamosepalous Superior. Corolla. Petals. Gamopetalous Perigyuoua. ± Stamens. Syugeuesious, Perigyuous. Two anthers are2-celled and one Icelled. ^ Pistil. Carpels. IP Stamens, ? Pistil. Carpels. o — o Syncarpons. Inferioi". t CUPULIFEROUS PLANTS. 51 71. Oak. The Oaks are amon^' oiir fmost and most valuable forest-trees, and while everyone is familiar with Fijf. 67. Fif,'. 6'. the appearance of the acorn, as the fruit of the Oak is Fig. GO.— Twi;; of Wyiito Oak witli sterilu catkiiij. Fig. 67. — Single staniiiiate llo'.vur. Fig. 68.— Fruit and loaf of Oak. (Wood and Steele.) •I . 'iH kn I Ih ;ri 52 ELEMENTS OP STRUCTURAL BOTANY. called, the fiu.'t that the flowers are not to be obtained without etlovt on account of their distance from the ground, as well as the circumstance of their being rather incon- spicuous, nit j lead to their being overlooked unless special attention is directed to them. The White Oak is perhaps the best known species with us. It may be pretty well distinguished from other species by its lea/es, the lobes of which (Fig. 65) are rounded. However', for the purposes of this less.... , any other species may be r.sed, if the White Oak is not at hand. The flowers are monoecious, the sterile ones foruiing long and slender drooping catkins, which are either single or, more generally, several in a cluster, from the same latjeral bud (Fig. GO). Each sterile flower (Fig. G7) consists of a perianth or calyx of a vari- able number of sepals, mostly from four to six, and gen- erally eight stamens. The fertile flowers spring mostly from the axils of tlie leaves of new shoots, and they occur either singly or two or three in a cluster. Each flower consists of a syncarpous pistil of three carpels. The ovary is three-celled, or nearlj' so, and two ovules are formed in each cell. The flower is surrounded at the base by a scaly involucr(3, which, at maturity, has become quite woody, and forms in fact the cu}) in which the acorn rests. If you dissect an acorn you will observe that there is hut one seed in it. Although the ovary contains six ovules at starting, it always happens tli;>t all but one disappear before the fruit is matured. The White Oak ripens its acorns the first year. The Red ( >ak, on the other hand, does not ripen its fruit till the autumn of the second year. 72. It will be a valuable exercise to compare flowers of the iieech with those just described. They will be found OUPULl PEROUS PLANTS. 53 to be moncjccious also ; the sterile ones in snuiU drooping heads, with stamens and sepals variable in nnm])er, and tlie fertile ones from tlio axils of new leaves, usually two togetlier, surrounded by an involucre of many bristle- pointed scales. These develope inlio the familiar bristly iour-valved involucre which encloses the pair of three- cornered nuts at maturity. Each nut is the product of one flower, and contains but one seed, although at first the ovary was (like that of the Oak) three-celled, with two ovules in each cell. These resemblances lead us to the conclusion thr^ the Oak and the Beech are nearly related plants. They belong to the same Order (Giqmliferw)^ as do also the Ironwood, the Chestnut, and the Hazelnut, all of which should be examined and compared, if within reach. 73. The following are the distinguishing characters of the Order : 1, The foivers are moncecious, the sterile ones heing in cat Jans (or, i7i Beech, in close heads), the fertile single or in small clusters, with an involucre form- ing at rtiatiirity a cup or covering for the l-seeded nut 2. The ovary is at first several-celled, hut at maturity is 1-celled and l-seeded. 4' The pupil will write out descriptions of one or more --rr-,^ representatives of the Order, taking the description of ro^ Cucumber for his model. i ) I'f ,"*■*■»* ^^wylPflt^tt^^ff"** * ■ Fig. 08. 54 ELEMENTS OF STRUCTURAL fiOTANY. CHAPTER X. EXAMINATION OF Pr.ANTS WITH DICEnOUS FLOWERS WILLOW — MAPLE. Tlie Howlers of most kinds of Willow appear in spring or early summer l)ofore the leaves. They grow from the axils in long, close clusters called eafJmis or ammts. Collect a few of these from the name tree or si) rub. You will find them to be exactly alike. If tlie first one you examine is covered with yellow stamens (Fig. Q>^), all the rest will likewise consist of stamens, and you will search in vain for any appearance of a pistil. If, on the other hand, one of your catkins is evidently destitute of sta- mens, and consists of oblong pistils (Fig. (39), then all the others will in like manner be found to be without stamens. plant, the staminate and pistillate flowers of the Willow are borne on different plants. These flow(iis are therefore said to be dioecious. As a general thing, staminate and pistillate catkins will be found upon trees not far apart. Procure one of each kind, and examine first the stami- nate one. You will probably find the stamens Fig. 70. in pairs. Pohow any pair of filaments down to Fis,^ 68.— SUmiiiate co.tkin o* "^•^'-- Fig. 69.— Fertile catlun. Fig. 70.— Single staminate flower. Fig. 69. Unlike our Cucumber '%^ Fi- 5 DiUiL'IOUS FLOWERS. 65 tlieir insertion, and observe that thoy spring from tlio axil of a minute bract (Fig. 70). Tliese bracts are the i^rah's of the catkin. Therg, is no appearance of eitlier calyx or corolla, and the flowers are therefore said to be achl(i)nj/a^c8, that is, without a covering. Now look at the fertile catkin. Each pistil will, like I/' the stamens, be found to spring from the axil of y// a scale (Fig. 71). The stigma is two-lobed, and, on carefully opening the ovary, you observe that though there is but one cell yet there are two roios of seeds. We tlierefore infer that the pistil Fi{f. 71. consists of two carpels. TIio pistillate flowers, like the staminate, are achlamydeous. In dioecious plants HRAET-LEAVED WILLOW. OKC.VN. No. 1 COIiKSlON. ADHESION. lli.MAllKS. Calyx. 0 • t Corolla. 0 '^ Stamens. 2 Diandrous. 0 ^ Pistil. 0 Q Stamens. 0 , Pistil. Syncarpous. 0 Carpels. 0 the process of fertilization is assisted by insects, especially when the flowers are showy or odoriferous and nectar- Fig. 71.— Single pistiHate flower of Willow. I ' t 1 ) V:. ^ i: .1 1 n ^ J i I I 'a '■'•^-r*«*A*s 56 ELEMENTS OP STRUCTURAL BOTANY. boarin<4 ; otlierwiso the wind is tlio principal agent. Flowers which depend on insects to effect the tmnsfer of pollen from tlie anther to tke stigma are said to bo ento-^ mophilons. Those which depend upon tlio wind are anemopliilous. The AVillow belongs to the former class. 7.5. Maple. In early S[)ring, while the branches are as yet Ijare of leaves, our Red Maples are covered witli a profusion of scarlet and yellow blossoms, and the air about them is alive with busy insects gathering honey for themselves, and performing at the same time an impor- tant service for the trees in return ; for it will be found on examining a few of the trees that, like the Willow, they do not all bear the same kind of flowers. In some, the ends of the reddish twigs will present the appear- ance shown in Fig. 72,witlinumcrous stamens protruding from the scaly lateral buds. On looking into one of these buds it will be found that there are several floAvers on short pedicels, each like that shown in Fig. 73, except that the number of stamens will probably be found to bo somewhat variable. Observe the fleshy disk in the bottom of the calyx, upon which the stamens are inserted. These flowers with the projecting stamens are without pistils. Tlnty produce nothing but which Fio-. 73. pollen, and th no other kind. upon y pr( 74. ers ar'- Fifij. 7-. — Twig- of Red Maple beariii Peri V S ■^ 1 c Star Pist », Ci ^' 87. ^^ natur are a , i 1. ' % ^ ir 1 1^ LILIACEOUS PLANTS. 65 ^.1 86. Comparing this flower with that of Dog's-tooth Violet, we find the two to exhibit a striking resemb- lance in structure. But in one respect the plants are strikingly unlike : the leaves of the Trillium are net- veined (Fig. 87), as in the Exogens. From this circum- stance we learn that we cannot altogether rely on the veining of the leaves as a constant characteristic of plants whose parts are not in fives. TRILLIUM. K^ ^■x. Oegan. No. Cohesion, Adhesion. Remarks. Perianth. Sepals. Petals. 3 3 Polyphyllous. Inferior. Sepals persist- ent. Stamens. 6 Hexandrous. Hypogynous. Pistil. Carpels. 3 Syncarpous. Superior. The inner face of eaoh style stigmatic. Leaves net- veined. ,J' 87. The two plants just examined are types of the natural Order Liliaceoi. The distinguishing characters are as follows : 1. The parts of the flower arc almost invariably in sets of three, the perianth heincf of two such sets, and also the stamens. The flowers are therefore sym- metrical ; thry are also regular. ^ 2. Tlie stamens are opposite the divisions of the perianth . 3. The ovary in nearly always 3-celled, and is superior. 6 I iirfii m jlif ()(j ELKMKNTG OF ^iTIiU(JTURAL BOTANY. The representatives of this large Order are very iiu- inerons. Eroin tlie gardens may be had lilies of various sorts, Asparagus, Star-of-Bethleheni, Tulip, Oni()n, Hya- cinth, &c., whilst the fields and woods supply the ijell- wort, Clintonia, Solomon's Seal, Sbii- lacina, and others. As a rule the plants liov er J cpring and early summer. 8b. J r.i For this lesson any variety of the oomm . 'garden Flag will answer very well. In our marshes in early summer abundant specimens of a wild species may oe obtained without much trouble, but the cultivated plants will probably be more accessible. Note first the fleshy underground stem or root- stock, with the fibrous roots below (Fig. 88). If you have a sufficient Fifjf. 89. length of this root- stock you v/ill notice the scars upon the' older portions, show- ing where the leaves of former seasons have been sent up. The new buds ex- pand into a crowded Fifj. 88. cluster of leaves, the shape and arrangement of v/hich should bo carefully observed.' Cut the whole cluster across near the base, and the section will be as repre- sented in Fig. 89, the section of each leaf being V-shapcd, Fig. 88.— Eoot-stock and loaves of Ti-is. (Gray.) Fig. 89.— Cross section of cluster of equitant leaves. (Gray.) IRIS. 67 and astride the next one within. Loaves disposed in this manner are consequently said to i)e e< in if ant [eqiies, a horseman). As the leaf rises upward it alters in sha"^'^, becoming fiat and sword-like. Besides being equitpn:, these leaves, on account of their direction, are described as vertical. You will observe, also, that they are straight- veined. From the centre of the cluster of leaves rises the scape which bears the flower. If your specimen has a flower- bud upon it, as is most likely, you will notice the way i:.. which its leaves are folded. Th<. w le of folding here cxln])it; 1 is connnon to a j^reat \|v. \\v\ ^-—/^ many flowers, and is described as (•(mvoLde. In the full-blown flowe bhe perianth will be found to consist of six pieces, in two distinct sets of three each ; the ' outer three are considerably larger than the others, and are bent backwards or reflexed; the Fig- 90. inner ones are erect. There are three stamens, each of them beneath and close against an over-arching l>ody, the nature of which is not at first quite manifest. Cut away the perianth and the stamens, and you will then have left the three radiating coloured arches (Fig. 90), which will be seen to unite below into a slender column. You have also left what is apparently the swollen top of the scape. This, when cut across, is found to be a three-celled ovary, which is thus, of course, inferior. The slender column above is the style, and the m Fig. 90— Pistil of Iris. (Wood and Steele.) 68 ELEMENTS OP STRUCTURAL BOTANY. A rvi" |j;U'* si.. three petal-like arches are its branches. Immediately beneath the tip of each arch will be found a thin Jip or plate, which is the stigma. ' The anthers open ouf'wards to discharge the pollen, and this fact, in addition to the peculiar situation of the anther as regards the stigma, makes it almost impossible that self-fertilization should take place in chis flower. As was the case with other flowers already examined, the Iris is honey-bearing, and, besides, exceedingly showy. The nectar is situated in a cavity at the bottom of the flower, and cross-fertilization is accomplished by the aid of insects. It will be remembered that flowers thus fertilized are said to be entomophilous. t \ \ V 89. The Crocus and Gladiolus of the gardens and the Blue-eyed Grass of our low meadows may be examined and compared with the Iris. They are all types of the natural Order JreVteer??, which you will observe differs from Liliaccm chiefly in having flowers with only three stamens and an inferior ovary. IRIS. Organ. Perianth. Leaves. No. 6 Cohesion. Adhesion. Remarks. Gamophyllous Superior. 2 sets. Outer, large and re- flexed ; inner, erect. Stamens. 3 Triandrotis. Perigynous. Inferior, Opposite the stigmas. Stigma : pet- al-like,arching over the ex- trorse anthers. Pistil. Carpels. 3 Syncarpous. 9 a !oi Tl ORCHIS. 69 90. Showy Orchis. The flower of this plant (Figs. 91, 92) is provided with floral envelopes, all coloured like a corolla. As in Dog's-tooth Violet, we shall call thcni collectively the perianth, although they are not all alike. One ox them projects forward in front of the flower, I : yig. 91. terming the Up, and bears underneath it a long, hollow sjmr which, like the spurs of Columbine, jiS honey -bearing. The remaining five converge together, forming a kind of Fifif. 91.--ohowy Orchis. 70 ELEMENTS OF STRUCTURAL IJOTANY. ;;■■!, 4 • ; arch over the centre of the flower. Each flower springs from the axil of a leaf-like bract, and is apparently raised on a pedicel. What seems to be a pedicel, how- ever, will, if cut across, prove to be the ovary, which in this case is inferior. Its situation is similar to the situation of the ovary in Willov/- herb, and, as in that flower, so in this the calyx-tube adheres to the whole surface of the ovary, and the three outer divisions of the perianth are simply upward extensions of this tube. Notice the peculiar ttrht in the ovary. \ The elToct of this t'.vist is to turn the lip away Fig. 92. from the scaj^e, and so give it the appearance of being the lower petal instead of the up2^ei' one, as it really is. 91. The structure of the stamens and pistil remains to be examined, and a glance at the flower shows you that we have here something totally different from the common arrangement ot these organs. In the axis of the flower, immediately behind the opening into the spur, there is an upward projection known as the column. The face of this column is the stigma ; on each side of the stigma, and adhering to it, is an anther-cell. These cells, though separated by the column, constitute but a single stamen. The stamen, then, in this case is united with the pistil, Fig. 93. a condition which is described as rpjnandrous. 92. If yon have a flower in which the anther-cells are bursting open, you will see that the pollen does not issue from them in its usual dust-like form, but if you use the Fig. 92. — Single flower of Orchis. Fig. 93.— Pollen-mass of Orchis, greatly enlarged. ORCHIS. 71 point of your needle careful!}' yon may remove tht. con- tents of each cell in a mass. These poll(ni-masaes are of the form shown in Fig. 93. The <:jrains are kept together by a fine tissue or web, and the slender stalk, upon which, each pollon-mass is raised, is attached by its lower end to a sticky disk on the front of the stigma just above the mouth of the spur. Insects, in their etlbrts to reach the honey, bring their lieads in contact with these disks, and, when they tly away, carry the pollen-masses with them and deposit them on the stigma of the next flower visited. In fact, it is diflicult to see how, without the aid of insects, flowers of this sort could be fertilized at all. SHOWY ORCHIS. OlUlAN. No. Cohesion. Adhesion. Hemaiiks. Perianth. Leaves. G 1 Gamophyllous Saperior. Stamens. Monandroiis. Gyuaudrous. Pollen-grains collected in masses. Pistil. Carpels. 3 Syncarpcus. Inferior. Ovary twisted. 93. ;Showy Orchis is a representative of the vast Order Orchidacece, the members of which are chiefly tropical. Some of our handsomest Canadiai. wild flow- ers, however, belong to it, such as the Lady's Slipper, the Rattlesnake Plantain, the beautiful littlr Calypso, and the Habenarias. Most of our orchids wiL jo found ii low and wet situations, and they flower rather early "51 '<^l ill 72 ELEMENTS OF STUUCTIJRAL BOTANY. in the year. The most remarkable characteristics of the Order arc the gynaiirlrous arrangement of the stamen or stamens, and the coliosion of the pollen-grains, though this latter peculiarity is exhibited also by other groups — notably, tlio Tvlilk weeds. fro th( 9G. Sfat ■X ■ CHAPTER XIII. EXAMINATION OP SPADICEOUS PLANTS — INDIAN TURNIP — CALLA. 94. Indian Turnip. This plant may be easily met with in our woods in aarly summer. If you are not familiar with its appearance, the annexed cut (Fig. 94) will help you to recognize it. Procure several speci- mens : these will probably at first seem to you to be alike in every respect, but out of a number some are pretty sure to differ from the rest. Notice the bull) from which the stem springs. It diflers from that of the Dog's-tooth Violet, and Lilies generally, in having a much larger solid part. It is called a conn. Between the pair of leaves you ol)servc a curious striped sheath, having an arching, hood-like top, and enclosing an up- right stalk, the top of which almost touches the hood (Fig. 95). Can this be a flower? It is certainly the only thing about the plant which at all resembles a flower, and yet how dilt'erent it is from any we have hitherto examined ! Carefully cut away the sheaths that and spec of ti groc INDIAN TURNIP. 73 from all your spocimens. ^lost, and perlr^ps all, ot' th(3iii will then present an appearanc(3 like that in Pii,^ 96. If none of them be like Fii^. 07 it wTi! he well to gather a few more plants. We shall suppose, however, Fij,'. 94. that you have been fortunate in obtaining both kinds, and will proceed with our examination. Take first a specimen corresponding with Fig. 9G. Ai'ound the biise of the colunni aie compactly arranged many spherical green bodies, eaeh tipped with a little point. Separate *' 1 I ■i Fig'. 94.— ItiJian Turnip. 74 KLKMENTS OF STRUCTURAL BOTANY, one of these from the rest and cut it across. It will be found to contain several ovules, and is, in fact, an ovary, the point at the top being a stigma. In the autumn a great cliange will have taken place in the appearance of plants. ■^^^ lilco the one we are now examining. The arched hood will have dis- appeared, as also the long naked top of the •.olumn, whilst the part below, upon which we are now en- gaged, will have vastly increased in size, and become a compact ball of red berries. Tliere can be no doubt, then, that we have here a structure anal- ogous to that found in the Cucumber and the fertile, or pistillate, flowers !)eing clustered together separate- ly. But in the Cucumber all the flowers were ol>served to be furnished with calyx and corolla, and in the Willow catkins, though floral envelopes were absent, each pair of stamens and each pistil was sub- tended by a bract. In the present plant there are no floral envelopes, nor does each pistil arise from a separate bract. 95. But, you will now ask, what is this sheathing Iiood which we find wrapped about our column of pistils? Fi;;. OS.-Spathe of Indian Turnip. Fijj. 06.— Fertile spadix of tlic siiniu. Fig. t>7.— Sterile spadix. Fi; the Willow, Fi „. 90. Fig-. 97. |lii INDIAN TURNIP. 7r> Iff Therft is no doubt that we must look upon it as a hract^ because from its base tlie flower-cluster springs. So that, whilst the flowers of Indian Turnip are, like those of Willow, imperfect and dia^cious, the clusters difler in having but a sinccle bract instead of a bract under each (lower. 96. We must now examine one of the other specimens ; and we shall have no ditiicultyin determining the nature of the bodies which, in this case, cover the base of the column. They are evidently stamens, and your magni- fying-glass will show you that they consist mostly of an- thers, the filaments being extremely short, and that some of the anthers are two-celled and some four-celled, all discharging their pollen through little holes at the top of the cells. INDIAN TURNIP. Organ, No. Cohesion. Adhesion. ^ Stamens. 1 Mouandrous. 0 g Fistil. Carpels. 1 A])ocarpouH. 0 Flowers crowded on a spadix, and aurroiiuded by a apatho. Leaves net- veined. 97. TIio column upon which, in plants like Indian Turnip, tl ; (lowers are crowded, is known as a .ymdix, and the surrounding bract as a s/xit/ie. You will observe that the leiues of this plant are 7iet- veined, as we found them in the Trillium. 1. ■..vj, ^. 7f^ ELEMENTS OF STRUCTURAL BOTi^N\. 98. Marsh Calla. Tliis plant must be looked for in low, marshy grounds, wliere it will l)e found in flower generally in the month of June. With the knowledge which you have of the structure of Indian Turnip, you ] 3 i ng. 99. will hardly doubt that the Calla is closely related to it. You will easily recognize the spadix and the spathe (Fig. 98), though in the present instance the spadix bears Howers to tlR' top, and the spathe is open instead of enclosing the column. Observe, however, that the veining of the leaf ( t'ig. 1)9) is ditferent, that of Calla being straight, lilvc the Dog's-Tooth Violet. There is also a difVerence in the flowers. Those of Indian Turnip were fou'.id to be diiecious, but the spadix, in the present Fig. 98.— Spadix ntid «!patho of Marsh Calla. Fig. 09.- iicaf of the sime. 4 'V n ^-^m^: % -V v^ v:,.' ^> V V) ) ? MARSH UALLA. 71 case, bear3 both stamens and pistils, and most of ti'j lower llowers, if not all, arc pf-rt'er^ : ^^^\ w[ soiiietimes the upper ones consist of . •- M'f/L 4/1^ mens only. Fig. 100 shows one of tiio perfect iiowers nnich enlarged. The sta- mens, it w411 be observed, have tv/o-celled anthers, opening lengthwise. MAESH CALLA. Organ. No. Cohesion. Adhesion'. Perianth. Wanting, llexandrous. Stamens. 1 Hypogyuoi.s. Pistil. Carpels. Apocarpous. Superior. 99. These two plants, Indian Turnip and Mr • ){ Cai^a, are representatives of the Order Araceoj, The (.'Iiaractfips which distinguish it are very well displayed in tiie t'vo types we have selected for examiii ition. The gi.:at feature is the aggregation of the fluwers on a spadix. (Jrenei.illy, though not invariably, a spaihe is also present. An)<)ng wild plants the Skunk Cab])nf;e and Sweet Flag (the latter without a spaihe) are common Araceous types, wl;ile the familiar green-house and ^v•indow plant, known as the Calla-Lily,will serve very well for examination in winter. It may bo added that the plants of this Order have a very acrid juice. Fig. 10O.--Perfect tlowcr of Cttlla. 'II' m ■X ) '8 ELEMENTS OP STRUCTURAL BOTANY. CHAPTER XIV. li m?. p -'B i 'l' .''' 11 '( 11 i J 1 i' 11 EXAMINATION OF GLUMACEOUS PLANTS — TIMOTHY AND OTHER GRASSES. 100. Timothy. The top of a stalk of this well- known grass is cylindrical in shape, and upon examina- tion vvill be found to consist of a vast number of similar pieces compactly arranged on very short pedicels about the stalk as an axis. Carefully separate one of these pieces from the rest, and if the gi/ass has not yet come into ilower the piece will present the appearance shown in Fig. 101. In this Fig. the three points in the middle are the pro- trudinjj: ends of stamens. The pieco which you have separated is, in fact, a flower enclosed in a pair of bracts, and all the other pieces which go to make up the top are flowers also, and, except perhaps a few at the very sum- mit of the spike, precisely similar to this one in their structure. ijy. 101. J'i-. V^-2. 101. Fig. 102 is designed to lielp you in dissecting a ilower v- i.ich has attained a greater degree of development than thr- o o shown in Fig. 101. Here tlie two bracts which enclose the iiower have been drawn asunder. To these bracts tlio name qIiuikj^ is applied. They are present in all plants of the Crass Family, and are often Fi;^. 101.— Closed flowtr of Timothy. E>:pandetl dower of the same. Fi{,'. lOil GRASSES. 79 found enclosing several flowers instead of one as in Timothy. Inside the glumes will he . • da second pair of minute chafF-like hracts, which are known lis j^ctU'ts or XJOles. These enclose the flower proper. 102. The stamens are tlirce. in nuinher, wi^'h the anthers fixed by the middle to the long slumler filament. The anthers are therefore vprsaiile. The styles are two iri number, hearing long, feathery stigmas. The ovary contains a single ovule, and when ri[)e forms a seed-like graiu^ technically known as a ea7'i/02ms. TIMOTHY. Okgan. No. 2 CoflKSIuN. 1 Adhksion. Glnmes. Pcilets. 2 Stameus. 3 Triaiidrous. llypogynous. Pistil. Carpels. 1 Apocarpous. Superior. 103. It will be observed that the stalk of Timothy ia hollow except at certain swolh-n knot-liite joints. This peculiar stem of the Grasses is called a culm. Occasionally, howtn'er, it is not hollow. The leaves are Inn^^ and narrow and straight-veined, and each of them at its base surrounds the culm with a split sheath. Observe also that at the 'I ao ELEMENTS OP STRUCTURAL HOTANY. n .1 junction of tho blade and tlio slieatli there is a thin appendage which is called a Uf/ule. 104. In many grass-flowers, besides the parts described a])ov(; there will bo found one or two minute scales below the; pistil. These are known as lodumles, and are analogous to the j)erianth in ordinary flowers. They are, on ac- count of their minuteness, very liable to be overlooked in a superticial examination. 105. The immense Order Gramincco (Grass Family) includes all our valuable grains, and is, on the whole, the most important and useful of all the Orders. Its representatives are to be found in every part of the world, and they vary in size from the stunted growths of the polar regions to the tree-like Bamboo of tiie tropics. Wheat, Indian Corn, Barley, Oats, Kye, Sugar-cane, Kice, are all Grasses, as well as the plants which nuike the verdure of our meadows and pastures. The flowers of all are very similar, but the Oi'der is sub-divided on the basis of -4?' Fijr. 104. Fig. 103. Fig. 103.— Paniclo of Red-top. Fig. 104.— SiuKle tlower. (Gray.) c.vV35^iiv»; ;?:'/'^ GRASSES. 81 modifications which will bo best understood by studying a few examples, 106. Procure specimens of the common Ked-top, and lirst compare the general aspect of the fiower-chister (Fig. 103) with that of Timothy. Instead of a dense spike we have here a loose, open intlor- '^^ J^ •^4^ ^^^^^ <^scence ; it is technically known as a "^^ f^— A panirle. You will see th.vt it is an irregular branched raceme. As in Timothy, cai'h iiair of glumei encloses Fig. 106. hut one flower (Fig. 104), and we must observe tliat the term spnceht^ so far as Grasses arc; concerned, is applied to the pair of glumes and whateA^er is contained in them, whether one flower, or many, as is often the case. In Red-top and Timothy, the spikclets are l-floii-ered. Ob- serve the Yvxy thin texture of the ^jalets, and also that one of them (the lower, i.e., tlie one farthest from the stalk) is nearly twice as large as the other, and is marked with three nerves. Fig. 105 Fig. 105. — Common Meadow-Gras-i. Fig. 10(3.— Spikelet onlai'u-cd, showing the glumes at the base. Fig. 107. — Single flower of same. S2 liLKMKNT.S OF STIIUCTUUAL BOTANY. f ii I ( ^. l-i 107. Next let us inspect a specimen of the Common jMeacJow-Crass. The inflorescence of this very common grass (Fig. 105) is a greenish panicle. The spikelets (Fig. lOG) contain from three to five flowers, and are laterally compressed. The (jinnies are the lowest pair of scales, and they are generally shorter th;in the flowers within them. Obsei've the delicate whitish margin of the lower palet of each flower (Fig. 107), and the thin texture of tlie upper one. Count also, if you can, the live nerves on the lower palet, and obsei've the two teeth at the apex of the upper one. In this Grass the principal thing to notice is that there are se/'eraljfowors withm each i> air of glumes. 108. A common pest in wheat-fields is the Crass known as Chess. It is comparatively easy of examination on account of the si/e of the spikelets (Fig. 108) and flow- ers. The spikelets form a spreading panicle, eachof them being on a long, slender, nod- ding pedicel, and containing from eight to ten flow^ers. Of the two glumes at the base of each spikel :t one is consider- ably larger than the oth(U'. The outer or lower palet of each 'lower is tipped with a bristle or awn (Fig. 109), while the upper palet at length becomes attached to the groom of the oblong grain. Observe that the glumes are not awned. 109. The Coucli Grass is another very common weed in cultivated grounds. In this Grass the spikelets are Fig. 108. Fij;. 109. Fig. 108.— Spikelet of Chess. Fij?. 109.— Single flower. (Gray.) GRASSES. 83 Of so of ddcr- so.HJvio on opposite sides of the zigzag peduncle, so that tlie wliole forms a spike. Each spikelet is four- to eight- flowered, and thei-e is but one at each joint of the peduncle, the sidp. of tlie spikelet heing against the stalk. The glumes are nearly equal in size, and tlio lower palet of each flower closely resembles the glum(!S, but is sharp- pointed or awned. The grass spreads rapidly by running root-stocks, and is troublesome to eradicate. 110. Old-Witch Grass is to be found everywhere in sandy soil and in cultivated grounds. The leaves are very hairy, and the panicle very large, compound, and loose, the pedicels being extremely slender. Of the two glumes one is much larger than the other. Unless you are careful you will regard the spikelets as 1 -flowered ; observe, however, that in addition to the one manifestly perfect flower there is an extra ]palet heloto. This palet (which is very niuchlike the larger glume)is a rudimentary or abortive second flower, s\d the spikelet may be :lescribed as H -flowered. 