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A MANUAL OF THE

NORTH AMERICAN
GYMNOSPERMS

EXCLUSIVE OF THE CYCADALES BUT

TOGETHER WITH CERTAIN

EXOTIC SPECIES

BY
DAVID PEARCE PENHALLOW, D.Sc.

MACDONALD PROFESSOR OF BOTANY, McGiLL UNIVERSITY

BOSTON, U.S.A.
GINN & COMPANY, PUBLISHERS

Clje SUjjenacum p
1907

COPYRIGHT, 1907, BY
DAVID PEARCE PENH ALLOW

ALL RIGHTS RESERVED

67.5

CClir 21 1 1) r n X u in TQrtss

GINN .V COMPANY • 1'KO-
PRIETORS • BOSTON • U.S.A.

TO ONE

WHO HAS ALWAYS MANIFESTED
THE KEENEST INTEREST IN MY PROFESSIONAL WORK,

THIS VOLUME IS

AFFECTIONATELY DEDICATED,—

MY WIFE

PREFACE

In presenting this volume to working botanists the hope is
indulged that it may also prove of service to engineers and
especially to foresters. During its progress through the press
various opportunities have been offered for testing not only the
accuracy and value of the diagnoses for the recognition of woods
about the identity of which there was some doubt, but also its
general application to the elucidation of important questions
relating to practical forestry ; and the fact that such a work is
greatly needed at this time, and may materially assist in the
development of modern forestry, has been strongly empha-
sized. An important field for useful research may be found in
an extension of the studies here indicated, not only with respect
to exotic gymnosperms, but in their application to dicotyledonous
woods, many of which present problems of great scientific interest
and practical value.

An effort has been made to keep the work up to date, espe-
cially with respect to the treatment of fossil woods, but the
author is only too conscious of many imperfections which it is
hoped the application of the book to practical service may assist
in making clear and ultimately removing.

D. P. PENHALLOW
MONTREAL, CANADA

CONTENTS

PART I --ANATOMY

PAGE

INTRODUCTION 3

CHAPTER

I. General Directions for the Preparation of Material and the Value

of Particular Sections 16

II. The Growth Ring : its structural features and relation to age ... 24

III. Tracheids : spiral, pitted, and resinous wood tracheids, — their structure

and relation to development 33

IV. Bordered Pits : their genesis, structural variations, distribution, and

phylogenetic relations 59

V. Medullary Rays : their morphology and kinds 78

VI. Medullary Rays (continued']: ray tracheids, — their morphology and

distribution 88

VII. Medullary Rays (continued) : relations to development 103

VIII. Wood Parenchyma : crystallogenous idioblasts and resin cells, — their

structure and relations to classification 109

IX. Resin Passages: their morphology 123

X. Resin Passages (continued} : their distribution and relations to phy-

logeny, and classification 138

XL General Phylogeny : based upon the data of the preceding chapters . 154
XII. Durability of Woods and their Preservation as Fossils : a discussion
of the principles involved in the durability of woods, and the princi-
pal ways in which they are preserved in a fossil state 162

XIII. Decay : Its Mode of Action and Effects : a discussion of the chief
factors concerned in promoting decay, the way in which it operates,
and the principles underlying treatment for its arrest 175

PART II — SYSTEMATIC

Synopsis of Genera for the Cordaitales, Gingkoales, and Coniferales . . . 195

Cordaitales 198

Cordaites 198

Dammara 203

Araucaria 203

Gingkoales 209

Gingko 209

vii

viii ANATOMY OF THE GYMNOSPERMS

PAGE

Coniferales 210

Torreya 210

Taxus 212

Thujopsis 215

Cryptomeria 216

Podocarpus 216

Taxodium 217

Libocedrus 219

Thuya 220

Sequoia 223

Cupressus 228

Cupressoxylon 238

Juniperus 244

Abies 253

Tsuga 265

Pseudotsuga 271

Larix 276

Picea , . 281

Pinus 291

Section I. Soft Pines 305

Section II. Hard Pines 318

Pityoxylon 346

APPENDIX A : TABLES OF ANATOMICAL DATA 353

APPENDIX B: VOLUMES OF TRACHEIDS AND THICKNESS OF WALLS . . 358

LITERATURE 362

INDEX 367

PLATES 375

NORTH AMERICAN GYMNOSPERMS

PART I — ANATOMY

PART I- -ANATOMY

INTRODUCTION

The present work had its origin in 1880, in an attempt to con-
struct a system of classification for the North American Coniferse
based upon the anatomy of the vascular cylinder of the mature
stem. The fundamental idea was that such a classification would
prove of great value in the identification of material used for
structural purposes, but investigations had not been carried very
far when it became manifest that some such arrangement was
imperatively demanded in other directions and for purposes of
a more strictly scientific character. In entering upon the study
of fossil plants it was recognized that the most fruitful source of
reliable data must be found in the stem structure. At that time
there was little in the way of an adequate basis for further study
of this sort, inasmuch as the current diagnoses of the vascular
structure were found in most cases to be singularly inadequate,
and often so incorrect as to require extensive revisions. It was
found furthermore that in order to reach correct conclusions in
the case of stems which must often present marked structural
alterations, arising through the influence of decay and other con-
ditions attending fossilization in its various forms, it was indis-
pensable that there should be a trustworthy means of comparison
with existing types, whereby sources of error arising from elimi-
nated structures might be definitely excluded, and the fossil
referred with certainty to its nearest relative. The original
intention was therefore modified with a view to meeting the
requirements of paleobotanical research. During the time these
investigations have been in progress there has been much change
in the views held by botanists respecting the significance of ana-
tomical features as affording evidence of descent; and our own

3

4 ANATOMY OF THE GYMNOSPERMS

studies brought forth facts which gave repeated emphasis of the
most positive kind to the idea that questions of phylogeny cannot
be settled either by the morphologist in the narrower sense or
by the physiologist when acting independently, and that a proper
historical point of view can be gained only when to such labors
we join the data derived from a critical study of the stem structure
in all its details.

The original intention was to make a complete study of all the
North American woods, comprising, as enumerated by Sargent
in his report in the Tenth Census of the United States, some four
hundred and nineteen species and varieties ; but the great impor-
tance of the Coniferae from an economic point of view, their fre-
quent representation in the fossil state, and their relatively more
simple structure eventually led to their selection as the one group
in which initial studies might be prosecuted with the most imme-
diate and profitable results. While the North American species
constituted the original basis, various exotic species were added
from time to time, with the result that our studies, as now com-
pleted, comprise ninety-two species from North America, twenty-
one species from Japan, and four species from Australasia. This
extension has proved of great value, not only from a paleonto-
logical point of view but also because of the important bearing
such exotic types have had in the solution of questions relating
to descent.

In determining the particular nature of the material to be dealt
with in the prosecution of these studies several considerations
of fundamental importance were kept in mind, among the more
prominent of which we may consider the following.

The economic application of wood involves the employment,
solely, of the material which lies within the woody zone between
the bark and the pith. It was therefore held that for the recogni-
tion of timber or wood derived from constructions of any kind that
these two latter regions of the stem would be worthless, and that
a system should be devised which would, if possible, permit the
recognition of the species apart from such structures. Experience
has not only shown that this is possible, but that the characters

INTRODUCTION 5

embodied in the structure of the pith and bark are, in most cases,
least definite, and therefore of minimum value for differential
purposes. Furthermore the structural variations which may be
assumed to arise in conformity with the general evolution of the
species or genus are always most pronounced in the xylem struc-
ture, in consequence of which the latter acquires exceptional value
for purposes of relationship and phylogeny. Woody plants which
are found in the fossil state often show a complete absence of
pith structure, due to the operation of extended decay which may
have been initiated before the tree or shrub ceased to live. Much
more commonly fossil plants are devoid of bark. Instances are
on record, as in the case of Juniperus virginiana from the Pleisto-
cene clays, in which the plant is so perfectly and hermetically
sealed up as to permit of a perfect preservation of the bark as
well as of other portions of the stem, but such examples are com-
paratively rare. More commonly the extended maceration and
decay to which plants are subjected before silicification or calci-
fication occurs, involves a loosening and subsequent removal of
the bark, especially when the tree is subjected to such mechanical
action as is associated with its transport by water. It is therefore
obvious that any system of classification which would serve the
highest purposes for paleontological research must be wholly
independent of both bark and the pith. Another consideration
of importance in this connection relates to regional differences
of such a nature that different parts of the stem exhibit more
or less striking variations of structural detail. As these will be
dealt with somewhat in detail in a subsequent chapter, it will be
sufficient for the present purpose to indicate that the characters
upon which the generic and specific differentiations rest are
essentially independent of location, and it therefore matters not
whether the sample selected comes from a branch or the main
stem, or whether it is derived from the top, bottom, center, or
circumference of the latter, though as a matter of preference the
wood of a mature stem would be selected as furnishing the best
average conditions of structure, and therefore the greatest facility
in determination.

6 ANATOMY OF THE GYMNOSPERMS

Two objects have been held in view in the preparation of this
work : (i) its application to the needs of the scientific botanist
in prosecuting researches either in recent or fossil forms, and
(2) its adaptation to the requirements of the practical engineer
who may be called upon to recognize material entering into the
construction of bridges or other important works. While, there-
fore, Part I deals primarily with the anatomy of the stem, dis-
cussing such features as are essential to a correct knowledge
and interpretation of the systematic portion, it also includes
special chapters having a more or less direct bearing upon the
practical utility of woods, - - such as may be found in those on the
general mode of operation of fungus parasites, the durability of
woods under different conditions, and the specific action of decay
upon the tissues. Owing to the great extent of ground covered
by the subject of timber diseases and the special methods to be
employed for their control, and the fact that an adequate discus-
sion of these important topics would extend the present work
much beyond all reasonable limits, the reader is referred for the
treatment of diseases to Tubeuf (72), and for methods of wood
preservation to important papers by Flad (20) and Constable
(10). If such treatment of the general subject serves to secure
a wider constituency among those who are called upon to make
large use of valuable woods, one of the larger aims of the
present work will have been achieved.

Part II is based upon the details of Part I, and it relates
exclusively to questions of classification and relationship. In
attempting to construct a classification of the Coniferales upon
the basis of the anatomical characters to be found in the woody
portion of the stem, it appeared that there was little to be obtained
from the work of previous investigators which could be employed
as a satisfactory working basis, since the results recorded by
Nordlinger, Hartig, Muller, and others, while of great impor-
tance with respect to certain aspects of structure and afford-
ing many important suggestions, had not been carried to that
point where they could be reduced to any very great practical
utility. A survey of the literature of the subject showed that

INTRODUCTION 7

the study of a particular group of woods was not sufficiently
exhaustive to permit of final conclusions, and that in many
cases the diagnoses were not drawn with sufficient attention
to strict accuracy of statement and that regard for exhaustive
detail which would render them of the greatest value. In deal-
ing with the structure of the wood for taxonomic purposes it
has been found that the diagnosis must take cognizance of a
wide range of detail, and that it must be most searching in
its character. This is a necessary result of the high degree of
development of the organisms and the consequent differentia-
tion of the structure along several lines of development. It is a
neglect of this fact in the past which appears to explain why
previous investigators have failed to construct a system of classi-
fication which would not only give some additional information
respecting phylogeny, but which would at the same time permit
of a satisfactory recognition of species and genera. Under these
circumstances it appeared desirable to commence de novo and,
in the first instance, make an exhaustive study of the anatomy
of the wood, utilizing for purposes of classification such facts
as might be obtained in this way. As a convenient starting
point for the discussion of relationships it was considered that
none could be secured which would be better adapted to the
purpose in view than the classification generally employed as
based upon the external morphology of the vegetative organs
and inflorescence. For this purpose I at first selected the then
most recent and authoritative compilation relating to the North
American Coniferales, as embodied in Professor Sargent's valu-
able work on the woods of North America in the Tenth Census
of the United States. To this were later added Sargent's Silva
of North America and the sequence of Engler and Prantl con-
tained in the Natiirlichen Pflanzenfamilien, as expressing the
latest views on the subject.

Assuming the typical character of the trees discussed by
Sargent, it was held that any well-authenticated specimen of
wood from any such tree would also be typical, and in this way
it would be possible to form a type series the structure of which

8 ANATOMY OF THE GYMNOSPERMS

could be discussed with direct reference to the assumed relation-
ships based upon external characters. The nucleus of such a
type series was found in the Sargent collection of woods derived
from his work in connection with the Tenth Census. To this
other specimens were added through the courtesy of Professor
Sargent and Mr. J. G. Jack of the Arnold Arboretum ; Dr.
N. L. Britton of Columbia University, and now Director of the
New York Botanical Garden ; Mr. Morris K. Jesup, President
of the American Museum of Natural History; and Dr. B. E.
Fernovv, then Chief Forester of the United States Department of
Agriculture ; also to the late Baron Ferdinand von Mueller of
Melbourne, Australia ; Sir W. T. Thiselton-Dyer, late Director
of the Royal Gardens, Kew; Mr. E. J. Maxwell of Montreal; and
more recently Dr. E. C. Jeffrey of Harvard University ; to all of
whom my grateful acknowledgments are due. Yet other speci-
mens were obtained by personal collection or from trustworthy
collectors whose reputation was sufficient guarantee for their
authenticity. In this way it has been possible to include in the
present list all of the North American species of the Coniferales
as enumerated by Sargent in his Si ha, with the exception of the
recently described Juniperus flaccida. Present lack of material
has also prevented me from making a critical study of Juniperus
barbadensis in order to determine anatomically the identity
which Sargent establishes on the basis of external characters ;
while the same conditions have also barred a study of Juniperus
scopulorum, Sargent, and Cupressus pygmaea, Sargent, with a
view to determining their validity as distinct species.

During the progress of the present studies a large amount of
material came to hand from Japan and Australia. Its elabora-
tion has afforded much information of the highest value, and it
has been considered expedient to incorporate it in the present
classification.

With this material in hand the first step was to secure an
accurate diagnosis of each species for each of the three sections
usual in such cases, and when it is recalled that, as at present
elaborated, this involved a critical study of twenty genera and

] INTRODUCTION 9

one hundred and sixteen species, thus representing a total of
three hundred and forty-eight sections, and that the diagnoses
were at first of a purely tentative character demanding frequent
revision and extension, it will be understood that the enormous
mass of detail involved not only presented considerable diffi-
culties but demanded the expenditure of much time and most
patient and painstaking effort. The concurrent prosecution of
paleontological studies, in which a very critical means of differ-
entiation was called for, because of structural defects arising
from decay and other influences attendant upon the process of
fossilization, fortunately gave just the insight into the require-
ments of critical diagnoses which was required. It soon became
clear that certain anatomical features stood forth with very great
prominence, and that they could be successfully employed for
the recognition of primary and secondary divisions of the group ;
while other less prominent characters naturally fell into the
categories of those which define genera and species. Upon this
basis it was soon possible to differentiate the various genera with
accuracy, as already set forth in previous publications (44). The
systematic treatment of the genera of the North American Coni-
ferales then elaborated has been in constant and successful use
for several years, as applied to the determination of both fossil
and recent woods. Such experience has shown the classification
to be substantially correct with respect to the accuracy of the
diagnoses and the efficiency of the artificial key connected there-
with. A few minor changes have been found necessary, and
these have been introduced in connection with the more recent
revisions. Later experience, especially as derived from a more
critical study of the anatomical details, has shown the need of a
revision of the generic and specific sequences, as embodied in
recently published papers (59) and now incorporated here. As
it now stands, comparatively slight familiarity with the classifi-
cation will enable one to refer most woods to their appropriate
genera without hesitation. Thus Taxus, Torreya, and Pseudo-
tsuga may be isolated at once by the single character which they
possess in common, — tracheids with spirals, - - while the last

10 ANATOMY OF THE GYMNOSPERMS

genus may be differentiated from the other two by the very
simple, constant, and well-defined characteristics found in the
presence of resin passages and fusiform rays. Yet once more,
Pseudotsuga, Larix, Picea, and Pinus fall into a natural group
characterized by the presence of resin passages, and within the
group differentiation of the individual genera follows on natural
and simple lines. This is particularly true of Pseudotsuga and
Pinus, in each of which the generic characters are so well defined
as to leave no room for doubt ; while yet once more, Pinus may
be subdivided into well-defined groups, or subgenera, representa-
tive of the soft and hard pines. Abies and Tsuga are differen-
tiated by the position of the resin cells and the character of the
terminal walls of the ray cells ; Sequoia and Taxodium are sep-
arated by the terminal walls of the ray cells, the character of
the bordered pits on the lateral walls of the ray cells, and by the
distribution of the resin cells ; Cupressus and Thuya are differ-
entiated by the terminal walls of the ray cells, the distribution
of the resin cells, the form of the pits on the lateral walls of the
ray cells, and the form of the ray cells in tangential section.
These principles are applicable to all other genera, and the key
as now presented affords a trustworthy guide.

For the species the question has been found to involve much
greater difficulties, especially with reference to the genus Pinus,
in which the number of essential elements increases greatly,
while extreme variation also introduces a factor which adds
much to the complexity of the problem. Two sources of error
were early recognized as probable, --( i ) incorrectly drawn or
incomplete diagnoses, and (2) deviation from the selected type.
The problem was to elaborate an analytical key of such com-
pleteness as to eliminate any such errors, and then apply to
it a test which would prove the extent of its accuracy, em-
ploying the data so obtained in further corrections if necessary.
For the purposes of a critical test I was furnished with care-
fully selected material by Mr. Jack and Dr. Fernow to the ex-
tent of eighty-five specimens representative of fourteen genera
and forty-nine species. The specimens received from Mr. Jack

INTRODUCTION 1 1

represented a great variety of material in common use for struc-
tural purposes. They included wood not only from the mature
parts of the stem but also from the center of the trunk, em-
bracing in some instances the structure of the pith and primary
wood zone. For these reasons they possessed special value,
inasmuch as they afforded an opportunity to determine the
extent and nature of those structural variations which I had
some reason to believe existed, as between the earlier and later
growths of the stem. In transmitting his material Dr. Fernow
stated that he had selected it "with reference to representing
typical wood, and it was not taken from butt logs, top logs,
nor branches or knots." It therefore represented exactly the
problems which would be met with in every-day practice.