111. Barnyard Grass is a stout, coarse plant, common in manured soil. It is from one to four feet in lieiglit, and branches from the base. The spikelets form dense spikes, and these are crowded in a dense panicle which is rough with stiff hairs. The structure of the spikelets is much the same as in Old-Witch Grass, but the p.ilot of the neutral flower is pointed with a roug]> awn or bristle 112. In the common Foxtail the inflorescence is apparently a dense, bristly, cylindrical spike. In reality, however, it is a spiked p.anicle, the spikelets being much the same as in Barnyard Grass, but their pedicfils are prolonged beyond them into awn-like bristles. In this M IMAGE EVALUATION TEST TARGET (MT-3) 1.0 I.I li^lM |2.5 us u IL25 i U 2.0 ilM 11.6 •71 /) -^ ^;. 7 -(^ Hiotographic Sciences Corporation 23 WEST MAIN STREET WEBSTER, NY. 14580 (716) •72-4S03 # i iV ^N^ [Vs -^\\ >}??* o^ o z 84 KLEMENTS OP STRUCTURAL BOTANY. plant the bristles are in clusters andiire barbed upwards. The i^pihra are taiony-f/fllow in colour. 113. Those examples, if conscientiously studied with the aid of the plants themselves, will give you a good general idea of the kinds of variation which may be looked for in the Grasses. They may be said, roughly, to consist in the presence or absence of glumes, of awns, and of the upper palet ; in the general aspect of the whole flower- cluster ; in the number of flowers in the spikelets ; and in the varying relative size of the glumes and of the palets. >j 114. The Order as a whole is distinguished by the ^' following characters : 1. The i^h^'af/is of the leaves are split on the side of the culvi opposite the blade. 2. The separate flowers are enclosed in glumaceous bracts \S called palets S. The perianth in represented by the lodicules. Jf, The stamens are three in number^ and the pistil is stjiicarpoiis (two car2)elsj, icltli a one-celled ovary jrroduciny a single seedj which is always albuminous with the embryo on one side. ^":3s I f n| hi CHAPTER XV COMMON CHARACTERISTICS OP THE PLANTS JUST EXAMINED STRUCTURE OF I'HK SEED IN MONOCOTYLEDONS. ^15. It is now to be pointed out that the plants examined in the last three chapters, though dilFering in various particulars, yet have some characters connnon to all of them, just as the group ending with Maple was CHARACTERS COMMON TO MONOCOTYLEDONS. 85 Fig. no. lie 111. found to be marked by characters possessed by all its members. The flowors of DicotyledoMs were found to have their parts, as a rule, in fours or fivers ; those of our second group have them in threes or sixes, never in fives. 116. Again, the leaves of these plants are straight- veined, except in Trillium and Indian Turnip, which must be regarded as exceptional, and they do not as a rule Bxhibit the division into petiole and blade which was found to characterize the Exogens. 117. We shall now compare the structure of a grain of Indian Corn with that of the Cucumber or rumpkin seed whicli we have already examined (page 59). It will facilitate our task if we select a grain from an ear which has been boiled. And, first of all, let us observe that the grain consists of something more than the seed. The grain is very much like the achene of the Buttercup, but differs in this respect, that the outer covering of the former is completely united with the seed-coat underneatli it, whilst in the latter the true seed easily separates from its covering. Remove the coats of the grain, and what is left is a whitish, starchy-looking substance, having a yellowish body inserted in a hollow (Fig. 110) in the middle of one side. This latter body is the einhryo, and may be easily removed. All the rest is alhumen. Fig. Ill is a front view of the embryo, and Fig. 112 shows a vertical section of the same. The greater part of the Fif<. 112. fi t*' if I!' i !. I Figs. 110, 111, 112.— iJections of a grain of Indian Corn. (Gray.) 86 ELEMENTS OP STRUCTURAL BOTANY. embryo consists of a single cotyledon. The radicle ?s seen near the base, and the plinuulo above. Compare an Uat (Fi<,f. 11.3) with the grain of Corn and make out the corre- sponding parts. In all essential particulars they are alike. 118. Comparing the result of our observations with what we have already learned about the Cucumber seed, we find that whilst in the latter there are two cotvledons, in the present case there is but owe, and this peculiarity is common to all the plants just examined, and to a vast number of others besides, which are consequently designated MonoCOtyledon- OUS plants, or shortly MonOCOtyledonS. The seeds of this great group may differ ns to ^ the presence or absence of albumen, just as the seeds of Dicotyledons do, but in the nam- her of their cotyledons they are all alike. The Orchids, however, are very peculiar from having no cotyledons at all. 119. In addition to the points just mentioned, viz : the number of floral leaves, the veining of the foliage leaves,the usual absence of distinct petioles, and the single cotyledon, which characterize our second great group, there is still another, as constant as any of these, and that is, the mode of growth of the stem, which is quite at variance with that exliibited in Dicotyledonous plants. In the present group the increase in the thickness of the stem is accomplished not by the deposition of circle after circle of new wood outside tlie old, but by the pro- duction of new wood-fibres through the interior of the stem generally. Inese stems are therefore said to be Fiy. 113. — Vertical section of Oat grain ; R, radicle ; G, plumule ; C, cotyledon ; A, albumen (or endosperm) ; O, hairs ; T, testa. (Thomd.) ■tsf- CHARACTERS OF MONOCOTYLEDONS. 87 e7idogenonH, and the plants composing the group are culled Endogens, as well as Monocotyledons. The term Endogen, however, is used in quite a different sense hy som\3 recent botanists, and is discarded hy them as a synonym for monocotyledon, as having been given originally under a misconception as to the true mode of growth of the wood in stems of this kind. We shall explain more fully the structure of exogenous and endogenous stems when we come to speak of the minute structure of plants in a subsequent chapter. 120. The typical flower of the Monocotyledons is that of the Lily ; it consists of live whorls, two belonging to the perianth, two to the anthers, and one to the pistil. Other flowers of the group, as we have ^een, exhibit departures from the type, chiefly in the suppression of whorls or parts of whorls. Thus in the Iris one whorl of stamens is suppressed. In this plant, also, the ovary is inferior. In the spadiceous plants the perianth is suppressed, and ID the Grasses there may be suppression in all the whorls. ti--i J. 111. t CHAPTER XVI. EXAMINATION OF CONIFEROUS PLANTS- GROUND-HEMLOCK. -WHITE PINE — 121. The cone-bearing trees are so striking and importam .: feature in Canadian vegetation that even an elementary v;ork liko the present would be incomph'to without a uotico of them. They form, besides, a very distinct group 88 ELEMENTS OF STRUCTURAL BOTANY. of plants, intermediate in structure, as we sliall see, betw ^en the groups upon which we have so far been Fig. 114. enga.<,'etl and others to which wo shall presently direct attention. 122. As perhaps the commonest Canadian type of the Coniferous Group, the White Pine first demands our attention. This noble tree, in its general aspect, is familiar to every one. It produces a straiglit trunk, wliich is continued upward year after year by the develop- ment of a strong terminal bud, the new branches of each year being developed from a circle of lateral buds formed behind the apex of the stem or old branch. The general aspect of the tree, therefore, unless it is a very old one, is that of a broad-based cone or spire. The leaves are straight BMg. 114. — Lcavea and cluster of staminato catkins of White Pine. (Wood and Steele.) Fi-j;. 115.— Pollen-grain of Pine. (Wood and Steele.) n i; all see, xr been -/" ■ direct of the Is our )ect, is trunk, evelop- )f each formed general one, IS traight . (Wood WHITE PINE. 89 needles, and are produced in clusters of five each. In the Ked Pine, on the other hand, tliere are but two leaves in the cluster. Other s[)ec'ies liave buudk'S of tliree each. These leaves, as is well known, are evcrgrcp.n^ that is to s.jy, they do not perisli in the first autumn, but persist througli tlio winter and untd the new leaves of the following season are fully developed. 123. The flowers of the Pine must be looked for in spring just before the new leaves are put forth. They are moncccious or dioecious. TliO staminate flowers, consisting of a single stamen each, are produced around the bases of the new shoots, where they form dense clusters of small catkins (Fig. 111:). Each anther is two-celled, and the pollen-grains (Fig. 115) are rather peculiar in shape, having, in fact, the appearance of three grains cohering together. The two outer portions, however, are only bladder-like developments of the outer coat (extine) of the real grain, which occupies the Fig. 116. centre. 124. The pistillate or fertile flowers are aggregated together upon an elongated axis, forming in fact the well- known cone of the Pine (Fig. IIG). The young concrs will be found to occupy lateral positions on the branches ; each of them is made up of many spirally arranged scales^ each scale being in the axil of a bract (Fig. 117). At the base of each scale, on the inside, will be found two ovules turned downwards (Fig. 118). Oljservo that these ovules are not enclosed in an ovarij. Pecause of this fact the group of plants of which the Pine is a type is said to be Fig. 116.— Cone of Pine. (Wood and Steele.) 90 ELEMENTS OF STRUCTURAL BOTANY. Fig. 117. f/l/mnospermous, that is, naked-seeded. All the plants previously examined, on the other hand, have their seeds enclosed in ovaries; hence they are all amjin^pcrinoiis. The scales of the cone are to be regarded as open carpellary leaves, and each of them, with its pair of GV'des, constitutes a fertile flower. The pollen is carried by the wind directly to the micropyle of the ovule, there being no intervening stigma; but, as the quantity of pollen produced is immense, the chances of failure to reach the ovules are very slight. At the time of pollination, tlie air in a pine forest is full of pollen. The yellow scum often found on water after a summer shower is chiefly Pine pollen. After fertilization the ovules develope into seeds, and the scales of the cone, which are origin- ally of rather soft texture, attain a woody consistency. This process of maturing, how- ever, in the Pine takes considerable time. The cones do not ri})en until the autumn of the second year, after flowering. At this time the scales diverge from the axis, and the seeds are allowed to escape, each of them being now furnished with a wing, which enables the wind more readily to waft it away. The number of cotyledons in the embryo is variable, but is always more than two ; sometimes there are as manv as twelve. The wood of the Gymnosperms is essentially like that of the Dicotyledons, and the stem thickens in the same way. Certain differences Fig-. 119. will be noticed in another place. Fig. lis. Fig. 117. — Single scale of Pino cone with its bract. (Wood and Steele.) Fig. 118. — Inner side of the scale, showing the two naked ovules. (Wood Fig. 119.— Staminato catkins of Ground Uemlock. [and Steele.) GROUND IIKMLOCK 91 plants ir seeds IS. The as open with its flower, sctly to eing no roduced B ovules air in a n often ay Pine ;o seeds, entiaily le stem ferences 2ele.) IS. (Wood nd Steele.) 12;"). It will 1)(! interesting now to compare with the striictiu'o of the Pine that of another memher of the same group — the Ground Hemlock, a low shrub common enough in our Canadian woods. This, like the ]*ine, is evergreen. The leave^', however, are not needle-shaped, hut flat ; and thoy are not clustered, but project singly from the sides of the stem. 12G. The staminatc flowers (Fig. 119) grow in small catkins at the ends of very short lateral shoots which m /N bear about their bases many scale-like bruv^ts. The stamens are somewhat differ- ent from those of Pine, being umbrella- shaped (pidtate), and bearing from three to eight pollen-sacs upon Fig. 120. Fig. 121. the niuler surface. The fertile flowers are also at the extremities of short, scaly-bracted branches, but in this plant the flowers occur singly, and arc not aggregated in cones. Fig. 120 shows a section of a fertile branch with its bracts and the single naked ovido at its extremity. Around the base of the ovule there is a fleshy ring or disk (shown in section at a in tlu figure). The pollen is conveyed by the wind directly to the micropyle, and after fertiliza- tion, and during the devt lopment of the seed, the fleshy ring ni)on which it rests grows upward so as to surround the seed and give the fruit a remarkable berry-like appearance (Fig. 121). This fleshy covering (which is Fig. 120. -Section of fertile branch of Ground Hemlock ; s, the apparently terminal ovule ; i, its inte},'umeMt ; k, the iiucellus ; in, the micropyle; a a, the rudiment of the aril, which finally surrounds the seed ; 6 b, bracts. (Prantl). Fig. 121.— The same with mature fruit, /. (Prantl). I ■III' 0'^ ELEMENTS OF HTIIUCTURAL llOTANY. T ji It !; 1; bright rod at maturity) is a good example of what is called an aril. 127. \V(^ lind, thou, that although there is at th'st sight little in coiiinioii, ai)i»aroiitly, botW(»en the cone of the Pino and the berry-like fruit of the Ground Hemlock (Taxus harcata), yet they both have the characteristic naked ovules. 128. Among our cone-bearing trees will readily be recognized the Arbor Vitro (commonly called Cedar), the Larch or Tamarack, which, however, is not evergreen, and the various kinds of Spruce or Fir. The fluniper, also, belongs to this group, but is marked by the peculiarity that the few scales of the cone cohere together in ripening and become succulent, thus forming what looks like a berry. 129. To sum up the results of our observations upon plant-structure, we have found (1) That all the plants to which our attention has so far been directed iwoduco foicprs ; they are all, therefore, flowering or i^lianerogamous plants, or, briefly, 2^ha7i(>ror/ams. (2) That in a large number of the plants there are ovaries enclosing the seeds. All such plants are grouped as angiosj^ei'ms. (3) That in others the seeds are not enclosed in an ovary. Hence we have a group known as gymno- sperms. (4) That the angiospcrms are either dicotyledonous or monocotyledonous. ' what is rstaiglit of tlio lemlock cteristic Lclily be lar), the erij;reeu, fimiper, by the ogether g what s upon has so are all. its, or, ere are Qts are in an ^yrnmo- \ou% or MuUr''OLOGY or ROOTS, STEMS, AND FOLIAGE-LEAVES. 93 The 'c conclusions may be conveniently shown in a tabular form as follows : PHANKUOOAMS. ANOIOSl'EUMS. (JYMNOSPEBMS. riCOTYLKDONS. MONOCOTYI.KDONS. CHAPTER XVII. MOmilOLOGY OF ROOTS, STEMS, AND FOLIAGE-LEAVES OF PHANEROGAMS. 130. Before proceeding with the examination of other selected plants illustrative of other divisions of the vegetable kingdom, we shall present in a systematic way the more important facts in connection with the Phanero- gams, dealing in turn with the organs of vegetation — the root, the stem, and the foliage-leaves — and then with the organs of reproduction as displayed in the flower. The various forms assumed by these organs, whether in different plants or in different parts of the same plant, will have our attention, as also their various modes of arrangement. We shall consider, also, rather more minutely than we have hitherto been able to do, the development of the seed from the ovule, the process of pollination and of fertilization, and the subsequent germination of the seed and development of the new plant. To this study of forms the name Morphology has been given. It need hardly iDe said that offective morphological work can only be accomplished by actual illr 94 ELEMENTS OP STRUCTURAL BOTANV. contact with .and inspection of tlu» forms which are, for the time being, tlie objects of study. Tiie young student must provide liimself with specimens, and learn to associate tl»e descriptive terms with the actual condition which the terras descril)e. Only in this way can this branch of botanical work be relieved of the element of Irudgery, and made what it ought to be — a moans of developing in a high degree those powers of observation with which the young are so exceptionally endowed. It is believed that with proper management even the more dilHcult technical terms, which are derived from Latin and Greek, and specially devised for botanical purposes, will be learned without extraordinary efibrt. It is the writer's experience tiiat a term is insensibly acquired and almost indelibly impressed upon the mind ij there is fird created the wani of the terin to describe what is seen when some new form has been the subject of obser- vation, and its peculiarities have been thoroughly grasped through the medium of the eye. With a good many of the terms there will be found no difficulty whntever, since they have the same meaning in their botanical applications as they have in their e very-day use. 131. The Root. This organ is called the descending axis of the plant, from its tendency to grow downward into the soil from the very commencement of its develop, ment. Its chief use is to imbibe liquid nourishment, and transmit it to the stem, from which it is well distin- guished by the presence of the root-cap (Fig. 122, a) and the absence of leaves. The absorbing surface of a young root or rootlet is largely increased by tl'.e development of root-hairs, the nature of which will be explained later on when we come to treat of trichomes or hair-like growths ROOTS. 95 are, for student 3arn to )ndition ;an this nent of leans of irvation /ed. It 'en the 3d from Dtanical ibrt. It sensibly mind i/ be what f obser- grasped nany of intever, Dtanical cending vnward levelop- shment, distin- , a) and I young nient of ater on ;rowths <^'' generally. It must l>o mentioned here, also, that there are some exceptions to tlie general stateiiK^nt that roots do not produce huds. It is well known that new stems are sent up hy the roots of Poplais and of Apple trees, for example, espcicially if the roots have been injured. These cases must be regarded as abnormal. 132.*you will remember that in our examination of som<^ common seeds, such as those of the Pumpkin and Ijean(Figs. 7 7-81), we found jfjiij at the junction of the cotyledons a small ^^ pointed i)rojection called the radicle. Now, when such a seed is put into the ground, under favorable circumstances of warmth W and moisture, it begins to grow or gcrmi- 7iat(\ and the radicle, which in reality is a ~T minute stem, not only lengthens, in most cases, so as to push the cotyledons upwards, but developes a root from its lower extremity. All seeds, in short, when they germinate, produce roots from the extremity of the radicle, and in a direct line u'ith. if, and roots so produced are called 2>i'i"iari/ roots. In Monocotyledons the primary root is but very slightly developed, the fibrous roots character- istic of these plants bursting forth fi'oni the sides of the radicle at an early period of growth. In other plants the primary root either assumes Fig. 123. the form of a distinct central axis larger than any of it i branches, and called a tap-root (Fig. 123), examples of which are furnished by the Mallow, the Carrot, and the Fig. 122. — Magnified tip of Hyacinth root ; a, the root-cap. (Hooker.) Fig. 123.— Tap-root of Dandelion. 9G ELEMENTS OF STRUCTURAL IJOTANY. Fi<'. 124. growth. Bean, or it may branch at an early stage into numerous similar threads, and so t'orni a librous root, as in Buttercup. 133. Tap-roots receive difl'erent naiiies according to the parti(;ular shape they Jiappeii to assume. Tims, the Carrot (Fig. 12Jr) is ctmiral, because from a broad topi: tapers gradually and regularly to a point. The Radish, being somewhat thicker at the middle than at» either end, is spiudle- iihaped. The Turnip, and roots of similar shape, are napiform (iiajms, a turnip). These fleshy tap-roots belong, as a rule, to biennial plants, and are designed as storehouses of food for the plant's use during its second year's Occasionally fibrous roots also thicken in the same maimer, as in the Peony, and then they are said to be fascAcled or cludere(L (Fig. 125). 134. But you must have observed that plants some- times put forth roots in addition to those develop- ed from the embryo of the seed. The V^erbena of our gardens, for example, will take root at every joint if the stem be laid upon the ground (Fig. 12G). The runners of the Strawberry take root at their extremities; and nothing is more familiar than that cuttings from various plants will make roots for themselves if put into proper soil, and supplied with warmth and moisture. Fi-'. 125. at a\ Fig. 124.— Tap-root of Carrnf. I'iy. 125 — Fasciclod roots of Peony. ROOTS. 97 ^ All such roots, not developed from the end of the radicle and in a straight line with it, arc called t'ccoudary or advent Ui(m>^ roots. Under this head should, of course, be placed the fibrous roots of all Monocotyledonous plants, the true primary roots of which are but very feebly developed. So, also,all branches of primary roots should )je re- garded as adven- titious. When such roots are developed from parts of the stem which are not in contact with the ground, they are aeridlf as, for example, the roots developed from the lower joints of the stem of Indian Corn. 135. There are a few curious plants whose roots never reach the ground at all, and which depend altogether upon the air for food. These are called epiphytp.s. There are others whose roots penetrate the stems and roots of other living plants, and thus receive their nourishment as it were at second-hand. These are parasitic plants. The Dodder and Beech-drops, of Canadian woods, are weil-known examples. Others, again, subsist upon decomposing animal or vegetable matter, and are hence known as saprophijtes. Indian Pipe and Coral-root are good examples of saprophytic plants. Both parasites and saprophytes are usually destitute of green leaves, ^f*" M ■■ Ml I I I I ■ I. I - ...11 — — ^ ^. _— . , , I ,--_-■ , ., I. ■ I , ■ ■■ ■ r — ^— .^^iW Fig. 126. — Adventitious roots of Verbena. Fig. 126. lil 98 ELEMENTS OP STRUCTURAL BOTANY. ' beirif,' either pale or brownish. The Mistletoe, however^ is a green parasite. / 136. As to duration, roots (and, consequently, the plants themselves) are either mutual^ or biennial, or 2^crennial. The plant is called an annual if its whole life, from the germination of the seed, is limited to one season. It is biennial if it flowers and ripens its seed in the second season. Between these two classes it is JifHcult to draw a sharp line, because, with proper care, some annuals may be induced to live for two years; and, on the other hand, some plants, as the Radish, which are properly biennial if the seed is sown in the fall, will flower and produce seed in one season if sown in the spring. Something, also, depends upon the climate in which the plant is grown, its life, in some cases, being prolonged in a more favourable situation. Perennials live on year after year, as is the case with all our shrubs and trees, and also with some herbaceous plants, as Peony and Dahlia, wiiich only die down to the surface of the ground in the autumn. 137. The Stem. As the root is developed from the lower end of the radicle of the embryo, so the stem is developed from the upper end, but with this important difference, that a hiid always precedes the formation of the stem or any part of it or its branches. If a bud, such as that of the Lilac, bo picked to pieces, it will be found to consist mostly of minute leaves closely packed together on a short bit of stem. A bud, in fact, is only a special condition of the extremity of the stem, and is not to be regarded as an organ distinct from it. As the bud unfolds^, the stem may lengthen so as to exhibit the internodes, or \ STEMS. 99 the it may remain short, in which case the expanded leaves form a cluster or rosette, as in Dandelion. The tender ^ ^ leaves of tlie bud are not uncommonly protected from the weather by coverings in the form of tough scales, with the additional safeguard sometimes of a wax-like coating on the surface of the latter, as seen in the conspicuous buds of the Horse-Chestnut, and the cap-like coverings of those of the Spruce. 138. Eotween the cotyledons of the Bean (Fig. 81), at the top of the radicle, we found a minute bud called the plumule. Out of this bud the first bit of stem is developed (leaving out of consideration the radicle itst^lf), and during the subserpieut growth of the plant, wherever a branch is to be formed or a main stem to be prolonged, there a bud will invariably be found. Tlic Ijranch buds are always in the axils of leaves, and so are called axillary, and it not uncommonly happens that several buds are found together in this situation. 139. Adventitious buds, however, are sometimes produced in plants like the Willow, particularly if the stem has been wounded. As already mentioned, they are also occasionally produced upon roots, as, for example, upon those of the Poplars. 140. The bud from which the main stem is developed, or a branch continued, is of course at the end of the stem or branch, and so is terminal. 141. Branching or Ramification. By a branch is meant an ofF-shoot similar in structure to the member from which it springs. Ilonco the side-shoots of roots are root-branches ; so, also, the lateral out-growtlis of the stem which resemble the stem itself in structure are I ii 100 ELEMENTS OF STRUCTURAL BOTANY. stem-branches. It is foiind that the branching of stems proceedri upon two \v(*li defined pkms. I 142. Monnpodial BrancMmj. This system is distin- guished by the circiimstaiico that all the bnuiches are the result of the development of strictly lateral buds. In other words, there is invariably a terminal bud at the apex of the stem distinct from the lateral buds produced behind the apex. Of this system ihere are several Fig. 130. Fig. 127. Fig. 128. modifications. If the terminal bud develops regularly, as well as the lateral ones, it is clear that we shall have a straight and well-defined trunk, easily distinguished by its vigorous growth from the branches. The Pine or the Spruce is an excellent example of this effect. Figs. 127, 128, 130,— Diagrams of variovis forms of monopodial branching. (Sachs.) MONOPODIAL BRANCHING. 101 as re a by or But if the terminal bud, though produced, ceases to ^row, while the lateral buds are vigorously developed, as is well exhibited in the spring by the annual shoots of the Lilac, then it is clear that the branches will overtop the original stem, and the latter will finally become unrecog- nizable. Fi^. 129. 143. The Pine and the Spruce and similar forms are said to be racemose or hotryose, and the Lilac, in the development of its annual shoots, is said to be cymose. Fig. 127 is a representation of the latter mode. Here 1 is the extremity of the main stem, but the terminal bud at that point has failed to grow, while two vigor- ous branches have been produced. The terminal buds of these branches (2 and 2), have in their turn failed, and the laterals immediately behind them have, as before, given rise to new shoots. This is the result, then, when both the lateral buds grow with equal vigour, and it is known as a forlied cyme. 144. But sometimes one member of each pair of buds is developed far more strongly than the other. If the strong buds are developed in succession on the same side of the stem an effect will be produced like that represented in Fig. 128. This is known as a helicoid cyme. If, however, the strong buds are developed alternately on both sides of the stem, we get the form sliown in Fig. 129, which is then called a timrjnoid cyme. Not un^ ling. Tig, J,29.— Diagram to illustrate 8corn)^ii underground stem. ^6ncn swollen extremities are known as tubers, whilst the Fig. 136.— Tubers of the Potato. 106 ELEMENTS OP STRUCTURAT; BOTANY. underground stem is called a root-'^torl- or rhizome^ and may almost always bo distiiiguisluMl from a true root by the presence of buds. Tlie Solomon's 8e.il and Toothwoil of Canadian W(,ods, and the Canada Thi.stie, are common instances of plants producini;- these slenis. Fig. 137 shows a rhizome. 152. T;ike now an vw. Onion, and compare it with a Potato. You will not find any such Fig. 1S7. outside appearances upon the former as arc presented by the hitter. The Onion is smooth, and has no buds upon its surface. From the under side there spring roots, and this circumstance will probably suggest that the Onion must be a stem of some sort. Cut the Oidon throu^]nj basrfi of the Imvcf^. But you will observe that at the bottom there is a rather flat, solid part upon whicli these coats or leaves are inserted, and ^vliicli must consequently be a stem. Sucli a stem as this, with its >..^«»i w «/i fleshy leaves, is caUed a huJh. If the ''^mMMiJmw leaves form coats, as in the Onion, tlie bulb is coaied or tnnicatefl; if they do 153. Tubers and bulbs, then, consist chiefly of masses of nourishing matter ; but there is this difleronce, that in the latter the nourishment is contained in tlie fleshy leaves themselves, whilst in the former it forms a mass more or less distinct from the buds. 154. The thickened mass at the base of the stem of our Indian Turnip (Fig. 94) is more like a tuber than a l)ulb in its construction. It is called a corm or solid bulb. The Crocus and Gladiolus of the gardens are other examples. The chief diflference between the corm and the ordinary bull) is in the relative space occupied by the stem or solid part. In the former it is very much greater than in the latter. The student should dissect specimens of Indian Turnip, Crocus, Tulip, Hyacinth, &c,, when these diflTerences will be readily apprehended. 155. In the axils of the leaves of the Tiger Lily are produced small, black, rounded bodies, which, on examination, prove to be of bulbous structure, They are, in fact, hulhlets^ and new plants may be grown from them. 156. Foliage-Leaves. These organs are usually more or less flat, and of a green colour. In some plants, Fifj. 139.— Bulb of a Lilj-. 108 ELEMENTS OF STRUCTURAL BOTANY. liO'vever, they ure extremely thick and succulent ; and in the case of parasites and saprophytes, such as Indian Pipe and Beech-di'ops, they arc usually either white or brown, or of some colour other than green. The scaly leaves of underground stems are also, of course, destitute of colour. The green colour is due to the presence of granular particles of a substance called chloroplujlL It is formed, as a rule, only in those parts which ai*e exposed to the action of sunlight, and it is intimately connected with the process of assimilating nutritious matter for the plant's use during growth. Further reference will be made to it later on. 157. As a general thing, loaves are extended horizontally from the stem or branch, and turn one side towards the sky and the other towards the ground. But some leaves are vertical^ and in the case of the common Iris (Figs. 88 and 89) each leaf is douljled lengthwise at the base,;uul dh astride the next one within. Such leaves are called eqjiltant. 158. Phyllotaxis or Leaf- Arrangement. As to their arrangement on the stem, leaves are alternate when only one arises from each node (Fig. 3). If two are formed at each node, they are sure to be on opposite sides of the stem, and so are described as op2}osite. If, as in Mint and Maple, each pair of opposite leaves stands at right angles to the next pair above, then the arrangement is decussate. Sometimes there are several leaves at the same node,in which case they 'axQiolwrled or verticillateQ^i^.lU)). Fii?. 140. Fig. 140. — Whorled leaves of Galium. rnVLLOTAXIS. 100 100. Even if the leaves are placed ningly and apparently irregularly at intervals along the stem, it will be found on examination that tlieir arrangement is governed by delinito laws. Take, for instance, a branch of Poplar with a number of leaves ui)on it. Fix upon any one loaf near the lower end of the branch, and then from its point of insertion draw a lino, hij fhe nearest way, to the insertion of the next higher leaf, and from this to the next, and so on till you reach a leaf which is exactly over the first one* If the branch itself has not been twisted out of its normal shape, it will be found tiiat the suih leaf is always precisely over tlie first, the seventh over the second, the eighth over the third, and so on, and that the line joining the points of insertion of successive leaves forms a spiral round the stem. It will also be found that this spiral goes twice round the stem before passing through the sixth leaf. The sixth leaf, as standing exactly over the first, begins a new sot, which lasts in a similar manner till we reach the eleveiith. The leaves are therefore in sets or cycles of five each, and the phyllotaxis in this case is conveniently described by tlie fraction |, the denominator of which gives the number of leaves in the cycle, and the numerator the number of turns in the spiral. 160. NoWjif through the insertions of the leaves which are vertically over each other — that is, through those numbered 1, 6, 11, 16, etc., and then through tliose numbered 2, 7, 12, 17, and so on — lines be drawn, it is evident we shall have five such vertical lines on the stem. These lines mark the raiilis of leaves, or orthostichies. The number of orthostichies in any case always corresponds to the number of leaves in the cycle. P 110 ELExMENTS OP STRUCTURAL ROTAXY. ?!; IGl. In tlie Elm, the phyllotaxis is much simpler. Here, starting with any given leaf, it will be found that the next one is exactly half way round the circumference of the stem, and tlie third one exactly over the first, and so on. So that the spiral completes the circuit in one turn, and the number of orthostichies is only two, the phyllotaxis being therefore described as ^-. The -J- arrange- ment is also common. The Poplar, as we see, has a ■-; arrangement ; this is extremely common. 162. If we set down these fractions in order, thus : ^-, h f,i it will be noticed that the sum of the first two numerators gives the third numerator ; so also with the denominators. If we proceed to make other fractions in this way, the series would read ^, ;?j, f, «, I'^i, iff, I'i, and these are, as it happens, the actual cases of phyllotaxy which we commonly meet with. The cone of the White Pine furnishes a very good exercise. In this case the scales (which, of course, are leaf-forms) have a ^;r arrangement. 1G3, The conclusion come to from a close examination of the incipient buds is, that the newer leaves are produced over the widest intervals between those next below. In short, the arrangement is that which secures to the leaves the most advantageous conditions for exposure to the light, and at the same time economizes space. As has been aptly said, the growth of the new leaVes follows the " lines of least resistance." 1G4. When leaves are in wliorls instead of in spirals, the members of any whorl stanil over the spaces of the whorl below, as might be expected. As to leaves which are clustered or fascicled, like those of the Pino and Larch, it may be pointed out that the clustering is due simply to FORMS OF FOLIAGE-LEAVES. Ill 1!' the non-development of intern odes. The clusters when carefully examined, show in some cases an alternate, and in others a whorled, arrangement. 165. As branches are produced in the axils of leaves, it is clear that the arrangement of branches will be the same as that of the leaves. It rarely happens, however, that all the buds develope into branches. Many of them fail, so that generally branches appear to have no very definite arrangement. 166. Vernation or Praefoliation. These terms have reffcience to the mode in which the new leaves are folded in the bud. Very commonly the leaf is simply doubled lengthwise, the upper side of the leaf witliin ; then its vernation is said to be conduplicafe. In the INFaplc and Mallow the folding is fan-like, and is described as plaited. In the Cherry the leaf is coiled in a single coil beginning with one edge : this is convoluta vernation ; but if the coiling is from botli edges to the mid ril), it is said to be involute ; if both edges are rolled bade ward, it is rcrohde. The vernation is circinate when the leaf is coiled from the tip, as in Ferns. 167. Forms of Foliage-Leaves. Leaves present an almost endless variety in their forms, and accuracy in describing any given leaf depends a good deal upon the ingenuity of the student in siilecting and combining terms. The chief terms in use will ])o given here. Compar'O a leaf of the Jlound-leaved Mallow with one of Red Clover (Figs. 141, 142). Ivu-h of them is furnished with a long petiole and a paii" of stipules. In the blade, however, there is a diflerence. The ])lado of the former consists of a ,s7'?/y/e^>/t'ce / tliat of the latter I 112 ELEMENTS OF STRUrTURAL BOTANY, Its is in three separate pieces, each of which is called a leaflet, but all of which, taken collectively, constitute the blade of the leaf. The leaf of the Mallow is simple ; that of the Clover is compound. Between the simple and the compound form there is every possible shade of gradation. In the Mallow leaf the lobes are not very oicarly defined. In the Maple (Fig. 143) they are well Fijr. 141. Fig. 142. marked. In other eases, again, the lobes are so nearly separate that the leaves appear at first sight to be really compound. 1G8. You will remember that in our examinations of dicotyledonous plants, we found the leaves to be invariably net- veined. But, though they have this general character in conmion, they diflor considerably in the details of their veining, or venatioil, as it is called. The two leaves employed as illustrations in tlie last section will Fig. 111. -Simple palmateiy-veined leaf of Mallow. Fig. 142.— Conipound leaf of Clover. FORMS OF FOLIAGE-LEAVES. 113 serve to illustrate our meaning here. In the MalloWj ' ' there are several ribs of about the same size, radiat- ing from the end of the petiole, something like the spread-out fingers of a hand. The veining in this case is therefore described as dvji- tafe, or radiate, or palmate. The leajJet of the Clover, on the other hand, is divided % exactly in the middle by a ^'^^- ^^^' single rib (the mid-rib), and from this the veins are given off on each side, so that the veining, on the whole, presents the appearance of a feather, and is, therefore, described as pinnate ^permia, a feather). 169. Both simple and compound leaves exhibit these two modes of venation. Of simple pinnately-veined leaves, the Beech, Mullein, and Willow supply familiar instances. The Mallow, Maple, Grape, Cur- rant, and Gooseberry have simple radiate - veined leaves. Sweet- Brier (Fig. 43), Mountain Ash, and Rose have compound pinnate leaves, whilst those of Virginia- yi^. \\\. Creeper (Fig. lit). Horse- Chest-nut, and Hemp are compound digitate. ■- I III I , ._ Fig. 143.— Palinatcly-lobeil leaf of Maple. Fig. 144.— Palmate leaf of Virjifinia Creo]ier. & ?f '41 ■■:,■■ \ 114 ELEMENTS OF STRUCTURAI. BOTANY. As has already been pointed out, the leaves of Mono- cotyledonous plants are almost invariably straight-veined. 170. In addition to the venation, the description of a Linear Oblonjj Oval Orbicular Fig. 145. Fig. 146. simple leaf includes ])articulars concerning : (1) the gen- eral outline, (2) the edge or margin, (3) the point or apex, (4) the base. 171. Outline. As to outline, it will be convenient to consider first the forms assumed by leaves without lobes, Lanceolate Ovate Deltoid Fig. 147. Fi-. 148. and whose margins are therefore more or less continuout . Sucli leaves are of three sorts, viz.: those in which both ends of the leaf are alike, those i)i which the apex is Fifa. 145 to 148.— Various forms of foliage-leaves. FOLIAGE-LEAVES. 115 narrower than the base, and those in which the apex is broader than the base. (■ 172. In the first of these three classes it is evident that any variation in the outline will depend altogether on the Fig. 152. Fig. 153. Fig. 149. Fig. 150. Fig. 151. relation between the length and the breadth of the leaf. When the leaf is extremely narrow in comparison with its length, as in the Pine, it is acicular or needle-shaped (J^'ig. 145). As the width increases, we pass through the forms known as linear, oblong, oval, and finally orhicidar, in which the width and length are nearly or quite equal (Fig. U6). Fig. 154. 173. In the second class the different •'- forms arise from the varying width of the base of the leaf, and we thus have subulate or aid- shaped (Fig. 147), lanceolate, ovate, and deltoid leaves (Fig. 148). Figs. 149 to 154. — Various foriiig of foliage leaves. 116 ELEMENTS OP STRUCTURAL BOTANY. 174. In the third class, as the apex expands, we have the fornis spaihulate (Fig. 149), ohlanceolate — that is, the reverse of lanceolate (Fig. 150), and ohovate (Fig. 151). 175. In leaves of the second kind we frequently find the base indented, and then the leaf is cordate or heart- Fig. 155. Fig. 156. Fig. 157. shaped (Fig. 152). The reverse of this — that is, when the indentation is at the apex — is ohcordate (Fig. 153). The hastate or spear-shaped (Fig. 154), sagittate or arrow- shaped (Fig. 155), and reniform or kidney-shaped (Fig. 156) forms are modifications of the second class, and will be readily understood from the annexed figures. If the petiole is attached to any part of the under surface of the leaf, instead of to the edge, the leaf is peltate (shield-shaped) Fig. 158. (Fig. 158). 176. Leaves which are lobed are usually described by stating whether they are palmately or pinnately veined; and Figs. 155 to 158.— Various forms of foliage-leaves. FOLIAGE-LEAVES. 117 Fig. 159. il 'he former, the number of lobes is generally given. If the leavers an; very deeply cut, they are said to be palmatijUl ovpinnatijid, according to the veining (Fig. 1 59). If the leaf is pinnatifid and the lobes point backwards towards the base, as in Dandelion, the leaf is said to be runeinate. If the leaf is palmately lobed, and the lobes at the base are them- selves lobed, the leaf is ^;ec/«^e (Fig. 160), because it looks something like a bird's foot. If the lobes of a pinnatifid leaf are them- selves lob^d, the leaf is hipinnatijid. If the leaf is cut up into fine segments, as in Dicentra, it is said to be multijid. 177. Apex. The princi[)al forms of the apex are the mucronate (F^'ig. 157), when the leaf is tipped with a sharp point, as though the mid-rib were projecting beyond the blade ; cuspidate, when the leaf ends abruptly in a very short, but distinctly tapering, point (Fig. J. 161); acute, or sharp; and obtuse, or blunt. It may happen that the apex does not end in a point of any kind. If it looks as though the end had been cut off square, it is truncate. If Fig. 161. the end is slightly notched, but not sufficiently so to warrant the description obcordate, it is emarjinate. 178. Margin. If the margin is not indented in any way, it is said to be entire. If it has shar{) teeth, j^ohiting Figs. 159 to 161. — Various forms of foliage-leavos. 118 ELEMENTS OP STRUCTURAL BOTANY. Fig. 162. i?', the direction of the aiiex^ it is serrate, and will he coarsely or finely serrate, according to the size of the teeth. Sometimes the edges of large teeth are themselves finely serrated, and in that case the leaf is doubly serrate (Fig. 162). If the teeth point outioardsy that is, if the two edges of each tooth are of the same length, the leaf is dentate; but if the teeth, instead of being sharp, are rounded, the leaf is cr'mate (Fig. 163). The term wavy explains itself. 179. Base. There are two or three peculiar modifica- tions of the bases of simple sessile leaves which are of considerable importance in distinguishing plants. Some- times a pair of lobes project backwards and cohere on the other side of the stem, so that the stem appears to pass through the leaf. This is the case in our common Bellwort, the leaves of which are accordingly described as perfoliate (Fig. 164). Sometimes two opposite sessile leaves grow together at the base and clasp the stem, as in the upper leaves of Honeysuckle, in the Triosteum, and in one of our species of Eupatorium. Such leaves are said to be connate or eonnate-perfoliate (Fig. 165). In one of our Everlastings the margin Fig. 164. of the leaf is continued on each side below the point of insertion, and the lobes grow fast to the sides of the stem, giving rise to wliat is called the decurrent form (Fig. 166)! Figs. 162 to 164.— Various forms of foliage-leaves. Fig. 163 FOLIAGE- LEAVER. 119 The terms by which simple leaves are described are applicable also to the leaflets of compound leaves, to the sepals and petals of flowers, and, in short, to any flat forms. Fig. 1654 Fig. 166. 180. Wo have already explained that compound loaves are of two forms, 'pinnate and palmate. In the former the leaflets are arranged on each side of the mid-rib. There may be a leaflet at the end, in which case the leaf is odd-pinnate; or the terminal leaflet may be wanting, and then the leaf is Fig. 167. abruptly pinnate. In the Pea, the leaf is pinnate and terminates in a tendril (Fig. 135). 'Very frequently the primary divisions of a pinnate loaf are themselves pinnate, and the wliole leaf is then twice-pinnatn (Fig. 1 07). If Figa. 165 to 167.— Various forms of foliage-leaves. 120 ELEMENTS OP STRUCTURAL BOTANY. \ the sub-division is continued through another stage, the leaf is thrice-pinnate, and so on. Sometimes, as in the leaves of the Tomato, very small leaflets are found between the larger ones, and this form is described as interrup)tedly pinnate (Fig. 168). In the palmate or digitate forms the leaflets spread out from the end of the petiole, and, in describing them, it is usual to mention the number of divisions. If there are three, the leaf is tri-follolate ; if there are five, it is quinque-foliolate. 181. In the examination of the Mallow we found a couple of small leaf-like attachuxonts on the petiole of each leaf, just at the junction Fig. 168. with the stem. To these the name stipules was given. Leaves which have not these appendages are exsti^mlate. 182. Besides the characters of leaves mentioned above, there re- main a few others to be noticed. With regard to their surface, leaves present every gradation from perfect smoothness, as in Winter- to extreme rouudiness or green, woolliness, as in the Mullein. Fig. 169. If hairs are entirely absent. Fig. 163. — Iiiturruptedly pinnate leaf. Fig. 169.— Leaf of Pitcher-Plant. FULIAGK-LEAVES. 121 the loaf is (jlahrous ; if present, the degree of hairiness is describocl by an appropriate adverb ; if the leaf is com- pletely covered, it is viUonti or villose ; and if the hairs are on the margin only, as in our Clintonia, it is ciliate. Seme leaves, like those of the Cabbage, have a kind of Ijloom on the surface, which may be rubbed off with the fingers ; this condition is described as glaucous. 183. A few^ plants have anomalous leaves. Those of the Onion are Jlllj'arm. Tiie Pitcher-Plant of our northern swamps has very curious leaves (Fig. 169), apparently formed by the turning in and cohesion of the outer edges of an ordinary leaf so as to form a tube, closed except at the top, and armed on the inner surface with bristles pointing towards the base of the leaf. 184. Finally, as leaves present an almost infinite variety in their forms, it will often be necessary in describing them to combine the terms explained above. F^or instance, a leaf may not be exactly linear, nor exactly lance-shaped, but may approximate to both forms. In such a case the leaf is described as lance-Uneai\ and so with other forms. The following form of schedule may be used with advantage in writing out descriptions of leaves. Two leaves — one of Maple and one of Sweet Brier — are desciibed by way of illustration. If a leaf is compound, the particulars as to outline, margin, apex, base, and surface will have reference to the leaflets. The exercise-book ])reparcd to accompany this work contains a supply of blank schedules for leaf-description, with space for drawings. 1:1 ' ;l 122 KLKMENTS OF STUUt^TURAI. BOTANY. LEAF SCHEDULE. Leaf of Maple. Sweet Brier. 1. Position. Cauline. Cauline. 2. Arrangement. Cnposite. Alternate. 3. Insertion. Petiolate. Petiolate, 4. Stipulation. Exstipulate. Stipulate. 5. Division. Simple. Odd pinnate, 7 leaflets. 6. Venation. Palmate. 7. Outline. Roundish or oval. 8. Margin. Deeply lobed. Doubly serrate. 9. Apex. Pointed. • Acute. 10. Base. Cordate. Hardly indented. 11. Surface. Glabrous above ; whitish beneath. Downy above ; covered with glands beneath. INFLORESCENCE. 123 CHAPTEK XVITT. •/ MORPHOLOGY OF FLOWFR-LEAVHS — INFLORESCENCE — THE CALYX — THE COROLLA — THE STAMENS — THE PISTIL — THE FRUIT — THE SEED — GERMINATION. 185. From an examination of the various forms presented by foliage-leaves, we proceed now to those of the floral ones, and we shall first consider the chief modifications in the arrangement of flowers as a whole, to which the term infloreSCence is applied. As the organs of which flowers are made up are strictly leaf-forms, the special stalks upon which they are produced (peduncles and pedicels) are true branches, and their development is in strict accordance with the principles enunciated in sections 141-144. As there stated, the almost invariable mode of branching in phan- erogams is monopodial, either after the hotryose type or after the cymose type. So inflorescence is found to proceed upon one or other of these two plans. 186. To understand these let us recur to our specimens of Shepherd's Purse and Buttercup. You vviW remember that in the former the peduncle continues to lengthen as long as the summer lasts, and new flowers continue to be produced at the upper end. Observe, however, that every one of the flowers is produced on the side of the stem, that as the stem lengthens new lateral buds appear, and that there is no flower on the end of the stem. The production of the flowering branches (pedicels) and the continuation of the main axis are, in fact, exactly analogous to the growth of the Spruce, as explained in section 142. ' >1 I'i^ ii yi 124 ELEMENTS OP STRUCTURAL BOTANY. You will easily iniderstand, then, that the production of llovvers in such a plant is only limited by the close of the season or by the exhaustion of the plant. Such inflorescence is, therefore, called indefinite, or inde- terminate, or axillary. It is sometimes also called centripetal^ because if the flowers happen to be in a close cluster, as are the upper ones in Shepherd's Purse, the order of development is from the outside towards the centre. 187. If you now look at your Buttercup you will be at once struck with the diflerence of plan exhibited. The main axis or stem has a/l.oirer on the end of it, and its further growth is therefore checked. And so, in like manner, from the top downwards, the growth of the branches is checked by the production of flowers at their extremities. The mode of inflorescence here displayed is definite, or determinate, or terminal. It is also called centrifugal^ because the development of the flowers is the reverse of that exhibited in the flrst mode. The upper, or, in the case of close clusters, the central, flowers open flrst. 188. In either mode the flowers are said to be solitary, if (1) single flowers are produced in the axils of the ordinary foliage-leaves (' )tryose), or (2) if a single flower terminates the stem, as in Tulip (terminal). 189. Of indeterminate or botryose infiores- Cence there are several varieties. In Shepherd's Purse we have an instance of the raceme, which may be described as a cluster in which each flower is supported on a lateral pedicel of its own, usually in the axil of a bract. If the pedicels are absent and the flov ^rs consequently INFLORESCENCE. 125 sessile in the axils, the cluster becomes a spiJcc^ of which the common Plantain and the Mullein furnish good examples. The caflmis of the Willow (Figs. G8 and 69) and Birch and the spadix of the Indian Turnip (Figs. 96 and 97) are also spikes, the former having scaly bracts and the latter a fleshy axis. If you suppose the Y\^. 170. Fig. 171. internodes of a spike to be suppressed so that the flowers are densely crowded, you will have a lieady of which Clover antl Button-lmsh supply instances. If the lower pedicels of a raceme are considerably longer than the Fijf. 170.— IMan of tho simple foryinb. Fijf. 171.— COuipouud raceme. ^Giay.) 126 ELEMENTS OF STRUCTURAL BOTANY. • ; upper ones, so that all the blossoms are nearly on the same level, the cluster is a corymb (Fig. 170). If the flowers in a head were elevated on separate pedicels of the same length, radiating like the ribs of an umbrella, we should have an umhel^ of which the flowers of Geranium and Parsnip (Fig. 51) are examples. A raceme will be coriip C4, A2+2''j G(^); the expression 2"^ indicating the reduplication of the inner stamens. 201. If there is no clear distinction between the calyx and corolla, the letter P (for perianth) may be used to include both ; and, filially, if the members of any whorl Fig. 174. — Diagram of a Grass-flower. (Prantl.) Fig. 176.— Diagram of flower of S', ^pherd's Purse. (Prantl.) . II THE CALYX. 131 stand oppositp. those of the one exterior to it, a vertical line may be placed between the symbols, thus : Cg | Ag. 202. Other methods of indicating symbolically the relations of the parts of the flower are in vogue ; the one just given is recommended by Prantl, and is sufficiently convenient. 1 203. It has already been mentioned that flowers are said to be irregular when the members of any whorl are of different sizes or shapes, as, for example, in the Pea ; and reguhir, when the opposite is true. Fig. 173 repre- sents one of these regular flinvers. A moment's reflection will show that any line whatever drawn across the centre of this diagram will divide it into two exactly similar halves. The term actinomorphie, as well as "regular," is applied to all such flowers. Flowers, on the other hand, which can be cut symmetrically in one vertical plane only are zygomor2)liic. 204. In this book, as in most English books, the term " symmetrical " is employed to indicate that the whorls consist of the same number of members each, and it is, in fact, the same in meaning as " isomerous." The later German botanists define a symmetrical flower as "one which can be divided vertically into two halves resembling each other like an object and its reflected image." We shall now proceed to consider in detail the variations in form assumed by the floral organs individually. 205. The Calyx. As you are now well aware, this term is applied to the outer circle of floral leaves. These are usually green, but not necessarily so -, in some Exogens, and in nearly all Eudogens, they are of some other colour. Eaoh division of a calyx is called a tsepali and if the sepals 132 ELEMENTS OP STRUCTURAL BOTANY. are entirely distinot from each other, the calyx is po??/' sepalous ; if th(;y ai'e united in any degree, it is gamo- sepalous. A calyx is regiihir or irregular according as the })('tals are of the same or different shape and size. 1^0 G. In a gamosepalous calyx, if the sepals are not united to the very to^), the free portions are known as calyx-teeth^ or, taken collectively, as the limb of the calyx. The united portion, especially if long, as in AVillow-herh, is called the calg.r,-t2ibe, and the entrance to the tube its throat. In many plants, particularly those of the Com- posite Family, the limh of the calyx consists merely of a circle of bristles or soft hairs, and is then described as pa^ipose. In other cases the limb is quite inconspicuous, and so is said to be obsolete. A calyx which remains after the corolla has disappeared, as in Mallow (Fig. 31), is persistent. If it disappears when the flower opens, as in our Bloodroot, it is caducous; and if it falls away with the corolla, it is deciduous. We must repeat here, that when calyx ^nd corolla are not both present, the circle which is present "s considered to be the calyx, whethoi- green or not. 207. The Oorolla. The calyx and corolla, taken together, are called the floral envelopes. When both envelopes are present, the corolla is the inner one ; it is usually, though not invariably, of some other colour than green. Each division of a corolla is called a petal^ and the corolla is polypetalous when the petals are completely disconnected ; but gamopetalous if they are united in any degree, however slight. The terms regular and irregular^ applied to tht^ calyx, are applicable also to the corolla, and the terms used in the description of leaves are applicable THE COROLLA. 13L^ to petals. If, however, a petal is narrowed into a long p.iui slender portion towards the base, that portion is k\iown as tlio claa\ whilst the hroader upper })art is called the Hmh (Fig. 170).' The leaf-terms are then applicable to the limb. 208. Gamopetaloua corollas assume various forms, most of which are described bv terms Fig. 176. easily understood. The forms assumed depend almost entirely on the shape of the petals which, when united, make up the corolla. If these, taken separately, are lintiur, and are united to the to}), or nearly so, the corolla will be tubular (Fig. 177). If the petals are wedge-shaped, they will, by their union, produce a fun npJ-^^l taped corolla (Fig. 178). In the campanulate or bdl- shaped form, the enlargement from base to sum- mit is more gradual. If the petals are narrowed Fig. 177. abruptly into long claws, the union of the claws into a tube and the spreading of the limb at G''^'':''WM^£m ^^S^^ angles to the tube will produce the salver-sJiajJcd form, as in Phlox (Fig. 1 79). The rotate corolla differs from this in having a very short tube. The corolla of the Potato is rotate. 209. The most important irregular gamopetalous corollas are the lu.late^ which has been fully described in the ^' ' examination of the Dandelion, and the labiate, of which we found an example in Catnip (Fig. 59). The corolla of T\irtle-head (Fig. 180) is another Fig. 176.— Single petal of a Pink. Fig. 177.~Tnbular corolla of a Honeysuckle. Fig. 178.— Funnel-shaped corolla of Calystegia. U 134 ELEMENTS. OF STRUCTURAL BOTANY. I example. When a labiate corolla presents a wide opening between the upper and lower lips, it is said to be rinrjtnt ; if the opening is closed by an upward projection of the lower lip, as in Toadflax (Fig. 181), it is said to be 'personate^ and the projection in this case is known as the 'palate. A good many corollas, such as those of Toadflax, Dicentra, Snapdragon, Columbine, and Violet, have protuberances or simra at the base. In Violet one petal only is spurred ; in Columbine the whole five are so. Fig. 179. Fig. 180. Fig. 181. 210. Estivation. This is the term applied to the mode in which the sepals and petals are folded in the bud. In general, the members of a calyx or of a corolla overlap in the bud, or they do not. If they stand edge to edge, as in the calyx of Mallow, the aestivation is valvate. If there is overlapping, and one or more of the members have both edges covered, the estivation is imbricate; and if each member has one edge covered and the other uncovered, as in the corolla of Mallow? Evening Primrose^, Phlox, tfec, it is then said to be con- volute. Gamopetalous corollas are frequently plaited in the bud, and the plaits may be convolute, as in Morning Glory. Fig. 179.— Salver-siiaped corolla of Phlox. Fig, 180.— Labiate corolla of Turtle head. Fig. 181.— Personate corolla of Toadflax. THE STAMENS. 