The results of these tests as at first obtained were far from
satisfactory. They clearly proved that the genera could be recog-
nized with ease, but for the species they made it clear that there
was need for a far more detailed diagnosis and differential key
than was at first supposed to be necessary. More searching
studies were made not only with respect to existing types but also
as applied to fossil species from the Devonian to the Interglacial.
These studies necessitated frequent recastings of diagnoses and
corresponding alterations of the analytical key. They brought to
light many important facts and relationships of the greatest value
from a phylogenetic point of view as well as from the taxonomic,
and they served to emphasize the fact that many of the more
detailed structural features of the pines in particular, hitherto
supposed to be of little or no value, were in reality of the greatest
importance. A final application of the test specimens under the
precise conditions which would obtain in ordinary practice showed
a verification of 91.5 per cent for all genera and species. In this
connection it may be of interest to note that the greatest sources
of error were to be found in the second section of the genus
Pinus, particularly in P. taeda, P. echinata, and P. glabra in the
order given, whence it appears that these species stand out as
the most variable of the entire Coniferales and, on the whole, the
most difficult to determine. This is in precise accord with the

12 ANATOMY OF THE GYMNOSPERMS

fact that these species are among the most highly specialized
representatives of the entire phylum, and that they therefore
stand as representatives of the highest order of development.
The sources of error having been determined by such tests, cor-
rections were applied to the key in such a way as to eliminate
them, while the original diagnoses were further modified to meet
the special requirements. It is manifestly impossible to construct
a key capable of providing for all exceptional cases. These can
only be met by the experience of the observer or by final refer-
ence to and critical comparison with type specimens. But the
experience so far gained justifies the belief that as now presented
the key affords sufficient data for the recognition of species under
all ordinary circumstances, and there is no reason for hesitation
in stating that it is fully as efficient in this respect as the keys
usually employed for the determination of species on the basis
of external morphology.

In the employment of this classification the novice will en-
counter certain practical difficulties the nature of some of which
it may be well to indicate. In the genus Picea the differentiation
of species is attended with more than the usual difficulty, and
the same fact appears once more in the second division of the
genus Finns. This appears to be the result of a general advance
toward a higher type of development, in consequence of which
there is a more uniform distribution of similar characters among
the various species. This feature also appears occasionally in
other genera, especially in Juniperus, where it is not altogether
easy to differentiate J. nana from J. communis, of which it has
commonly been regarded as a varietal form. But J. rigida shows
precisely the same relations to both of these, and I therefore
prefer to retain the specific status of all three, though somewhat
provisionally. In Pseudotsuga there is as much anatomical differ-
ence between P. Douglasii and P. macrocarpa as there is between
any well-known and well-recognized species. There is therefore
no reason for assigning the latter to a varietal position, and it
should be given the status of a species, as correctly suggested
by Sargent. In the genus Pinus, P. Murrayana cannot be regarded

INTRODUCTION 1 3

as anatomically identical with P. contorta, as suggested by Sar-
gent, for the same reasons as already applied to Pseudotsuga.
Similarly P. Jeffreyi is a valid species and P. ponderosa scopu-
lorum must be raised to the position of a species, while yet others
fall into the same category.

The sequence of genera and species, as well as the relations
of the larger groups, is based upon the anatomical data presented
in Part I, and it will be found to deviate considerably from most
of the systems of classification now in use. In exhibiting this
sequence, which appears abundantly justified from one point
of view, it must nevertheless be carefully kept in mind that
such an arrangement is in no sense regarded as final. At best
it is a purely tentative measure, which shall serve as a contri-
bution toward a final classification, and this latter can be com-
pleted only when data from several sources are assembled and
coordinated.

As derived from our present studies the sequence of the
Gymnosperms may be stated as in table on the following page.

With respect to fossil forms an effort has been made to include
all known North American species so far as they have been
recognized through the structure of the wood alone. These have
been included under their respective genera as now known for
existing species, and thus Cupressinoxylon1 or Cupressoxylon are
described under Cupressus, while Pinoxylon and Pityoxylon fall
under Pinus. Unfortunately, in most cases, it is not possible to
determine the structural characters with that detailed thorough-
ness which is desirable, owing to the imperfect nature of the
material, and it has therefore been found necessary to arrange
the fossil species in a separate section of the genus and provide
separate analytical keys. The very great difficulty of obtaining
full differential characters necessitates reference to type speci-
mens whenever a serious doubt arises. In several cases the

1 The genus Cupressinoxylon, as elsewhere shown, embraces what may prove
upon revision of existing descriptions Sequoia in some cases and Cupressus
in other cases, while according to Jeffrey's latest publications he employs the
term for fossil Sequoias. Provisionally I prefer to include it under the genus
Cupressus.

14 ANATOMY OF THE GYMNOSPERMS

CLASS I. CYCADALES.

II. CORDAITALES.

Order i. Cordaitae.

Family i. Cordaitaceas.

Genus i. Cordaites.

2. Araucariineae.

2. Araucariae.

1. Dammara.

2. Araucaria.

III. GlNGKOALES.

3. Gingkoineae.

3. Gingkoaceae.

i. Gingko.

IV. CONIFERALES.

4. Taxoideae.

4. Taxaceae.

1. Torreya.

2. Taxus.

5. Podocarpaceae.

i. Podocarpus.

5. Coniferas.

6. Taxodiineae.

1. Cryptomeria.

2. Taxodium.

3. Sequoia.

7. Cupressineae.

1. Thujopsis.

2. Libocedrus.

3. Thuya.

4. Cupressus.

5. Juniperus.

8. Abietineas.

1. Abies.

2. Tsuga.

3. Pseudotsuga.

4. Larix.

5. Picea.

9. Pinoideaa.

i. Pinus.

INTRODUCTION 1 5

diagnoses are given provisionally, since it is quite probable that
in consequence of the fragmentary nature of the available mate-
rial future studies will show several supposed species to be really
identical with one another. In the case of a large number of
fossil species it has not been found possible to obtain the type
sections for descriptive purposes. Under these circumstances,
although the original diagnoses differ materially from the general
plan adopted, it has been thought best to incorporate them in
the form of first publication, but with the name of the author
appended.

All of the illustrations employed in the preparation of the
present work have been prepared from drawings and photographs
by the author, and they may therefore be regarded as being par-
ticularly applicable to the various questions brought under dis-
cussion. Nearly all the text figures were first published in the
American Naturalist, and are here reproduced through the cour-
tesy of that journal. Some of the half-tone reproductions of
photomicrographs appeared in earlier papers relating to fossil
and recent gymnosperms, while yet others are introduced here
for the first time. It has been impossible to introduce all the
illustrations which the clearest exposition might make desirable,
owing to the limitations imposed by the expense of such a pro-
ceeding ; but it is felt that the very generous allowance made by
the publishers in this respect will suffice to render the leading
facts of structure and relationship clear enough for our present
purpose.

CHAPTER I

GENERAL DIRECTIONS AS TO THE PREPARATION

OF MATERIAL AND THE VALUE OF

PARTICULAR SECTIONS

In determining the course to be followed in the preparation of
material and its subsequent study, it is impossible to too strongly
emphasize the fact that a correct and complete conception of the
details of structure embraced in the vascular cylinder of the stem
can be obtained only when the latter is studied from three points
of view, or in three planes of section, - - the transverse, the radial,
and the tangential, the last two of which are of necessity also
longitudinal. Although the importance of these three planes of
section is well recognized by scientific botanists, it seems desirable
to restate the fact in order to avoid any misconception which
might otherwise arise through the minor importance attached to
the longitudinal sections by recent authors (79, 350). Under cer-
tain circumstances it sometimes happens that all three planes of
section are not available, and the student is then compelled to
rely upon two points of view or possibly even one for his con-
clusions. In such an extremity it becomes possible to draw
deductions from the material in hand as to the aspects of the
structure presented by the remaining plane or planes of section,
and so to reconstruct with approximate accuracy the entire
fabric. But such a method should never be resorted to except
when absolutely necessary, since to employ it under other cir-
cumstances would involve a measure of doubt which would bring
justifiable discredit upon the conclusions reached. The relative
value of each section for such purposes will appear shortly.

In proceeding to the study of a given wood too much stress
cannot be placed upon the importance of very searching and accu-
rate observations, especially if one is about to draw a diagnosis

16

GENERAL DIRECTIONS 17

of a new species. In making a diagnosis for comparison with
that of a previously described species similar care is a neces-
sity, particularly in the case of the different hard pines, where a
comparatively slight deviation may involve one in considerable
difficulty. Until one is thoroughly familiar with the course of
procedure to be followed, and has an extensive knowledge of the
anatomical details in all their varying aspects as characteristic
of different genera and species, the only safe course to follow,
when attempting to identify a species, is to make a carefully
written diagnosis in full. After this is done comparison with
the key or with the supposed species may be made in detail. A
comparatively brief acquaintance with the systematic portion of
this work will enable one to recognize most of the genera at
sight, since the characters are in most cases very clearly defined
and easy of recognition ; but the same does not hold true of
species, since these are defined by a larger number of characters
which vary somewhat widely, and exceptional cases are of much
greater frequency. Where there is a final doubt as to the iden-
tity of a given species, the specimen should be compared with a
type section or be submitted to an expert for decision.

The transverse section exhibits in the main an end view of the
various component elements. It should always be the first of
the three to be examined, since it immediately permits a separa-
tion of the genera into two great groups and affords suggestions
of such a nature as to permit of economy of time at a later stage
of the examination. It conveys a correct conception of the pres-
ence or absence of certain structural features, such as resin
passages, resin cells, or resin cysts and the presence or absence
of thyloses ; it affords the only accurate measure of regional dis-
tribution and of the general character of the growth rings, the
relative volume and character of the spring and summer woods,
and of the variations which distinguish the tracheids of those
regions of growth. When elements have similar terminal aspects,
as the spiral and pitted tracheids, as well as wood parenchyma
and parenchyma tracheids, the transverse section has no special
value beyond that which is to be found in a recognition of

1 8 ANATOMY OF THE GYMNOSPERMS

regional distribution, although to a limited extent it is true that
certain aspects of these elements may lead to correct inferences
as to their structural features when displayed in other planes of
section, whereby approximately correct data may be obtained
even in the absence of longitudinal sections. This is particularly
true with respect to the distribution of the resin passages, the
relations of their longitudinal and radial distribution being such
that where the one occurs the other may be inferred ; hence, if
resin passages occur in the transverse section, we may conclude
with certainty that they are also to be found in certain of the
medullary rays, which will also present a fusiform aspect in tan-
gential section.1 The general character of the medullary ray is
also displayed in this plane of section, but in its least important
aspect. Although all the details of width and composition may
be obtained much more accurately, and in some cases only from
longitudinal sections, nevertheless the absence of these latter
enables us to determine from the transverse section whether the
rays are one or more seriate and if some of them contain resin
passages.

In order that the features thus indicated may be exhibited in
their typical aspects, it is of the greatest importance that the
plane of section be exactly at right angles to the axis of growth,
otherwise the distortion of structure which necessarily results
will not only make observation difficult, but it will serve to
seriously impair the accuracy and value of any diagnosis which
may be drawn.

The radial section is also a longitudinal section the plane of
which should exactly coincide with the radius of the stem. Any
deviation from this position will cause the section to become
more or less tangential, and just in proportion as it approaches
this latter will its value diminish. In stems or branches more
than five centimeters in diameter there should not be the least
difficulty in securing the desired result, inasmuch as the abun-
dance of material will admit of somewhat reckless cutting ; but
in small branches of one centimeter or less, such as one must
1 Certain exceptions to this law are to be met with in the case of fossil species.

GENERAL DIRECTIONS 19

encounter in the case of fossil material, great care should be
exercised in order to secure the few truly radial sections which
the scanty material affords. When properly prepared such radial
sections supply some of the most important data for diagnostic
purposes. They furnish but little information as to regional dis-
tribution, a feature which is of secondary importance in this case.
They do, however, furnish evidence of the highest value as to
the form and structure of the tracheids, the character and extent
of the transition zone, the regional distribution of the bordered
pits and the various important details of their structure, size, and
aggregation, the disposition and character of the spirals, and,
above all, it gives the only adequate knowledge of the medullary
ray with respect to those features which are of the greatest value
in the final differentiation of species. It is true that some of the
features of the ray may be inferred from a transverse and more
particularly from a tangential section, but they cannot be utilized
fully except in generic differentiations. The radial section gives
a complete side view of the ray, exposing the entire structure in
all its details throughout the whole radial extent. It is from such
data that we obtain our final decision respecting the separation
of the first and second sections of the genus Pinus, the differen-
tiation of Sequoia, Libocedrus, and Taxodium, the recognition of
species wherever found, a differentiation of the Taxodiineae from
the Cupressineae ; and since it exposes the entire structure in all
its details, which are presented chiefly in side view, it permits us
to determine their relations to one another and to the activities
of the plant as no other section can. As features of subordi-
nate value the radial section completes our knowledge of the
bordered pit, which it presents in section wherever these struc-
tures lie in the tangential walls, a distribution which may be
more accurately ascertained in this plane of section than in the
tangential, since they are more certain to occur within the limits
of a given field. For similar reasons the radial section affords
the most convenient means of studying the longitudinal aspects
of resin passages, resin cysts, resin cells, and crystallogenous
idioblasts.

20 ANATOMY OF THE GYMNOSPERMS

The tangential section, which is also a longitudinal one, is such
as cuts a given radius at right angles, and it is most completely
such in all its parts when none of the included medullary rays
are cut diagonally. This result is always possible in stems of large
size from which typical tangential sections of several square centi-
meters may be cut without difficulty ; but in small stems it often
happens that only one or two sections of value can be obtained,
since the nearer the plane of section approaches the center of the
stem the more nearly does it approximate to a radial section.
It follows from this that in many cases sections will have to be
employed in which only a limited area exposes the typical struc-
ture, all the rest being partially radial. With respect to the latter
it should be pointed out that any deviation from a strictly tangen-
tial plane will involve a distortion of the structure of the medul-
lary ray, and inasmuch as the value of the latter for diagnostic
purposes rests very largely upon the form of the ray cells, it will
be evident that even a slight reduction of the angle from ninety
degrees must introduce an alteration of form which renders the
ray of no value. The chief value of the tangential section is
thus seen to lie in its exposure of the extremities of the rays,
the general composition and number of which may then be
ascertained with accuracy. From this it is possible 'to infer the
presence of certain structures in the tranverse section, such as
the resin passages, since as already pointed out there are very
constant relations between the occurrence of such passages in the
rays and in the longitudinal structure. Important exceptions to
this otherwise general law are to be met with in certain resin
cysts of traumatic origin among recent plants, and also in the
case of certain extinct species. Thus Sequoia Burgessii does not
exhibit resin passages in a transverse section, though they do
occur and are characteristically developed in the medullary rays.
Precisely similar structural conditions are to be found in Pity-
oxylon chasense. From the recent studies of Jeffrey, however
(25), we are led to the inference that such unusual relations,
which at first seem to indicate some peculiar feature in develop-
ment, may in reality be due to the fact that the longitudinal resin

GENERAL DIRECTIONS 21

passages occur at such wide intervals, or are so grouped within
narrow areas, that a given specimen may show none of them in
transverse section, although a very considerable area is examined.
In a minor degree the tangential section is also useful but not
necessary in extending our knowledge respecting the distribution
of bordered pits in the tangential walls of the tracheids, but
whenever such features are to be studied critically it will be
necessary to provide two tangential sections for each species,
one passing through the spring wood and the other through the
summer wood.

For the preparation of sections of fossil woods which are
strongly silicified or calcified, or otherwise infiltrated with mineral
matter, special apparatus for cutting and grinding is required,
and this part of the work is best accomplished by intrusting it
to one who has gained the necessary dexterity through long
experience. For those fossil woods of comparatively recent
deposits, such as the Pleistocene or later formations, which have
undergone little or no modification by the infiltration of mineral
matter, the methods applicable to woods from existing species
will be found to meet all the requirements of the case. Where
there has been a slight infiltration of mineral matter, boiling
with sodium carbonate will in most cases serve to remove the
carbonate or silicate, as the case may be, and bring the material
into such condition that it may be cut with facility by the micro-
tome knife. In all such cases, however, before mounting for
examination, care must be taken to fully neutralize the action
of the alkali by the action of dilute acetic acid, which serves to
restore the structure to its normal volume.

In the case of recent coniferous woods it will meet all the
requirements of the case and amply provide for species deter-
minations if blocks about one centimeter cube are boiled in water
from one half to two or three hours and then sectioned while hot.
The sections should be cut as thin as possible, carefully freed
from air, stained, and mounted in Canada balsam. In thickness
the sections should be as nearly as possible of the diameter of
a tracheid or less, and this may be accomplished by means of a

22 ANATOMY OF THE GYMNOSPERMS

carefully sharpened plane, which is, in some respects, one of the
very best of section cutters where the work does not call for the
most critical methods. Preferably the blocks which have been
boiled as described may be sectioned on a microtome in the
usual way. For this purpose any instrument which provides a
high degree of rigidity may be employed.1 For purposes of very
exact study more elaborate methods and more expensive instru-
ments will have to be employed, but since these relate chiefly to
botanical laboratories where they are already well known, they
need not be specified here.

For the purpose of freeing the sections from air, a somewhat
troublesome process where sections are prepared as specified,
the air pump may be used ; but a far more simple and less costly
method is to boil the sections in water for five or ten minutes and
then plunge them directly into 95 per cent alcohol. At intervals
of five minutes or so alternate the treatment with alcohol and
water, and, except in some of the most troublesome woods, such
as the spruces and larches, it will be found that the air is all dis-
charged in the course of half an hour. As a matter of precau-
tion the sections should then be left over night in 95 per cent
alcohol in order to secure complete dehydration.