135 211. The Stamens. As calyx and corolla are called collectively the floral envelopes, so stamens and j)istil are spoken of collectively as the esxcntlal or^avs of the llower. The circle of stamens alone is sometimes called the andrmdum. A complete stamen consists of a slender stalk known as the filament, and one or more small sacs called collectively the anther. The filament, however, is not uncommonly absent, in which case the anther is sessile. As a general thing, the anther consists of two oblong cells with a sort of rib between thera called the connective, and tliat side of the anther which presents a distinctly ff waved appearance is the face, the opposite side ])eing the hack. Fig. 182. Fig. 183. Fig. 184. !rhe filament is invariably attached to the connective, and may adhere through the entire length of the latter, in which case the anther is adnate (Fig. 182); or the base of the connective may rest on the end of the filament, a condition described as innate (Fig. 183); or the extremity of the filament may be attached to the ijdddle of the back of the connective, ,:0 that the anther swings about : it is then said to be versatile (Fig. 184). In all these cases, if the face of the anther is turned towards the centre of the flower, it is said to be introrse ; if turned outwards, extrorse. Figs. 182, 183, 184.— Stamens showing adnr.te, innate, and versatile attach- ments of the anther. 136 KLEMENTS OF STIUJCTURAL RoTANY. The cells of anthers commonly open along their ontcr (!(lges to discharge their pollen (Fig. 185). In most of the Heaths, however, the i)ollen is discharged through a niinnte apertnre at tlu; top of each cell (Fig. 186), and in our Blue Cohosh each cell is provided with a lid or valve near the top, which opens on a kind of hinge (Fig. 187). Occasionally, examples of barren or abortive stamens are met with, as the fifth stamen in Turtle Head and Pentstemon. These are lilaments without anthers, and are known as stcmniodss. 212. Stamens may be either entirely distinct from each other — in which ciso they are described as diandrous, 'pcnta7i(lroiis, odaiidroiis, &c., according to their number (or, if more than twenty, as indefinite) — or they may be united in various ways. If their anthers are united in a circle, while the filaments are separate (Fig. .57), they are said to be sunaencsiuiis : but if the filaments unite to form a tube, while the Figs. 18:3. 1S7. 18G. anthers remain distinct, they are said to be mpnadelpJwus (Fig. 32) ; if they are in two groups the;y are diadelphous (Fig. 37) ; if in three, triad elphous ; if in more than three, poh/adclpJiotis. 213. As to insertion, when stamens are inserted on the receptacle they are huporjjpious ; when borne on the calyx, pGfi^Jinousj when borne on the ovary, eing^nous ; and if inserted on the corolla, epipetalojis. They may, however, be borne even on the st^le, as in Orchis, and then they are described as gynandrous. 214. If the stamens are four in number, and in two Figs. 185, 186, 187.— Anthers exhibiting iMfferent modes of dehiscence. TUB PISTir.. 137 pairs of (lifrcreiit Icngtlis, they mv- siiid to bo (hili/uamofi.^ (Fig. GO); if six in ninuIuM', fuiu- long and two sliort, tlioy aro fctrcuhjucutLom (Fig. 28) ; and, finally, if I ho Ktaniens aro liitldon in tho tulu' of a gamo})etaloiis corolla they are said to he indiuh'd,, hut if tlioy protrude beyond the tube they aro ex^^erted (Fig. 177). 215. The Pistil. This is the name given to the central organ of the flower. It is sometimes also called the fjljnairtum. As in the case of the stamens, the structure of the pistil must be regarded as a modification of the structure of leaves generally. Tho pistil may be formed by the folding of a single carpellary leaf, as in the Bean (Fig. 188), in which case it iii swff)Ie ; or it may consist of a number of car[)els, either entindy separate from each other or ui ted to'^ether in various ways, in whieh case it is compound. By some botanists, however, the term com})ound is restricted to tho case of united carpels. If tho carpels are entirely distinct, as in Buttercup, the pistil is apocarpous ; if they are united in any degree, it is syncarpous. A pistil of one carpel is mo7iocarpcllar jj ; nf two, dicarpellarij ; and so on, to pohj carpellary. 216. The terms inferior and superior^ as applied to the pistil, describe its situation upon the axis relative to that of the calyx, corolla, and stamens. It will l)o remembered that the end of the peduncle is usually enlarged, forming what is called the torus or receptacle. Usually the receptacle is a little highei' in the centre Fig. 188. — Legume of the Bean. ii 138 ELEMENTS OP STRUCTURAL BOTANY. I than at its margin, and as the gynoccium occupies this central part, its position is above that of the other floral leaves, as shown in Fig. 189. Here the pistil is svppvior, and the stamens and petals liypogynous. But frequently the outer part of the receptacle grows moi'o vigorously than the centre, forming, in fact, a cup with the pistil in the bottom of it, and the stamens and petals around Fiff. 189. Fijf. 190. Fig. 101. its margin (Fig. 190). In this case the pistil may be described as half-inferior, and the stamens and petals as perigynous. Often the cup-shaped receptacle .rows fast to the ovary all round. In other cases, the carpels, instead of being developed fror.i the bottom of the cup, spring from the margin, thus forming a roof-like disk, around the edge of which the stamens are attached (Fig. 191). Here the stamens are epigynous, and the ovary is truly inferior. Otiier cases of epigyny and perigyny arise from the adnation (grcnving together) of the floral whorls without exceptional development of the Figs. 189, 190, 191. — Diagrams illustrating hypogynotis {II), perigynous {P), and cpigyiiotiH (/'/') flowors ; a, axis; /r, calyx ; c, corolla; jS, stamens; /, carpels ; n, stigma ; sk, ovulo. (Prantl.) THE PISTIL. 139 teceptacle. The cases of the Rose, Cherry, and Apple have ah'eady been referred to (Chapter YI.). 217. In our examination of tlie ]\rarsh Marigold (Figs. 21: and 25) we found an apocarpous pistil of several carpels. We found also that each carpel contained a number of seeds, and that in every case the sewls were attached to that edge of the carpel wliich iras turned towards the centre of the fiower^ and that, as the carpels ripened, tliey invariably split open along that edge, ])ut not along the other, so that the carp(^l when opened out presented the appearance of a leaf with seeds attached to the margins. The inner edge of a simple carpel, to which the seeds are thus attached, is called the ventral suture, the opposite edge, corresponding to the mid-rib of a leaf, being the dorsal suture. 218. If we suppose a number of simple carpels to approach each other and unite in the centre of a flower, it is evident that the pistil r,o formed would contain as many cells as there were carpels, the cells being separated from each other by a douhle wall, and that the seeds would be found arrang(;d about the centre or axis of the pistil ; and this is the actual state of things in the Tulip, whose pistil is formed by the union of three carpels. When the pistil ripens, the double walls separating the cells split asunder. To these separating walls the name dissepiment or ])artition is given. 219. The cells are technically known as loculi. An ovary with one cell i^ unilocidar : with two, bilocular ; with several, muJtiloru/ar. Between the unilocular and inultilocular forms there are all shades of gradation. In some cases, as, for example, in Saxifrage, the carpels f*lt I M ^•^ n iVJ T Bt IE 140 ELEMENTS OF STRUCTUPAL BOTANY. are united below but separate above. Sometimes, also, false partitions are formed across the loculi in the course of growth. In the Mints, for instance, there are at first but two loculi ; eventually, however, there are four, which completely separate at the time of ripening. 220. But it often happens that though several carpels unite to form a compound pistil, there is but oiia ('ell in the ovary. This is because the separ- ate carpellary leaves have not been folded before uniting, but have been joined edge to edge, or rather with Fig-, 193. Fig. 192. their edges slightly turned inwards. In these cases the seeds cannot, of course, be in the centre of the ovary, but will be found on the loalls^ at the junction of the carpels (Figs. Hy2 and 193). In some plants the ovary is one-celled, and the seeds are arranged round a column which rises from the bottom of the cell (Figs. 194 and 195). This case is explained by the early ol)literation of the partitions, which nuist at first have met in the centre of the cell. Special cases, how- ever, ai'e found in which no trace of parti- tions has been observed, and these must consequently be explained by the actual ^"' ' " '^" ^' upward growth of the axis into the centre. of the ovary. 221. In all cases the line or projection to which the seeds are attaclu^d is called the placfuta, and the term plclCentation has reference to the manner in which the placentas are arranged. Iji the simple pistil the placentation is mavginaJ or natural. In the syncarpous Fifrs. 192, 193.— Compound one-celled ovary of Mignonette. Figs. 194, 195.— Sections of ovary of a Pink, showing free central pla- centation. I" ■*' PHYLLOME AND TRICIIOME. 141 Fig. 196. K^ Fig. . 197, 103. pistil, if the dissepiments meet in the centre of the ovary, tlius dividing it into separate cells, the placentation is central or a.n/f ; if the ovary is one-celled and bears the seeds on its walls, the placentation is parietal ; and if the seeds are attached to a central colunni it is free central. 222. Besides the union of the ovaries there may also be a union of the styles, and even of the stigmas. 223. A very exceptional pistil is found in plants of the Pine Family. .Here the ovules, instead of being enclosed in an ovary, are usually simply attached to the inner surface of an open carpellary leaf or scale, the scales fornnng wjiat is known as a cone (Figs. 196, 197, and 198). The plants of this family are hence called (jijumot^permous, or naked-seeded. 224. Nectaries. This name is given to that part of a flower which has been specially formed for the secretion oi honey. The nectaries need not, however, be looked upon as separate or independent organs. Sometimes they are to be found at the base of the petals, as in Buttercup ; sometimes at the base of the stamens, as in the Grape. Very connnonly they are at the bottom of :leep spurs formed on one or more divisions of the perianth, as in Violet, many Orchids, and in Columbine. 225. Phyllome and Trichome. To all leaf-forms, whether ordinary foliage-len i or those special modifica tions which make up the flower — sepals, petals, stamens, Fipf. lOfi.— A cono. Fi^'. 197. - Sitiulti scale showing position of the tu'C seeds on the inner face. Fi":. 19S. — One of the winded bceds removed. '.■■m il^ 142 ELEMENTS OP STRUCTURAL I30TANY I n !! and carpels — the general term 2)^njllonie is applicable. The characteristic of the phyllome is that it is a lateral outn;Towth of the stem or its branches. 226. The term triclwme, on the other hand, is applic- able to any hair-like appendage on the surface of the plant generally, whether of root, stem, or leaf. The commonest form of trichome is the hair. The root- hairs which generally clothe the surface of young roots are of great importance as absorbing agents. Each root-hair consists of a single, delicate, tube-like cell with extremely thin walls. Other hairs may consist of several such cells placed end to end. Others, again, may branch extensively. It sometimes liappens that the terminal cell of a hair produces a gummy substance which comes away with the slightest touch. The sticky surfaces of many common plants are due to the presence of such hairs, which are then described as glandular. Gummy matters are also secreted by glands close to the surface of the plant. Peltate hairs are occasionally met with, as in the leaves of Shepherdia. They give a scurfy appearance to the surface upon whicli they grow. Then there are hairs which secrete odorous fluids, as, for example, those upon the surface of the Sweet Brier- These probably serve to attract insects. Stinging hairs are also common. They contain an irritating fluid. When the point of the hair pierces tlie skin it is broken oflf, and the Ikiid then escapes into the wound. 227. Besides the trichome forms just mentioned, there are also hri^tles^ formed from hairs by the gradual thick- ening and hardening of their walls, and pricHes, such as those of Sweet Brier (Fig. 199), which consist of many THE FRUIT. 143 Fig. 200. Fijj. 199. hard-walled woody cells closely packed together. That prickles are really trichomes is shown by the fact that when the bark is stripped off they come away along with it. Spines^ on the other hand (Fig. 200), are lateral outgrowths of the stem. They are, in fact, gener- ally stunted branches, and will be found to spring originally from the axils of leaves. Occasionally the petiole of a leaf is converted into a spine, which then becomes a true phyllome. Ovules are generally regarded as trichomes since they arise from the inner surface of the carpels. 228. The Fruit. In coming to the consideration of the fruit, you must for the present lay aside any popular ideas you may have ac(|uired as to the meaning of this term. You will find that, in a strict botanical sense, many things are fruits which, in the language of common life, are not so designated. For instance, we hardly speak of a pumpkin or a cucumber as fruit, and yet they arc clearly so, according to the l)otanist's definition of that term. A fruit may be defined to be fJie riponed pistil together witli any other orga)), fericarp. This pericarp, with the seed which it contains, is the fruit. The principal difference between the fruit of jM-irsli Marigold and that of Buttercup is that, in the former, the pericarp envelopes several seeds, and, when ripe, splits open down one side. The fruit of Buttercup does not thus split open. In the Pea, again, the pericarp encloses several seeds, but sj^lits open along both margins. The fi-uits just mentioned all result from the ripening of apocarpous pistils, and they are consequently spoken of as apocar])nus fmits. 230. In Willow-herb, you will recollect that the calyx- tube adheres to the whole surface of the ovary. The fruit in this case, then, must include the calyx. Wheu the ovary ripens, it splits longitudinally into four pieces (Fig. 41), and, as the pistil was syncarpous^ so also is the fruit. 231. In the Peach, Plum, Cherry, and stone-fruits or drupes generally, the seed is enclosed in a hard shell (i'dWiiCi a 2)ntanien. Outside the putamen is a thick layer of pulj), and outside this, enclosing the whole, is a skin- like covering. In these fruits all outside the seeds is the pericarp. In one respect these stone-fruits resemble the THE FRUIT. 145 fruit of the Buttercup : they do not split open in order to discharge their seeds. All fruits having this peculiarity are said to he indehiscent, ^vllilst those in which the pericarp opens, or separates into pieces, are dehiscent. 232. In the Apple (Fig. 50) and Pear, the seeds are contained in five cells in tlie middle of the fruit, and these cells are surrounded by a firm fleshy mass, which is mainly an enlargement of the calyx. In fact, the remains of the five calyx-teeth may be readily detected at the end of the apple opposite the stem. As in Willow-herb, the calyx is adherent to the ovary, and therefore calyx and ovary together constitute the pericarp. These JJesliy fruits, or ])07nes, as they are sometimes called, are of course indehiscent. 233. In the Currant, as in the Apple, you will find the remains of a calyx at the top, so that this fruit, too, is inferior, but the seeds, instead of being separated from the mass of the fruit by tough cartilaginous cell-wall^, as in the Apple, lie imbedded in the soft, juicy pulp. Such a fruit as this is a herry. The Gooseberry and the Grape are other examples. The Pumpkin and other gourds are similar in structure to the berry ; but, besides the soft inner pulp, they have also a firm outer layer and a hard rind. The name pepo is generally given to fruits of this sort. 234. A Raspberry or Blackberry (Fig. 201) proves, on examination, to be made up of a large number of juicy little drii[)es, aggregated t^'j?- 201- upon a central axis. It canuot, tlierefore, be a true berry, but may be called an aggregated fruit. w I Fig:. 201. — Aggregated ruit of the Raspberry. 146 ELEMENTS OP STRUCTURAL BOTANY. I I *l ■*.y 235. A strawberry (Fig. 202) is a fruit consistin^^ chiefly of a mass of pulp, having its surface dotted all over vi^ith little carpels (achenes), similar to those of the Buttercup. The flesh of the Strawberry is simply an enlarged recep- tacle ; so that this fruit, also, is not a true berry. 236. The fruit of Sweet Brier (Fig. 45) Fig. 202. consists of a red fleshy cfiyx, lined with a hollow receptacle which bears a number of achenes. This fruit is, therefore, analogous to that of the Strawberry. In the latter the achenes are on the outer surface of a raised receptacle, while in the former they are on the inner surface of a hollow receptacle. When other parts of the flower are combined with the ovary in fruit, as in Api)le, Rose, and Strawberry, the result is sometimes described as a pseudocarp^ or spurious fruit. 237. The cone of the Pine (Fig. 116) is a fruit Avhich differs in an important respect from all those yet mentioned, inasmuch as it is the prcxluct, not of a single flower, but of as many flowers as there are scales. It may, therefore, be called a collective or multiple fruit. The Pine Apple is another instance of the same thing. 238. Of dehiscent fruits there are some varieties which receive special names. The fruit of the Pea or Bean (Fig. 188), whose pericarp splits open along Z/o^A margins, is called a legume ; that of Marsh Marigold (Fig. 25), which opens down one side only, is a follichi. Both of these are apocarpous. Fig. 202.— Section of a Strawberry. THE FRUIT. U7 239. Any syiicarpous fruit having a dry ilehiscent pericarp is called a cai>sule. The dehiscence of syncarpous or polycarpellary fruits is of several kinds. If the ruptuii; takes place along the partitions the fruit will he split up into its original carpels ; this form of dehiscence is septicidal (Fig. 203). But the dehiscence may take place along the dorsal suture of each carpel, half- way hetween the partitions, so that the opening is into the loculus ; this ■^'^- ^'^^- mode is known as loculicidal 204). Or again, the valves (separate pieces of the pericarp) may fall away, leaving the partitions stamling ; this dehiscence is septifragal (Fig. 205). 240. A long and slender capsule having two cells separated by a membranous partition bearing the seed, and from which, wlien ripe, Fig. 204. the valves fall away on each side, is called a silique (Fig. 206). Tf, as in Shepherd's Purse (Fig. 29), the capsule is short aiul broacllin(i self-fertilization. Ikit it is well (established that in a vast number of cases the ovules in any given nower liave to depend for fertilization upon the pollen of some other flower. Nature seems to have provided against self-fertilization by various contrivances. Some- times the relative positions of the anthers and the stigma in the same flower are such as to render it impossil>le. Sometimes the pollen comes to maturity and is shed from the anthers before the stigma is in a suitable condition to receive it ; whilst, on the other hand, the stigma is often developed first and has withered before the opening of the anthers. (Flowers showing these peculiarities are said to be didiogamou^.) When for any reason cross- fertilization has become a necessity, the conveyance of the pollen from one flower to another is ensured in various ways. When the flowers are inconspicuous, as in Grasses, the wind is the great agent, and flowers so fertiL*,:ed are said to be anemophilons. In other cases the flowers, cither by their brightness or their odour, attract insects in quest of honey, and these then become the carriers of the pollen. Flowers of this sort are said to be ento}n(jpldl()iis, and are usually so constructed as to the situation of tlieir honey receptacles, and the relative position of anthers atid stigma, as to ensure the transfer of the pollen from the anther of one flower to its destination upon the stigma of another. The case of the Orchids has already been referred to in section 92. 248. After fertilization, the embryo, or young plantlet, as exhibited in the seed, begins its growth in that end of 152 ELEMENTS OF STRUCTURAL BOTANY. the embryo-sac which is next the micropyle, and about the same time, in the other end of the eiubryo-sac, there begins a deposit of matter intended for the nourishment of the embryo during the germination of the seed. This deposit has been ah-eady referred to under the name of albumen. lu is also known as endosperm. As the embryo developcs, this endosperm or albumen may be completely absorbed by it, so that at maturity the embryo will occupy the whole space within the seed-coats, as in the Bean. In this case the seed is exalbuminous. In other cases, as in Indian Corn, tho endosperm remains as a distinct mass with the embryo embedded in it, or sometimes wrapped round it. Seeds of this kind are albuminous. Rarely this nourishing material is deposited outside the embryo- sac, in the body of the ovule. It is then known as perisperm. 249. The ripened seed presents very different aspects in dilfei'ent plants. It may be resolved, however, into the nucleus and the integumeiiv (the spermoderin of some botanists). The former is made up of the embryo, together with the endosperm or perisperm, if present, while the latter consists of two layers: an outer, known as the testa^ and an inner, the tnjnien. The scar showiivj, where the seed has beon attached to the placenta is called the hilum ; it is very distinct in the Bean. 250. Besides the integument just mentioned, occasionally an additional outer coat is formed, to which the term aril is applied. The fleshy red covering of the seed in our Ground Hemlock is a good example. 251. The seeds of Willow-herb, Milkweed, and many other plants are furnished with tufts of hair-like bristlQS I ;,1 GERMINATION. 153 which facilitate their dispersion by the wind. These tufts grow from the testa of the seed, and are not to be confounded with the pappus of the Thistle, Dandelion, Ac; the latter, it will be remembered, is an outgrowth of the calyx. 252. The embryo, as already explained, generally consists of an axis or stem called the radicle (or, more properly, the cmdtde, because it is in all respects a true stem and not a root), and one or more leaves called coiyledonn, with sometimes, also, a bud known as the plumule. As to the number of cotyledons, it may be repeated here that seeds are, as a rule, either dicotyle- donous or monocotyledonous. Some plants of the Pine Family, however, have six cotyledons, whilst, on the other hand, in the Orchids and a few other plants, these organs are altogether wanting. \ 253. The cotyledons vary greatly in thickness. In the Maple, for example, they are very thin, while in the Pea, the Bean, and the Oak they are extremeJy thick and fleshy. 254. Germination. If a seed is supplied with proper warmtli and moisture it soon begins to swell and soften by absorption of water, with the effect of bursting the seed-coats to a greater or less degree. At the same time the process of f/rowfh is begun. This early growth of the embryo is (lenniuation. Tlie details of the process vary somewhat according to the structuie of the seed. In dicotyledons, if the seed-leaves are thin and leaf-like, containing within theniselves but scanty store of nourish- ment, tiie ratlicle will grow throughout its length sTo as to raise the jotyledona above the soil, where they at once ■ >\ 154 ELEMENTS OF STRUCTURAL BOTANY. :i' expand and become the earliest leaves of the new plant ; and during this upward extension of the radicle a root alsso is being rapidly developed from its lower end. It is important, also, to notice here that tlie mod^^ of growth of tlie root portion is at variance with that of the radicle or stem proper, for while the latter grows Uivowjhuut its_ iGmjthjJhsi former grows by the addition of successive ne\y_ portioiis to its extremity. (The protection of the growing root by a root-cap has already been referred to.) As soon as the root is prepared to absorb nourishment from the soil, then, and not till then, the development of the next bit of stem commences between the first pair of leaves. 255. But when the cotyledons are loaded with nour- ishment, as in the Bean, it will generally be found that the elements of additional ])its of stem (the plumule) are already present in the embryo, and although the radicle may lengthen so as to lift tlie cotyledons above the surface, yet these do not, as in the thin-leaved embi-yos, fully perform the office of foliage-leaves ; their true function is to supply the newly developing parts with nourishment, and when this duty is performed they usually drop off. In fact, it is not uncommon for such extremely il(;shy cotyledons to remain under the surface altogether, as in the case of the Pea and the Acorn. In these cases the growth of the radicle is but slight. The plumule and the end of the radicle are lil)erated from the seed, and the former at once grows vigorously upward, being practically independent of the root as long as the stock of nourislnnent in the cotyledons holds out. Simultaneously with the development of the stem, the root is strongly developed from the end of the short radicle. GERMINATION. 155 258. In the monocotyledons the process of germination is much the same as that just described, with the important dilference, however, that the primary root from the end of tlie radicle can scarcely be said to develope at aii, a cluster of librous roots bursting out almost at once from its sides. Indian Corn answers very well as an illustration. Here the seed, largely made up of endosperm or albumen, remains in the ground. The single cotyledon is wrapped round the plumule and adheres by its back to the endosperm, acting thus as a medium through wliich nourishment is absorbed, and of course not being carried up to the surface. The plumule is rapidly carried upward, developing alternate leaves, and the numerous fibrous roots are given off from the sides of the short radicle. 257. The young student is strongly recommended to investigate for himself the phenomena of germination as exhibited in common seeds. For this purpose he may place a few Windsor beans and grains of Indian Corn between layers of moist flannel or coarse paper in a shallow dish. If kept damp, germination will begin in a day or two, and if suiHcient specimens have been provided the process may be observed at various stages. Trial should also be made of the length of time during which seeds will retain their vitality. Many seeds, such as those of Elm and Poplar, will be found to germinate only if they have been kept fresh and not permitted to dry up, whilst others, such as Indian Corn and Wheat, and in general those containing starch, may be kept for a very long time without losing their germinating power. w 156 ELEMENTS OF STRUCTURAL JJOTANY. l\ 1 ■ CIIAPTKU XIX. ON THE MINUTE .STUUOTURM Ol'^ PLANTS — THE CELL TISSUES — TISSU K-S YSTK MS — KXO(} lONOUS AMi> KNDOCiKNOUS STEMS. 258. Up to this point wc liavo 1)goii (iiigagcd in observ- ing such particulars of structure in j^lants as arc manifest to the naked eye. It is now time to en([uire a little more closely, and find out what we can ahout the c/fnianfari/ structure of the diti'iM-ent organs. We iiave all observed how tender and delicate is a little planil(>t of any kind just sj)routing from the seed ; but as time elapses, and the plant developes itself and acijuires strength, its substance will, as we know, assume a texture varying with the nature of the plant, either becoming hard and lirni and woody, if it is to be a tree or a shrub, or continuing to bo soft and compressible as long as it lives, if it is to be an herb. Then, as a rule, the leaves of plants are of (juite a different consistency from the stems, and the ribs and veins and petioles of foliage-leaves are of a liriuer texture than the remaining part of them. In all plants, also, the newest portions, both of stem and root, are extremely soft compared with the older parts. It will be our object in this chapter to ascertain, as hiv a."> we can, the reason of such dillerences as these : aivd to accomplish this we shall have to call in the aid of a microscope of nmch higher power than tliat which has hitherto served our purpose. 259. First let us examine under our microscope a very thin slice of the pith of the Elder. You see at once thaw i!f -J ^ THE CEf-L. 16? E CELL Fig. 2U. the whole slice is made up of more or less rounded, nearly transpiiront bodies, rather loosely thrown together, as shown in Kig. 21'». Next h^t us examine, in the saine way, a thin slice of the tuher of the Potato. Here, agaiji, it is evident that the object under examination is wholly composed of en- closed spaces, not so much rounded, how- ever, as th()S(^ of the Elder pith, because they are mort; closely packed together. * Fig. '2 1 4 is a repres(;ntation of two of the;... spaces. Now look at the leaf of a Moss, and you see again that we have an aggregation of enclosed si')M,ceH as befoj'e (Kig. '215). So, also, if we examine a hair from the surface of a P(!tunia or a Geranium, we have some such app(\'ii'ance presented to us as that shown in Figs. 210 and 217, the hairs manifestly consisting of several enclosed spaces placed end to end. In short, the microscope reveals to us the ' fact that every part of a plant is made up of such enclosed spaces, varying greatly in shape and size and general aspect, it is true, but always (except in some of the V(;ry lowest plants) clearly exhibiting bound- aries ; and since these boundaric^s are visible, no matter in what direc- tion we make our cutting, it is clear Fij,'. 214. that the spaces must be shut in on all sides. These enclosed spaces are called rclis, and their boundaries are known as the cdl-)mUs. Fijf. 218. - LooHoly-packcd colla of EUlcr-pith. FiR. 214.— Two cells of I'otato tuhor oontiiiiiliijr starch-granulot: and ctvs- talloids. (Gray.) 158 ELEMENTS OF STRUCTURAL BOTANY. 1 :i II ill! !i; ' il i 260. Whilst looking at the parts of plants just sub- mitted to examination, it nnist have struck you that the interior of the cell presents a very dif- ferent appearance in different cases. The Potato section, for example, is not at all like the Moss-leaf section in tiie matter of ceU-conffids, and the cells of the Elder- pith appear to be quite empty. We shall discuss these dillei-ences presently. In the meantime let us study the appear- Pj,. oj.^ ance of some cells taken fresh from son ^ part of a plant where growth is actually goini? on — say the point of a new rootlet. If our section is taken near enough to the point we shall ^^^^^^^^^^""^-.^.^^ / get cells which "■^~^^^:::::-~^X' have just been ^ ^^ \ formed. Such a *''^""^^- Fig. 2i7. section is very well shown in Fig. 218. Here the cells are seen to be completely tilled with liquid having a Ftpr. 215.— Cells from leaf of a Moss containing protoplasm and chlorophyll- granules. Fig. 216.— Hair from Petunia leaf. Fig. 217.— Hairs from Geranium leaf. ttie cell. 159 tlet. If our \\>\ chlorophyll- Jcraiiiuin leaf. granular appearance, and in the centre of each a rounded denser portion may be made out, each of these again enclosing one or more smaller bodies. This li(iuid which thus tills the newly-formed cells is cii\\ed2ir()to2)/ai<^i ; the large rounded central mass is the nucleus, consist- ing of denser protoplasm, and the smaller enclosed masses are the nucleoli. Now let us consider Fig. 219. This is a representation of a section of the same rootlet, taken a little farther back from the point, so that the cells now in view are a little older than the first ones. They are manifestly larg(;r ; that is to say, they have groioii. The nucleus and the nucleoli can still be made out in some of them, but the protoplasm no longer entirely [ills tlie cell. There are now transparent spaces {vacuoles) which are tilled with water, and between these the protoplasm is seen in the form of strings or bands, as well as lining the cell. The water has been absorl^ed through the cell-wall, and after saturating the protoplasm the excess has formed the vacuoles. Fij,'. 218.— Young cells filled with protoplasm (/>) ; h, cell wall ; h, nucleus ; kk, nucleolus. (Sachs.) Fig. 219. — Cells a little older, exhibiting' vacuoles (s). (Sachs.) Fijr. 219. V. rl ■ %i 160 ELEMENTS OF STRUCTURAL BOTANY. Fig. 220 shows some cells from the same rootlet taken .till farther back. It is clear that the change observed n Fig. 219 has been carried to a still greater extent. In some of these cells the proto- plasm is restricted to the lining of the cell and the nucleus. 261. It is now to be observed that the protoplasm is the es- sential part of every living cell, ^a, *^^i II Through its agency all the vital v| H Ir processes of the plant are carried on. Every cell of every plant at some time or other contains this substance, and when at length it disappears the cells which are deprived of it no ^Monger take any active part in the growth of the plant, but serve merely mechanical purposes, such as that of support or conduction, and are in that stage of their history filled usually with air or water. The pith of the Elder is made up of such dead cells, as is also the greater part of the wood and bark and older parts generally of all plants. 262. The most marked feature of the living protoplasm is its adivify. We may observe this property by Fig-. 220. — Cells still older; h, the wall; s, vacuoles; p, protoplasm; /r, nucleus; xii, swelling of tiuclcus caused bj' water used in preparation of the bcctiou. (Saoha.) Fig. 220. THE CELL.* 161 examining plant-hairs and other parts under high powers of the microscope, when it will be seen that there are movements of two kinds. The whole mass of protoplai'- has a rotary motion, sliding, wpon the cell-wall, dov^vi wards on one side and upwards on the other. This is the 77iafis-7novem^]2L^ Also, currents may be traced passing across the protoplasm in different directions. This is the streaming-movement. In some o£ the very lowest plants, where there is no cell-wall, and the whole is a mass of naked protoplasm, these movements may be observed m( ^e readily because they are less restricted. 263. There is some doubt as to the exact chemical composition of protoplasm. It is, ho .vever, a very complex substance belonging to a gro _) of bodies known as albuminoids^ _of which nitrogen is an important con- stituent. The consistence of protoplasm depends upon the amount of water it contains. In dry seeds, for example, it is tough and hard, but when the same seeds are soaked in water it becomes partially liquid. 264. Forms of Cells. As cells become older they tend as a rule to change their form, though sometimes we find them differing but little from their original conformation. Com- monly a cell grows more rapidly in some one direction, thus giving rise to long forms, as is ^Jff- 221. the case in stems generally, and in the petioles and veins of leaves, the superior toughness and strength of which Fig. 221. — Prosenchyma of the wood. (Gray.) 1G2 ELEMENTS OP STRUCTURAL BOTANY. are dnc to the lengthening and hardening of the cells of which they are composed (Fig 221), 265. The Cell- wall. In the portions of plants just selected for microscopic examination we have seen that the protoplasm is in every instance bounded by a wall. It has been ascertained that the wall is kl chemical com- pound of carbon, hydrogen, and oxygen, and to this compound the name cellulose has been given?| We have said that the protoplasm is tiie active principle through the agency of which all the vital processes of the plant are carried on. It contains at some time or other every constituent of the plant. The cell-wall is itself, tlierefore, a product or secretion of the protoplasm, and is at first an extremely thin film, which, however, gradually increases in thickness by the addition of further material. This new material is deposited between the molecules of the original film, and so extends not only the surface of the wall, but, by deeper deposits, the thickness also. This process of acquisition of new material is known as 'hdussuscep tio n . 266. As the wall between two cells increases in thick- ness, a distinct middle layer is discernible in it, known as the middle lamella. This portion of the common wall is different m chemical com[»osition from the rest, so that it may, under proper treatment, be dissolved and the ceils thereby separated. 267. It is in the earlier stages of their history, while the walls are comparatively thin, that the cells possess the greatest activity. By these alone is carried on the process of growth, which consists in the multiplication and enlargement of cells. THE CELL 163 268. It is seldom the case that the wall is thickened uniformly. Often numerous round thin spots are left, so that the cell has a dotted appearance (Fig. t^22), When the thin spots in adjacent cells arc contiguous, as they commonly are, a ready means of inter- communication is atibrded. Sometimes the spots, instead of being round, are oblong, so that the cell under the microscope presents a ladder-like appearance, and so is said to he^calwjjMiii. Then again, the thickening may take the form of spiral bands upon the inner surface ; or, instead of a continuous ^spiral band, we may tin d a series of Fig. 222. isolated rings^ when the marking is said to be aiimdar. Eeticulatcd cells arc also found, in which the markings, as the name implies, form a sort of network on the walls. Several of these forms are shown in Figs. 223 and 224. 269. Sometimes round thin spots will be left in the wall, and over each of these a thick-walled dome with an opening at the top will be formed. At the same time a similar dome is raised at exactly the same spot on the other side of the wall m the next cell ; and, finally, the thin par- tition between the opposite domes breaks away, permitting free communication. Thus are formed what are called havdpfpd. Fig. 223. Fig. 224, 'pits, which abound in the wood of Conifers. 270. When cells stand end to end, and thin spots are Fig. 222.— Dotted duct. (Gray.) Fig. 223.— Spiral and annular mai'kings on cell-wall. (Gray.) Fig. 224.— Various marltingp on cell-wall. (Gray.) \ " ^^3" ^^s?- \k 164 ELEMENTS OF STRUCTURAL BOTANY. loft in tho cross-partitions between them, sieve-cells are formed. Here, again, the thin spots linaiiy disappear, thus practically uniting adjacent cells. 271. It sometimes ha)>pens that tho thickening takes place throughout tho length of a cell but in its anribiH onlij. Cells of this kind, which are often found im- mediately under tiic surface of the stem in the higher plants, are called collcncJiyma cells. 272. Besides the markings on the inside, cells often show markings on the outside. The pollen-grains of the Mallow, for instance, are seen under the microscope to be covei'ed with pointed projections. Other pollen-grains, also, exhibit outside markings of diiienuit sorts. 273. The thickening deposit may be so excessive in some cases as to almo.st completely fill up the cavity of the cell (Fig. 225). The shells of nuts and the tough coatings of seeds consist of cells of this kind ; but even in these cases the wall may be seen to be traversed by slender pores or canals, either simple or branched, radiating from the centre of the cell. To these hardened cells the name srh'zem'.hiima is applied. 274. The Contents of Cells. If you look at Fig. 215, or, better still, if you have the op[)ortunity of viewing a Moss-leaf through a good microscope, you will see that in the protoplasmic lining of the cells there are numerous greenish, rounded granules. These are the bodies to which the green parts of plants owe their colour. They are called chloi'ophyll-granuleSy and consist of protoplasmic matter in which particles of green Fig. 225.— Sclerenchs'ma, the cell-cavity being almost obliterated. (Gr«^.y Fig. 226. jir ' \ THE CELL. 165 colouring matter are embedded. The colouring matter itself is clilorophyli, and may ])e dissolved out of the granules, leaving the latter as ordinary protoplasm. Almost without oxcopLion chlon)i)hyll re([uires the action of sunlight for its production, and the chlorophyll dis- appears from green parts when sunlight is withdrawn, as IS well seen in the process of bleaching celery. In many of our brightly coloured foliage-plants the chloropliyll is concealed from view by other colouring matters. In flowers various colours are found in the protoplasm, but these, unlike chlorophyll, are produced in darkness as well as in sunlight. 275. Chlorophyll is of the utmost importance to the plant, seeing that only in the cells which contain it, and in the presence of sunlight, can the materials which the plant imbibes from the soil and the air be assimilatpA^ that is, converted into matter which the plant can use for » the purposes of growth, 27G. Now consider Fi<^ 214. Here are exhibited cell- contents of an entirely dilferent aspect. The rounded bodies here visible are starch -tjranules^ as may be easily demonstrated by adding a drop of iodine solution to the Potato section under the microscope, a characteristic blue colour being at once produced. Such granules, differing somewhat in shape in different cases, abound in the cells of tubers 9 "id in grains of all sorts, where they have been stored up for use during the process of germination. They are originally formed during sunlight in th" chloro- "\ phyll granules of the green parts. When the light is / withdrawn, as at, night, they are dissolved and carr' d in V solution to other parts to promote growth or be / atorpd up. ^/ ^t '^.. a: c 1.. 166 ELEMENTS OF STRUCTURAL BOTANY, % - 277. If starch-granules be subjected to the action of saliva, it will be found that a portion of each granule is slowly dissolved out, leaving an insoluble skeleton behind. The granule, therefore, consists of two distinct parts, the more soluble portion being known as r/ran2cloHe, and the less soluble framework as starch-cellulose. 278. Crystals. These are of common occurrence in many plants, not only in the cell - cavities, but also imbetlded in the substance of the cell-wall. They are also of various wshapes, and may either occur separately or be massed together in clusters. The needle-shaped forms are known as i'a])hkles. These crystals consist for the most part of calcium oxalate, but calcium carbonate is also found, and may be readily distinguished from the former by the eilervescence occasioned on the addition of hydrochloric acid. The oxalate dissolves in this acid without eifervescence. Crystals may be readily observed under the microscope in thin secti(jns of acah^s from the Onion bulb, Khubarb, Indian Turnip, and many other plants. 279. In the leaves of plants of the Nettle Family it frequently happens that a wart-like growth of cellulose takes place on the inside of the cell-wall, the inwardly projecting mass being attached to the wall by a slender stalk, and having multitudes of small crystals imbedded in it. Such inward growths are called cf/stolifhs ; they may be readily seen in cross-sections of the Nettle leaf. 280. Crystalloids. Seeds, especially tliose of an oily nature, as they approach maturity and become dry, develope in their cells multitudes of small rounded bodies of an albuminous nature known as aleurone-grainSf and FORMATION OP NEW CKLLS. 167 occnrrence in »v a slender these often envelope minute substances of crystalline asi)ect, which, however, under the action of potash and other re-agents, inidergo such changes of form as to lead to the belief that they are not true crystals. They are called cnjstalloidd, and are to be regarded as forms of protoplasm. Occasionally crystalloids are observed without the albuminous envelope, as, for example, in the tuber of the Potato. Fig. 214 shows a cell having two or three such crystalloids of a cubical shape. The aleurone-grains in seeds containing starch fill the spaces between the starch-granules. In oily seeds, such as the Brazil-nut, they replace the starch. 281. Other cell-contents. Besides the important substances already enumerated as products of the proto- plasm, many others are found, such as sugar, inuline (a substance nearly related to starch, and found in a few special plants), fixed oils (castor, olive, linseed, &c., chiefly in seeds), essential oils (turpentine, oil of lemons, and essences of different kinds), gums, resins, and various acids. 282. How new cells are formed. There are several methods by which new cells are jjroduced, but i:i the higher plants the common metliod is that of cel/- division. We have already stated that only the newer thin-walled cells are capable of exercising this function. The process is briefly as follows : in the cell about to divide, the protoplasm first se})arates into two portions, each containing part of the nucleus ; then a partition-wall of cellulose is develojted between the two portions, tlius forming two cells out of the original one. Each part then 168 ELEMENTS OP STRUCTURAL HOTANY. \U' enlarges and divides again, and so the process goes on. When cell-division takes place in one direction only. filaments or threads are formed ; if in two directions, surfaces are "formed ; while division in three directions gives rise to masses. It is evident that every part of a plant, however much altered in its later history, must in its earlier stages have consisted of this thin-walled cellular substance, or mei'istem^ as it is called from its power of dividing. 283. Cell-division, then, is the method of new cell formation which prevails in the vegetative parts of the higher plants. In the production of pollen, however, and of the spores of vascular cryptogams, four new nuclei are formed in the cell, and the protoplasm collects about tliese, eventually secreting walls, so that four' new and complete cells are formed wltJiin the original one, and these sooner or later make their escape. This mode is known as fTee_cell-formation. In the production of the endo- sperm cells in the embryo-sac and the spores of many of the lower plants a similar process goes on ; but here the division of the nucleus is not limited to four portions, as in the cases just mentioned, but may be carried on to an indefinite extent. 284. In some lower plants the entire contents of two adjacent cells may coalesce to form a single new cell. This mode is known as roirJaQafimi. Also, the contents of a cell may contract and dovelope a new cell-wall, a process known as the rejuvenesj^^ce or renewal of a cell. 285. Tissues. An aggregation of similar cells is called a tissue. Originally, every part of a plant consists of 7neristcm, that is, of cells capable of dividing. But TISSUES. iGa changes set in, as we have seen, at a very early stage, and eventually all the cells assume pcrnianott forms, some developing in one way, others in quite a diilerent way, according to the function of each particular part. So that in any given plant we find tissues, or groups of cells, of very various kinds, and very different arrangements of these tissues in different cases. By examining sections taken in succession from the growing point backwards, every degree of change from meristem to permanent tissue may be made out. 286. In the growing parts of all plants, in the pulp of fruits, in the pith, in the green parts of leaves, and in the entire substance of many plants of low organization, we find tissue composed of short and comparatively thin- walled cells, to which the name parpiiclnima has been given. On the other hand, in the sul»stance of wood, in the inner bark, in the petioles and veins of leaves, tfec, we meet with tissue consisting of long, pointed, and overlapping cells, and known as /mit^cnrl/'/ina. That of the wood hfibroui^ tissue, and that of the inner bark is the had, specially characterized by the extraordinary length and flexibility of the cells. Sclerendnjma and coUeucht/ma have already been referred to. In the former the cells are commonly, though not always, short; while in the latter they are usually long, but the ends are not pointed. 287. Cells have been described which are characterized by peculiar markings on their walls. When such cells stand end to en \, the cross-partitions conmionly dis- appear, with the effect of forming long tubes, generally of larger diameter than the other cells with which they i (* I » ^^ i^; f:ii 170 ELEMENTS OF STROCTUPAT. !]OTi\NV. are associatod. Sucli largo cells i.\ kutiViJi .ih f^rsscls^ and tissue i'or'nicd of tlicui is called ?:a-!'-iil",,>, aiuiular, rcfirulntc'/, and (/(iff>"? vessels. These diller(>nt kinds of vessels are usually found associated with lihrous tissue, and the conilnnation of the two is known ;is th ) p'J/ro- rascular si/t^fmn. 288. INFany ]>lauts, such as Dandelion, iUood-root, ISIilkwced, and Spucge, (;niifc a coloured or milky juice wlieu wounded. This juice is technically called tlie lal(\i\ It is contain, d in a sin^ciai tissuii v/hicli is peculiar to such plants, known as /^in'/rro/:,^^ tissue. Its foi-ni difr(M's ill diiPei-cMit eases. In some instances it consists of long tuhes which may or may not l)ra,nch. Ju others, the cells composing it form a net-work. As in the case; of vess(»ls, the latex tubes are connnonly formed by the coalescence of cells originally separate, but sometimes by the continued apical growth of single cc-lls. 289. Sieve-tissue has been already i\oticed. The cells are usually rather wide, and the wrdls are not hardened, but the cross-partitions between the cells are thickened and perfo; aeU. . 290. It may be added that siuf/le eelh which resemble vessels in their markings are often spoken of as tmclwUU 291. Tissue-Systems. While groups of similar cells are d(\sign;i,ted tissues, we may have also different combinations of thene tissues in different plants, or in dillerent parts of the same plant, and these various combinations are known as t/.'Hfi. These are now usually i-anged under thret> heads: (1) The Ejmkruial Si/ah'r.i, includiiig those combinations of tissue which go to r TISSUE-HVSTEMi^, 171 form tho coverings? of }oung steuus, rn(,ts, and ler vey v, (2) Tii<: Fibn)ra^er opiil'Tniis, and loose tissue with intercellular spaces below the palisade cells. (Ora.v.^ 1'^ ii . A. 172 ELEMENTS OF STRUCTURAL BOTANY. I". fit '•f 293. An examination of the under surface of almost any leaf will show the presence of large numbers of oval openings, somewhat similar to that shown in Fig. 227. These are stomata. They are formed by two epidermal crescent-shaped cells with a space between them, and these have the power of separating or closing together according to circumstances ; separating in the light, in moist weather, and closing in dry. The 1 ji — \\j/ openings comnuinicate with uitnrcelhdar \ spaces in the body of the leaf, a number of which are seen in Fig. 226. In ordinary leaves with an upper and a lower surface, the stomata are far more numerous on the Irnl \\ lower side ; indeed, many such leaves are ' ^'~\ entirely without stomata on the upper sur- Fig. 227. face. Vertical leaves have them rather equally distributed on both surfaces. Immersed leaves and underground stems have hardly any at all, and they are never found on roots. The use of the stomata will be referred to presently. 204. The stems of Dicotyledons lose their epidermis at a com^'aratively carl}? period, and a tissue consisting of cells of corh^ filled with air, takes its place. These cork- cells are modifications of the C(;lls beneath the epidermis, and they form an effectual protection to the tissues ^vithi: , The skin of tlie Potato-tuber exhibits this corky layer very clearly. The special tissue from which the cork it developed is called phdluiJUn. 295. In the flbro-vascular system different plants exhibU a very different airangement of the component Fig. 227. — Stoma from the urfo'^e of a leaf, showiiisj the creBceiit-shapod guLird -cells. r '^-■:;: TISStfE-SYSTKMS. 17:^ tissues. As a rule, these tissues are capable of division into two groups, in one of which the wood is developed, and in the other the bast. To the former '^^ these groups the general term xiilcin is applicable, and t- ihe latter the term iililoem. The xyli^m is made up of the elongated woody cells with pointed and overlapping ends, already referred to as fibrous tissue, the wide tubes (vesagls) with variously marked walls, formed by the disappearance of the cross-partitions between cells placed end to end, and more or less short-celled tissue or parenchyma. The phloem is likewise made up of three constituents : the long, thick-walled, flexible cells called bast-cells, which correspond to the fibrous tissue of the xylem ; the wide thin-walled sieve::cells, corresponding to the vessels; and a certain amount of thin-walled parenchyma. 29G. The fibro-vascular hundlen^ as they are called, have their origin in the meristem of the growing point. This meristem is at first uniform, but soon groups of long cells arise in it, and these are then known as irrocainhiwjj^ to distinguish them from the surrounding ground- tissue. This procambium is gradually converted into the fibro-vascular bundles. Fig. 228. Hceiit-shapcd 297. In dicotyledonous ]ilants, the fibro-vascular bundles are more or less wedge-shaped, as shown in Fig. 228. The inner part of each bundle consists of xylem and the outef of phloem, and between the xylem and the phloem there is a layer of meristem, known as the cainhimn. The soft cells of Fig. 228.— Cross-section of a young dicotyledonous stem, showing sixbundles. IP 174 ELEMENTS OF STRUCTURAL llOTANY. '!* . i:;? the cambium divide, uud the new cells thus continually being formed become modified on the one hand into tissues which incaease tlie thi(.'kness of the xylem, and, on tho other, into tissues wliich are added to the phloem. Later on cambium cells are formed in the ground-tissue between the bundles, thus linking together the cambium-layers of the various bundles, and forming a continuous ring. Tho liid<:s are then known as interfascicular cambium, that of the bundles themselves being the fascicular. Bundles of this kind, characterized by the cambium-layer, and so capable of continuous enlargement, are called open bundles. 298. In monocotyledons, on the other hand, there is no cambium-layer, and consequently the bundle when once formed is incapable of further in- crease, and so is said to be closed. Fig. 229 is a representation of the cross-section of an endogenous stem in which many of these closed l)unilles '■re visible. Of course in such stems 1 0 bark is formed. 299. It has been explained that in the exogenous stem the xylem occupies one side of the fibre- vascular bundle, while the phloem occupies the other. In the closed bundles of Ferns and Club-^NFosses, as well as of some monocotyledons, however, a different arrange- ment prevails, the xylem occupying the central part of the bundle, and the phloem forming a circle around it. The foi-mer arrangement is described as collateral^ while the latter is concentric. In many of the monocotyledons, as well as in the exogens, the bundles are collateral. Fig. 229.— Cross-section of nionocotyledonous stem, showing' closed bundles. IJ d-T'VL^^ rf-'tV? — ' TIHSUE-HY.STEM3. 175 sed bundles. 300. Fig. 230 sliows a section of an exogonous stem somewhat older than that shown in Fig. 228. Here new buneUes have been formed between the earlier ones, so that the whole centre of the stem, except the jnfh and the lines radiating from it, is occupicul by the wood. This cylinder of wood is now encircled by a ring of cambium, beyond which are the tissues of the l)liloem. ,.. , .j.^i , 301. The appearance presented by ^^ the cross-section of an exogenous stem Fig. 230. is that of a series of concentric rings, each ring showing the limit of a year's growth. The; portions of wood formed late in the summer are more compressed by the outlying tissue than those formed iii spring, and lience the outer part of each year's ring appears^ denser, and is sharply marked off from the ring of the / following year. No growth of the cambium takes place ! in winter. The rays which intersect th(;se rings as fine \ lines consist of portions of the ground or fundamental \ tissue which have been squeezed into their present form by the increasing fibro-vascular bundles on each side of them; they are called medutlanj raij\ and, as the stc^n grows, new ones are formed from the cambium. Only tl)(^ primary ones, however, extend from the pith to the bark;/ those formed later are shorter. "^ 302. In roots a special arrangement of the tissues of the bundles prevails, the xylem and phloem forming alternate raij,^. This is the radial arrangement. 303. Tlie fundamental or ground tissue com- prises all the parts of the plant not already included in Fig. 230. —Section of an older dicotyledon, the bundles now forming a rinjjf. ii*M 17G ELEMENTS OF STRUCTURAL BOTANY. the epidermal and fibro-vascular systems. In the 3xogens it embraces the ^h, the medullary rays, and parenchyma generally. The collenchyma found just beneath the epidermis, sclerenchyma occurring in diffeient parts, and laticiferous tissue are also constituents of the fundamental system, as well as the cork cells already referred to. In the monocotyledons ground-tissue in the form of parenchyma lills the space between the closed bundles of the stem ; while in many plants in which fibro-vascular bundles are not produced, the ground- tissue constitutes the whole of the interior. 304. In exogenous stems the wood developed from the cambium is often different from that of the primary bundle as developed from the procambium. Pines, for example, have vessels in the primary X3dem, but none in the secondary, the latter being almost entirely made up of the cells with bordered pits, already described. 305. The bundles of the leaves are continuous with bundles in the stem. Leaves appear at first as protuber- ances on the side of the stem close to the growing point, and the upper ends of the primary bundles almost at the very beginning bend outwards towards the new leaves, the lower part being continued down the stem. In the monocotyledons these bundles first arch inwards towards the centre of the stem, and then outwards and downwards, thinning out as they descend. Hence, in a cross-section (Fig. 229) the bundles appear more crowded towards the cii'cumference, and also smaller. Such a stem is, therefore, found to bt^ harder at the outside than at the centre. CONSTITUENTS OP PLANTS. 177 CHAPTER XX 1<'00D OF PLANTS — CHEMICAL PROCESSES — MOVEMENTS OF WATER PHENOMENA OF GROWTH. 306. The materials of wliich tlio substance or a plant is made up are various, and some of tliem occur in far larger quantities than others. Water forms a very considerable percentage of the whole weight, but is present to a greater extent in some portions of a plant than in others. Fleshy roots, for example, may contain as much as 90 per cent, of water, while dry seeds contain only about 12 per cent. 307. The water may be expelled by careful drying, and if what is left is then burnt, what is called the organic part of the plant disappears, and a small quantity of «,s7i remains behind. The organic part is found to consist mainly of carbon, hydrogen, oxygen, nitrogen, and sulphur ; while the inorganic part (or ash) contains very small quantities of phosphorus, iron, calcium, mag- nesium, and potassium. All these materials are obtained from the air or the soil. There is constantly present in the air carbonic acid gas, a compound of carbon and oxygen, which is exhaled from the lungs of animals, and which is always found wherever wood or coal, or carbon in any form, is being burned. This gas is carried down in any form, is being burned. This gas is absorbed directly from the air by the leaves of land-plants, and (being soluble) from the water in which thoy live by innnersed plants. In the presence of chlot'ophyll and in sunlight the gas is decomposed into its carbon and oxygen. The excess of oxygen is then inhaled and the carbon chemically combined with the other elements to ,%. ^a. ^^W, ^.^.^a IMAGE EVALUATION TEST TARGET (MT-S) 7 {/ 4 / r/u « 1.0 I.I 1.25 • 50 ■"^™ ■■■ ■^ 1^ |2.2 2.0 us ME ^1^ V] /. ^% ^jf o 7 ?^.