Before mounting in balsam the sections must be stained. For
this purpose almost any of the well-known aniline stains or
Delafield's hematoxylin may be employed, the object being to
secure a perfectly sharp and well-defined image on a clear field.
But in the study of woods it is often of importance to be able to
photograph what is seen, and as all the stains are not equally
valuable for this purpose the dye should be selected with special
reference to the results sought. Where instantaneous exposures
are to be employed nothing is better than Delafield's hema-
toxylin, which is allowed to act until a deep purple color is pro-
duced. But this stain will not answer for time exposures as well

1 One of the best of simple instruments is the table microtome made by Bausch
and Lomb, but the knife used with this form of instrument should be a plane blade
mounted in a heavy wooden handle of such form as to secure a perfectly firm grip.

GENERAL DIRECTIONS 23

as some others. Under these requirements we may employ a
strong alcoholic solution of Bismarck brown which is actinically
opaque. By its use walls which are presented in section do not
transmit enough light to affect the plate even after rather long
exposures, while those walls which are presented in side view
and are relatively of little volume transmit enough light to make
a strong contrast. By using such process plates as the Imperial
a well-taken negative will show sharply contrasting black and
white and will bring out all the details. All of the photographs
in the present work were taken in this way.

After staining the sections should be passed into oil of cloves
until thoroughly cleared, after which they should be mounted in
xylol balsam.

CHAPTER II

THE GROWTH RING

In proceeding to a study of the transverse section the first
feature to which attention is naturally directed is the growth
ring. These are either broad or narrow, variable or uniform,
eccentric or regularly concentric according to their relative pro-
portions in radial extent, the constancy of their radial volume,
and their equal or unequal development at all points about a com-
mon center. While a recognition of such features often serves
an important purpose in confirming data from other sources, they
are in reality of secondary importance and too much stress
must not be laid upon them ; in fact, they may, if necessary, be
entirely neglected in most cases. This element of doubt is due
to the fact that within a given transverse section of an entire
stem the growth rings vary very greatly among themselves as
the result of varying rates of growth induced by external con-
ditions of soil and climate. These variations are of such a nature
that, in general terms, the growth rings will have the greatest
radial dimension in a young stem or at the top or toward the
center of an old stem, while such dimension diminishes within
the same stem radially outward, so that in the peripheral portion
of a very old trunk the rings will be either actually or relatively
very narrow. This general rule is subject to many exceptions.
In consequence of the suggestions furnished by this structural
feature it is desirable to include its description in every diagnosis
of a species, and we may therefore consider somewhat in detail
its principal aspects of structure and variation.

All of the North American Coniferales without exception,
both fossil and recent, and also all of the Japanese species so
far investigated, are characterized by well-defined growth rings.
These regularly recurring zones of growth, arising through

24

THE GROWTH RING 25

alternating periods of physiological rest and activity, correspond
very closely with annual periods, whence it is possible to utilize
them in determining questions of age which may be ascertained
in northern latitudes within an error not exceeding and usually
much less than one per cent (53, 162). This law has been
applied with success to the determination of the probable age
of certain blazes found in beech trees in Canada, tracing them
to the year 1721 and their probable origin at the hands of some
of the early Franciscan missionaries (54, 356, and 55, 500);
while Campbell has similarly applied it to a determination of the
age of certain Sequoias and the years in which forest fires or
other injuries were inflicted (9, 335). The chief sources of
error in such estimates lie in the difficulty of clearly recognizing
under all conditions the relation of a particular growth ring to
a certain year, since it is a well-known fact that under peculiar
conditions more than one ring may be formed in one season.
Thus Penhallow has shown that while in northern latitudes there
is an essential constancy in the relation of rings to annual periods,
this constancy diminishes toward the equator with a tendency
to the obliteration of the growth rings, whence it follows that at
some intermediate point in latitude there will be more rings
formed within a given period than there are years of age (53,
162). This is supported by the observed fact that in the
state of New York the common red maple (Acer rubrum) has
been known to form an average of three rings for each year of
growth, while in Florida at least forty rings have been found in
trees less than thirty years old. In such cases experience will
soon indicate to the observer that the demarcation between
rings of successive years is much more pronounced than bet\veen
those of the same year, directly corresponding to the duration
and intensity of the rest periods in each case, and from this
it is possible to reduce the error from such a source to a mini-
mum. Thus De Bary has shown that such double growth rings
as are referred to are the direct result of some disturbance of
the normal course of growth for the season, such as may arise
through the operation of frost, drought, insects, etc. (13, 514)-

26 ANATOMY OF THE GYMNOSPERMS

A concrete illustration of the conditions which would be likely
to produce such a result is presented in a late frost which seri-
ously affected vegetation in the neighborhood of Montreal in the
spring of 1902. On the 9th and loth of May of that year a cold
wave passed over Montreal, and inflicted such serious losses upon
early crops and effected so much damage to trees and shrubs
as to excite much comment. At that time nearly all trees and
shrubs were in tender leaf. Many were either in bloom or the
flower buds --as in the horse-chestnut -- were well formed
but not open. In such cases the new branches had already
attained a considerable length, but in many of the later species,
such as Catalpa, the English maple (Acer campestre), sumac
(Rhus typhina), and the ash, the leaf buds were not opened and
no material injury resulted. In all of the earlier forms, however,
the leaves and young branches were killed, and in the horse-
chestnut and elder (Sambucus racemosa) recovery involved the
formation of an entirely new set of organs from latent or adven-
titious buds. In such cases it is altogether likely that an exami-
nation of the wood for that year would show two rings of growth,
between which the distinction might be expected to be less
clearly defined than between those of successive years.

Variations in the width and prominence of growth rings of
successive years are in some cases so marked that, were pieces
of wood from the same stem to be examined without any knowl-
edge of their previous relations, they might be regarded as
representing wholly different species. This is notably the case
in the hard pines, such as P. palustris, P. cubensis, P. echinata,
etc., while it is also true of Pseudotsuga Douglasii, in which this
feature has been critically studied. In a large cross section of
this wood, embracing five hundred and thirty-eight growth rings,
the latter were found to be disposed in well-defined zones, which
vary greatly in width, while the component rings of contiguous
zones show well-marked differences in radial volume. An in-
structive example of such growth is given by Hartig (22, 40) in
the case of the Tyrolean larch, taken from a height of a thou-
sand meters and having an age of one hundred and ninety years

THE GROWTH RING

though only nineteen centimeters in diameter. Further, within
each zone (Pseudotsuga) the range of variation is narrower, and
oftentimes the rings present a remarkable degree of uniformity.
So well marked are these differences that when a number of trees
are examined it is possible to establish an exact correspondence
of zones by means of the average dimensions of the component
growth rings. These facts point with some force to the probable
operation of similar, if not identical, conditions of growth over a
somewhat extended period, while the periodicity of growth also
suggests a corresponding periodicity in environmental conditions.
It has elsewhere been shown (52, 35) that in the case of trees
exhibiting four such zones the following results are obtainable :

VARIATIONS OF ZONES AND GROWTH RINGS IN
PSEUDOTSUGA DOUGLASII

ZONE i

ZONE 2

ZONE 3

ZONE 4

No n

r Total width of zone, cm.
\ Number of rings

2.12

e

15-77
71

16.48
141

O.OO
O

J' OJ

I Average width of rings, mm. .

4.24

2.16

1.17

O.OO

No. 2

f Total width of zone, cm. . . .
•i Number of rings

o.oo
o

11.95

5°

4-52
38

O.OO
0

I Average width of rings, mm. .

o.oo

2.38

1.19

0.00

No 789

f Total width of zone, cm. . . .
•< Number of rings

17.07

T.Q

2.85
10

4-77
27

1.36

14

I Average width of rings, mm. .

4.38

2.85

1.70

0.97

No. 428

f Total width of zone, cm. . .
•s Number of rings

272

8

16.38
66

0.70
4

0.00

o

I Average width of rings, mm. .

3-40

2.52

i-75

o.oo

No 316

r Total width of zone, cm. . . .
4 Number of rings

16.28
«

4.42
17

3-23
28

0.85

IO

I Average width of rings, mm.

4.96

2.60

1.15

0.85

Totals, mm

i6.qc

12. CI

6.96

1.82

4-24

2.?O

1.39

0.91

28 ANATOMY OF THE GYMNOSPERMS

The variations thus indicated are usually accompanied by a
more or less marked alteration in the relative volumes of the
spring and summer woods, in consequence of which the same
tree may show regions of coarse-grained and fine-grained wood.
Plate i exhibits the characteristic features of such fine-grained
wood, and a comparison with plate 46 will serve to emphasize
the deviation from the usual type of structure.

Eccentricity of the growth ring is a feature more or less com-
mon to all woods (31, 5 13), and it is determined by external con-
ditions of light and warmth (22, 41 et seq.}, but ordinarily such
variations are not sufficiently marked to merit comment. In the
genus Juniperus, however, eccentricity is developed to an un-
usual extent, and it serves as a more or less distinguishing fea-
ture. From the photograph presented in plate 2 it will be seen
that the rings not infrequently coalesce on one side, while gain-
ing great prominence as separate structures on the opposite side.
A like eccentricity characterizes the genus Taxus.

We are then to conclude that growth rings are a normal and
constant feature in the stem structure of the Coniferales as a
whole, and the same is also true of the Gingkoales so far as we
know them through both fossil and recent examples of the genus
Gingko. But the same law does not apply to the Cordaitales as
a whole, and in this may be found one of the leading distinctions
between these two groups. This is especially true of the genus
Cordaites in which the " growth rings when present are obscure,
rarely somewhat conspicuous," and even in the latter case they
appear simply as regions of somewhat unequally variable density,
dependent upon regional changes in the thickness of the tra-
cheid walls and the volume of the lumen, the one region merging
into the other by somewhat gradual transitions and always
without that sharply defined alteration of structure so charac-
teristic of the growth rings in the Coniferales (plate i). In
existing Araucarias the " growth rings are not determinate, or
at most poorly defined," though De Bary (13, 513) cites the case
of a specimen of A. excelsa grown in the open ground, which
showed sixteen sharply defined growth rings, and Kraus has

THE GROWTH RING

29

observed somewhat similar phenomena in the case of A. brasi-
liana. Specimens coming under my own observation, but repre-
senting growth which was completed in a conservatory, show that
in A. excelsa and A. Cunninghamii the growth rings are either
not determinable or at most very imperfectly defined ; while in
A. Bidwillii they are only faintly defined by a slightly more open
structure in the earliest spring wood. The same law holds true
for fossil species in which it meets with only partial exceptions,
as in A. Edvardianum. In Dammara the " growth rings are more
or less clearly defined," approximating in this respect to what
is found in the Coniferales, and between which and the typical
Cordaitales they may be held to represent a transitional form.

Apart from those conditions of internal tension which arise
incidentally to the formation of dissimilar tissues, and which
induce structural alterations, growth rings may be regarded in
the main as a direct expression of the alternation of sharply
defined growth and rest periods ; and since these in turn are cor-
related with sharply defined seasonal changes, such as are com-
mon to more northern latitudes, it becomes possible to utilize
these facts in forming an approximate estimate of the general
climatic conditions under which the tree must have developed.
From this it is also possible to draw important inferences as
to the climatic conditions which must have prevailed in earlier
geological periods, as indicated by the presence or absence and
the specific character of growth rings in fossil woods, a conclu-
sion which gains force from the relation which the formation
of growth rings in Araucaria bears to climatic conditions, as
already stated.

Every growth ring presents two structurally dissimilar regions
which correspond with different periods of activity, and it is the
apposition of these in successive years which principally deter-
mines the recognition of the growth ring. The initial growth of
a given year arises at the earliest possible moment at which the
cambium is capable of generating new tissue. The elements
which thus arise are applied directly to the outer face of the
growth ring for the preceding year. In the formation of such

30 ANATOMY OF THE GYMNOSPERMS

elements two important factors are involved. Owing to the
peculiar conditions of growth attending their organization, they
are formed under a minimum tension, in consequence of which
they rapidly attain to relatively great size, and it is therefore
found that the first tissue of the season is always most open.
But this feature depends again upon the second factor. In con-
sequence of the great excess of nutrition supplied during this
period of growth, and the very rapid process of construction
which follows, secondary growth of the walls is limited and these
structures remain thin, while the lumens are correspondingly
large. In transverse section such cells almost invariably show a
greater length of the radial diameter, which is never less than
the tangential. As growth advances there is a slight but pro-
gressive change whereby the secondary development of the wall
increases somewhat and becomes constantly thicker ; but the
principal alteration occurs in the form of the cell in such manner
that the radial and tangential diameters tend to equality. Such
thin-walled structure is developed during the first four or six
weeks of growth, and it is therefore designated as spring wood.
Toward the end of the general growth period, which has elsewhere
been shown to terminate by the second or third week of July for
about ninety per cent of trees and shrubs in this latitude (80),
the structural character of the ring is subject to more or less
profound change as the rate of growth diminishes and the inter-
nal tension of the tissues increases. The isodiametric form of
the tracheid is then replaced by an extension of the tangential
diameter and a shortening of the radial diameter, the latter pro-
gressing more rapidly than the former. This alteration is of such
a nature that in those tracheids which represent the last product
of the season's growth the opposite tangential walls are closely
approximated or even in actual contact, while the tangential
dimension is sensibly increased as compared with tracheids of
the same row in the spring wood. Coincident with these changes
the secondary wall acquires an unusual prominence, and in many
of the hard pines, as also in Pseudotsuga, it becomes so exces-
sively thickened that the lumen is reduced to small dimensions

THE GROWTH KING ?>l

and not infrequently is almost obliterated. The summer ^vood
thus characterized is also distinguished by its greater hardness,
which in the Douglas fir imparts an almost flinty character to
the structure ; and commonly also, as exhibited in Pseudotsuga
Douglasii, Pinus palustris, P. resinosa, etc., by a considerable
amount of resinous matter, which, by reason of its definite color,
establishes a more or less striking contrast between the two
regions of growth. It is therefore obvious that the demarcation
of the growth rings depends upon the direct apposition of spring
and summer woods, each of which is characterized by special
structural and other physical features.

The transition from the spring to the summer wood is gradual
when there is no sharply defined limitation of the two zones, but
the one seems to merge into the other by a series of more or
less insensible gradations. This is exemplified in its typical form
in the Cordaitales, and among the Coniferales it is a feature
of the great majority of species. Under such circumstances the
internal limits of the summer wood can be determined only
approximately, and they are necessarily established where the
greatest alteration of structure and color occur. Less frequently
the transition is abrupt, as in the hard pines, notably P. palustris,
or in the Douglas fir (plate i). There is then a strong contrast
between the two structural regions. A further variation of this
relation is to be seen in those cases in which the somewhat grad-
ual transition from the spring to the summer wood is followed
the next year by a corresponding change to the spring wood.
This is of rare occurrence and is to be met with in only one case,
-Pinus Torreyana, — in which also such double graduation seems
to arise only in the case of thick summer wood, since, when the
latter is thin, the transition is abrupt. Rarely the summer wood
exhibits a zonal development whereby it becomes doubled through
the interposition of a zone of thin-walled and rather large-celled
tissue. This finds its typical development in Taxodium distichum,
of which it is a characteristic feature. It may also be met with
occasionally among the higher Coniferales, especially among the
hard pines. It is a constant feature of taxonomic value.

32

ANATOMY OF THE GYMNOSPERMS

The relative volume of the spring and summer wood is subject
to wide variation not only as between different genera and spe-
cies but also as between individuals of the same species. While
this depends in the first instance upon inherent qualities, it is also
dependent to a very large extent upon conditions of growth. In
Juniperus and some species of Cupressus, as also in Torreya and
Taxus, the summer wood may constitute the bulk of the growth
ring and render it impossible to determine where the spring wood
ends. The opposite extreme is to be met with in the genus
Thuya and in many species of Cupressus, where the summer
wood is reduced to from two to six rows of tracheids, which are to
be distinguished chiefly by their greater color and shorter radial
diameters. The Douglas fir offers an excellent illustration of
such variations within the limits of the species. This is shown
by the following data, taken from five different trees, and also
by plates i and 46.

RELATIVE VOLUMES OF SPRING AND SUMMER WOODS

SEQUENCE
VALUES

GKOWTH RINGS IN MILLIMETERS

RATIOS

Average Volume
of Ring

Summer Wood
Average Volume

Spring Wood
Average Volume

No. 2 . .

I

1.950

0.891

1.059

l.iS

" 428 . .

o

2.725

I.I IO

1.615

1.45

" 789 . .

3

3-250

0-975

2.275

2-33

" 35« • 1

f 4.600

1.200

3400

2.83

" 35'' • J

t 1-455

0.383

1.072

2.79

4

3-097

0.791

2.236

2.81

" 316 . .

5

5.100

0.950

4.150

4-37

While it is thus evident that estimates of relative volume
are of no great value for purposes of exact differentiation, they
nevertheless do serve a useful purpose in some instances, and
they should always be taken into consideration in a diagnosis.

CHAPTER III

TRACHEIDS

In the Gymnosperms the woody structure of the stem is com-
posed of more or less fibrous elements to which the generic
term tracheids may be applied in conformity with the definition
adopted by De Bary (13, 155), but which, for our present pur-
poses, may be described as elements of indeterminate or more
generally of determinate length, of either a prosenchymatous or
parenchymatous type, and characterized chiefly by the presence
of bordered pits. As such tracheids exhibit important varia-
tions among themselves, chiefly with respect to form, distribu-
tion, and structure, it is necessary to distinguish carefully between
the various types entering into the structure of the woody axis.
First of all it is possible to distinguish between those of the
prosenchymatous type and those of the parenchymatous type,
the differentiation being readily effected by means of the ex-
ternal form. Those of the parenchymatous type are to be met
with in either the medullary rays, when they may be described
as ray tracheids, or they arise in series parallel with the prosen-
chymatous elements with which they are therefore mingled as
wood parenchyma, and they are to be distinguished as paren-
chyma tracheids. A further discussion of these forms will be
deferred until they can be brought into connection with the gen-
eral structures of which they form characteristic features, while
at this time our attention may be directed more particularly
to the tracheids of the prosenchymatous type. The fibrous tra-
cheids are of two kinds, spiral and pitted. The spiral tracheids
are chiefly met with in the protoxylem region of which they are
characteristic and dominant elements and where they are of in-
determinate length. Their spirals represent a secondary growth
of the cell wall, and the latter is therefore devoid of pits

33

34 ANATOMY OF THE GYMNOSPERMS

except in transitional forms. Rarely the spiral tracheids are
met with in the secondary wood of which they then constitute
the chief part. But in such situations the spirals represent
a tertiary growth of the cell wall, which is also characterized
by the presence of bordered pits in the secondary wall. Such
tracheids are always of determinate length and their extremities
are tapering.