>t'> ^% Photographic Sciences Corporation 23 WEST MAIN STREET WEBSTER, N.Y. 14580 (71«) •7a-4S03 l\ iV rO^ ^ 1)8 ELEMENTS OF STRUCTURAL BOTANY. form starch for purposes of growth. The oxygen required by the plant is derived chiefly from the carbonic acid gas and from water. Hydrogen is obtained by the decomposition of water, and nitrof-en from the ammonia, which, like the carbon dioxide, is carried down from the air by rain, and also from nitrates contained in the soil. Sulphur is obtained from salts (such as calcic sulphate) found in the soil, as are also, of course, all the inorganic elements. Of all thesv. constituents of the dry plant, carbon is the most abundant, amounting to about half of the entire weight. 308. The inorganic elements, though small in quantity, are, nevertheless, essential. If, for example, a plant be altogether deprived of iron it will produce vn chlorophyl'; while, if potassium is withheld, it will not pro^'uce starch. These facts are proved by causing seeds to g 'ow under conditions which enable us to accurately coi trol tho supply of nutrition in the form of carefully prepared solutions of the different ingredients. Several sul 'taiicef: of common occurrence in the ash of plants, as Uica, sodium, and some others, are in this way shown n«» * to be essential to healthy growth. 309. The process by which the carbon, obtained froii> the carbon dioxide, is combined with the elements o^ water to form starch is called axfi initiation. As alread) explained, the particles of starch which arb formed by the chlorophyll granules in sunlight are converted by combination with oxygen into soluble foiMiis, and carried away, when the ligiit is withdrawn, to other parts where growth is going on, or to storehouses such as tubers and §eeds, This oxidising and converting process is metobjum. RESPIRATION. 170 In consequence of having such a store of material, tubers can grow in the dark as long as the material holds ' out, but will not, of course, produce green leaves. Besides starch, oil is a common form of reserve material, particularly in seeds. Sugar, also, is found; as, for example, in the Sugar-Beet. 310. Parasites and saprophytes, which are as a rule without chlorophyll, do not assimilate, but obtain their nourishment from the stores of other plants or from decomposing organic matter. 311. Tbe so-called carnivorous plants, such as the Bladder-wort and the Pitcher-plant, obtain a portion of ' their nitrogen by entrapping insects and other small animal organisms, and absorbing them as they decompose. Some such plants appear to cover their prey with an acid secretion, and to go through a digestive process not altogether unlike that performed by animals. 312. Respiration. Plants, like animals, are continu- ally inhaling oxygen, and the presence of this gas is essential to their existence. The oxygen so inhaled is combined with carbon to form carbon dioxide, and this in the day-time is at once decomposed and the carbon assimilated. The absorption of oxygen and its subsecpient combination with organic matters in the plant is accom- panied by evolution of heat, a fact well illustrated in the process of malting, where damp barley is heaped together. As soon as the grain begins t(j t^prout, oxygen is rapidly absorbed, and a very decided rise of temperature takes place. The starch of the grain is oxidised and converted into sugar, and the growth is then stopped by rapid drying. The sugar, on fermenting, produces alcohol. 180 ELEMENTS C STRUCTURAL BOTANY. 313. Transpiration. The openings in the epidermis, called atowatay liave 'vhoady bc<*n described. Th^oufjh these tlio excess of watur-Viii)()ur in ilio plant is (\Klialed. it may often ])e observed, in liot, bright weatlier, tliat tlie leaves t)f plants tlroop if exposed to the sun. This is because the rate of evaporation through the stomata is greater than the rate of supply at the roots. At night, however, the stomata close and the balance being restored the plant recovers. The water which is thus supplied to the leaves appears to be conveyed through the stem by means of the ccfl-walh of the wood-prosenchyma, since the supply is not diminished if a ring of bark and the under- lying bast and cambium be removed. 314. But water is also supplied to the growing points, and in a different way. It is well known that if two liquids (or gases) of different density are separated by a porous diaphragm they will tend to change places, the fluid of less density passing through the diai)hragm more rapidly than the other. This is the principle of c^smose^ and wherever in a plant a cell-wall separates cell-coutents of different density it is found to apply. Hence, water is absorbed by freshly-formed cells, containing dense proto- plasm, from neighboring colls which are a little older and in which the protoplasm has been diluted. These absorb from the older cells behind them, and so on. Such water is transmitted, not through the prosenchyma of the wood, but through the parenchyma and the meristem. 315. It is a matter of common observation that the stems of many plants " bleed " if cut in the spring. This is due to the upward pressure of thn water with which the roots are charged at that time, und it takes place in the GROWTH. 181 absonco of transpiration. When tlio leaves are fornuMl atul. tniMspiratiou Hots iu actively, Ukj i'()()t-i)reHHiiro is relieved ami the stems will no loii^L^er ])lee«l immediately on beinj^ wounded. In some plants ilm excessive root- pressure even causes drops of water to exude from tliij leaves. 3 1 G. We may observe, then, three distinct movements of water in the plant: (I) the rapid movement to make up for the loss by transpiration, (2) the slow movement to supply the growing cells with requisite moisture, and (3) Uie movement duo to root pressure. 317. Growth. Growth has already been referred to as consisting in the formatioti and subsecpient enlargement of new cells, accompanied in many cases by change of form. It has also been mentioned that the enlargement is the result of the introduction of new particles of vegetable material into the spaces between the molecules of the parts already formed — a process known as intussus- ccption. It is now generally admitt(!d that each of the molecules of which the plant-bo ly is made up is enveloped in a sheath of './ater. We know tliat the presence of water is essential to growth ; when it is absorbed by a growing cell tlu; immediate elFect is to stretch the cell, as it were, to its utmost ca[)acity ; in other words, to separate the molecules as far as possible and so increase the amount of water between them, thus making it possible to inter- pose new molecules of solid matter. The use of the water, also, as a vehicle for conveying the new material is obvious. This new material, the presence of which is essential to growth, is commonly supplied to the growing points from older parts which serve the j)urpose of storiihouscs, as seeds ::nd tubers, or of manufactories, as the leaves. 182 ELEMENTS OP STRUCTURAL BOTANY. V I ijh lill « 318. Stems and roots, as a rule, exhibit tlirec distinct regions according to ino stage of development at which they have arrived. There is, first, the growing point, the chief characteristic of which is tlie rapid formation of new cells by division ; secondly, the elongating part, chiefly characterized by the growth of the cells in length, there being practically no further division here ; and, thirdly, the fully developed part, in which there is no further division or enlargement, though the cells may continue to discharge various important functions. 319. Growth, whilst dependent upon an adequate supply of water and of new material, is also largely affected by external conditions, such as temperature and light. Growth may be stopped altogether by either too low or too high a temperature, and between the limits within which any given plant is found to be capable of growth there will be found a particular degree of temperature more favourable to growth than any other either above it or below it. This may be called the optimum. The effect of tempera- ture differs considerably according to the amount of water present in the part affected, dry seeds, for instance, resist- ing a temperature, either high or low, to which soaked seeds would at once succumb. 320. Light is essential to assimilation, but seeds and tubers, as well as many of the lower plants which are without chlorophyll, such as Mushrooms, will grow in the absence of light as long as the stock of assimilated material upon which they draw is not exhausted. The growth which takes place in the cambium-layer of dicotyledons and in roots is another example of increase in size in the absence of light. The assimilated nuiteral GROWTH. 183 in all these cases, however, has been previously elaborated elsewhere. 321. Light is found to exercise a retarding influence upon growth. A plant, for instance, in a window will bond towards the light, because the cells on the side nearest the window grow more slowly than those which are shaded, thus causing curvature of the stem and petioles. 322. Gravitation also affects growth, as we know that the stem and root, or axis of the plant, are usually in the line of the radius of the earth at the place of growtli. If a seedling plantlet be laid with the stem and root horizontal, the stem will curve upward and the root downward in the endeavour to restore the vertical direction. 323. The twining movement of the stems of many plants is due to inequality of growth at successive points in the sides of the stems. Loaves unfold from the bud because the growth on the upper side at the time of unfolding is more rapid than on the under side. These movements are called Jiutafiom, and are not due to the external action of light, but entirely to internal causes. The movements of tendrils, however, are affected by contact with the object which they grasp. 184 ELEMENTS OF STRUCTURAL BOTANY. t CHAPTER XXT. EXAMINATION OF A FERN A HORSETAIL A CLUB-MOSS. 324. We shall now proceed to tlie examination of some common plants which will be found to he tyi)ical of groups differing in important respects from the phanerogams. Ferns. Fig. 231 is a representation of our com- mon Polypody. You may find it in almost any shaded rocky place. Running horizontally beneath the surface you will find the stem cf the plant, which in this case is, therefore, a rhizome, A portion of the rhizome is shown in the lower part of the figure, with fibrous roots on the under side. From the upper side are developed the leaves, which, as you see, have long petioles, and if you find one which is still in the bud you will observe that it is rolled up lengthwise, as shown in Fig. 232. The vernation is, therefore, circinate^ and this is the case in nearly all the Ferns. On examining the back of the leaf (Fig. 231 shows the back) we observe rows of brownish dots on each side of the middle veins of the upper lobes. ]?ig. 233 is an enlarged view showing the position of these dots at the extremities of the veinlets. When we put one of these dots under the microscope it is seen to be a cluster of minute, stalked bodies, such as that shown in Fig. 234. These bodies are further found to be sacs filled with extremely fine dust, and the dust consists of multi- tudes of rounded particles all exactly alike. They are, in short, spores, and the sacs m wnich they are contained are the spore-cases, or sporannia ; while the clusters of sporangia are tlie fruit-tlots, or sori. Around each spor- angium there is an elastic jointed ring which breaks at / I FERNS. 185 LUB-MOSS. maturity, and by its elasticity rupturos tlic spore-case, Tvhich then discharges its spores, as sliown in Fig. 234. The leaf of the Fern, then, is something raore than an ordinary foliage- leaf, and is known as the frond. The petiole is called the stipn^ while the mid-rib is the rlxaclm. 325. A spore under proper conditions develr pes a slender thread-like cell which eventually gives rise to a thin, flat, green ^ expansion, resembling that '- shown in Fig. ■"1. o 235. This is called the vro- tliallium. From the under sur- face root-hairs are produced as shown in the figure. On the same surface, among the root- hairs, arise mi- nute projections Fig. 232. hX\K.!-^ Fig. 2.31. Fig. 231. Root-stock and frond of Poly|X)dy. Fijj. 'I'M. Circinato vernatioai of the frond. Fig. 233. -Magnified vi'^w of the sori. Fig. 234.— Sporangium discharging spores ; greatly magnified. 18G KLKMKNTS OF STRUCTURAL BOTANY. ' I of tissue in which are developed cells corresponding to the })olk'n-gniins of phanerogams. These projt'-iioHa arc the f/MXMX^2 antjjjixidia; they contain cells in which are fertilizing boiliea_ U^^ Vi ^W^^ ^^ anthenmids. Also on the nnder .surface of the ^^ ^ ^ ^ ^ vC pi'"thalliiim, near the notch, we iind structures analogous to tlie enihryo-sac of the phanerogamous ovule. These are the mrlu'tjonia. Tliey^ ^pXQ mostly flask-shaped bod- ies, having a germ-cell — the o(»i])hcrH — in the lower end. The antherozoids, on escap- ing from the antheridia, make their way down the necks of the archegonia, and Fiff. 235. . • , , -ii XI coming in contact with the oospheres fertilize them. As a result of this fertilization, a plant is developed in all respects like the one Avhich originally bore the spores on its fronds. 326. It is manifest, then, that we have hero two distinct generations : first, the spore produces the prothallium which bears the antheridia and archegonia ; secondly, the interaction of these gives rise to a plant which bears the spores. This phenomenon is spoken of as the alternation of generations, vf IV'-^' ' '' ''^-^t^^A Vrj^ix'^^^ ^kJ^M^A". 327. The stems and roots of Ferns are found to contain vascular bundles which, like those of monocotyledons, are closed. Fiff. 235.— Prothallium of a Fern, under side ; /i, root-hairs; an, antheridia^ ar, archeg^onia. Magnified 10 times. (Prantl.) THE HORSETAILS. 187 in, antheridia; 328. From tho account here jrivon of the mode of reprod'.toiion in tlie Ferns, it ^viil ]»(» evident that the (lymnospenns occui)y an intermediate position between them and tlie Angiosporms. For a description of other common Ferns differing in detail frf)m tlie Polypody, the student is referred to Part II., i)age IG9. 329. The Horsetails. At page 181. Part II., will be found a description of the common Horsetail, with an illustration of the fertile stern, or rather branch, because botli tlie pale s[)ore-bearing branch and the later green shoots witli whorled branches are sent up from an under- ground stem or rhizome. The spores, upon germination, give rise to prothallia bearing anthf^ridia and archegonia })ro(;isely as in the Fern§. The prothallium is usually «niall, flat, and irregularly branched or lobed, developing tlie antheridia at tho projecting ends of the lobes, and the archegonia in the angles between them ; or, in other cases, the prothallia may be dia'cious. Fertilization of the germ- cell, which occupies a cavity at the base of the archegonium, takes place exactly as in the Ferns, and, as a result of f(Ttilization, tbe germ-cell developes into a spore-bearing plant similar to the original one. Here, therefore, we have again exhibited an alternation of generations. Other species of Equisetura of common occurrence, instead of producing a special fertile branch, develope sporangia at the extremities of the ordinary leafy stems. 330. These plants, like the Ferns, exhibit fibro-vascular bundles, and the epidermis is especially characterized by the excessive amount of silica contained in it, some of the species being used for scouring or polishing by reas»Q- '*f this property. !l i » I'ig. 236. f! 188 ELEMENTS OP STiWcTURAL IJOTANY, IVM. Tlu> curious r/afcrs (Fig. 23()) uttachctl to the spores tlonl»tli'ss assist thcin to csciipi from tlio .spore-cjjsos, jiiul suhstMpU'ntly aid iu dispersing tiuMU. a:')2. The Olub-Mosses. Fig. 2;i7 is a representation of a branch ^^ of l.iirojuuliuni claratntn, one of our oom- nion Club-Mosses. The creeping stem lies 'h Hat upon the ground, and often attains a gr(Mt length, sending up at intervals crec^t branches uith crowded linear-awl-shaped leaves, some of which, lik*^ tho ono shown in the figure, arc terminated by a slender peduncle IxMring one or more cylindrical spikes. These are tho fertile branches, and the leaves upon them, or at all events upon the slender upper part, arc very much smaller than upon tho ordinary sterile branches. * It is to be observed that tho stems and roots of these plants branch dlcliotomously (ur.,. 333. The sporangia are produced in the axils of the leaves of tho terminal spike. One of these leaves, greatly magnified, with its attached sj)orangium, is shown in Fig. 238. The sporangium opens by a slit at the top to discharge tho spores. 334. It is only quite recently that the prothallium has been detected. It is described in the case observed as a "yellowish-white Fii:. ""fi. — Spore of Equisotmu wiMi elators ; liighl> magnifid. Fit'. '2:>7.— Branch of LycopoUiumclaratum; natural size. (Thom^.) Fig. 237 11 sV CHARACTEKS OP PTKIUI/OPIIYTICS. 189 irrognlar lol)C(l Ixxly, spurin^^'ly fnrnisluMl on its iinilnr aur- fuco villi sniiill rodt-liaiis." TIm^ antii(M"i(lia and anlu^j^'onia appear to Ix; pioduccd on tlio iippca' sur- face, and tlics(! ])y tlusir inicn-action, give viso to tlu! now plant wliicli bears the .s]i(»rt's, just as in tlm Kerns and Horse- tails ; so that a^ain i]irn\ is an alternation of generations. 335. It is a fact of great interest that Fi),'. 238. i>> soinc! ])lants nearly related to the Club- Mosses, f/ro /.vV/r/.s' (»r spores — large and small — are produced in soparat(^ sporangia. Tlu; largo on(!S d(;volopo prothallia ui)on Avliich arehegonia are formed, and the smaller others upon which antheridia api)ear. 330. The three plants just considered, while evidently differing in certain details of structure and in general aspect, nevertheless have a number of characters in common : 1. TJicy arjree in their nindo. of reproduction^ tvhich is hf/ sporesj the.^e bodies heimj quite unlilce the skkds with which wr. arc now familiar^ and which, you will recollect^ alwaf/s con fain the embryo of the new plant. 2. They all ej'hihit an alternatiou of generations, 3. They all ham true roots, ' 4. The three tissue-systems — the epidermal, the fihro- vascular, and the fundamental — thouyh not all developed to so high a degree as in the Phanerogams^ still can be very clearly made out in both roots and ste)ns. The fihro-vascular bundles are always closed, as in monocotyledons, arul are, as a gewral rule, concentric (299). Fig. 238.— Leaf of Lijcojtodium bearinoran(jium. Fig. 241 is an enlarged view. This capsule is closed at the top by a circular lid, the o^ver^Witoii. which falls away when the cap- sule is mature, thus allowing the escape of the s2)ores, which are produced in it. The spores are developed upon the surface of a central column which rises from the bottom of the capsule, and which is known as the (•ohnmdla. The opening through which the spores escape is called the titoma* and a good lens reveals the fact that around the stoma there is a circle (sometimes two) of minute teeth, known collectively as the vcristcnjie. In the Moss now be- fore us the peristome consists of sixty-four teeth. In other IMosses the number varies, being always, however, some power of 2 ; either 4, or 8, or IG, or 32, or 64. Occasionally the teeth are altogether absent. Kijr. 239. — Two fertile stoms of a Moss {Polytrichum commune) of the natural size ; at c the calyptra ia seen enveloping the capRule. (Wood and Steele k. Fig. 239. i 102 ELEMENTS OP STRUCTURAL BOTANY. 342. We shall now coiisidf;r tlie mode of reproduction in the Mosses. Let us comuieiice with the spore. This, upon meeting with proper conditions, bursts its outer coat (the f'.vnsjH)?'e), and the inner coat (the endospore) is then pro- truded as a slender tube. This continues to grow by repeated divi- sion, until at length, in most cases, a tangled thj-(>ad-like mass of vege- tation is produced, to which the name pwtonenta has been given. After the lapse of several days ^^^- 2^°- minute buds are developed at differ- ent points upon the protonema, and these are found to cr;nsist of whorls of scaly leaves. This is the beginning of the development of the ordinary Moss-plant. Upon the plants thus arising from the buds are developed antheridia and archogonia, the former in the axils of the leaves forming the rosettes shown in Fig. 240, and the latter at the apex of other stems, as shown in Fig. 239. The antheridia ire seen under the microscope bo be club-shaped bodies, containing a mass of cells in which the Jintherozoids are formed. The archegonia are flask-shaped bodies, with a lower expand(;d poi-tion and a long neck above. Fig. 2 12 sliows the apex of a fertile Fisj. '240. — Apex of sterile stem, showioj'' rosette of purigoiiial leaves, in the jxils of whii-'li are tlio antheridia ; greatly ctilarj^ed. Fiu'. 241. — Ktilartred vinw of capsule, aho\viii;af i)cnstoino and detached opor- .luUun. (Wood and Steele.) Fig. 241. k /,/V^^^"*^^^'^ /V '-^^ uaves, in the EXAMINATION OF A MOSS. 193 stem with several archegonia in the centre, and Fig. 243 shows a single archegoniuiu very highly magnified. The antherozoids upon being set free make their way down the necks of the Jtrchegonia, and unite their substance with that of special cells in the lower end (one in each archegonium). These cells, as a consequence of being thus fertilized, become sur- rounded by a thin coat and immediately begin to grow up- wards, developing the slender stalks (setiv) with the capsules at the summit, and surmounted by the calyptra, which is, in fact, nothing but the wall of the archegonium which is torn away at its base and carried upwards. Then the ^Ai spores are developed around the columella, and the round of life of the plant is com- pleted. As in the Ferns, we have here also exhibited an alternation of generations, the one generation being that arising from the ^ Fig. 243. development of the spore and resulting in the production of the autheridia and the archegonia ; the other being that arising from the fertilization of the Fig. 242.— Enlarged view of apex of the fertile stem of a Moss; a, archegonia; b, leaves. Fig. 243. —Very highly magtiifled view of an archegonium; b, the base; h, the nec-k ; m, the mouth ; the germ-cell ia seen at the bottom of the flask- shaped cavity. (Sachs.) , 194 ELEMENTS OF STRUCTURAL BOTANY. special cells in the archegonia, and resulting in the production of spores. 343. Liverworts. Figs. 244 and 245 are representa- tions of portions of a very common Liverwort, Marchantia jwlymorpha. It may be found growing along the borders of marshes and in wet places generally, often with inter- mingled moss. It is of a deep green colour, and usually spreads over a consid- erable extent of sur- face. There is no ap- pearance of leaves, the plant-body lying flat upon the surface upon which it grows, and putting forth root-hairs on the under side. FijT. 244. From the upper side arise peculiar stalked bodies of two sorts, as shown in the figures ; the one consisting of flattened or slightly convex disks, and the other being star-shaped. These stalked bodies contain the reproductive organs. In cavities on the upper surface of the flattened disks are produced the antheridia, from the cells of which are liberated the antherozoids. On the under surface of the rays of the star-shaped bodies are produced clusters of flask-shaped archegonia, each with a germ-cell at its base, and fertilization takes place in the manner already described in the account of the Moss. As a result of fertilization a capsule is developed which produces spores, Fi]?. 244. — Portion of a Liverwort {Marchantia polymorpha), showing' the thallus and several stalked disks which bear tho autheridia ; natural size. (Thome.) EXAMINATION OF A LIVERWORT. 195 es spores, pretty much as in the Mosses, though in Marchantia the stalk of the capsule is very short, and the whole is surrounded by a loose sheath which grows up from the base and at length completely encloses it. The spores on germinating develope into plant -bodies such as we have described, so that the alternation of generations is here also well marked. 344. Other Liverworts more nearly resemble the Mosses in form, having leafy stems, from the summit of which arise slender stalks with capsules at the upper end. TlM3se capsules, however, do not open by a stoma, but are four- Fig-. 245. valved, and at maturity the valves split asunder, allowing the escape of the spores. In the leaves of these latter forms there are no veins of any kind. Forms in which the plant-body is a flat expansion, as in Marchantia, are distinguished as thalloid, while the leafy forms are said to be folio f^e. • • 345. It remains to be added that Marchantia undi other Liverworts reproduce themselves by buds as well as by spores. These buds (gemmm) are formed in little cup- shaped receptacles which appear on the upper surface of the plant-body. Tluiy consist of simple masses of tissue, which fall away wlien fully grown, and immediately develope into new plants. Fip. 245.— Thallua with star-ghapcd receptacle bearintf archegonia ; natural size. (Thom^.) 196 ELEMENTS OP STRUCTURAL BOTANY. 346. The Mosses and Liverworts constitute a distinct group of plants called Bryophytes. It will be evident from the preceding descriptions that in the matter of reproduction they do not differ n-iiterially from the Pteri- dophytes. They are, however, distinctly separated from them by the simpler^ organizaHon of their tissues. The Bryophytes have no true roots, but only root-hairs or rhizoids. The whole plant-body is, as a rule, composed of thin-walled parenchyma, and only in a few cases is there any appearance of a development of a fibro-vascular system, and that only of the vaguest possible kind. There is, however, a well-defined epidermal system, and stomata are not uncommon. I CHAPTER XXIII. EXAMINATION OF A MUSHROOM — A LICHEN — A CHARA. 347. Mushroom. Fig. 246 is a represe.itation of the Common Mushroom of the natural size, while Fig. 247 shows i\ several stages of *its growth. At A is seen a matted fibrous mass, which is the underground portion of the plant. It is called the mycelium; at several places on it rounded outgrowths of different sizes are visible. These eventually develope into the overground part of the Mushroom. At // is shown a vertical section tlirough one of these outgrowths at an early stage ; at I in this figure you will observe two dark dots ; these are the open ends of a channel which forms a complete ring EXAMINATION OF A MUSHROOM. 197 in the interior. At /// they are much more distinct, and here is also manifest a difference between the npper and lower sections, which is still more marked at IV and K The upper spreading portion is called the pileus ; at V the lower edge of the pileus is still attached by a circular membrane to the stalk. In this stage the membrane is I is seen Fig. 24G. called the veil; later on, as seen in Fig. 246, it is torn away from the pileus and now forms the annalus^ or ring, about the stalk. Upon the under side of the pileus are produced a great many vertical, thin plates, called lojnellce or gills. If we make a vertical section through the pileus so as to cut across a number of the lamellae, they will Fig. 246.— The Common Mushroom {Afiaricus campestris) ; a, the pileus; 6, the lamclla3 ; <;, the antiulus. (Thoni^.) 198 ELEMENTS OF STRUCTURAL BOTANY. present the appearance shown at A, Fig. 248, and if we magnify one of these cross-sections it will appear as at B, L ^■■ Fig. 247. where there is seen an outer layer of cells standing on end. The whole of both surfaces of the lamellge is covered with such cells, and this special layer is the Fig. 247. — Various stages in the developmeni; of a Mushroom. (Sachs.) ,f ill EXAMINATION OF A MUSHROOM. 199 hymenium. At (7, the left hand portion of the figure shows a number of these long cells much more highly ' sh. ^v Fig. 248. . magnified, some of them narrowed in at the top so as oo form slender points, upon each of which is a rounded body. Fi^. 248.— Greatly enlarged views of sections of the lamellte of a Mushroom. (Sachs.) 200 ELEMENTS OF STRUCTURAL BCTANT. V :i iWv 'I m\^' Those r()un(l(3(l bodies are tlie n/Hm'.fi; the narrowed ends of tlie eells are called uterhjniata., and the projeelin"^ cells which bear them are specially known as hdsidia. The spores are formed by the simple narrowing in of the cuter ends of the basidia. The mycelium is, therefore, the vegetauxvo part of the Mushroom, while the stalked pileus above the surface is the fructification. The mycelium is developed directly from the spore, but so far there have not been dis- covered any indications of the interaction of sperm- cells and germ-cells such as characterize the Bryophytes and Pteridophytes. 348. You will note the entire absence of green colouring- matter. The Mushrooms produce no chlorophyll, and, consequently, are incapable of assimilation. They are always fouTul growing upon decaying organic matter, as the leaf-soil of forests and meadows, &c. 349. The Mushrooms are representatives of a b,rge class of plants called Pungl, all the members of which are destitute of chlorophyll. The cells of which they are made up are generally in rows so as to form long threads which are known as Jiyphw, and these may be either loosely interwoven, as in ordinary Moulds, or firmly compacted together, as in the Mushroom. 350. As just mentioned, Mushrooms are saproohytic in their habits ; but there are also Fungi which are parasitic, such as Kust and Smut. To the Fungi belong sucli organisms as the Yeast-plant, and the Bacteria which are found in putrefying matter, and are the cause of, or are associated with, diseases of various kinds. Ml Hi KXAMINATION OF A LICHEN. 201 -?^' 351. Lichens. Thoso })lants may lui found ^lowiny oil llhi 1)aik of trees, on old fences, on roeks, or cm tho ground. They dill'er widely in external a]>pearance, sonielinies growing erect and iniilating a stem and branches, as in Fig. 249 ; sometimes forming flat expansions which adhere to the surface upon which they grow, as in Fig. 250. Some species are yellow, others red, others grey. A very common one is that represented in Fig. 250. It may ho found upon many tree-trunks, and will be easily recognized by the yellow disks which dot its surface. 