The pitted tracheids are exclusively elements of the secondary
wood of which they constitute the dominant features. They are
of determinate length and their extremities are tapering. Their
walls are characterized by the presence of peculiar pits which
belong to the secondary layer, and they are devoid of spirals
except in the case of Taxus, Torreya, Pseudotsuga, Larix ameri-
cana, and Pinus tseda, where the spirals represent the tertiary
layer of the wall. It follows that in this type the tracheids are
characterized by the presence of both spirals and pits. Before
proceeding to discuss these two forms of tracheids more in
detail, a synoptical view of the tracheids as a whole may serve
to make their relations more clear.

TRACHEIDS. Elements of a cylindrical or fibrous character, including
vessels and their derivatives, together with certain specialized forms
of a parenchymatous type, the whole distinguished by the presence of
bordered pits upon their terminal, tangential, or chiefly upon their
radial walls.

I. Wood tracheids. Elements which constitute the dominant structure of
the so-called wood. They are as follows :

a. Resinous. Not structurally different from the pitted tracheids, but

distinguished by the presence of resin, usually in the form of local-
ized masses like transverse septa in the immediate vicinity of
medullary rays. Common to the Cordaitales.

b. Spiral. Characterized by the presence of a spiral structure which

is typical of the protoxylem of all genera and is of secondary
origin ; also of tertiary origin and typical of the secondary wood
in special cases, being then accompanied by bordered pits.

c. Pitted. Characterized by the absence of spirals except in the

special cases indicated in b, and by the uniform presence of bor-
dered pits of secondary origin, chiefly on the radial walls; typical
of the secondary wood in all genera.

SPIRAL TRACHEIDS -r

3 0

2. Wood parenchyma trachcids. Usually short, cylindrical cells with thin
walls, transverse terminal walls, and bordered pits. Confined to the
higher Coniferas.

a. ParencJiyina tracheids. Characteristic of the xylem of the higher

Conifers, with which their general direction of growth coincides.
Found in association with the resin passages.

b. Ray tracheids. Characterized by their occurrence in the medullary

rays with which their general direction of growth coincides.

We may now proceed to a more detailed consideration of the
structure and distribution of the tracheids thus classified.

SPIRAL TRACHEIDS

The spiral tracheids are so called because of certain narrow
bands of secondary or tertiary growth which lie upon the inner
face of the cell wall and take the form of definite spirals. These
structures are found to present great diversity in the form of
their transverse section, which, as shown many years since by
De Bary (13, 156), may vary from elliptical or round-rectangular
to an almost quadratic form. In general terms they may be de-
scribed as ribbonlike and localized thickenings of the cell wall,
which are designed for the obvious purpose of strengthening
the latter. While this purpose is not always a prominent feature
in the Coniferae, it may nevertheless be recognized in the struc-
ture of the protoxylem, and it is conspicuously defined in those
thin-walled elements to be met with among Pteridophytes or in
the higher seed plants, notably in the spiral tracheids of Zea, in
which there is a strong disproportion between the thickness of
the initial wall and the volume of the cell. In more general
terms, therefore, it may be looked for in succulent stems of
vigorous growth rather than in those of a more woody character
and slow growth ; or it appears more frequently in plants of a
primitive type of organization than in those of a more advanced
type, in which the elements have experienced a more general
growth in thickness, and where, in consequence, special contriv-
ances for support are not demanded. From the standpoint of
development, therefore, we may consider that the typical spiral

36 ANATOMY OF THE GYMNOSPERMS

of the primitive forms has been lost through replacement by or
through its being merged by extension and fusion into a growth
which is continuous between all points of the cell wall. The
capacity for the formation of spirals is thus eliminated from the
greater portion of the structure of the wood, though survivals
are commonly met with in many of the higher seed plants, where
they impart to the wood more or less well defined characters of
diagnostic value. This capacity is also lost most completely in
the greater number of the Cordaitales, Gingkoales, and Coni-
ferales, - - indeed, it may be said that for the secondary growth
of the wall it is eventually lost in all species ; but the tendency
still survives, a fact made apparent by the observation that in
certain species the tertiary layer of the wall invariably gives rise
to such spirals, which then constitute definite and reliable diag-
nostic features, while in other species they are only imperfectly
formed. In all such cases the spirals are to be regarded as sur-
vivals,--as the last phases of a tendency which elsewhere has
become completely obliterated.

The origin of the spirals may be traced to a localized second-
ary growth of the cell wall. They constitute, in fact, the primi-
tive form of the secondary wall which later becomes modified
in accordance with altered conditions of growth in such way
as to involve an obliteration of the spirals. Such changes are
features of progressive development, in consequence of which
it is generally true that such structures are always most promi-
nent and abundant in the more primitive types, becoming more
rare in plants of a higher type of organization and development.
Similar relations exist as between the primary and secondary
wood of all known Gymnosperms, whence it is possible to recog-
nize the general law that spiral tracheids are a feature of the
protoxylem, to which region they are wholly confined in the
Coniferales and Gingkoales, and almost strictly confined in
the Cordaitales, being, with few exceptions among the higher
Coniferales, wholly absent from the secondary xylem.

The direction of the spirals is constant in most cases, being
right-handed or ascending from right to left on the side nearest

SPIRAL TRACHEIDS 37

the observer. Usually more than one spiral is developed in the
same tracheid, but it does not follow that the full number will
be present at all points throughout the length of the tracheid. As
between different genera and species, the number usually varies
from one to four. This is much less than in the Angiosperms,
where they may be as many as sixteen to twenty. Localization
also occurs in such manner that the spirals often run in series,
these latter being separated from one another by wider intervals,
and as this relation is subject to somewhat wide variation within
the same species, it follows that it cannot be utilized success-
fully for diagnostic purposes, although it is quite possible to rec-
ognize and define and utilize the more general differences of
distribution in the terms few and distant, numerous and approxi-
mate. The variation in distribution above referred to is largely
expressed in the fact that in the tracheids first formed in a sea-
son's growth the spirals will always be most widely separated,
while those which are formed later constitute a more compact
series. This fact becomes prominent wherever such structures
can be observed through a. considerable radial extent of wood, and
it is therefore particularly well shown in growth rings, though it
may also be seen in the protoxylem region when the latter is of
great radial extent, as in Cordaites. Thus in Taxus or Torreya
or Pseudotsuga it may be seen that in passing from the earli-
est spring tracheids to the last-formed summer wood there is a
graduated condensation of the spirals which agrees with the
relative rate of development in the tracheids themselves. A
similar variation is to be seen within the limits of an individual
tracheid in such way that the spirals in the central region are
more widely separated than those nearest the extremities. This
has been adequately explained by De Bary (13, 157), who has
shown the more distant coils to result from stretching of the
walls during the period of very active development, but subse-
quently to the formation of the spirals ; while the condensed
forms would be an expression of a slower rate of growth in the
cells or in special regions of them, in consequence of which the
spirals more nearly retain their original relations to one another.

-8 ANATOMY OF THE GYMNOSPERMS

*_}

In the Coniferales the spirals throughout the entire extent
"f the protoxylem structure are more or less distinct, though
there is a more or less definite tendency to coalescence. Such a
tendency becomes most pronounced in the lower Gymnosperms,
being especially well denned in the Cycadaceae and the Corda-
itaceae. In the former the spirals become approximated and
blend in such a manner as to definitely reduce the areas devoid
of secondary growth, which then assume an elongated form ; and
as this latter diminishes still further in length, the spirals are
eventually replaced by a more general thickening of the wall
through secondary growth, and definite pits arise. Such changes
are progressive from the protoxylem radially outward through
the entire extent of the secondary wood, so that there is a defi-
nite series commencing internally with typically spiral elements
and terminating outwardly with typically pitted elements, the
two being connected by transitional forms. The same structural
alterations may be seen in Cordaites, which offers a peculiarly
instructive illustration of the process because of the regularity
with which the changes arise and the extent of the structure in
which they lie. As these transformations which are completed
within the transition zone are of great phylogenetic importance
as well as of taxonomic interest, it will be necessary to trace
them somewhat in detail as they appear in Cordaites Brandlingii.

In the protoxylem region the structure is wholly composed of
spiral tracheids (plate 3). In the successive radial development
of new tracheids there is a constant tendency to a more uni-
form thickening of the cell wall by a secondary growth. This at
first finds expression in the more compact arrangement of the
spirals (plate 4), which later coalesce at various points, thus giving
rise to more localized areas devoid of secondary thickening, and
hence to a scalariform structure in which the general lines con-
form more or less closely to the direction of the original spirals
(plate 5). By a further modification the elongated, thin areas
become converted into shorter, often isodiametric areas substan-
tially by a process of division. A further tendency to general
thickening of the walls causes the margins of the scalariform

SPIRAL TRACHEIDS 39

structure to project from all sides and extend over the area <>1
arrested growth as a lip which never completely closes at the
center, where there is left a usually circular, sometimes oval or
again lenticular or even oblong, opening, and in this manner the
bordered pit is formed (plate 6).

From the statements so far presented it may be correctly
inferred that the structural alterations which arise within the
transition zone are subject to great variations, whereby the
change from spirals to bordered pits may arise very gradually
through a broad, radial zone, as in Cordaites Brandlingii, or it
may take place very abruptly, as in the modern Coniferae. The
general tendency of such evidence is to show that with a higher
type of organization there is a corresponding diminution in the
transition zone and an increased abruptness in the structural
alterations. The logical result of an extension of this process
would be the reduction of the bordered pit to the condition of
a simple pit, and ultimately to its complete obliteration. In the
Coniferae the reduction of the bordered pit to a simple pit some-
times occurs in the case of medullary rays or even in the case
of tracheids with very thick walls, but it becomes most promi-
nent in the Angiosperms, where it is a characteristic feature.
Instances also occur in some of the hard pines, in which the pit
is completely obliterated. This applies in particular to tracheids
of the summer wood, the walls of which have become unusually
thickened.

The relations to which attention has thus been directed some-
what in detail have been expressed in more general terms by
De Bary (13, 321) in the statement that, "Outside the primi-
tive elements wider tracheae follow. Their development takes
place successively, advancing from the inner edge of the bundle
outwards, and, as a rule, at a time when the elongation of the
entire part to which they belong is nearly at an end. The
thickenings on their walls, therefore, have a successively denser
arrangement ; dense spirals and annular tracheae, then reticu-
lated and pitted tracheae, follow one another in succession from
within outwards, with gradual transitions, or with the omission of

40 ANATOMY OF THE GYMNOSPERMS

one or the other intermediate form." It is probably a justifiable
inference from the preceding facts that the relation which exists
between the spiral tracheids of the protoxylem and the pitted
tracheids of the secondary xylem in the Coniferae is, in general
terms and from the standpoint of development, the same as
that exhibited between the lower and higher types of vascular
plants.

Inasmuch as specimens derived from fossil woods or from
recent woods which have been employed for constructive pur-
poses will almost invariably represent some portion of the sec-
ondary wood only, it follows that in all but exceptional cases
the spiral structures so far considered will be entirely absent,
and in those few instances in which they may occur the de-
termination that they belong to the protoxylem region can be
made without difficulty. It is nevertheless true that in a few
genera definite spirals are to be met with in the secondary wood
structure of which they may then be characteristic features
throughout the entire extent of the growth rings, or they may
be more or less localized. Such spirals, which are obviously of
an exceptional nature, are features in the development of the
tertiary wall of the tracheid, and they are therefore character-
istics of thick-walled elements. In all their essential character-
istics of form and distribution they conform to the laws which
govern the spirals of the secondary wall, but they show a marked
tendency to obliteration through degeneration in the relatively
thicker walls. Thus in the genus Taxus or Torreya such spirals
are common to all the tracheids of the growth ring, but in Larix,
as also in Pinus tseda, in both of which the walls are relatively
thicker, the spirals are reduced to a vestigial form, being spo-
radic and in the one case distant, while in the other case the
individual spirals are only partially developed. This law is more
exactly and specifically illustrated in Pseudotsuga, where there
is a strong contrast between the thin-walled spring wood and
the very thick-walled summer wood. In the former the spirals
are perfectly formed and constant, and they bear a very strong
resemblance to what may be observed in the Taxaceae. In the

SPIRAL TRACHEIDS

latter case, however, the spirals are either sporadic and vestigial
(P. Douglasii) or they are often almost completely obliterated
(P. macrocarpa). So well defined and constant are these relations
that they serve as an important differen-
tial character for the genus.

Tracheids with spirals developed in the
tertiary layer of the wall are thus seen to
be typical features of Taxus, Torreya, and
Pseudotsuga, while they are also more or
less distinctive features of Larix ameri-
cana and Pinus taeda.

In all investigated species of Torreya
there is a rather wide variation in the
angle which the spirals make with the
axis of growth, and this becomes most
pronounced in T. californica, which gives
the lowest angle for any species of either
Torreya or Taxus. Usually the spiral
has an angle quite distinct from that of
the lines of striation in the cell wall, but
in Torreya taxifolia (fig. i) the two often
coincide. The following will show the various details derived
from the average of ten measurements for each species:

©

0
0

0

FIG. i. TORREYA TAXIFOLIA.
Radial section showing
spirals of tracheids and
bordered pits. X 210

AVERAGE
ANGLE

HIGHEST
ANGLE

LOWEST
ANGLE

EXTREME
RANGE

Torreya nucifera . .
Torreya taxifolia . .
Torreya califomica .

70.5°
70.4
46.2

87.0°

77-o
63.0

57-o°
61.0

30.0

30.0°
16.0

33-o

Means

62. f

715.7°

4Q-1°

26.3°

In the genus Taxus (fig. 2) the spirals are rather close and in two,
rarely three, series. As in Torreya, they are typical throughout
the spring wood, but with a pronounced tendency to obliteration
in the summer wood. This tendency is subject to considerable

ANATOMY OF THE GYMNOSPERMS

variation in different species. In T. canadensis the spirals are
conspicuous throughout. In T. floridana they usually disappear in

the later growth, and are wholly wanting
in the two or three last-formed tracheids.
In T. brevifolia they become very imper-
fect in the outer summer wood and tend
to disappear completely, only vestiges
remaining in the last-formed tracheids.
In T. cuspidata the spirals are generally
absent from the summer wood, or when
present are merely vestigial. The angle
is somewhat greater — about 7 degrees
- than in Torreya, and with respect to
certain species this fact is apparent with-
out special measurement. The four spe-
cies appear to be paired off in such a
way as to represent a mean difference of
about 10.9 degrees as between T. cana-
densis and T. floridana on the one hand,

FIG. 2. TAXUS BREVIFOLIA. and T" brevifolia and T. cuspidata on
Radial section showing the other. In all cases the angles of

spirals of tracheids and the jrals are jte distinct from those
bordered pits, x 210

of the lines of striation. The follow-
ing details are based upon an average of ten determinations :

AVERAGE

HIGHEST

LOWEST

EXTREME

MEAN OF

ANGLE

ANGLE

ANGLE

RANGE

Two

Taxus canadensis . . .

72.4°

88.0°

66.0°

22.0°

Taxus floridana

78.4

90.0

72.0

18.0

75-4

Taxus brevifolia . . .

63.0

76.0

55-Q

2I.O

Taxus cuspidata . . .

66.1

87.0

45-Q

42.0

64-5

Means

6q.q°

8<;.2°

sq.<;0

2C..70

jy'j

-_)•/

A comparison of these results in detail emphasizes the fact
that the distribution of the spirals, as between spring and sum-
mer wood, is in direct harmony with the principles already

SPIRAL TRACHEIDS 43

stated, and furthermore that the angles at which the spirals
develop do not afford an adequate basis for generic differentia-
tion. It is nevertheless possible to recognize subgeneric groups
in such wise that in both genera a general line of division may
be established at 70 degrees. In the case of Torreya californica
the very low angle of 46.2 degrees may be regarded as a differ-
ential character of specific value.

In the genus Pseudotsuga spirals are confined to the tra-
cheids of the spring wood. This has a partial exception in
P. macrocarpa, in which vestigial spirals may be observed in
the tracheids of the earlier summer wood. In this species the
mean angle is 70 degrees, but the spirals are always character-
ized by lack of prominence, they are often widely distant, and
the somewhat extended areas within which they are wholly
wanting or fragmentary suggests a process of obliteration. In
P. Douglasii the average angle is 82 degrees ; the spirals are
characterized by considerable prominence and they are also, on
the whole, close. In P. miocena the angle ranges from 49 de-
grees to 83 degrees, with a probable mean of about 65 degrees,
from which it would seem likely that this species occupies a
position superior to that of P. macrocarpa, but this relation can-
not be determined with certainty on account of the difficulty
of ascertaining their distribution within the limits of the summer
wood. In the genus as a whole the angle, the prominence of
the spirals, and the closeness of the turns obviously possess
well-defined differential value with respect to the limitations of
the species.

Among the higher genera of the Coniferae only two cases are
known in which spirals occur, but in each the character is of a
very sporadic nature. In Larix americana the spirals are fre-
quently found in the summer wood, but they are so inconstant
in their occurrence and present such varying aspects that the
angle cannot be determined. In Pinus taeda, where the walls
of the summer tracheids are very thick, rudiments of spirals
may sometimes be seen. Here also it is manifestly impossible
to determine the angle.

44 ANATOMY OF THE GYMNOSPERMS

Viewing these five genera collectively, their spirals conform
fully, in their occurrence and relation to progressive develop-
ment, to the general principles already stated, and especially
as formulated by De Bary. They possess no differential value
of generic rank with respect to Pinus and Larix, but they do
have such value with respect to Torreya and Taxus on the one
hand and Pseudotsuga on the other, the differentiation resting
upon their occurrence in the summer wood in the former and
their exclusion from that region in the latter. Were any ques-
tion to arise in this connection, it could be authoritatively decided
by the definite association of resin passages and fusiform rays
in Pseudotsuga.

It only remains to determine how far such structural features
may be employed as a basis upon which to determine the general
phylogeny of the genera. Between Torreya and Taxus there is
very little upon which to base conclusions respecting sequence in
development, and it is apparent that both of these genera have
attained to nearly the same level. Such differences as do exist,
however, seem to point to the relatively though slightly inferior
position of Torreya as indicated by (i) the smaller angle in that
genus, and (2) the generally more compact spirals of Taxus. This
view, so far as it possesses phylogenetic value, appears to confirm
the conclusions respecting the relative positions of these two gen-
era as already determined upon the basis of external morphology
and stated by Eichler (15, 103).

It is fairly clear, from the facts at hand, that all such spirals
as are to be met with in the higher Coniferales are to be regarded
as survivals of structures which gained greater prominence in
a more primitive state of development of the organism. They
do not, therefore, indicate simple parallelisms between plants
occupying a similar horizon in the scale of development, but they
rather direct attention to derivation from a common ancestry,
and, as previously pointed out (59, 255), they lead us to the con-
sideration that Torreya, Taxus, Pseudotsuga, Larix, and Pinus
represent different branches of a general phylum, - - undoubtedly
also including other closely related genera in which the spirals

PITTED TRACHEIDS 45

have been wholly obliterated, -- which had its origin at a point
anterior even to such types as Cordaites, and therefore in a group
probably represented by the Cycadofilices.

PITTED TRACHEIDS

The pitted tracJieids may be so distinguished because of the
invariable presence of bordered pits upon their radial and, under
some circumstances also, upon their tangential walls. Such pits
belong to the secondary layer of the cell wall in all cases. In
comparatively few instances such pits may be associated with
spirals in the tertiary wall, when the two structures will be found
so related that while the latter may overlap the former, the
orifice always lies between the turns of the spirals (figs. I and 2).

In their transverse aspect there is no feature which may be
employed to distinguish the pitted from the spiral tracheids. In
the longitudinal aspect the former differs from the more primi-
tive forms of the spiral tracheid with respect to length and
definite terminations in such way that the one is a wood cell
while the other is a vessel, but between the two no sharp line
of demarcation can be drawn, since, as already indicated, they
pass the one into the other by insensible gradations.

All tracheids exhibit the same structural features with respect
to the development and composition of the wall, and as a knowl-
edge of these is antecedent to a correct understanding of certain
alterations which arise incidentally to growth and also to decay,
it will be desirable to examine into the structure of the wall
somewhat in detail.

Assuming the primitive form of the cell to be that of a sphere,
this form undergoes alteration in accordance with the immediate
environment whereby growth first of all becomes excessive in
one direction coincident with the axis of growth for the plant
as a whole, while it remains practically equal in the radial and
tangential planes which cut the first at right angles. From this
it follows that while in a longitudinal aspect the tracheid is
always presented as a fibrous element with tapering extremities,

46

ANATOMY OF THE GYMNOSPERMS

tw.

in a transverse section it approximates more nearly to the primi-
tive form and thereby exhibits a hexagonal outline as directly
derived from the circular by mutual compression of contiguous
elements. As the woody elements arise by division, their tend-
ency at first is to assume the spherical form ; hence they split
away from one another. But such separation is never fully com-
pleted ; in fact, it is never developed to any marked extent in
woody tissues and it remains localized. The separation is usu-
ally confined to the angles of the tracheids, and it results in the

formation of intercellular spaces,
which therefore originate scJii-
zogcnously (fig. 3). In the subse-
quent modification of the wall by
secondary growth these spaces,
when not too large, are com-
monly obliterated by infiltration.
The presence of such intercellu-
lar spaces always emphasizes the
fact that what appears as a single
membrane is in reality a double
s-w. wall, one half of which belongs

FIG. 3. PSEUDOTSUGA DoucLAsii. toeach of the adjacent cavities.

Transverse section showing the struc- jn thg secondary growth of the
ture of the cell wall: p.w., primary

wall; j.w., secondary wall ; t.w.t ter- wall new layers are laid down

tiary wall; *j., intercellular space. on opposite Sides of this primary

wall (fig. 3), and in their devel-
opment they give the dominant features of thickness, color, and
hardness (fig. 3, s.zv.). When brought into such relations the pri-
mary wall, apparently lying between two cells, is often designated
the intercellular substance. The secondary wall not only exhibits
very variable development in thickness according to the condi-
tions of growth, as between the spring and the summer woods,
but its growth is also more or less localized, and there thus arise
such structural features as have already been described in the
spiral tracheids, or such as will be discussed more in detail in
a subsequent chapter under the title of "Bordered Pits." Upon

1T1TKI) TRACHKIDS

47

the inner face of the secondary wall there is what is known as the
tertiary wall (fig. 3, t.w.}. This is of limited volume in the great
majority of cases, and it is to be recognized as a thin layer. It
rarely attains any prominence or contributes to the structural
variation of the tracheid, but in Taxus, Torreya, and Pseudotsuga
it does follow the same course of development as the secondary
wall of the primitive tracheids, and develops spirals which are
constant and distinctive structural features. Vestiges of such ter-
tiary spirals are to be found also in Larix and Pin us, and wherever
they occur they are to be interpreted as representing a phase
in the degeneration of the spiral structure which has already
permanently disappeared from the secondary wall but survives
in the tertiary wall to a certain extent. In any transverse sec-
tion of a thick-walled tracheid, under favorable conditions, we
may observe fine lines disposed concentrically with one another
and with the primary wall. These represent the stratification
of the secondary wall, and they are substantially due to the
process of upbuilding by successive layers. In a longitudinal
aspect the wall also shows a series of fine lines cutting the axis
of the tracheid and the lines of stratification diagonally, or in
a transverse section cutting the latter radially. These repre-
sent the lines of striation, due probably to localization of water
of organization along definite planes of growth. They are not
readily observable under ordinary conditions, but when the cells
are macerated in potassium hydrate they stand out with great
prominence, and it will be seen in a subsequent chapter that
the same effect is also produced by decay.

The substance of the cell wall consists primarily of cellu-
lose, represented by the formula C6H10O5, but in the course of
growth alterations arise through the introduction of carbo-
hydrate bodies of various kinds, so that the composition can no
longer be represented by such a simple formula. Thus in the
primary cell wall there is usually a large amount of pectin, which
may be differentiated and localized by ruthenium red, which
develops a bright cherry or rose-red color and affords a very deli-
cate test. In the secondary walls also the cellulose represents

48 ANATOMY OF THE GYMNOSPERMS

various modifications which may all be embraced under the com-
prehensive term lignin. Such lignification is, in general terms,
characteristic of the woody tissue of all plants in various degrees,
but usually in such manner that the hardness of the parts is
directly related to the extent of lignification. The differences
thus briefly indicated not only bear an important relation to the
action of various chemical reagents and stains, but they are
of the first importance in explaining the variable phenomena of
decay ; since it is found that neither chemical agents, stains, nor
decay act uniformly upon all parts of the cell wall, their action
varying according to locality as well as according to the particular
agent or the specific organism concerned. It will therefore be
profitable to inquire somewhat more closely into these relations.

According to Weiss (75, 61) the percentage composition of
the unaltered cellulose may be taken as C44 4H6 .18O49 38. In the
course of growth, however, alterations of various kinds arise
through the introduction of carbohydrate bodies of various kinds,
though all belonging to the cellulose group, so that the com-
position can no longer be represented by such a simple formula
as that given. The composition of these secondary products or
incrusting substances, though somewhat widely different in dif-
ferent plants, may be said to vary within an approximate percent-
age range of 5.99 for carbon, 0.53 for hydrogen, and 8.15 for
oxygen, while their mean composition may be stated as C 50.7,
H 6.08, O 43.03 per cent. On the other hand, the incrustation
substance from the same plant (Fagus sylvatica) may be found to
vary from C 48. 10, H 6.09, O 47.81 per cent to C 67.91, H 6.89,
O 25.20 per cent. A comparison of these modified forms with
normal cellulose brings out the important fact that while there is
essentially no change in the percentage proportion of hydrogen,
the oxygen has been reduced in varying quantities from 1.57
per cent to 24.18 per cent with a corresponding increase in the
relative proportion of carbon.

Accompanying changes of the nature thus far discussed -
the formation of the secondary wall and the deposition of lignin
substance - - are always associated with the deposition of mineral

PITTED TRACHEIDS 49

matter which is localized in the cell walls as the only way pro-
vided for the disposal of waste matter. Such mineral salts are
important factors in imparting an increased specific gravity and
a greater element of hardness to the structure as a whole, while
they appear upon combustion in the form of an unoxidizable ash
residue, which varies in the North American Coniferac from 0.08
per cent in Libocedrus and Pseudotsuga - - in specific cases of
the latter falling as low as 0.02 per cent --to 1.34 per cent in
Torreya taxifolia (65, 333).

The variations in the cell wall thus noted are accompanied
and more or less exactly indicated by the reactions of the wall
toward chemical reagents and stains. Thus aniline chloride or
sulphate imparts a brilliant yellow color to the entire lignified
membrane, serving at the same time to differentiate the primary
from the secondary walls by virtue of the greater depth of color
and the greater degree of translucency imparted to the former.
Iodine is absorbed with great energy by all parts, but rather more
strongly by the primary wall, which thereby acquires a deeper yel-
low or yellowish brown. When lignified membranes are treated
with strong sulphuric acid the secondary wall is attacked and
brought into solution, while the primary wall is left intact if the
action be properly limited. In this case the action is one of
hydrolysis. On the contrary, a strong oxidizing agent, such as
Schulze's maceration, acts first upon the primary wall, thereby
separating the secondary walls from one another ; or, in accord-
ance with Mangin's reaction with alcohol and hydrochloric acid,
whereby the pectic acid is set free from its original combinations,
it is possible not only to secure a more intense reaction with
ruthenium red but also to separate the cells from one another
when the pectic acid has been neutralized by ammonia. Similar
disintegrations may be effected in the primary wall by other
reagents, in which case they constitute the scientific basis for
such important economic processes as are involved in the manu-
facture of wood pulp by chemical means.

The total thickness attained by the cell wall necessarily varies
as between the spring wood and the summer wood. This relation

50 ANATOMY OF THE GYMNOSPERMS

is subject to somewhat wide variation as between different spe-
cies and genera, and it is also found to be of a marked nature,
even in the same species under different conditions of growth.
For more extended details reference should be made to the table
in Appendix A, but for our present purposes a few examples may
be selected. Thus in all three of the investigated species of
Araucaria the ratio of the walls -- spring to summer wood --is
i : i, a relation which exactly corresponds with the absence of
growth rings. In Juniperus virginiana the ratio is i : 2 ; in Cryp-
tomeria japonica it is 1:4; in Tsuga Sieboldii it is 1:5. On
the other hand, the same species may exhibit two ratios as deter-
mined by the peculiar conditions of environment under which
the growth has been formed. Thus in Taxus canadensis we may

have ' , L : 4.8 /u, ; in Larix Lyallii ., L : 8.4/u,; and in Libo-
4.SJ i.bj

r 2.4

cedrus decurrens we may get 1.4 : -I , /LA. While, therefore, it is

[4.8

obvious that there are certain ratio differences between the walls
of these two structural regions, --differences which are more or
less directly associated with species, --and while such differences
may be of some value in confirming conclusions derived from
other data, they are not of such a nature as to permit the formu-
lation of a general law applicable to species in such a way as to
establish a precise differentiation, since variation arises within
the same species as a result of different internal and external
conditions of growth, such as tension, soil, and climate, the lat-
ter being influenced by situation and exposure. In many cases,
where the actual thickness of the walls is the same, the apparent
thickness will vary considerably. This is directly attributable
to differences in the transverse volume of the tracheid, whereby
the spring tracheid, from its greater size, will have a wall rela-
tively thinner, and thus apparently thinner than that of the
summer wood. Our investigations show that for twenty genera
and one hundred and fourteen species the mean ratio is i : 2.12.
The following summary for genera may be consulted in this
connection :

PITTED TRACHEIDS

TABLE OF RATIOS FOR THE TRACHEID WALLS — GENERA

VOLUME OF TRACHEID,
SUMMER TO SPRING
WOOD IN TRANSVERSE
SECTION

THICKNESS OF WALLS,
SPRING TO SUMMER
WOOD

NUMBER OF SPECIES
FOR AVERAGE

Dammara . . .

I

1. 80

,

1.66

I

Araucaria . .

I

1. 10

I

I.OO

3

Gingko ....

I

3-64

1-33

i

Torreya ....

I

1.62

1.99

3

Taxus

I

1.67

1.56

4

Thujopsis . . .

I

I-13

2.50

i

Cryptomeria .

I

1.68

4.00

i

Podocarpus .

I

2.01

i-43

i

Taxodium . . .

I

1.25

2.OO

i

Libocedrus . . .

I

2.6O

f

I.70-)

i

I

3-43 1

Thuya

I

2.26

2.88

,

Sequoia ....

I

2.5I

i

2.75

2

Cupressus . . .

I

1.98

i

1.71

9

Juniperus . . .

I

2.24

i

i-43

ii

Abies

I

2-35

i

2.27

ii

Tsucra .

I

1.97

i

3.01

5

Pseudotsuga . .

I

2.31

i

2-95

2

Larix

I

2.76

j

2.86

4

Picea

/

2.12

j

2.27

t
q

Pinus .

i

i nS

i

/
T <T7

:?
41

T

Grand average . .

i 11.95

I : 2.12

114

Variations in the transverse volume of the tracheid as ex-
pressed in square microns constitute the most prominent feature
of any transverse section. They are expressed most conspicuously
between the spring and summer woods, and they are clue to the
same causes which operate in the formation of the ring itself.
Their relations are such that the earliest spring tracheids are
always of greatest volume, but there is a progressive diminution
radially outward at a somewhat uniform rate. At a certain point
in radial development, however, there will usually be found a some-
what more marked alteration, which in specific cases becomes
most pronounced --Pinus palustris - - and results in an abrupt
transition from one zone to the other. In other cases — Taxus

52 ANATOMY OF THE GYMNOSPERMS

and Torreya (plates 20 and 22) --the transition is so gradual
that it is often difficult or impossible to establish the exact
boundary between the spring and summer woods. Such dimi-
nution in volume is accompanied by alteration of the two axes
in such a manner that the tangential is steadily lengthened
while the radial is correspondingly shortened. It is, therefore,
commonly found that in the last-formed cells of the season the
tangential diameter is somewhat longer in accommodation to the
increased circumference of the zone, while the radial diameter
is so shortened that the opposite walls are closely approximated
or even in direct contact.

The relative volume of the spring and summer tracheids is
subject to somewhat wide variation within the limits of the
genera, being in the ratio of i : i.io for Araucaria, where there
is practically no distinction of the two zones, and of i : 3.64 in
Gingko, where there is a correspondingly sharp definition. The
mean ratio for twenty genera, represented by 114 species, is
i : 1.95. Within species limits similar variations arise, the most
marked extremes being represented by Sequoia and Juniperus.
In the former case the ratio varies from i : 1.77 in S. gigantea
to i : 3.26 in S. sempervirens. In the latter genus the variation
lies between i : 1.33 in J. conjugens and i : 4.4 in J. sabina. A
somewhat extended study of the Douglas fir has given an oppor-
tunity to examine these differences with respect to a somewhat
wide range of individuals. Thus in seven specimens taken with-
out special selection, the following values are found :

No. i.

2.

3-
4-

5-
6.

7-
8.

9-

10.

. „ > Regional variations in the same specimen.

-.1.14
'• 3-23

Regional variations in the same specimen.

12.14

: 2.50

: 1.70 )

. ,, /-o ( Regional variations in the same specimen.

RESINOUS TRACHEIDS 53

The mean ratio for all these specimens is i : 2.21, which very
closely approximates to that for P. macrocarpa (i : 2.41), and it
shows that the spring tracheid is normally twice the volume of
the summer tracheid. But such a ratio is subject to important
exceptions within the limits of the individual. Thus the values
for i and 2 relate to regional differences in the same specimen,
and the same is also true of 5 and 6, and 9 and 10. It is there-
fore obvious that such variations are in no sense of specific value
for diagnostic purposes, since they are often as widely divergent
within the limits of the species as between different species,
being determined by peculiar conditions of growth. Inasmuch as
variations in the relative volume of the tracheids is a feature of
the density of the wood as a whole, it may be supposed to bear
a certain relation to the strength of material and so to the value
of the wood for constructive purposes, but this has been shown
not to be the case (52, 39).

RESINOUS TRACHEIDS

In Araucaria excelsa a transverse section shows more or less
numerous elements containing resin. These are not to be dis-
tinguished in their general structure from the surrounding tra-
cheids, and they are to be recognized solely by their contents,
which are usually somewhat prominent. Their distribution is
characteristic. They occur in small, scattered groups, or more
commonly in rows one or two elements wide, parallel with the
medullary rays and in immediate contact with them on each
side. When the plane of section passes near the position of
apparently terminal walls, the latter are cut through in various
ways, but they never exhibit any structural features, and they
are therefore in no way comparable with the terminal walls of
the wood -parenchyma cells. In a radial section these elements
are seen to be long and fusiform, exactly resembling the wood
tracheids except for reddish-brown, transverse plates which occur
either close to or exactly opposite a medullary ray, --a posi-
tion which is more clearly seen in a tangential section (fig. 4).