352. The flat part of the Lichen is the thallus, or vegetative portion, while the yellow, cui)-shaped disks (the apothecia) contain the fructifica- tion. Fig. 251 sh(3ws a section of the apothecium, and also the lobing of the margin of the thallus. Fig. 252 ^''J?-'^^^- is a very highly magnified view of a section of a thallus, showing it to be largely made up of cells, or li]i])luv., similar to those of the Mushroom. But in the Fig. 2r)i. Lichen there are visible, in addi- tion, large numbers of spherical green cells {cf g in the Fig.) known as gonidra^ which either occupy well-marked Fig. 249. — A fruticose Lichen (Cladonia digitata) of the natural size ; b, the cup ; c, the thallus ; the rounded Ijodies at the summit are the apothecia. (Thomd.) Fig. 250.— A foliaceous Lichen growing on a stone ; natural size. (Gray.) Fig. 251. —Section of an apothecium. (Gray.) 202 El.KMKNTS OP STRUCTURAL BOTANY. layers, as in tlu^ i)resent instanco, or an; scattered thr()U<'li tlie bo'ly of the thallus. Th(3 prcscnco of tlieso gonidia may bo said to be tlio tlistinmiisliiiiLj feature of Uk? Lichens. Their true relation and function were for a lonji time doubtful, widely diilerent opinions being held, but Fig. 252. it is now generally admitted that the gonidia are them- selves chlorophyll-hearing plants^ and that the remainder of the Lichen is a true Fungus, parasitia upon the gonidia. i Fig. 252. — Very hiprhly magnified view of section of the thallus of a Lichen ; r, rhizoids ; m, spurious tissue of hyphsG ; g, green gonidia ; o, boundary cells of upper side ; u, boundary cells of under side. (Sachs.) CHARA. 203 The question as to tho origin of the gonidis is not yet settled. 353. The structure of the apothecium is very well sliown in Fig. 253. From tlie hyphie are develojied large, club-shaped, vertical colls (the asci) which penetrate between the narrower vertical branches of the hyphae (the paraph f/!^cs). In the asci arise the spores (technically, as('ox}>ores)^ usually eight in each, and these when mature are discharged from the asci, and give rise to new plants. The ascospores are formed in the asci by tho process known as free cell-formation (283). The protoplaam in the asci collects about as many ditferent points as there Figr. 253. are spores to be formed, and a wall is then secreted about each. This mode, which is characteristic of a large number of Fungi, is quite distinct from that which prevails in the Mushrooms, where, as we have seen, the spores are formed by ahstricUon. 354. Ohara. Fig. 254 represents a Chara of the natural size. It grows almost everywhere in fresh waters, and is quite readily distinguished from other thread-like Fi;<. 253. — Very highly mayrnified view of section o an apothecium, showing the club-shaped asci. (Thome.) 204 ELEMENTS OF STRUCTURAL BOTANY. i^ I ifl v., *^ c Fig. 254. aquatics by the whorls of so-called leaves which encircle the stem, and also hy tlie general gritty nature of the plant. A very offensive odour is emitted hy the phint in the course of decay. Its green colour shows at once the presence of chlorophyll. On the branches you may observe num- bers of minute, more or less rounded, bodies ; Fig. 255 is an enlarged view of one of them. Here, at 6, is shown a large central nucleus (the nucule) enclosed in a spiral covering. This spiral consists of five long cells side by side, all of which wind about the central body, and have their ends projecting above it. The nucule is a row of cells of which the highest is the germ-cell, and the whole answers, in fact, to the archegonium of the Bryophytes and Pteridophytes. It is, in this plant, called the carpo- gonium. Just below it is a globular body made up of eight triangular shield - shaped segments arranged about a central cavity. From the inner end of each segment several coiled fdaments of many cells each projp,;t into the cavity. At maturity the shields separate, and the fila- ments eventually break up into their Fig. 2bi.—Charafrayili8; natural size. (Thoiu^.) CHARA. 205 (M)nstituent cells, each of which then liberates an anthero- zoid. The antherozoids make tlieir way down the necks of the carpogonia and fertilize the germ-cells. The spiral cells then harden, and form a firm coat for the spore within. As the plant decays in the autnmn, these seed- like sporocarps^ as they are now called, drop off and fall to the bottom of the water, where they eventually ger- minate. On germination, they first produce a simple form to which the name iwo-rmhryo has been given, ani from whicli arises the plant- body which bears the antheridia and carpogonia. There is, therefore, displayed in this case an alternation of genera- tions. 355. Chara belongs to a group of Fig. 255. plants known as AlgSB. They grow either in the water or upon damp surfaces. They differ from the Fungi principally in developing chlorophyll, so that they are able to assimilate. In colour, the Algee are often green, but in other cases the chlorophyll is obscured by the presence of other colours, such as brown and red. In the lowest forms of both AlgiB and Fungi reproduction takes place by simple division of the cells. In higher forms the entire contents of two similar adjacent cells coalesoer to form a new one, from which the new l)lant springs. This is the process of conjugation (284). In still higher forms, as in Chara, reproduction takes place by fertilization. Ficf. 255.— Highly magnified view of part of the fertile thallua of Chara. (Thoiuti.) 206 ELEMENTS OP STRUCTURAL BOTANY. 35G. The Algae, Fungi, and Lichens together constitute a great group called Thallophytes. The Lichens from their peculiar constitution may be regarded as transitional between the Algai and the Fungi, and by some the Charas are looked upon as links between the AlgaB and the Bryophytes. Some further reference will be made to the Thallophytes in the next chapter, in which is given a brief outline of the classification of plants generally. CHAPTER XXIV. CLASSIFICATION OF PLANTS ACCORDING TO THE NATURAL SYSTEM. " • 357. Hitherto our examination of plants has been confined to a few selected specimens, and we have examined these chiefly in order to become acquainted with some variations in the details of growth, as exem- plified by them. Thus we have found plants which agree in exhibiting two cotyledons in the embryo, and others, again, which are monocotyledonous. Some members of the former group were found to exhibit two sets of floral envelopes, other only one, and others, again, were entirely without these organs. And so on through the various details. We now set out with the vegetable world before us — a world populated by forms almost infinite in number and variety. If, therefore, our study of these forms is to be carried on to advantage, we shall have to resolve upon some definite plan or system upon which to proceed; otherwise we shall merely dissipate our energies, and our results will be without meaning. Just as, in our study It: CLASSIFICATION. 207 : NATURAL of language, we find it convenient to classify words into what we call parts of speech, and to divide and sub-divide these again, in order to draw finer distinctions, so, in our study of plants, it will be necessary to arrange them first of all in comprehensive groups, on the ground of some characteristic possessed by every member of each group. Just as, in Latin, every noun whose genitive case is found to end in ai is classed with nouns of the first declension, so in Botany every plant presenting certain peculiarities will be placed in a group along with all the other plants presenting the same peculiarities. 358. Some hints have already been given you as to the kind of resemblances upon which classification is based. For instance, an immense number of plants are found to produce seeds with a dicotyledonous embryo, while an innuense number of others have monocotyledon- ous embryos. This distinction, therefore, is so pro- nounced, that it forms the basis of a division into two very large groups. Again, a very large number of dicotyledonous plants have their corollas in separate petals ; many others have them united, whilst others again have oo petals at all. Here, then, is an opportunity to sub-divide the Dicotyledons into polypetalous, gamo- petalous, and apetalous groups. And so we go on, always on the plan that the more widely spread a peculiarity is found to be, the more comprehensive must be the group based on that peculiarity ; and so it happens, that the smallest groups of all come to depend upon distinctions which are, in many cases, by no means evident, and upon which botanists often find themselves unable to agree. 359. As our divisions and sub-divisions will necessarily be somewhat numerous, we shall have to devise a special 208 ELEMENTS OF STRUCTURAL BOTANY. name for each kind of group, in order to avoid confusion of ideas. We shall, then, to begin with, draw a broad line of distinction between those plants which produce Jfotcers of some kind, and those which do not, and to each of these great groups we shall give the name Series. We thus have the Flowering, or, to use the Greek term. Phanerogamous, Series, and the Flowerless or CryptOgamoUS Series ; or we may speak of them briefly as Phanerogams and Cryptogams. Then, leaving the Cryptogams aside for the moment, we may break up the Phanerogams into two great OlaSSeS, Dicotyledons and Monocotyledons, for reasons already explained. By far the greater number of Dicotyledons produce seeds which are enclosed in a pericarp of some kind ; bat there is a remarkable group of plants (represented in Canada only by the Pines and their immediate relatives) which dispense with the pericarp altogether, and whose seeds are consequently naked. So that we can make two Sub-Classes of the Dicotyledons on the basis of this difference, and these we shall call the Angiospermous Sub-class and the Gymnospermous (naked-seeded) Sub-class. The first of these may be grouped in three DivisionS, the Pol upefalonti, Gamopetaloiis, and Ai^etalouSy and the Monocotyledons also in three, the Spadiceons, the Petaloideous, and the Glfunaceous, types of which we have already examined in the Marsh Calla (spadiceous), Trillium (petaloideous), and Timothy (glumaceous), and the distinctions between which are suHiciently obvious. The Cryptogams ai-e divided into thi'eo great Classes, vi/.: PteridophyteS, embracing Ferns, Horsetails, and Club-mosses ; Bryopliytes, embracing CLASSIFICATION. 209 Mosses and Liverworts ; and Thallophytes, embracing Lichens, Seaweeds (Alga?), and Mushrooms (Fungi). 360. So far, then, our classification is as follows : r5 O o 'A M w w n ■< H o > Series I. Phanero- gams. Class I.— Dicotyle- dons Class II.— Mono- cotyledons . . ^Sub-class l-Anj,MOsperm&. Polypetaloun Division. ■<( Gamopefalons do. ApetalouH do. VSub-class 2-Oynnio8perm3 ^Spadiceous Division. Petaloideous do. [jGflumuceous do. ' Series II. Cryptogams. (" Class III.— Pteridophyt'3S. J Class IV.-Bryophytes. Class. V.—Thallophytes. 36 L The above is very nearly the arrangement adopted by Gray, but many botanists prefer another arrangement 'as follows : o » » H O > Group I Phanerogams. Group n. Pteridophytes. Group III. Bryophytes. JA— Angi Group IV. Thallophytes. f Class 1,— Dicotyledons. lospcrms. < V Class 11.— Monocotyledons. £.— Gymnosperms. Class 111,— Gymnosperms. 1^ Class lY.— Ferns. ■s Class Y,— Horsetails. V Class Vl.-Chtb- Mosses. y Class Yll.— Mosses. \ Class Ylll.—Liverivorts. y Class IX,— Fungi. V Class X,—Al;j(P. In this arrangement the last three Groups constitute the Cryptogams, and the Gymnosperms are raised to the rank of a sub-division of the Phanerogams, instead of ± M .»■ 4' * 11 ^1 1^ 210 KMCMICNTH OK NTIHIOTtTllAI, UOTANY. ijoing «i. NulMlivjMion of (In* DicotylpdoiiH. Tlio LioIumih, also, two '\\\c\\uUh\ in IIm^ l*'nMi»i. ♦^02. 'V\\o Nvliol«> »|noH(.i(M» oi' holmili'iil I'luMsiliciilion '\h still in MM uns('(il(»(l sdiio. I*\>r rurllior inl'diinniioii in n^i^Mrd h> (ho VMiious moiNvs (hnt luivc^ \\or\\ |miIi lorwivrd, (l»o s(»uliM»( must roMsull. InrLror works. In (liosocMtncI part of this hook, whilst, th(> ciMssiru'Mlioii of (Jniy (who follows l^tMUhiUM and llookiM')i^ followed in ii, ^jjoncfid way, thoso wht> j>r<*for i\\o wtu'ond inTMniijt^inoMt. of tin* IMi;in(M*OL»Mnis jis i^ivtMi iil»ov(> inny (»n.sily niako i\\o iv«|uisit(> tlunimv 'MMy Kixrh of t hr />;>/>•/(»//>• is suh-dividod into ii nundKM" of Faillilios or Ordt")rs ; <'n«h Ordor into a. niunhor of Genera ; and {>a,rh ('umuis into Species. 'I'ho nanu's of tho Orth^'H as a. rulo havo tlu^ (Milling -rirctr, as: /uf/z/zz/iV/ArfVir, Ifosactd: Tluvso luinios tiro adjoftivos aijn^oinjjj with tho noun r/aiif that th(>v nuMin " Uosacoous plants," " lv!ininuudac(M)iis plants, " A'l'. .'U> I. A sptvi(\s is tho sum of all tho individual plants \vhos(» ri*si>nd>hnn'(^s in all ossontial rosptu^t.s avo so i^roat. ajs to \van*ant tho lu^liof that t.lu»y ha\-o spi'uni; from ono oonnnon stock. I>t> (^mdollo lias this statonaMit. : " \V(5 unito imdtM* tho dosijjjnation of a. .s'/^vvVx all tlioso indi viduals that nuitually hoar to oai-h othor so (ilosi^ a, rosond>lanoo a^^ to allow of our suj>posin<;' that th(>y may ha.vo proooodod originally from a siniijlo boinsj; or a sinr tinishiui*- tho llrst It^sson of this hook, that you havo oxaniinoil a .^^pcrif,^ of ihtffrmip. M nanicis an^ luhM'Ht.ood, so niiunilacoous I'olour or si/o aius ii«.;. nuniricnl. lo commMIuI-o did'croiil, si)('('i«*H. 'I'lm IJalHaiiiM ol' our j^M.rdrnM, I'oi' iiiMl,ji.ii(N', iirn of varioUH <:olomH, mikI l.lm pliinlH vary ^^f'st^ly in ni/.*', yo\, llu*y nil Ih'Ioii;^ l<» oiin HjH'cic!,. 'I'Im'So minor (liMl'i- (MMM'H, wliirli !un inn.inly l-lio roHiiK- cd' <'n,rn niid rul(/i vatioi?, ^iv(^ riso to rtrriiffH. 'riicsn an? of ^nial, inl,oi"(iKl, (,o fJin liorl iciilrnrist, Iml l.lio Htudy (>( HpcrirH in Uio gniali ond an(i ;iiiii of (Ik? l)o(iiniM(<. 'M)tK TlioMd Sprcic;-} whicii am roiiiiidcird to nimiliihin cu'li otluM' most iicaiiy Jii'd ;.',r(iu|)<'(| into (IciKH'ii., uml llio (JciKirii, ill lik(? maniirr, iiil.o ( )r(|(Mvt ; Ixil, iJicso particular grouiun^'H an? moi'i? or Ics,; art ilic.i;il, and arc, ;iui)jc(',t to conliimal alt«!i'ation in couMccpicncci of our imperfect kiiowlc(l}^'(?. Am y('ai' l)y y(?a,r ik^vv fact', arc I)roii;.;lit to light, iiiodilicatioiiM in arraiigctiKUit take place. In the, ('lassiiic.'ition of common plants whicdi constitute,! the Socond Tart of this work, the iJivisionM spoken of ahovr; lire pkuMMl in tin? ord(?r named. In th(! PolypelahmH .Division, those Orders ar(? put lirst wliicli emhraej; plants with IniixxiipioiiH Kldiiii'tiH and ajioravjKuir, p/s/i/,H, the j)ints of the llowers heinjg c(tnse(piently si'pani/f. ; then those with sinnlarly iiiKtirtcfl utannMis, hut n////j:(t.r/i(//t,H pis/ /7k; then those? with /^<'/vV/v///ow.s' stamens; and, generally, W(! procoud from plants whosi? llowers hav(i all tli(;ir parts sepaiati? to those oxhihiting more or less rolicMOJi and (iilhcsiov., and iinally to tho.so having one or luoro partH of th(3 llower wanting. 3()6. In looking np the namc! of a plant, it will he your object to det(?rininu tin? (jlcuufi to which it b(!l(jngs, and also th(3 >S/)('rJes. The name of ev(!ry plant consists of two purta : its Genus lirst, and then its Species. The name of 212 ELEMENTS OF STRUCTURAL BOTANY. ii f\ ' 4 m W 'Ml' the Genus is a Latin noun, and that of the Species generally a Latin adjective agreeing with the noun. The Buttercup, for example, which we examined at the outset, belongs to the Genus limmncuhis. In this Genus are included many Species. The particular one examined by us is known as acris; so that the full name of the plant is Ranunculus acris. In like manner, the name of the plant popularly called Marsh-Marigold is Caltha palustris. 367. The Key which is prefixed to the Classification will enable you to determine without much difficulty the Order to which a plant belongs, but nothing more. Having satisfied yourselves as to the Order, you must turn to the page on which that Order is described, and, by carefully comparing Die descriptions there given with the characters exhibited by your plant, decide upon its Genus, and, in the same manner, upon its Species. THE HERBARIUM. 368. Those who are anxious to make the most of their botanical studies will find it of great advantage to gather and preserve specimens for reference. A few hints, therefore, on this subject will not be out of place. It will, of course, be an object to collectors to have their specimens exhibit as many of their natural characters as possible, so that, although dried and pressed, there will be no difficulty in recognizing them ; and to this end neatness and care are the first requisites. Specimens should be collected when the plants are in flower, and, if possible, on a dry day, as the flowers are THE HERBARIUM. 213 lost of their then in better condition than if wet. If the plant is small, the whole of it, root and all, should be taken up ; if too large to be treated in this way, a llowur and one or two of the leaves (radical as well as cauline, if these be different) may be gathered. As many of your specimens will be collected at a distance from home, a close tin box, which may be slung over the shoulder by a strap, should be provided, in which the plants may be ke})t fresh, particularly if a few drops of water be sprinkled upon them. Perhaps a better way, however, is to carry a portfolio of convenient size — ;-say 15 inches by 10 inches — made of two pieces of stout paste board or thin deal, and having a couple of straps with buckles for fastening it together. Between the covers should be placed sheets of blotting-paper or coarse wrapping-paper, as many as will allow the specimens to be separated by at least five or six sheets. The advantage of the portfolio is, that the plants may be placed between the sheets of blotting-paper and subjected to pressure by means of the straps as soon as they are gatliered. If carried in a box, they should be transferred to paper as soon as pos- sible. The specimens should be spread out with great care, and the crumpling and doubling of leaves guarded against. The only way to prevent moulding is to place plenty of paper between the plants, and change the 2Mper frequentlij; the frequency depending on the amount of moisture con- tained in the specimens. From ten days to a fortnight will be found sufficient for the thorough drying of almost any plant you are likely to meet with. Having made a pile of specimens with paper between them, as directed, they should be placed on a table or floor, covered by a flat 2U ELEMENTS OP STRUCTURAL BOTANY. board, and subjected to pressure by placing weights on the top ; twenty bricks or so will answer very well. 369. It is of great importance that the sheet of paper within which the plant is first placed should not be interfered with during the drying process. The directions as to frequent changes refer only to the sheets not immediately in contact with the plant. These, to ensure the best results, should be changed once a day for the first few days ; less frequently thereafter. Gray recom- mends ironing with hot irons in order to remove more rapidly the moisture from fleshy leaves, and in any case to warm the driers in the sun before putting them between the plants. When the specimens are thoroughly dry, the next thing is to mount them, and for this purpose you will require sheets of strong white paper ; a good quality of unruled foolscap or cheap drawing paper will be suitable. The most cor^venient way of attaching the specimen to the paper is to take a sheet of the same size as your paper, lay the specimen carefully in the centre, wrong side up, and gum it thoroughly with a very soft brush. Then take the paper to which the plant is to be attached, and lay it carefully on the specimen. You can then lift paper and specimen together, and, by pressing lightly with a soft cloth, ensure complete adhesion. To render plants with stout stems additionally secure, make a slit with a penknife through the paper immediately under- neath the stem ; then pass a narrow band of paper round the stem, and thrust both ends of the band through the slit. The ends may then be gummed to the back of the sheet. THE HERBARIUM. 215 weights on The cpecimen having been duly mounted, its botanical name sliould be written neatly in the lower right-hand corner, together with the date of its collection and the locality were found. Of course only one Species should be mounted on each sheet ; and when a sufficient number have been prepared, the Species of the same Genus should be placed in a sheet of larger and coarser paper than that on which the specimens are mounted, and the name of the Genus should be written outside on the lower corner. Then the Genera of the same Order should be collected in the same manner, and the name of the Order written outside as before. The Orders may then be arranged in accordance with the classification you may be using, and carefully laid away in a dry place. If a cabinet, with shelves or drawers, can be specially devoted to storing the plants, so much the better. INDEX AND GLOSSARY. /S. The numbers refer to Sections^ unless Figures are specifiea^ Abruptly pinnate, 180. Absorption by roots, 2. Abstriction, 353. Acaulescent; apparently without a stem, 18. Accessory fruits : such as consist chiefly of ^an enlargement of some organ, such as the calyx or receptacle, not organically united with the pistil, 235. Achenium or Achene, 54, 56, 241. Achlamydeous : having neither calyx nor corolla, 74. Acicular, Fig. 145. Acorn, 71. Actinomorphic flowers, 203. Acuminate : with a long tapering point. Acute : sharp-pointed, 177. Acyclic flowers, 195. Adherent : a term applied to the union of unlike parts, e. g., sta- mens with corolla, &c., 26. Adnate, 62, 211. Adventitious : occurring out of the natural position. Adventitious roots, 134. Adventitious buds, 139. Aerial roots, 134. iEstivation : the folding of the floral envelopes in the bud, 210. Aggregated fruits, 234. Air-plants (epiphytes), 87. Albumen (of the seed): solic^i nour- ishing matter distinct from ths embryo, 12, 80, 117, 248. Albuminoids, 203. Albuminous seeds, 80, 248. Aleurone-grains, 280. Algse, 3o5. Alternate (leaves), 168. Alternation of generations, 326, 329, 334, 342, 343. Ament or Catkin, Figs. 68, 69. Amplexicaul : clasping a stem. Anatropous : a term applied to ovules when inverted, so that the micropyle is close to the point of attachment, 246. Androecium : the circle of stamens collectively, 211. Anci ous : an ending of adjectives descriptive of stamens, e. g., monandrous, polyandrous, &c. Anemophilous, 74, 247. Angiospermous : applied to plants whose seeds are enclosea in an ovary, 124, 129. Annual : a plant which|grows from the seed, flowers, and dies in the same season, 136. Annular vessels, 268, 287. Annulns, 347. Anterior, 197. Anther : the essential part of a stamen containing the pollen, 6, 211. Antheridium, 325. Antherozoid, 325. Apetalous: with'^ut a corolla; hav- ing only one bet of floral en- velopes, 20. Apex of leaves, 177. Apocarpous : applied to pistils when the carpels are free from each other, 7, 21, 215, 229. Apothecium, 352, 353. Appendage : anything attached or added. Appressed: in contact, but not united. Aquatic : growing in the water, whether completely or only partially immersed. Arborescent : resembling a tree. Archegonium, 325. Aril, 126, 250. Arrow-shaped, Fig. 155. INDEX AND GLOSSARY. 217 are specifiea^ isping a stem, term applied to nverted, so that is close to the ment, 246. circle of stamens L. ing of adjectives stamens, e. g., ilyandrous, &c. t, 247. applied to plants •e enclosedTin an a corolla; hav- }C of floral en- itact, but not Asfendiiif,' : rising upwards in a slanting direction ; applied chiefly to weak stems. Ascending axis: the stem of a plant. Asci, 353. Asfidium: a pitcher-shaped leaf, Fig. 169. Ascospore, 353. Asli of plants, 307. Assimilation, 275, 309. Auriculate : same as auricled, hav- ing rounded lobes at the base ; applied mostly to leaves. Awl-shaped, Fig. 147. Awn : a bristle, such as is found on the glumes of many Grasses, Barley for example, 108. Axil, 3. Axile : relating to the axis, 221. Axillary : proceeding from an axil, 44, 138. Axillary buds, 138. Axillary flowers, 186. Axis : the stem and root, 131. Baccate : like a berry. Bark, 286. Bases of leaves, 179. Basidium, 347. Bast, 286. Bearded : furnished with hairs, like the petals of some Violets, &c. Bell-shaped, 208. Berry, 233. Biennial: a plant which grows from seed in one season, but produces its seed and dies in the following season, 133, 136. Bifoliolate : having two leaflets. Bilabiate: two-lipped. Fig. 180. Bilocular, 219. Bipinnate : twice pinnate, Fig. 167. Bipinnatifid : twice pinnatifid,176. Blade : the broad part of a leaf or petal, 4, 45. Bleeding of plants, 315. Bordered pits, 269. Botrj'ose, 143. Botryose inflorescence, 185, 189. Bracts, 19, 44, 194. Bracteate : subtended by a bract. Bractlets : secondary bracts grow- ing on pedicels, 194. Branches, 3, 132, 141. Branching, Modes of, 141. Breathing-porea (stomates), 293, 313. Bristles, 227. Bryophytes, 346. Bud : an undeveloped stem oi branch, 137. Buds on roots, 131, 139. Bulb, 82, 94, 152. Bulbiferous : producing bulbs. Bulblets, 155. Bulbous : like a bulb in shape. Bundles, 296. Caducous, 206. Calcium, 307. Calcium carbonate, 278. Calcium oxalate, 278. Calyptra, 341. Calyx, 5, 13, 205. Calyx- teeth, 206. Calyx-tube, 206. Cambium layer, 297. Campanulate, 208, Campylotropous, 246. Capillary : fine and hair-like. Capitnlum : same as head, 189. Capsule, 239, 341. Carbon, 307. Carbon dioxide, 307. Carbonic acid, 307- Carina, or keel : the two coherent petals in the front of a flower of the Pea kind. Fig. 36. Carnivorous plants, 311. ' Carpel 7. Carpellary: relating to a carpel, e.g., a carpellary leaf, &c. Carpogonium, 354. Cartilaginous: tough. Caryopsis, 102, 241. Catkin, 71, 74, 123, 189. Caulescent: with an evident stem. Caulicle : another name for the radicle, 79, 252. Cauline : relating to the stem, e.g.f cauline leaves, &c., 4, 13, 28. Cell-contents, 260, 274. Cell-division, 282. Cell-formation, 282. Cells, 259. Cellulose. 265. Ii ,.i\ Z: I'i V 218 INDEX AND GLOSSARY. Cell-wall, 259, 265. Centrifugal inflorescence, 187. Centripetal inflorescence, 186. Chalaza: the part of an ovule where the coats are united to the nucleus, 245. Chlorophyll, 156, 274, 307. Ciliate, 182. Circinr te : curled up like the young frond of a Fern, 166, 324. Circulation in cella, 262. Circumcissile: opening like a pyxis, Fig. 207. Classification, 357. Claw (of a petal), 45, 207. Oleistogamous flowers, 247. Climbing stems, IGO. Closed bundles, 298. Club-shaped : with the lower part more slender than the upper, as the style of Dog's-tooth Violet, Fig. 82. Clustered, 133, 164. Coats of the ovule, 244. Coherent: a term applied to the union of like parts, 26. Cohesion, 26. Collateral bundles, 299. Collective fruits, 237. Collenchyma, 271, 286, 303. Colour of flowers, 274. Columella, 341. Column, 91. Coma : a tuft of hairs, such as that on the seed of Dandelion, Fig. 58. Complete, 8. Compound or Composite flowers, 62. Compound leaf, 43, 167. Compound pistil, 215. Compound spike, corymb, &c ,189. Concentric bundles, 299. Conduplicate vernation, 166. Cone, 124, 223. Co rical, 133. Cob 'erous : bearing cones. Conjugation, 284, 365. Connate : grown together. Connate-perfoliate, Fig. 165. Connective, 65, 211. Convolute : rolled inward from one edge, 38, 88, 166, 210. Cordate, 175. Cork, 294, 303. Corm, 94, 154. Corolla, 5, 13, 15, 207. Corymb, 189. Corymbose : like a corymb. Cotyledons, 78, 117, 252. Creeping, 149. Cremocarp, 243. Crenate, Fig. 163. Cross-fertilization, 247. Cruciform: cross-shaped, as the flowers of Shepherd's Purse, &e. Cryptogams, 359. Crystalloids, 280. Crystals, 278. Culm, 103, 150. Cuneate : wedge-shaped. Currents of water, 315^ 316. Cuspidate, Fig. 161. Cuticle, 292. Cycle. 159. Cyclic flowers, 195. Cyme, 191. Cymose : like a cyme, 143, 185. Cystoliths, 279. Decandrous: with ten separate stamens. Deciduous, 6, 206. Decompound : applied to leavcH whose blades are divided and sub-divided. Decumbent: applied to stems which lie on the ground but turn upward at the extremity. Decurrent, Fig. 166. Decussate : applied to the arrange- ment of leaves, when successive pairs o opposite leaves are at right ; igles, as in the plants of the Mint Family, 158. Definite inflorescence, 187, 191. Deflexed : bent down. Dehiscence of anthers, Figs. 185, 186, 187. Dehiscent, 231. Deliquescent: applied to stems which dissolve into branches. Deltoid, Fig. 148. Dentate, 178. Depauperate : unnaturally imall. Depressed : flattened down. fill m^-i (ir i INDEX AND GLOSSARY. 219 ), 207. e a corymb. 117, 252. 3. on, 247. ss-shaped, as the spherd's Purse, &e. 9. [). B-shaped. er, 315, 316. 161. 195. cyme, 143, 185. rith ten senaratb 1)6. applied to leaven are divided and pplied to stems le ground but turn extremity. 