54

ANATOMY OF THE GYMNOSPERMS

The dark plates closely resemble Sanio's bands, for which they

might very readily be mistaken upon casual observation, or they

might likewise be mistaken for terminal
and unpitted walls. In Dammara australis
these features are presented in their typ-
ical form. The transverse section shows
such elements to be numerous and dis-
posed in radial rows on each side of the
medullary ray (fig. 5). In a radial section
they present the
same fibrous and
fusiform charac-
ter as in Arau-
caria, but, in
addition, the wall
usually experi-
ences a marked
increase in sec-
ondary growth
within the region

exactly opposite a ray (fig. 6). This fea-
ture is also prominent in the transverse

section (fig. 5). Such local increase in

thickness always arises in adjacent cells

in such a way that the more strongly

thickened regions are exactly opposite,

and they serve to constrict the cell cavity

gradually from above and below, in such

manner as to leave a channel about half FlG-5- DAMMARA AUSTRA-

LIS. Transverse section

the usual width of the cell cavity, which showing the disposition of

gradually widens upward and downward

(fig. 6). It is at the position of maximum

constriction that we find a transverse

plate of variable thickness, but always of a reddish-brown color.

These plates are always thinnest in their central region, and they

may be of uniform thickness for the greater part of their extent.

FIG. 4. DAMMARA AUSTRA-
LIS. Tangential section
showing the relation of the
resin plates and the medul-
lary ray, and a fractured
plate (r.p.). X 225

the resinous tracheids on
opposite sides of the med-
ullary ray at r.t. X 300

RESINOUS TRACHEIDS

55

At the region of contact with the tracheid wall they become
thicker and thereby attain a vortical distribution to an extent
four or five times greater than the general thickness. At such
position also there is a somewhat clear differentiation between
the plate and the wall of cellulose in point of color. Such plates
show absolutely nothing of the nature of pits, and they are in no
sense comparable with the terminal walls of the wood-parenchyma
cells, except in form and position (fig. 6). The peculiar position
of these plates, their resinous color, and their simulation of both
Sanio's bands and terminal walls excited a suspicion as to their
true nature, and led to the belief
that they might not be structural
features at all. They were there-
fore subjected to a series of care-
ful tests to determine (i) if they
were structural, (2) if they were
resinous, and (3), if the latter,
to what extent. It was recalled
in this connection that, although
devoid of any special secretory
reservoirs in the wood, Dammara
is nevertheless well known for its
production of the resin known as
kauri or gum dammar. It was sus-
pected that the plates might be
local deposits of resin, and they
were therefore brought into direct comparison with gum dammar,
the characteristics of which are well known and described by
Wittstein (77, 63). Tests were applied to thin radial and tan-
gential sections, employing for this purpose (i) various essential
and fixed oils, (2) ether, (3) alcohol, (4) ammonia, (5) potassium
hydrate in i^ per cent solution, and (6) concentrated cupric
acetate. The plates were found to be very refractory with re-
spect to all these reagents, and in all cases no change was to
be observed, even after the action had extended over a period
of several weeks, except partially in the case of ether and

FIG. 6. DAMMARA AUSTRALIS. Radial
section showing the local thickening
of the tracheid wall, and the occur-
rence of resin plates (r.p.) opposite
a medullary ray. x 225

ANATOMY OF THE GYMNOSPERMS

alcohol, and completely in the case of potassium hydrate. In the
ether reaction there did appear to be a certain diminution in
volume, apparently through solution, when the reagent was first
applied, but after that there was no further alteration. The
application of alcohol, both in the hot and in the cold, showed
that while the resin contained in the medullary rays was all
dissolved, the plates were only partially affected. The reaction
of the reagent was chiefly manifested in the development of
strong curvature, often accompanied by fracture (fig. 4, r.p}.
This was evidently due to an increase in volume as the first tend-
ency toward solution, and it gave the first definite evidence that
the plates could not be of a cellulose character. Beyond this

no further change was brought
about, even after several weeks
of action. The potassium hy-
rp rp drate gave the most positive

results. At first there was no
apparent change, but after
an interval of about ten days
or two weeks the plates were
found to have completely dis-
FIG. 7. DAMMARA AUSTRALIS. Radial appeared, leaving a perfectly

section showing the origin of the resin i , i • ., n •,

clear channel in the cell cavity.

plates (r.p.). x 225 J

A further proof of the resinous

character of these plates is to be found in the ruptures which
they not infrequently exhibit (fig. 4, r.p.}, and in the various
developmental stages which may be observed without difficulty
(fig. 7). These show that the resin gathers locally upon the
inner face of the tracheid wall, and as its volume increases it
projects from all sides toward the center, where it coalesces
to form a continuous and imperforate septum. The facts thus
obtained prove most conclusively that the plates are not cellu-
lose, and although immersion in concentrated cupric acetate for
eight weeks failed to develop the characteristic reaction, they
point to the idea that the plates are probably resinous. The con-
clusion is probably justifiable that they consist of gum dammar,

RESINOUS TRACHEIDS 57

which they closely resemble in many of their reactions, but of a
highly refractory and modified character. The same evidence also
conclusively shows that the cells in which the plates are devel-
oped are normal wood tracheids and not wood parenchyma, which
is altogether unknown in any of the Cordaitales.- Any transverse
section of the wood of Cordaites will show these resinous plates
to be present, usually in much larger numbers than in either
Dammara or Araucaria, and they exhibit the same features in dis-
tribution (plate 12). Compare also plates 14 and 16.

We are naturally led to ask, What is the purpose of these resin
plates ? The peculiar form in which the resin is deposited and
the particular location of the plates points with much force to
their connection with some functional activity, since if it were
simply a question of the storage of secreted products, the latter
would hardly be disposed as found, but rather after the manner
common to so many of the Cupressineae ; and this suggestion
gains strength from the fact that with respect to the peculiar
form of the resin masses as well as their location in the tissue,
the Cordaitales are peculiar among the Gymnosperms. No exact
comparison can be established with other plants, and it is diffi-
cult to suggest an adequate explanation. One thing does seem
clear, however, and that is that since these plates are of an
impervious nature and developed in some cases, at least, in con-
nection with a special constriction of the tracheid cavity, they
offer and possibly are specially designed to afford a definite
obstruction to circulation in a vertical direction. In this sense
they may be designed to serve the same general purpose that is
accomplished by the development of thyloses in the vessels of the
Angiosperms or in the resin passages of the higher Coniferales.
It is therefore possible that they may be connected in some way,
not at present clear, with a more complete restriction of the
circulation to a horizontal direction, and particularly through
the medium of the medullary rays as specialized channels for
that purpose. Among existing Gymnosperms resinous tracheids
are almost exclusively confined to Dammara and Araucaria,
though it is a noteworthy fact that similar structures occur rarely

58 ANATOMY OF THE GYMNOSPERMS

among the higher Coniferales. In the genus Abies they are prom-
inent features in both A. Fraseri and A. grandis. In the former
a transverse section shows them to be prominent and scattering
through the summer wood, more rarely in the spring wood; while
in the radial section the resin is seen to be massive in the sum-
mer wood, forming a peripheral layer in the spring wood. In
A. grandis the resin is usually more abundant, but otherwise the
features are the same.

The taxonomic value of the resinous tracheids applies exclu-
sively to the Cordaitales, where they are of ordinal value, though
in Dammara and Araucaria they may also become of specific
value. In Abies they are so sporadic and present so little con-
stancy as to be of no value.

From a phylogenetic point of view it is possible to determine
the position which they occupy in the general scale of develop-
ment, and so to utilize them in determining the position of plants
in which they may occur. That they are met with in their most
characteristic form almost exclusively in one of the most ancient,
as also in one of the relatively primitive, groups of Gymnosperms
points with force to the idea of their being also a primitive form
of the secretory reservoir. This view is greatly strengthened by
the fact that in such plants there are no special secretory reser-
voirs such as may be met with in the higher Coniferae, nor do
we even find specialized wood-parenchyma cells devoted to such
purpose. In this sense the sequence of the resin-producing struc-
tures would be (i) resinous tracheids, (2) resin cells, (3) resin
cysts, (4) resin passages. The relation of such a sequence to the
general phylogeny would be that, since resinous tracheids appear
in a sporadic form in Abies and thereby represent a limited sur-
vival of a primitive character, the Coniferales have a common
origin with the Cordaitales, which, developing as a lateral member
of the main phylum, has retained this feature as an essential
characteristic while it has disappeared almost completely from the
main line of descent. Such obliteration is fully expressed in the
Gingkoales, which have also been developed as an offshoot from
the parent stem.

CHAPTER IV

BORDERED PITS

In a preceding chapter it has been shown how the bordered
pit originates in the spiral structure of the protoxylem through
a more general and continuous development of the secondary
layer of the cell wall. We are now concerned with an inquiry
into the detailed structure of these markings, their variations
under different conditions of growth and situation, and their
relations to taxonomy as well as to phylogeny.

It has been seen that in the genesis of the bordered pit the
bands of adjacent spirals or the bars of a scalariform structure
generally enlarge toward one another so that the intervening
area contracts about a common center, but the edges never com-
pletely meet, so that a pit is left at the central point. In such
contraction, however, the secondary wall is not joined to the pri-
mary, but is free and springs from it as an arch which has a
circular outline and a central orifice (fig. 8). As such pits are
always paired on opposite sides of the primary wall, the entire
structure, when seen in tangential section, is lenticular in form
(fig. 1 1), with a membrane traversing the central plane and two
openings opposite to one another at the extremities of the minor
axis. From this it is obvious that the pit as usually seen is a
double structure which does not at first present a direct opening
from one tracheid cavity to the other, for so long as the tracheids
are growing or the protoplasm is present communication between
adjacent tracheids is cut off by the primary wall, which consti-
tutes a closing or pit membrane. By a subsequent change in this
latter it may eventually become displaced from its central posi-
tion and then lie against one of the arches. Under such circum-
stances it is often not readily discernible, and the pit appears as
if the primary wall had been obliterated within its limits. In the

59

6o ANATOMY OF THE GYMNOSPERMS

last instance, when the active protoplasm is withdrawn and the
cell passes into a permanent condition, the membrane disappears,
and the pit then forms a lenticular cavity in the line of the cell
wall, which opens into adjacent tracheids. This is the appearance
presented by all fully developed wood of the Coniferse. The
obvious purpose of such pits is to provide channels of communi-
cation between adjacent tracheids which would otherwise be com-
pletely isolated by the impervious nature of the secondary wall.
This fact serves to explain the situation in which such pits occur.

Radial lualls. The characteristic situation of the bordered
pits is on the radial walls, where, as was shown many years since
(13, 160), "the pits of contiguous tracheids always correspond to
one another in such a way that on each limiting surface all the
cavities of the pits of one fit exactly over those of the other.
The plano-convex cavities are thus applied to one another in pairs
so as to form the lens-shaped pit cavities," as seen in tangential
section. But on surfaces abutting on elements of another order,
e.g. parenchyma cells, the bordered pits of the tracheids corre-
spond to nonbordered pits or else are opposite an unpitted wall.
Four typical variations of the bordered pits may be recognized,
-(i) the multiseriate, when they are disposed in any number
of rows more than two, (2) the two-seriate, (3) the one-seriate
with occasional pairs of pits, and (4) the strictly one-seriate. The
general sequence thus presented will be found to be in direct
accord with the evolution of higher types of structure and
organization.

The most primitive type of Gymnosperm presenting a multi-
seriate arrangement is the genus Cordaites. Among eleven
species of this genus which have been critically studied within
recent years (45) there is a general agreement in the constancy
of this character which thereby becomes of generic value. In
all the species the pits are disposed in such a compact manner
throughout the entire extent of the tracheid as to present a
hexagonal outline. In Cordaites acadianum they are two- to five-
seriate (plate 7). In other species they vary from two-seriate
in C. hamiltonense and C. Newberryi (plate 8) to occasionally

BORDERED PITS

61

four-seriate in C. Clarkei. In the majority of species the rows are
not constant, but show a varying number from one to three, or
two to five, this variation being exhibited by adjacent tracheids
in accordance with the variation of the latter in radial diameter;
and viewing this distribution as a whole, it cannot be doubted
that it represents corresponding differences in development. One
of the most striking features of the genus is to be met with in
C. Newberryi (plate 8), which is unique in the segregation of
the pits into groups of six to thirteen.

In Araucarioxylon (28, 614), while conforming to the char-
acteristic form and compact arrangement presented in Cordaites,
the pits exhibit far less constancy in their serial arrangement,
and in this respect they are at once comparable with those of the
existing Araucarias. Among the latter A. Cunninghamii shows a
one- to three-seriate disposition, A. excelsa is one- to two-seriate,
while A. Bidwillii is strictly one-seriate. All of the extinct species
as comprised in the genus Araucarioxylon not only show similar
variations, but such variations are found to cover a much wider
range. A comparison of all the species, both recent and extinct,
now available for that purpose is of interest in this connection.

I-SERIATE

2-SERIATE

3-SERIATE

4-SERIATE

A Bidwillii : . . . . ...

X

wurtembergianum
Schmidianum

X
X

X

excelsa ^

X

X

Edvardianum . ...

X

virginianum ....

X

Doeringii

X

subtile

X

X

Heerii . ....

X

Cunningharnii ^

X

Robertianum

X

Existing species.

62 ANATOMY OF THE GYMNOSPERMS

Such a comparison brings into strong relief the fact that the
Araucarias, both past and present, constitute a transitional group
with a somewhat wide range of variations, and in this respect
they may be said to stand between the more stable Cordaites
and Dammara on the one hand, and the far more variable Coni-
ferae on the other, since in Dammara australis we find essentially
the same features of structure and distribution as in Cordaites,
the pits being one- to three-seriate. The sequence presented
above may be held to be in the inverse order of development,
and A. Robertianum must therefore be held to represent the
most primitive form.

It is apparent that in Cordaites, Araucaria (including Arauca-
rioxylon), and Dammara the pits are invariably distinguished by
two constant features, -- (i) their hexagonal form, and (2) their
very compact disposition throughout the entire extent of the
tracheid. They often deviate from the multiseriate arrangement
typical of the group as a whole in that in individual cases they
are reduced to a one-seriate arrangement. They thus tend to
overlap the next group, which is distinguished by a two-seriate
disposition, but any confusion which might arise from this cause
may be overcome by reference to the special form and disposi-
tion of the pits, as will more fully appear in the following lines.

Among the remaining Coniferales twenty species of various
genera, or 17.2 per cent in all, show a two-seriate arrangement, and
to this group we must also add the Gingkoales and various fossil
species. Here the multiseriate disposition of the pits involves
features which at once distinguish the group as a whole from the
preceding, clearly placing it upon a higher plane of development.
The pits are never hexagonal but are generally elliptical or round,
while they also show a strong tendency to extreme segregation.
When brought into a compact arrangement, as in Cupressoxylon,
Sequoia, or various species of Finns, they are flattened only along
the lines of limited contact, which are usually confined to one
end of the pit (fig. 8). A very characteristic feature of this group is
the further fact that the two-seriate arrangement is not constant,
either in the same section or in the same tracheid. Both Pinus

BORDERED FITS

taeda and P. cubensis, as also Larix americana and Tsuga cana-
clensis, afford illustrations that, while typically two-seriate, a given
section may show a strictly one-seriate arrangement, and this
difference also obtains as between contiguous cells. In all such
cases examination will show that the variation is directly related
to the relative size of the tracheids in such a way that the
narrower tracheids, or those arising from
a less vigorous growth, are one-seriate.
Within the individual tracheid there is

o

. —

o 1 o

o

.

o

s x

o

FlG. 9. PlNUS STROBUS.

^^ Radial section showing the

FIG. 8. PINUS CUBENSIS. Radial section showing form and disposition of the

the form and disposition of the bordered pits. bordered pits. X 280
X 280

a strong tendency to a one-seriate arrangement in the central
region, while it is two-seriate at the extremities ; and this law
holds so true that in those species which are exceptionally two-
seriate judgment should be reserved until it is seen that the
one-seriate form holds throughout.

The antithesis of the multiseriate type is found in the one-
seriate form. This is typical of 50 per cent of all the species
included in the present studies. In such cases the form of the
pit is never hexagonal or specially flattened. When the disposi-
tion is somewhat compact, as in Firms strobus (fig. 9), the outline

64

ANATOMY OF THE GYMNOSPERMS

becomes more or less strongly elliptical, but as the segregation
is more pronounced a definitely circular form prevails (fig. 10).
Within the limits of the individual tracheid the same law of dis-
tribution obtains as in the two-seriate type, whereby segregation
is always most pronounced in the central region.

Between species of the strictly one-seriate and those of the
strictly two-seriate type there is an intermediate or transition
group comprising thirty-four species, or 29.3 per cent of the in-
vestigated species, into which members of the other two groups

may occasionally be projected. The distin-
guishing feature of this group is the occur-
rence of pits in pairs, which are usually
distant and in no case so numerous as to
distinguish a two-seriate disposition. They
give undoubted proof of the passage from one
type to the other. Like the two-seriate type,
this feature is not confined to any one genus
or to any particular group of genera, but it
applies with equal force to any genus, the
members of which may therefore represent
any or all of the three types here specified.
Viewing the distribution of the bordered
pits from the standpoint of zonal devel-
opment, it is found to be universally true
that in the earlier spring wood there is the
strongest tendency to a multiseriate arrange-
ment. With a radial increase of the xylem this tendency con-
stantly diminishes, with the general result that the pits become
more strictly one-seriate and more distant toward the summer
wood in which they are sometimes wholly obliterated, this being
the case when the cell wall acquires unusual thickness.

Upon careful examination the foregoing facts will be found
to be in exact accord with the law formulated by De Bary with
reference to variations in the structure of spiral tracheids and
the genesis of bordered pits, as already stated. In accordance
with this law it is possible to conclude that relatively rapid

FIG. 10. PINUS STRO-
BUS. Radial section
showing the bordered
pits of the summer
wood. X 280

BORDERED PITS

Cordaites . .
Araucarioxylon
Araucaria
Dammara . .
Gingko

I More or less,

j. often strongly,

segregated.

growth is coordinated with a primitive development, while the
converse is true of a slow rate of growth which is again con-
vertible into terms of maturity. On this basis we may pre-
sent the following general outline of sequence in development,
as preliminary to further and more detailed discussion of
phylogeny :

. 2-5 seriate, hexagonal pits "1

. 1-4 seriate, hexagonal pits Compact throughout the
. 1-3 seriate, hexagonal pits f tracheid.

. 1-3 seriate, hexagonal pits J
. 1-2 seriate, round or oval pits 1

Higher Coniferales, 1-2 seriate, round or oval pits
Higher Coniferales, i-seriate and pairs, round or oval pits
Higher Coniferales, i-seriate, round or oval pits

Tangential walls. The occurrence of bordered pits in the
tangential walls is a well-known and characteristic feature of
the Coniferae. In the case of fossil forms, to which Araucari-
oxylon offers a partial exception, they cannot be satisfactorily
demonstrated because of the peculiar altera-
tions of the cell wall, but that they are pres-
ent we are permitted to infer from analogy
with existing species upon which dependence
must be placed for an elucidation of the gen-
eral law. The typical position for such pits
is upon the tangential walls of the summer
wood, where they are seen most satisfactorily
in radial section, inasmuch as they are always
readily observable when present, and their FIG. n. SEQUOIA GI-
most essential features are displayed in a GANTEA. Radial sec-

. . tion showing bordered

manner not possible m a tangential section pits in the tangential

(fi0". II). walls of the summer

This position obviously results because of

limitation of the radial walls through radial compression. The
pits are therefore always confined to the few outermost tracheids
of the last-formed summer wood, and in some cases they are con-
fined exclusively to the last tracheid.

66 ANATOMY OF THE GYMNOSPERMS

Pits occur in this position in 71.7 per cent of all the investi-
gated species, and their absence in 28.3 per cent points to some
special features in development which may be assumed to have
a general bearing upon the questions of descent and relationship.
In Dammara, as represented by the one species D. australis, such
pits are a prominent and characteristic feature, but in the nearly
related Araucaria they are remarkable for their uniform absence.
In the primitive Gingkoales they are also present, but among the
Taxaceae, while generally present, they are occasionally wanting,
as in Torreya taxifolia and T. nucifera, or in 66.6 per cent of
the investigated species of that genus. Nowhere else among the
Coniferales do we find such a feature until we reach the genus
Pinus, the second and higher section of which is almost invariably
characterized by their absence, thus presenting an exceptional
feature to the extent of 68.3 per cent of that genus. That such
absence represents a process of obliteration conformable to De
Bary's law cannot be doubted, while the sporadic recurrence of
this feature in often widely separated genera, or in particular spe-
cies of a given genus, must be held to have a more or less direct
bearing upon the general course of development. This is empha-
sized by the observation that in Larix americana and L. lepto-
lepis, as also in Picea bicolor, there is a more or less pronounced
tendency to an obliteration which is never fully developed. This
is expressed in the somewhat remote position of the pits and
their very small size, which renders them obscure and often diffi-
cult to discover. In this respect these species represent transi-
tional forms.

As an exceptional feature bordered pits may sometimes be
found upon the tangential walls of the spring wood. This is espe-
cially noticeable at the ends of tracheicls, and in rare cases it
may apply to the entire extent of the wall. The most notable
instance of this kind, because practically unique, is to be met
with in Sequoia gigantea (figs. 1 2 and 1 3). Those spring tracheids
which lie in direct contact with the summer wood of the pre-
vious year often exhibit this feature with great prominence, but
it may also extend radially through several successive tracheids.

BORDERED PITS

This is undoubtedly a primitive character, and in the one case

cited it possesses some value for the purpose of specific differ-
entiation, but in general terms the occurrence of bordered pits

in such positions is of so sporadic a nature

as to give this feature no well-defined value,

either for taxonomic or phylogenetic purposes.

It may, nevertheless, be stated with respect

to the pits on the tangential walls of the tra-

cheids in general, that in their distribution

they distinctly conform to the law governing

similar structures on the radial walls.

Reference to Cordaites acadianum shows

that in the multiseriate pits of the hexagonal

form these structures always preserve the

spiral arrange-
ment character-
istic of the
structures from

which they FIG. 12. SEQUOIA GI-
were derived GANTEA. Radial

section showing the
bordered pits on
the tangential walls
of the spring wood.

/

x 280

FIG. 13. SEQUOIA GIGANTEA. Tan-
gential section showing bordered
pits in the tangential walls of the
spring wood, x 280

(plates 3-6),
and this con-
formity also ex-
tends to the

direction of the spirals which gen-
erally ascend from left to right.
The general law in this respect has
already been formulated so fully
by De Bary (13, 163) as to make it
unnecessary at this time to enter
upon its consideration more in
detail, beyond a reference to one

or two special features and some apparently exceptional cases.
While the spiral arrangement is always typical in such genera as
Cordaites, Dammara, Araucaria, etc., it is not obvious in those
cases where the pits are strictly one-seriate and often remote

68

ANATOMY OF THE GYMNOSPERMS

from one another. Nor is it apparent at first sight in those cases
of two-seriate pits where, as in Cupressoxylon Dawsoni from the
Cretaceous, Larix americana, Sequoia, and various species of
Pinus, the pits are always paired off in such a way that the axis
of each pair is at right angles to the axis of the cell (fig. 8).
Two explanations are here possible : (i) the spirals are in reality
two-seriate, and are projected through the alternate members of
the two rows of pits ; or (2) the disposition of the pits repre-
sents an extreme phase in the flattening of
the original spirals conformably to a higher
type of development. This view, which seems
the more reasonable, is in direct harmony with
De Bary's law, while it receives additional
support from the form and direction of the
pit orifice.

The orifice of the pit is variable, at differ-
ent times being round, when the pits are also
round and more or less distant ; oval or oblong,
when the pits assume corresponding forms ;
or, in the summer wood, lenticular or oblong.
The transversely elliptical pits of Pinus stro-
bus (fig. 9), the orifice of which is also trans-
versely oblong, as also the similar pits of Pinus
cubensis (fig. 8), afford substantial proof in
confirmation of the probable correctness of
this view. In the summer wood the pit orifice
commonly assumes a position which appears to
offer a direct contradiction to this conclusion. In Pinus strobus
(fig. 10) the orifice is oblong and parallel with the tracheid axis.
In Pinus pungens, as in many others of the same genus (fig. 14),
the narrow orifice is extended above and below into a diagonal
slit of great length, forming a narrow angle with the tracheid
axis. At first sight this would seem to imply that these features
represent primitive spirals, the original direction of which has
not been greatly if at all modified, but one or two considerations
will assist us to a correct interpretation of this feature. In the

FIG. 14. PINUS PUN-
GENS. Bordered
pits on the radial
walls of the sum-
mer wood. X 280

BORDERED PITS

69

©

first place, it is to be observed that such positions and modifications
of the orifice are invariably associated with the summer wood;
if they occur in the spring wood, it is the result of maceration
and commonly appears in fossil plants or woods in process of
decay, and they are always most conspicuous in those tracheids
which have experienced the most profound modifications with
respect to the growth in thickness of the secondary walls. It
has already been shown in the case of Taxus and Torreya that
there is no necessary connection between the spiral bands and
the spiral lines of striation, -- that, as a
matter of fact, as particularly illustrated
by Torreya taxifolia, the two are quite
distinct from, one another under ordi-
nary conditions of development ; but in
cases where the wall experiences extreme
growth in thickness the obliteration of
the original spiral structure is complete,
and at the same time it is replaced by the
normal striation of the wall, which then
becomes most pronounced. Instances
such as those afforded by Pinus strobus
and P. insignis may, according to this in-
terpretation, be held to represent the final

phases in the obliteration of the original

FIG. 15. CUPRESSUS NOOT-

spirals, and they therefore constitute char- KATENSIS. Radial section
acters indicative of the highest type of de- showing deformed bor-

- , dered pits, x 280

velopment. In a few cases the structure

of the bordered pit presents exceptional forms. In Cupressus
nootkatensis the pit orifice shows either unusual want of regu-
larity in outline and marked eccentricity of position, or it is so
enlarged as to leave only a narrow border to the round or oval
pit (fig. 15). Similar features occur occasionally in other genera,
and they are generally conspicuous in Pinus taeda. De Bary has
directed attention to the same feature in Ephedra (13, 159)
and Pinus sylvestris, and he correctly interprets it as a form
of arrested development. Alterations also arise as a feature of

ANATOMY OF THE GYMNOSPERMS

secondary growth in those cases in which the wall acquires
unusual thickness. This is typically the case in Finns cubensis,
where in plan (fig. 16) the orifice is extended

vertically to a length often

twice the diameter of the

original pit. In tangential

section, according to the

particular direction of the

plane of section (fig. 17),

the orifice is either of uni-
form width or it enlarges

FIG. 16. PINUS cu-
BENSIS. Radial constantly through the en- FlG I? PlNUS CUBEN.

sis. Tangential sec-

section showing
deformed bordered
pits, x 280

tire thickness of the later

tion of bordered pits
as in fig. 1 6. X 280

growth, from within out-
wards. That such unusual
forms are features of extreme secondary growth of the wall,
and that they may be anticipated in all cases where such modi-
fications of the walls occur, is a reasonable deduction from the
observed facts.

BORDERED PITS — TAXONOMIC AND PHYLOGENETIC

For taxonomic purposes the bordered pits possess a definite
though often limited value. In the genus Cordaites, as also in
Araucarioxylon, Araucaria, and Dammara, this is expressed in
the hexagonal form together with their very compact, chiefly
multiseriate arrangement throughout the entire extent of the
tracheids, - - characters which are of generic value and at once
serve to separate these genera from all others. The contrast-
ing differential feature is then to be found in the pits of the oval
or round form, together with their two-seriate or one-seriate dis-
position, with a more or less marked tendency to segregation.
This is characteristic of the Gingkoales and all the Coniferales,
both fossil and recent.

As a differential character of subgeneric value, the occurrence
of bordered pits on the tangential walls of the summer wood of

BORDERED PITS 71

the first section of Finns (the soft pines) and their almost
invariable absence from the same structural region in the second
section (the hard pines) is one which may be always relied upon.

For the purposes of specific differentiations the pits on the
tangential walls possess a distinctly inferior value, which must be
confirmed in most cases by the evidence of other factors. Their
utility in this respect is made sufficiently clear in the various
diagnoses and in the artificial key, without further discussion
at this time.

In the genus Cordaites, according to the provisional specific
differentiations of fossil forms as at present generally employed,
the number of rows of pits, or their segregation into definite
groups, are characters of well-defined specific value, since they
are among the few features which maybe utilized with certainty
for this purpose. Thus C. acadianum with its two to five rows,
C. materiarium with two, rarely three to four, rows, C. hamil-
tonense with two rows, and C. Newberryi with two rows, in groups
of six to thirteen pits, rest upon a basis which is not only easy
of recognition but which may be applied with full assurance.
In Araucaria the three species investigated may be similarly
differentiated from one another. The same rule is applicable to
Torreya taxifolia, which is thereby separable from the other spe-
cies; likewise to Cupressoxylon Dawsoni, Tsuga canadensis, and
Larix americana, and, among the pines, to P. Lambertiana,
P. clausa, P. Sabiniana, P. taeda, P. palustris, and P. cubensis.
It is to be observed, however, that the constancy which charac-
terizes this feature in Cordaites and Araucaria is wanting in the
higher Abietineae. In Larix there is such variation that very
careful scrutiny is required, while in the genus Pinus the num-
ber of exceptions to the typical character increases greatly and is
liable to cause some difficulty in the final determinations unless
much care is exercised. Pinus taeda offers a conspicuous illustra-
tion of this fact, as may be seen by reference to the analytical
key. It is therefore manifest that the value of the bordered pit
for taxonomic purposes is most clearly defined in the lower types
of the Coniferales, and that their value diminishes steadily with

72 ANATOMY OF THE GVMNOSPERMS

an advance towards higher forms of organization and develop-
ment. In all cases where exceptional forms introduce diagnostic
difficulties these may be overcome by the controlling effect of
associated characters.

We are now in a position to examine the data at hand with a
view to determining the bearing of the bordered pits upon ques-
tions of phylogeny.

Having reference to the origin of the bordered pit and the
various modifications it presents in the course of development,
it cannot be doubted that the hexagonal, multiseriate pits of
Cordaites, Araucarioxylon, Araucaria, and Dammara place these
genera in a relatively inferior position, --a view which gains a
large measure of support from the well-known and extensively
multiseriate disposition shown in Heterangium Grievii (81, 341),
but the facts so far discussed have not as yet thrown any special
light upon the relative positions of the separate genera.

An examination of twelve species of Cordaites shows that the
bordered pits exhibit a much wider range of serial variation than
any other genus covered by the present studies. If then we
accept the general principle with respect to the development of
the bordered pits as already illustrated, it cannot be doubted that
the two- to five-seriate pits stand much nearer to the primitive
form of the tracheid than do the one-seriate. From this point
of view it is then evident that in C. recentium, the name of which
is thereby seen to be fully justified, the one-seriate pits place it
at the upper end of a series which has its inferior termination in
the two- to five-seriate C. acadianum, while intermediate forms
appear between the two as members of a series of nine variants,
and it is possible to arrange these in such a manner as to exhibit
the probable sequence in development, as seen by table on the
following page.

The wide range of variations here shown, especially when
compared with other genera, at once serves to suggest that
Cordaites was in this respect somewhat of the nature of a tran-
sition group from which others were given off, or else that it
epitomized the collective changes through which a number of

BORDERED PITS

73

genera must have passed. And inasmuch as this genus ex-
hibits a more highly developed multiseriate arrangement than
any other within the general phylum, we must concede that it
is, with respect to this character, the most primitive of all.

SERIAL VARIATIONS IN THE BORDERED PITS OF CORDAITES

^

^

>

^

u

r|

J

>j

*^

J

H)

£-,

H

d,

u.

b

H

w

K

u

H

K

K

H

H

5

2

V «

X «

S <•)

< 1-

S «

E N

2:
u

M a:

u

K

u
-t

u

fO

U

u

in

\

1

1

I

1

1

1

fl

CO

M

""

C. acadianum

X

ohioense

x

ouangondianum

X

materiarium

X

Clarkei

x

annulatum

X

Brandlingii

X

materioide

X

illinoisense

X

hamiltonense ....

x

Newberryi

x

recentium

X

The genus Araucaria shows a much more restricted range of
variations, there being only four variants pretty uniformly dis-
tributed among fourteen species, both recent and fossil (ante,
p. 61). While the most highly developed members, four in num-
ber, are represented by one-seriate pits, the most primitive form
of four-seriate pits occurs in only one case, --A. Robertianum.
It is therefore manifest that this genus is obviously of a more
advanced type than Corclaites, from which it undoubtedly origi-
nated. Dammara being represented by only one species, it is
not possible to locate it more definitely than to say that the one-
to three-seriate disposition of its pits would place it in a posi-
tion equivalent to that occupied by Araucaria Cunninghamii, and
therefore about three fourths of the way down the scale for that
genus. This fact points with much force to the idea that of the
two genera Dammara is of relatively lower type.

74 ANATOMY OF THE GYMNOSPERMS

The Gingkoales and the Conifcrales as a whole exhibit an
obviously higher type of development than the preceding group,
in consequence of the more pronounced tendency to segrega-
tion of the pits, which are now either elliptical or round, and
never hexagonal. This distinction is so clearly defined and con-
stant as to support the idea, which gains force in other ways,
that Cordaites, Araucaria, and Dammara are clearly related
members of a principal branch of the original stock, and that
they therefore diverge considerably from the particular line
of descent within which we find both the Gingkoales and the
Coniferales.

Gingko, being the unique representative of an ancient line,
cannot very well be brought into the present discussion very
much in detail. On other grounds it is known to be a primitive
form representing a group distinctly inferior to the Coniferales,
and this view is supported by the disposition of the pits in two
series, a character which, if taken alone, would give the genus
rank with Torreya taxifolia among the Taxaceae, but when re-
garded collectively would place the genus distinctly below the Co-
niferales as a whole. This evidence, then, indicates that the
Gingkoales must have arisen as a side line at some point inferior
to the Coniferales but superior to the Cordaitales.

In the Taxaceae the bordered pits do not in themselves afford
very conclusive evidence as to the relative position of the family.
Among the eight investigated species, representative of three
genera, only three, and chiefly two, variants occur. Taken alone,
the disposition of the pits would lead to no final conclusion, but
other factors permit of placing this family in the inferior posi-
tion usually assigned to it. In the genus three variants are
found, --the one-to-two rows of T. taxifolia, the one row or
pairs of T. californica, and the strictly one-seriate form of T.
nucifera. In Taxus only two variants appear, --the one row
or pairs of T. floridana and the one-seriate disposition as found
in the remaining three species. The one representative of Podo-
carpus shows but one variant, and that is one-seriate. From
this it is obvious that the generic sequence must be in the order

BORDERED PITS 75

given, and that the sequence of species must be approximately
as given in the table of anatomical data.1

The observations so far made apply altogether to the pits on
the radial walls. We may now pass to a consideration of their
relation to the tangential walls, a factor which does not call for
very extended discussion. This feature is found to apply to
71.7 per cent of all investigated species exclusive of fossils.
It is wanting in three species of Araucaria, representing 2.58
per cent ; in two species of Torreya, or 1.72 per cent ; and in the
entire second section of Pinus to the extent of twenty-eight
species, or 24. i per cent. But the occurrence of pits on the
tangential walls, in common with those on the radial walls, is
a well-known feature of the Sigillarias (81, 198), where their
primitive character is well established, and we can hardly doubt
that their final elimination in the higher pines is the expres-
sion of a final phase in development consistent with the position
usually assigned those plants.

The absence of pits from the tangential walls of certain
Araucarias and Torreyas is to be interpreted as one of those
sporadic tendencies toward a higher type of development which
never become permanent in the same line, but which are to be
met with as one of the invariable features of evolution.

The remaining genera of the Coniferales present so few devia-
tions from a typical form that they cannot be differentiated
fully on the basis of the bordered pits. This character never-
theless has a definite value in association with others, as in the
genus Sequoia or some of the hard pines, Larix americana, etc.
The general sequence of genera may be recognized by the bor-
dered pits only in so far as these structures serve to confirm
and emphasize the conclusions reached in other ways, and this
will become apparent from an inspection of the table already
referred to. It will nevertheless serve a useful purpose at the
present moment to ascertain the general sequence based upon
the percentage distribution of the principal variants, as seen by
the table on following page.