166. ied to the arrange - , when successive site leaves are at IS in the plants of ily,158. cence, 187, 191. own. nthers, Figs. 185, ipplied to stems into branches. nnaturally imall. ened down. Descending axis : the root, 131. Determinate inflorescence, 187, 191. Diadelphous : applied to stamens, 40, 212. Diandrous : with two separate stamens, 212. Dicarpellary, 215. Dichasium, 146. Dichlamydeous : having both sets of floral envelopes. Dichogamous, 247. Dichotomous branching, 145, 332. Dicotyledonous, 78. Dicotyledons, 80. Didynamoup (stamens), 29, 65, 214. Digitate, 168. Dimerous flowers, 196. Dioecious, 74. Disk : in flowers of the Composite Family, the centre ot the head as distinguished from the bor- der, 62 ; a fleshy enlargement of the receptacle of a flower, 58, 75, 126. Dissected : finely cut. Dissepiment, 218. Distinct: not coherent, (see Cohe- rent). Divergent: separating from one another. Dodecandrous : with 12 distinct stamens. Dorsal suture, 217. Dotted ducts. Figs. 222, 287. Double flowers : abnormal flowers in which stamens and carpels have been transformed into petals. Downy : covered with soft hairs. Drupe, 51, 231. Drupelet : a little drupe. Ducts, 287. Earthy constituents of plants, 307. Elater, 331. Elementary constituents of plants, 307. Elliptical : same as oval, Fig. 146. Emarginate, 177. Embryo, 12, 78, 117. Embryo-aac, 16, 245. Emersed: raised above the sur- face of water. Endocarp : " When the walls of a l)€ricarp form two or more lay- ers of dissimilar texture, the outer layer is called the Epicarp, the middle one Mesocarp, and the innermost Endocarp." — Gray. Endogen, 119. Endogenous growth, 119. Endospore, 342. Endosperm, 248. Enneandrous: with nine distinct stamens. Entire, 178. Entomophilous, 74, 75, 88, 247. Ephemeral : lasting one day only. Epicalyx, 35, 50. Epicarp : see Endocarp. Epidermal system, 291, 292. Epidermis, 292. Epigynous : inserted on the ovary, 58, 60, 213, 216. Epipetalous : inserted on the cor- olla, 60, 65, 213. Epiphytes, 135. Equitant (leaves), 88, 157. Essential organs, 17, 211. Evergreen : retaining foliage dur- ing winter, 122, 125. Exalbuminous, 80, 248. Excurrent ; said of main stems which are distinct and well- marked to the top, as in the Pine and Fir ; the reverse of deliquescent. Exogen, 81. Exogenous growth, 81. Exospore, 342. Exserted: protruding, 214. Exstipulate, 181. Extine, 123. Extrorse, 211. False dichotomy, 14C. Families, 363. Fascicle : a close bundle, either of leaves or flowers. Fascicled (roots), 133; (leaves), 164. Fascicular cambium, 297. Feather- veined: same as pinnately- veined, 108. Fertile-flower, 68. Fertilization, 17. 220 INDEX AND GLOSSARY. Fibrous : thread-like, 2, 18, 22. Fibrous tissue, 286. • Fibro-vascular system, 287, 291, 295. Filament, 6, 211. Filiform, 183. Fimbriate: fringed. Fleshy fruits, 232. Flora : a description of the plants of a district ; a collective name for tho whole of the species of a district. Floral diagram, 197. Floral envelopes, 14, 207. Floral formula, 198. Floral symmetry, 195. Floret, 61. Flower: the part of a phanero- gamous plant in which the sta- mens and pistil are situated. Flower-head, 60. Flower-leaves, 11. Flowering plants, 369. Flowerless plants, 359. Foliaceous : like a leaf in appear- ance. Foliage-leaves, 11, 156. Foliolate : having leaflets. Foliose (Liverwort), 344. FoUicle, 238. Foot, 144. ' Forked cyme, 143. Free, 5, 7, 41. Free cell-formation, 283, 353. Free-central placentatiou, 221. Frond, 324. Fruit, 228. Fruit-dots, 324. Fugacious : falling away early. Fundamental tissue, 291, 303. Funiculus, 245. Funnel-shaped, Fig. 178. Furcate: forked. Fusiform : same ?.«» spindle-shaped, 133. Galea: an arching petal or sepal, as the two upper ones in Catnip, Fig. 59. Gamopetalous, 207. Gamophyllous, 84. Gamosepalous, 34, 205. GemmtB, 346. Genera : plural of genus. Genus, 363. Germ : same as embryo. Germ-cells, 347. Germination, 132, 254. Gibbous : swollen on one side. Gills, 347. Glabrous, 22, 182. Gladiate : sword-shaped. Glands : applied generally to cells or hairs on the surfaces of plants, in which resinous or oily mat- ters are secreted ; but the term is also used to describe any pro- jection, the use of which is not clear, 226 Glandular : bearing glands, 226. Glaucous, 182. Globose ; like a globe or sphere. Glumaceous: bearing or resemb- ling glumes, 114, 359. Glumes, 101. Gonidia, 352. Gourd, 233. Grain, 102, 117, 241. Granules : particles. Granulosa, 277. Gravitation, 322. Ground-tissue, 303. Growing point, 145. Growth, 317. Gum, 281. Gymnospermous, 124, 223. Gymnosperms, 124, 129, 359. Gynandrous, 9i, 213. Gynoecium, 199, 215. Habitat : a term applied to the region most favourible to the growth of a plant: the place where it grows naturally. Hairs, 226. Hairy, 4. Halberd-shaped, Fig. 154. Half-inferior, 49, 216. Half-superior, 49. • Hastate, Fig. 154. Head, 189. * Heart-shaped,^75. Helicoid cyme, 144. Hemicyclic flowers, 195. Heptandrous : with seven distinct stamens. INDEX AND GLOSSARY. 221 -shaped. generally to cells mrf aces of plants, lous or oily mat- d ; but the term is escribe any pro- 3 of which is not ng glands, 226. Herb, 148. Herbaceous, 3, 89, 136, 148. Herbarium : a botanist's collection of dried plants, 368. Hermaphrodite, 247. Heteromerous flowers, 196. Hexandrous: with six distinct stamens. Hilum, 249. Hirsute : rough with hairs. Hispid : covered with stifif liairs. Hoary: densely covered with tine grayish hairs. Hortus siccus : same as herbarium. Hybrids : plants resulting from the crossing of nearly related species. Hydrogen, 307. Hymenium, 347. Hypliffl, 349, 352. Hypogyuous, 24, 29, 213. Imbricate : . overlapping like the shingles on a roof, 210. Immersed : wholly under water. Imperfect, 68. Included, 214. Incomplete, 19. Incurved (petals), Fig. 52. Indefinite, 26, 212. Indefinite inflorescence, 186, 189. Indehiscent, 231. Indeterminate inflorescence, 186, 189. Indigenous : naturally growing in a country. / Inferior : underneath ; farthest from the axis; the ovary is in- ferior when the calyx adheres to it throughout ; the calyx is in- f ferior when free from the ovary, S 45,40,52,88,216. Inflorescence, 75, 185. Innate, 211. Inorganic elements, 307. Inserted : attached to. Insertion : the point or manner of attachment, 40, 212. Integument, 249. Intercellular space, 293. Interfascicular cambium, 297. Internodes, 4. Interruptedly pinnate, Fig. 168. Intine, 123. Introrse, 211. Intussusception, 265, 317. InuHne, 281. Involucel, 194. Involucre, 35. 61, 71, 72, 194. Involute : rolled inward from both edges, 166. Iron, 307, 308. Irregular, 39, 205, 207. Isomerous : having the parts equal in number, 196. Joints : a name sometimes given to the nodes of a stem. Keel, see Carina. Kernel, 16. Key-fruit, 241. Kidney- shaped. Fig. 156. Labellum (or lip), 90. Labiate, 65, 209. , LamellaB, 347. . Lanceolate, Fig. 148. Latex, 288. Laticiferous tissue, 288, 303. Leaf, 4, 13. Leaf-arrangement, 158. Leaf-green, see Chlorophyll. Leaflet, 167. Leaf-schedule, 184. Leaf-stalk, 4 Leaf-tendril, 150. Legume, 43, 238. Leguminous : producing or relat- ing to legumes. Light, 320, 321. Ligneous : woody. Ligulate, 62, 209. Ligule: a strap-shaped corolla ; in Grasses, a scale-like projection between the blades of a leaf and the sheath, 103. Limb, 207. Linear, Fig. 146. Lip, 90. Lobe, 4, 167. Loculicidal (dehiscence) ; splitting midway between the partitions, 239. Loculus, 219. 222 INDEX AND GLOSSARY. Lodicule, 104. Loment : a jointed legume, 242. Lj'rate : pinnately-lobed, with the terminal lobe much larger than the others. Magnesium, 307. Marcescent : withering persistent. Margin of leaves, 178. Marginal: relating to the margin, 221. Markings (on cells), 268. Mass-movement of Protoplasm, 262. Median plane, 197. Medullary raj's, 301. Membranous : thin, like a mem- brane. Mericarp, 242. Meristem, 282, 285. Mesocarp : see Endocarp. Metastasis, 309. Micropyle, 16, 244. Middle lamella, 266. Mid-rib, 168. Mixed infloreRcence, 192, Monadelphous, 36, 40, 212. Monandrous : with a single stamen. Monocarpellary, 215. Monochlamydeous : with only one set of floral envelopes. Monocotyledonous. 118. Monocotyledons, 118. Monoecious, 68, 71. Monomerous flowers, 196. Monopodial branching, 142. Morphology, 130. Mucronate, 177. Multifid, 176. Multilocular, 219. Multiple fruits, 237. Mycelium, 847. Naked flowers : those which are destitute of calyx and corolla. Naked seeds : those not enclosed in an ovary, 127. Napiform, 133. Natural system of classification, 857, &c. Naturalized: introduced from other countries, but growing spontaneously from seed. Nectary : that in which nectar is secreted, 88, 224. Needle-shaped, 122. Net-veined, 4, 18. Neutral flowers : those having neither stamens nor pistil. Nitrogen, 307. Nodding : hanging with the top downward, like the flower in Fig. 82. Node, 4. Normal: regular; according to rule. Nucleolus, 260. Nucleus (of an ovule), 16, 244, 249 ; (of a ceil), 260. Nucule, 354. Nut, 241. Nutations, 323. Nutlet: a small nut or nut-like body, 65. Obcordate, 175. Oblanceolate, 174. Oblique : having the sides unequal. Obliteration (of partitions), 220. Oblong, Fig. 146. Obovate, 174. Obsolete, 206. Obtuse, 177. Ochrea: a tube formed by the union of both edges of a pair of stipules. Ochreate : having ochreaB. Octandroiis : having eight separ- ate stamens, 45. Odd-pinnate, 180. Offset: a short, prostrate branch, rooting at the end. Oils, 281, 309. Open bundles, 297. Operculum, 341. Opposite, 158. Optimum temperature, 319. Orbicular, Fig. 146. Orders, 863. Organic elements, 307. Organs : the parts or members (f a living body. Organs of Reproduction tlie paH of the flower. Q- INDEX AND GLOSSARY. 2f>3 ; introduced from ies, but growing jT from seed. in which nectar is !24. 122. 3. 3 : those having ns nor pistil. jing with the top ke the flower in ; according to rule, vule), 16, 244, 249; I nut or nut-like the sides unequal, artitions), 220. formed by the edges of a pair of ction the part Organs of Vegetation : root, stem, and leaves. Orthostichies, 160. Orthotropous : applied to ovules when straight, so that the mi- cropyle is as far as possible from the point of attachment, 246. Osmose, 314. Outline of leaves, 171. Oval, Fig. 146. Ovary, 7, 25. Ovate, Fig. 148. Ovoid: egg-shaped. Ovule, 7, 16. Oxygen, 307. Palate, 209. Palet, 101. Palmate, 168. Palmately-lobed, 176. Palmatifid, 176. Panicle, 106, 190. Papilionaceous, 39. Pappose, 206. Pappus: a circle of bristles or hairs representing the limb of the calyx in flowers of the Com- posite Family, 62. Parallel-veined : same as straight- veined, 83. Paraphyses, 353. Parasites, 135, 156, 310. Parenchyma, 286. Parietal : on the walls, 221. Parted: almost completely cut through. Pectinate: pinnatifid with lobes like the teeth of a comb. Pedate, Fig. 160. Pedicel, 28, 58. Peduncle, 5, 28. Peltate. 126, 175. Pentamerous flowers, 196. Pentandrous : with five distinct stamens. Pepo, 233. Perennial : ti lines to 136. Perfect: having both stamens and pistil. a plant which con- grow year after year, Perfoliate, 179. Perianth, 84, 90. Pericarp, 229. Perigynous, 40, 48, 213, 216. Perisperm, 248. Peristome, 341. Permanent tissue, 285. Persistent, 34, 206. Personate, 209. Petal, 5, 207. Petaloideoufl, 359. Petiolate : having petioles. Petiole, 4. Phanerogamous or Phaenogamous, 129, 359. Phellogen, 294. Phloem, 295. Phosphorus, 307. Phyllome, 225. Phyllotaxis, 158. Pileus, 847. Pilose : having long, soft hairs. Pinna: a primary division of a pinnately-compound leaf. Pinnate, 168. Pinnately-lobed, 170. Pinnatifid, 176. Pinnule : a secondary division of a pinnately-compound leaf. Pistil, 7, 13, 215. Pistillate : having a pistil, 68, 70. Pitcher-shaped (leaf), Fig. 169. Pith, 300. Placenta, 221. Placentation, 221. Plaited, 166, 210. Plumose : feathery. Plumule, 79, 117, 138, 252. Pod : a dehiscent fruit, 25. Pollen, 6, 16. Pollen-masses, 92. Pollen-tube, 16. Pollination, 124, 247. PoUinia : pollen-masses, Fig. 93. Polyadelphous, 40, 212. Polyandrous: witli numerous dis- tinct stamens, 6, 24. Polycarpellary, 215. Polygamous: having perfect as well as imperfect flowers. Polygamo-dicRcious, 75. Polypetalous : having separate petals, 5, 207. 094 «^ m4 A INDEX AND OLOSSARY. h :i' Polyphyllons, 84. Polysepalous : having separate Bi^pala, 5, 205. Pome, 53, 232. Posterior: next the axis, 197. Potassium, 307, 308. Prffifloration, see Estivation. Prffifoliation : the disposition of leaves in the bud. 16G. Prinkles, 227. Primary roots, 132. Primine, 244. Procambiuni, 20G. Procumbent : lying on tlie ground. Proembryo, 354. Prosenchyma, 286. Prostrate, 149. Prothallium, 325. Protonema, 342. Protonlasm, 260, Pseudocarp, 236. Pteridophytes, 337. Pubesoent: covered with fine down. Punctate: having transparent dots, like the leaves of St. John's Wort. Putamen, 51,231. ,.^xis, 240. Quinquefoliolate : having five leaf- lets, 180. Raceme, 189. Racemose : like a raceme, 143. Radial bundles, 302. Radiate, 168. Radical: pertaining Ut the root, 4,13,18,60. Radical leaves, 4, 28. Radicle, 79, 117, 132, 252. Ramification, 141. Raphe, 246. Raphides, 278. Ray: tbe murginal florets of a Compositt* flo\ver,as distinguish- ed from the disk. Receptacle, 8. Recurved : curved backwards. Reduplication, 200. Reflexed : bent backwards, 88. Regular: with parts of tlie siune size nud shape, 6, 206, 207. Rejuvenescence, 284. Reniform, Fig. 156. Resin, 281. Respiration, 312. Reticulated cells, 268, 287. Retuse : slightly notched at the apex. Revolute : rolled back, 166. Rhachis : an axis, 324. Rhizoid, 340. Rhizome, 151. Riugent, 209. Root, 2, 13, 131. Root-cap, 131. Root-hairs, 131, 226. Rootlet, 2. Root-pressure, 316. Root-stock, 88, 151. Rotate, 208. Rudimentary : imperfectly devel- oped. Rugose : wrinkled. Runcinate : with teeth pointing backwards, hs in the leaf of Dandelion, 176. Runner, 134. Sagittate, 28, 175. Salver-shaped, Fig. 179. ' Samara, Figs. 76, 208. Saprophytes, 135, 156, 310. Sarccxjarp : the flesh of a drupe, Scabrous: rough. Scalariform cells, 268, 287. Scales, 74, 124, 137, 194. Scandent: climbing. Scape, 19, 60, 88. Scar, 88. Schizocarp, 242. Scion : a young shoot. Sclerencbyma, 273, 286, 303. Scorpioid cyme, 144. Secondary roots, 134. Secundine. 244. Seed, 12, 244 Seed-leaves, 78. Seed-vessel, see Ovary. Self-fertilization, 88. Sepal, 5, 205. Septicidal (dehiscence): splitting open along the partitions, 239, INDEX AND GLOSSARY. 225 S 268, 287. y in)tfl]ed at th« mperfectly devel- li teeth pointing; in the leaf of Mice): Bpli feting artitions, 231). rreptifragal, 239. Septum : a partition. Series, 359. Serrate, 178. Sessile, 4, 28, 211. Seta, 341. Setaeeous : like a bristle. Sheath : a tube surrounding a Kteni, 103. Sheathing : surrounding like a sheath. Shield-sliaped, see Peltate. Shoot: a newly-formed branch. Shrub, 148. Si(;ve-tubes, 270, 289. , Silica, 308, 330. Silicle, 240. Silique, 240. Simple (leaves), 1G7; (pistil), 21.5. Sinuate : wavy on the margin. Sodium, 308. Solitary, 188. Sori, 324. Spadiceous, 359. Spadix, 97, 98, 189. Spathe, 97, 98, 194. Spathulate, 174. Species, 363, 364. Sperm-cells, 347- Spernioderm, 249. Spike, 100, 189. Spikelet, a secondary spike, 100. Spindle-shaped, 133. Spine, 227. Spiral markings, 268, 287. Spores ; the reproductive bodies inv;ryj)togam8 which correspond to the seeds of Phanerogams, 324, 341, 347. Sporangium, 324,341. Sporocarp, 354. Spur, 90, 209. Stamen, 6, 13,211. Staminate (flower); having no pistil, but only stamens, 68, 70. Staininode, 2j 1. Standard: the broad upper petal of a papilionaceous corolla. Starch, 276. Starch-cellulose, 277. Stem, 3, 13, 137. StemlesH, 18. Sterile (flower): having no pistil,fi8. Sterigma, 347. Stigma, 7. Stignui.tic : bearing the stigma. Stinging-hairs, 226. Stipe, 324. Stipulate!: having stipules. Stipule, 33, 181. Stolon: a short branch which droops to the ground and takes root, 1 li). Stoma (of Moss), 341. Stomata, 293, 313. Stone, see Putamen. Stone-fruit, see Drupe. Straight- veined, 83. Strap-shaped, see Ligulate. Streaming of ])rotoplasm, 2(12. Striate: marked lengthwise witii lines or furrows. Strobile : same as Cone. Style, 7. Subulate, Fig. 147. Succulent: juicy; fleshy. Sucker: an imderground branch, at length emerging and forming a stem. Sugar, 309. Sulphur, 307. Superior, 7, 41, 45, 49, 216. Suppression : absence of parts. Surface of heaves, 182. Suspended : hung from above. Suture, 217. Symmetrical, 47, 204. Sympodial, 144, 145. Syncarpous, 30, 215, 230. Syngenesious, 60, 68, 212. Tap-root, 32, 132. Teeth (of calyx , 34. Tegmen, 249. Temperature, 319. Tendril, 150. Terete : cylindrical. Terminul: at the end of a stem or brancli, 44, 122, 140, 187. Ternate : in threes. Testa, 249. Tetradynamous, 29, 214. Tetramerous flowers, 196. Vil 226 INDEX AND GLOSSARY. Tetrandrous : having four distinct stamens. Thalamifloroua : having the sta- mens inserted on the receptacle. Thalamus : the receptacle. Thalloid (Liverwort), 344 Thallophytes, 35G. Thallus, 352. Theca, 341. Thread-shaped, see Filiform. Throat ^of calyx), 206. Thorn, see Spine. Thyrse, 192. Tissue, 285. Tissue-systems, 291. Tomentose: woolly. Toothed, see Dentate, 112. Torus : same as receptacle, 216. Tracheary tissue, 287. Tracheids, 290. Trailing, 149. Transpiration, 313. Tree, 148. Triadelphous, 40, 212. Triandrous: having three distinct stamens. Trichomes, 131, 226, 292. Triennial : lasting three years. Trifoliolate : having three leafiet-i, 180. Trimeroua flowers, 196. Truncate, 177. Trunk : the main stem. Tube, 34, 128. Tuber, 151. Tuberous : like a tuber. Tubular, 208. Tunicated, 92. Twining, 150. Two-lipped, see Labiate. Types, 27. Umbel, 58, 181). Unibellet : a secondary umbel. Unguiculate : having a claw. Unilocular, 219. Ui-n, 341. Vacuoles, 260. Valvate : edge to edge, but hot overlapping, 38, 210. Valve, 46. Valved : having valves. Varieties, 364. Vascular cryptogams, ,337. Vascular tissue, 287. Veil, 347. Veins : the finer parts of the framework of a leaf. Venation, 168. Ventral suture, 217. Vernation, same as Prsefoliatiin, 166. Versatile, 102, 211. Vertical leaves, 88, 157. Verticillate, 158. Verticillaster, 193. ^ Vessels, 287. Villose, 182. Volatile oils, 281. Water in the plant, 306, 315, 316. "Wavy: with alternate rounded hollows and pi'ojections, 178. Wedge-shaped : like a wedge, the broad part being the apex. Wheel-shaped, see Rotate. Whorl : a '^ii'cle of three or more leaves at the same node, 23, 120, 158. Wing, 75, 124, 241. '^'v Woody stems, 148. Xylem, 295. Zygomorphic flowers, 203. aving a claw. APPEITDIX. jclcrtion0 ixom (Examination ^apcr0. UNIVERSITY OF TORONTO. 1. Define suckers, stolons, offsets, runners, tendrils, thorns, and prickles, describing their respective oi'igins and uses, and giving examples of plants in which they occur. 2. What are the functions of leaves ? Describe the different kinds of compound leaves. 3. What is meant by inflorescence ? Describe the different kinds of flower-clusters, giving an example of each. 4. Mention and explain the terms applied to the various modes of insertion of stamens. 5. How are fruits classified ? What are multiple or collective fruits ? Give examples. G. Relate the differences in structure between endogenous and exogenous stems. Describe their respective modes of growth. 7. What is the food of plants? how do they obtain it? and how do they make use of it ? 8. Descrite the component parts of a simple flower. How ia reproduction effected ? 9. Describe the anatomical structure of a leaf, and the formation and office of leaf-stomata. 10. Explain the consequences of flowering upon the health of a plant, and show how these effects are remedied in different climates. What practical bearing has this upon horticulture ? 11. Trace the development of a carpel from a leaf. Describe the different forms assumed by placentae in compound ovaries, and explain the origin of these variations. 12. Mention the principal modes in which pollen gains access to the stigma. What are hybrid plants, and how are they perpetuated ? 13. Describe the anatomy of a leaf. What are stomata? 14. What is the placenta in a seed-vessel ? Describe the different modes of placentation. Show how the varieties of placentation agree with the ** altered-leaf theory " of the pistil. 15. Give the characters of the Compositoe. How is the order sub-divided ? Describe the composite flower, and mention sowe i by air and leaves which float npon water. Give any laws according to which leaves are arranged H})ou the stem. 34. Give the names and relative positions of the parts of a com- plete flower. Can you name a flower which is perfect but not cottiplete ? 35. When a pea is soaked in water it splits into two parts, united by a small ligament, but a grain of corn does not. Explain the meaning of this difference. 36. Is an apple a Botanical fruit? If not, what is it? 37. Name any plants belonging to the following natural orders : — Cruciferae, CarophyllaceeB, Compositae, Labiatte. 38. From what does the root of an exogenous plant originate? What are the chief functions of roots ? How may roots be distin- guished from underground stems ? 39. From what do stems originate? Compare in appearance transverse sections of the stem of an elm and of a stalk of maize. How do these stems differ in their modes of growth ? 40. What are the functions of foliage-leaves ? Describe briefly the general structure and appearance of the leaf of (a) the Sugar Maple {Acer saccharinum) ; {b) the Indian Turnip (Aris(B7na triphyllum). 41. Name the parts of a complete flower, and briefly describe the chief modifications due to cohesion, adhesion, and suppression of parts. (Name illustrative examples of each modification you describe.) 42. Contrast a strawberry, a raspberry, and an apple, and compare a gooseberry, a lemon, and a melon. 43. What are the general characters of the Cruciferse, the Legu- nrinossB, the Liliacese, and the Gramineae ? 44. What are the morphological characters of roots? How do adventitious roots differ from normal roots as respects their origin ? Briefly describe the normal mode of growth of the roots of Gym- nosperms and Dicotyledons. 45. Describe briefly the structure of the stem of the Sunflower (Helianthus annuus). Mention the chief differences in the structure and the mode of growth of the bark in different dicotyledonous trees ? 46. What is meanii by an inflorescence? Distinguish between definite and indefinite inflorescence, and briefly describe the chief kinds of indefinite inflorescence, giving an example of each. 47. Describe the structure and the process of germination of the following named seeds : bean, buckwheat, marsh-marigold, oat. 48. What are stomata ? On what plants and parts of plants are they found ? What are their functions ? 'H 232 EXAMINATION PAPERS. i 49. Give the distinguishing characters of the Sapindaceae, the RosacesB, the Coniferae, and the Iridacese. Name a Canadian plant belonging to each of these orders, and mention any uses made of it or of any part of it. 50. Define the following terms : bract, scale, involucre, spathe, scape, pedicel, asepalous, monoecious, monadelphous, perianth, stamen, pistil, pome, thallus, drupe. 51. Describe briefly the structure, the mode of growth, and the use to the plant of roots. Name an example of a plant with aerial roots. 52. Name the enveloping and the essential organs of the flower, and give a morphological comparison o^ foliage-leaves, floral en- velopes, stamens, and carpels. 53. Describe briefly the general process of plant- nutrition, and name tbo essential elements in the food of plants. 54. Give the chief distinctive characters of the Cruciferae, the Leguminosae, the Umbelliferae, and the Liliaceae. Name three common examples of each of these families. 65. Describe the modei* by which the fertilization of a flower is accomplished, 66. Distinguish between " definite " and " indefinite " inflorescence. 67. Which are the nutritive and which the reproductive organs of plants ? Briefly describe the principal ones of each kind. 68. Describe the structure of a " follicle," a " siliqua " and a "legume." 59. When is a flower said to be " complete," " regular," and "symmetrical? " 60. Fill the accompanying Floral Schedule with an accurate description of the specimen before you, referring it to its proper order, &c. 61. Distinguish between (the series) : Phanerogams and Crypto- gams. State their divisions and note the distinctions of those of the first (series). 62. What is the foundation of all vegetable tissue? and of its elements which is essential for its growth and development ? 63. Describe the functions of the roots, sterna, and foliage-leaves of plants. State the kinds and sources of their nourishment. Mention the changes the nutritive elements undergo in their passage through them and the agencies by which these changes are effected. 64. Name, describe, and give the functions of the several parts of a typical flower. State which are essential and why. 65. Give the general characteristics of the Leguminosaa, Rosaceaa and Coniferae. 66. Refer to their botanical orders, genera, etc.: the plum, pear, orange, pumpkin, cucumber, carrot. 67. Describe the structure and mode of growth of exogenous and endogenous stems. W^i EXAMINATION PAPERS. 233 ! at- nutrition, and 68. Grive the meanings of apocarpous and syncarpous, and name two allied genera which may be distinguished by the difference these terms express. 69. Where, in plants, are stomata most abundant ? What is their chief function ? Describe chlorophyll and explain its physiological importance. 70. By what means is fertilization effected (1) in Phanerogams, and (2) in Cryptogam s ? 71. How would you distinguish a root from a stem ? Enumerate the most important varieties of roots, giving examples. 72. Make a drawing of the leaf of the sugar maple {Acer Sacchari- num) and of the beech {Fagus ferrugiiiea), and describe them with special reference to form, parts, and venation. 73. Fill the accompanying Floral Schedule with an exact descrip. tion of the specimen before you. Classify, if you can. tion of a flower is FIRST CLASS CERTIFICATES. 1. What are the cotyledons ? Describe their functions, &c. State their value in systematic botany. 2. Describe the difference in structure and modes of growth of exogenous and endogenous stems. 3. Describe the circulation in plants. "In the act of making vegetable matter, plants purify the air for animals." Explain this fully. 4. What are Phsenogamous plants? Define Raceme, Corymb, Head, Panicle, Anient. 5. Give the characters of {a) the classes Exogens and Endogens; [h) the Mint and Lily families. 6. To wnat family do the Cedar, Clover, Mustard, and Dandelion respectively belong? 7. Why does a botanist consider the tuber of the potato an under- ground stem. 8. Give the philosophical explanation of the nature of a flower cciisidered as to the origin and correspondence of its different parts. 9. Draw a spathulate, an obcordate, a truncate, a palmately- divided and an odd-pinnate leaf. 10. Explain the constitution of a pome or apple-fruit. 11. What organs appear in the more perfect plants, and in what divisions are they comprised ? 12. Give the function of the flower, its origin, and its essential and accessory parts. 13. Describe the nature and chief varieties of roots, and distinguish between them and underground stems. 234 EXAMINATION PAPERS. if" 4 14. " Aa to the Apex or Point leaves are Pointed, Acute, Obtuse, Truncate, Retuse, Emarginate, Obcordate, Cuspidate, Mucronate." Sketch these difEereut forms. 15. " There is no separate set of vessels, and no open tubes for the sap to x'ise through in an unbroken stream, in the way people generally suppose." Comment on tliis passage. 16. The great series of Flowering Plants is divided into tw^ classes. Describe these classes. 17. Give the cniet characteristics of the order GriicifercB (Cress Family), and name some common examples of this order. 18. State the difference betwefn definite and indefinite inflores- cence, and give examples of the latter. 19. Of wnat does the food of plants consist? In what form is it found in the soil? How is it introduced into the plant? What inference may be drawn respecting the culture of the plant? 20. Distinguish weak climbing stems according to the mode in which they support themselves, the direction of their growth, and the nature of their clasping organs. 21. Name the three classes of Flowerless Plants, and give an example of each. 22. Explain the terms Spore, Capsule, Bract, Stipule, Albumen, and Epiphyte. 23. What are tendrils, and of what organs are they supposed t.^ be modifications ? 24. Give the characters of the Cress Family, and name as many plants belonging to it as you can, 25. Tell what you know about the minute structure and the chemical composition of vegetable tissue. 26. Describe the origin of the different kinds of placentas ; and of the difierent parts of the fruit of the plum, the oak, and the maple. 27. Describe fully the process by which it is supposed that water is carried up from the roots of plants. 28. Give the meaning of the terras stomate, indehiscent, thyrsc, glume, pyxis. Distinguish epiphytes irom parasites. 29. Describe any plant you have examined ; if you can, tabulate your description. 30. Name all the families of monopetalous dicotyledons which you remember, and give the characters of any one of them. 31. Describe the following : primordial cell (utricle), protoplasm, cyclosis, mode of plant growth. 32. Describe the process of reproduction in a phanerogamic plant. 33. How are the pulse family — order Leguminosae — distinguished? Show the utility of the plants of this order. 34. What is ^Estivation ? Describe the different kinds, and men- tion a natural order of which each is characteristic, 35. Describe the course of the sap through the root and trunk of an exogenous tree. EXAMINATION PAPERS 235 ivided into two 36. Enumerate the chief nitrogenous and nou-Ditrogeuona sub- stances which are found in plants. 37- Fill in the accompanying Floral Schedule with a full and accurate description of the specimen under observation. lefinite inflores- McGILL UNIVERSITY. 1. Describe the germination of a plant. 2. Explain the differences in the structure of the embryo. 3. Explain the functions of the Root. 4. Describe the structures in a leaf, and explain their action on the air. 5. Mention the several parts of the stamen and the pistil, and explain their uses. 6. Describe an Achene, a Samara, a Drupe, and a Silique. 7. Describe the differences in the stems of Exogens and Endogens, and the relations of the ',e to the other parts of the plant and to classification. 8. Explain the terms Genera, Species, Order. 9. What is an exeurrent stem, an axiJary bud, bud scales ? 10. Explain the terms primordial utricle ^ parenchyma^ proto- plasm, as used in Botany. 11. "What are the functions of the nucleus in a living cell ? 12. Explain the movements of the sap in plants. 13. Describe the appearance under the microscope of raphides, spiral vessels, and disc-hearing wood-cells: 14. Describe the structure of the bark of an Exogen. 15. Describe freely the anatomy of a leaf. 16. Describe shortly the parts and structures denoted by the following terms : spine, aerial root, phyllodium, cambium,, stipule, rhizoma. 17. Give examples of pJieenogams, cryptogams, exogens, and