1 Appendix A.

ANATOMY OF THE GYMNOSPERM6

COMPARISON OF THE PRINCIPAL VARIATIONS IN THE SERIAL ARRANGE-
MENT OF BORDERED PITS, BY PERCENTAGES

TOTAL
VARIATIONS

=-5

z-4

2-3

«-3

2

1-2

i +

PAIRS

I

Cordaites .

9

8-3

25.0

1 6.6

25.0

1 6.6

3.3

Dammara . . I

6.6

20.0

40.0

33-3

Araucaria . .

4

6.6

20.0

4O.O

33-3

Gingko . . .

I

1 00.0

Sequoia . .

I

100.0

Larix

3

33-3

33-3

33-3

Taxodium . .

2

25.0

75.0

Libocedrus

I

100.0

Thuya . . .

I

1 00.0

Pseudotsuga .

2

50.0

50.0

Pinus . . .

3

17.1

41.5 41.4

Abies

3

13.6

V)

59.1

Taxus .

-»

25.0

75-°

Tsuga . . .

3

16.7

16.7

66.6

Picea . . .

2

IO.O

90.0

Podocarpus .

i

IOO.O

Thujopsis . .

i

1 00.0

Crvptomeria .

i

IOO.O

With respect to specific differentiations it has already ap-
peared that the bordered pits may be employed with success
in Taxus and Torreya. In Cupressus this rule also applies to
C. pisifera and C. macrocarpa, both of which are distinguished
by having their pits in one row or pairs, while the remaining
seven species have strictly one-seriate pits. An instructive ex-
ample is afforded by Cupressoxylon Dawsoni. In this species,
which is of early Tertiary age (Lignite Tertiary), the pits are
typically two-seriate, being disposed in a very compact manner
similar to that found in existing Sequoias. But in a series of
eleven specimens it is clearly seen that two variants are repre-
sented, the second being a one-seriate form. These variations
are also found, as in the other Coniferales, to be directly related
to variations in the size and rate of growth of the tracheid. It
cannot be doubted, then, that C. Dawsoni is a more primitive

BORDERED PITS 77

representative than any species now existing, and that it is sub-
stantially the ancestral form of the genus, so far as we know.

In Larix the four investigated species may be differentiated
pretty fully, and this rule applies with particular force to L.
americana and L. occidentalis, both of which are distinguished
by two-seriate forms. Among the pines P. Lambertiana, P. clausa,
P. Sabiniana, P. taeda, P. palustris, and P. cubensis are readily
differentiated from the others by the two-seriate pits. In all
other cases than those specifically indicated the bordered pits
afford an inadequate basis for specific differentiation.

It is now apparent that segregated round or oval pits in one
row must be taken as representing the highest type of develop-
ment in the Coniferales, and any deviation from this must be
taken to indicate the survival of more primitive conditions,
pointing to derivation from a type like that of Araucaria or
Cordaites. From this point of view the occurrence of pits in
one-to-two rows in Larix americana, Torreya taxifolia, Sequoia,
Tsuga canadensis, and various species of Pinus indicates the
survival of ancestral characters which are partial to the extent
of 7.2 per cent, and complete to the extent of 10.8 per cent.
That such deviations from the usual type of structure are either
survivals or reversions which serve to indicate a common origin
cannot be doubted, more especially as they do not occur at a
fixed point near the original type, but they arise sporadically
in widely separated genera. The tendency of such evidence,
then, is to show a common ancestry for the various genera of
the Taxaceae and Coniferas, a view which is greatly strength-
ened by the testimony afforded by the spiral tracheids of Larix
americana, Pseudotsuga, and Pinus taeda.

CHAPTER V

MEDULLARY RAYS
GENERAL STRUCTURE

The medullary ray, in the various details of its structure,
as presented radially and tangentially, comprises some of the
most important features for diagnostic and taxonomic pur-
poses. While it presents numerous variations, these are, in the
main, of such a nature as to give them very positive value for
both generic and specific differentiations. Primarily the medul-
lary rays are to be regarded as a residue of the original funda-
mental structure, which has been left over in the genesis of the
primary stele, but they are capable of reproduction or extension
under the influence of the cambium in the course of secondary
growth. In all such cases, however, they are typically composed
of the same elements which are necessarily parcnchymatous.
Deviations from this structure may appear through the intro-
duction of other elements, but such alterations always arise in a
manner which indicates their relation to the evolution of higher
types of organization.

In a transverse section the medullary ray appears usually as
a simple, radial series of elongated cells with transverse termi-
nations. Deviations from this type of structure occur only in
the case of the rather rare two-seriate forms, which appear in
the transverse plane of section only at wide intervals, or in the
case of rays which contain resin passages, as in Picea, Pinus,
Larix, etc., when the structure presents a varying aspect depend-
ent upon the particular plane of section. In Pinus reflexa the
side walls of the ray cells may be seen projecting into the
cavities of adjacent tracheids, where they form short, saclike
bodies of the general nature of thyloses, which they really

78

MEDULLARY RAYS

79

are (fig. 18). Such a feature is of specific value in differentia-
tion. With this exception the ray presents no features in this
plane of section which merit special consideration.

Radial section. Viewed radially, the medullary ray is seen to
be composed of a series of cells extended in a radial direction and
superimposed so as to form a muriform band from one to many
cells in height. In general terms, the higher the ray the lower
the component elements, from which it follows that in one-celled
rays the cells are usually highest ; but this
feature is only of general interest, since
it rarely has a bearing upon the chief ques-
tions at issue. In some cases two struc-
tural types may be recognized, - - the one
containing resin passages, the other devoid
of such structures. Where such passages
occur the structure of the ray shows a
variation of detail which makes it of no
value for diagnostic purposes, and the rela-
tion is one which possesses interest only
in so far as it applies to the distribution of
the resin passages themselves.

A feature of primary importance in the
constitution of the ray is the occurrence
of two kinds of parenchyma cells. In 95
per cent of the genera the upper and lower
walls are always thickened by secondary
growth and more or less strongly perfo-
rated by simple pits (figs. 19 b, 25, and 27).
This feature also applies to 56.1 per cent of the genus Pinus.
It possesses no special value for either specific or generic differ-
entiations except so far as it applies to cells which are markedly
different and justify the special terms thick walled23\& thin walled.
It is obvious, then, that the thick-walled cell is to be regarded as
the normal structure for the ray of the Coniferales as a whole,
while the thin-walled represents the exceptional form which is
introduced in response to some special demands. Although the

FIG. 18. PINUS REFLEXA.
Transverse section of
a medullary ray show-
ing the inflation of the
cells opposite tracheids.
X 300

So

ANATOMY OF THE GYMNOSPERMS

thick-walled cells occur in the genus Pinus to the extent of 56 per
cent, they show a diminishing frequency, eventually becoming rare
and are ultimately replaced by thin-walled cells. Reference to
them in the following diagnoses is always specified by (i). In 43.9
per cent of the genus the upper and lower walls are thin and
absolutely devoid of pits. For diagnostic purposes such cells are
always referred to as (2). In some cases they are so undeveloped
as to be obscure and readily broken out in the process of section

FIG. 19. PINUS PALUSTRIS. Radial section of a medullary ray showing charac-
teristic pits on the lateral walls : a, a thin wall broken out ; b, thick-walled
parenchyma ; c, thin-walled parenchyma. X 280

cutting, so that they are often entirely wanting (fig. 19, a-c).
Such thin-walled cells are typically developed in P. palustris,
P. taeda, etc., and it is to be observed that they are always asso-
ciated with the highest forms of development. Transition forms
occur. These are first seen in the soft pines, where occasional
thin-walled cells devoid of pits are interspersed and are often
conterminous with the thick-walled elements. In the hard pines
the same relation exists, but it is gradually reversed until the

MEDULLARY R.\\S

81

thin-walled cells altogether predominate. Such gradations are
exhibited in P. Coulteri, P. Jeffreyi, P. pungens, P. taeda, P. cu-
bensis, and P. inops, and they afford valuable evidence as to
the sequence in development of the species. In P. Murrayana,
P. cubensis, and P. insignis the transition forms exhibit much
more detailed gradations, by virtue of which it is often ex-
ceedingly difficult to distinguish between the two forms of cell,
since whether conterminous or parallel the variations in thickness

FIG. 20. TAXODIUM DISTICHUM. Medullary ray showing the structure and posi-
tion of the pits on the lateral walls; the straight ray cells and the thin,
straight, terminal walls, x 280

change in such a way that the one type passes gradually into
the other. When these variations are viewed collectively and
taken together with the general fact that the thin-walled cells
are a feature of the higher types of organization, we may reason-
ably conclude that the thin-walled cells have been derived from
the thick-walled through a process of arrested development. The
cause of such alterations is to be sought for, and it will doubt-
less be found in connection with another component of the ray.
The terminal walls of the ray cells present three typical vari-
ations,— (i) thin-walled and entire, (2) thin-walled and locally
thickened, and (3) thick-walled and coarsely pitted.1 The first

1 See Appendix A.

82

ANATOMY OF THE GYMXOSl'KRMS

feature is a characteristic of 52.6 per cent of all the genera, inclu-
sive of Gingko, from Dammara to Sequoia, while it also appears in
Cupressus and Abies in part as exceptional, and in the genus Pinus
to the extent of 85.3 per cent. The wall presents no secondary
growth in thickness, either locally or generally. In the majority
of cases it crosses the line of the principal cell axis either at right
angles or diagonally, - - features which are usually of very second-
ary value, although in a few cases, as Taxodium, it may serve a
useful purpose as an associated character for differentiation from
closely allied genera (fig. 20). In other cases the wall is more
or less strongly curved. This feature is prominent in Thuya,

Cupressus, Podo-
carpus, Thujopsis, and
Cryptomeria, as also in
the more highly devel-
oped hard pines. To
a less extent it also oc-
curs in Taxodium, and
it constitutes a char-
acter of some value for
differential purposes

(fig. 21).

The second variant
differs from the first
in that the otherwise
thin wall is locally thickened (fig. 22), the secondary growth
forming one or more beaded enlargements. This is a feature
which occurs exceptionally in Abies, Pseudotsuga, Picea, and
Pinus, but it is typical in Cupressus (66 per cent) and Juniperus
(72.7 per cent), where it constitutes a diagnostic element of great
value. It is in all cases, however, to be regarded as a transi-
tional form between the first and the third variant, and from this
point of view it also possesses a somewhat definite phylogenetic
value. The third variant is characteri/ol by a marked general,
secondary growth of the wall, which thereby becomes more or
less strongly thickened and traversed by numerous simple pits

FIG. 21. THUYA GIGANTEA. Medullary ray show-
ing the form and disposition of the pits on the
lateral walls ; the thin and curved terminal walls ;
the cells contracted at the ends, x 280

MEDULLARY RAYS

8

(fig. 23). It occurs exceptionally in Juniperus and Finns, but it
is typical in Abies (90.9 per cent), Tsuga (100 per cent), Larix
(100 per cent), and Picea (90 per cent). In Abies and Juniperus,
where transitional forms sometimes occur, the walls in the spring

FIG. 22. CUPRESSUS MACNABIANA. Medullary ray showing the form and position
of the pits ; the thin, curved, and locally thickened terminal walls, x 280

wood may be only locally thickened, but in such cases the typ-
ical feature always appears in the summer wood, where such
secondary alterations are most strongly emphasized.

For taxonomic purposes such features possess a definite value.
The thick-walled cells of Tsuga, Larix, and Picea permit of an

FIG. 23. JUNIPERUS OCCIDENTALIS. Medullary ray showing the form and dispo-
sition of the pits on the lateral walls ; the thick and coarsely pitted terminal
walls, x 280

easy and definite segregation of these three genera in those cases
which otherwise might involve a strong element of doubt, and
the same rule holds true, though to a less extent, with respect
to the locally thickened walls in Cupressus and related genera.
Pits on the lateral walls of the ray cells are an invariable
feature of all investigated species of Gingkoales and Coniferales,

84

ANATOMY OF THE GYMNOSPERMS

including fossil representatives and the Cordaitales. They vary
very much in form, size, and number. In such types as Junip-
erus they are most diminutive (fig. 23) and generally numerous,
while in many of the pines, such as P. resinosa or P. koraiensis

..b

b

FIG. 24. PINUS REFI.EXA. Medullary ray showing (a) the form and disposition
of the pits on the lateral walls ; (/>) the ray tracheids. x 280

or P. reflexa (fig. 24), they attain to maximum size and occupy
nearly the entire surface of the wall within the limits of a wood
tracheid, thereby becoming few in number. In Sequoia (fig. 25)
or Taxodium (fig. 20) they are typically oval, in Pinus cubensis

Fir.. 25. SEQUOIA GIGANTEA. Medullary ray showing the form and disposition
of the pits on the lateral walls. X 280

or P. taeda (fig. 26) they are variously lenticular, while in P. resi-
nosa or P. koraiensis they are oval or oblong, or even quad-
rangular. Such variations as a whole are far more numerous
and sharply defined in Pinus than in any other genus known.
In all the investigated genera the pit is bordered. This finds

MEDULLARY RAYS 85

either partial or complete exceptions in the genus Pinus to the
extent of 78. i per cent of the species, in which the pits are either
simple throughout or else they exhibit a more or less definite bor-
der in the summer wood only. That a border is a characteristic
feature of fossil representatives is justified by comparison with
existing species, but it is not always recognizable in consequence
of the alterations of structure due to the general process of
petrifaction. Such obliteration not infrequently involves the pit
orifice also. It is thus apparent that such structures often fail
in the determination of fossils. In existing species the border

FIG. 26. PINUS SEROTINA. Medullary ray showing (i) the ray tracheids with
dentate walls ; (2) the structure of the parenchyma cells ; (3) tracheids con-
terminous with parenchyma cells, x 280

is often so faintly defined as to be difficult of recognition, and
this is especially the case in rays of a resinous character. In
all such cases, however, the requirements of a correct diagnosis
are fully met by the pit orifice. The general law of development,
then, is such that all genera except Pinus may be held to be
characterized by bordered pits. Their strong tendency to obliter-
ation in that genus is found to coincide with the more marked
development of ray tracheids, which undoubtedly assume more
completely the original functions of the parenchyma cells, these
latter in consequence suffering constant structural reduction, as
in the hard pines.

86 ANATOMY OF THE GYMNOSPERMS

In the distribution of the pits an important feature appears in
the numerical variation in different parts of the ray. For diag-
nostic purposes it is necessary to have reference to the number
of pits not upon the entire surface of an individual cell but
within the limits of a spring or summer tracheid, as the case
may be. They are invariably most numerous in the region of
the earliest spring tracheids, usually diminishing toward the
summer wood, where the change may sometimes take place ab-
ruptly, and in which they are most commonly reduced to one,
with occasional obliteration in the most highly modified tracheids
last formed. A similar law of distribution is applicable within
the vertical limits of the ray. When these structures are several
cells in height the number of pits is typical, and, within certain
narrow limits, constant for all except the marginal cells. Thus
if the normal number is one to two for the central cells, it may
sometimes rise to four, six, or eight in the marginal cells only,
and such exceptions must be noted in diagnosis. When the
ray is only one cell in height the number of pits agrees with
that for the marginal cells. Such numerical variations possess
but little value for generic purposes, but as a specific character
they may be held to constitute the principal differential feature
in the last analysis. These relations are expressed typically in
the genus Sequoia, the two species of which may be definitely
differentiated. S. gigantea is characterized by oval and com-
monly narrowly bordered pits, the broadly oblong orifice equal to
the outer limits of the pit and chiefly parallel with the cell axis,
one to two, more rarely three to four, per tracheid. In some-
what sharp and definite contrast to this, S. sempervirens has
large, oval, narrowly bordered pits, two to six per tracheid, the
round or broadly oblong orifice being either parallel with or diag-
onal to the cell axis. In Libocedrus the pits are small, narrowly
bordered, oval, with a lenticular, diagonal orifice, one to four
per tracheid. Or again, in Larix americana, the pits are "two to
six per tracheid, becoming distinctly smaller toward the summer
wood where they are abruptly reduced to two and finally one
per tracheid." In Cupressus pisifera the pits are " chiefly two

MEDULLARY RAYS 87

in radial series, or in the marginal cells and low rays upwards
of six per tracheid." In Taxodium distichum the pits are round,
conspicuously bordered, and large, with a very narrowly lenticu-
lar and diagonal orifice, which is often as long as the outer limits
of the pit. But in the analytical key it will be observed that
this genus is naturally brought into close relations with Sequoia,
which is also distinguished by large bordered pits. The ulti-
mate differentiation then rests upon the fact that in the latter
the pits are oval, the border often narrow, sometimes obscure,
while the oblong or lenticular, usually rather broad, orifice is
generally parallel with the cell axis. As a final illustration, the
four pits of Pinus monophylla, or the one to five throughout,
finally reduced to one to two in the summer wood of P. Bal-
fouriana, point with much definiteness to these particular species,
while among the hard pines the occurrence of large oval or
squarish pits, one or rarely two per tracheid, segregates a group of
four species. Detailed as these features are, they are not acci-
dental, but of such constancy as to admit of no hesitation in
accepting the conclusions to which they point.

The length of the ray cell is subject to considerable variation
not only within the limits of an individual but also between one
species and another. Our studies, however, do not permit the
formulation of a law applicable to specific differentiations, even
if such a law does exist, which present evidence leads us to doubt ;
but details of length, in terms of spring tracheids, have been
incorporated in all the diagnoses, since they are often very
suggestive and thus may assist in the ultimate recognition of
the species.

The form of the cell is of more evident value, although too
much stress must not be laid upon it. The cell is either straight,
as in Juniperus, Libocedrus, or Picea (fig. 23), or it becomes
fusiform through contraction of the extremities, as in Cupressus,
Sequoia, Taxodium, etc. (fig. 21). As a well-defined differential
character its value is only one degree higher than the length of
the cell, and for the same reason it has been introduced into the
diagnoses as a controlling factor of secondary importance.

CHAPTER VI

MEDULLARY RAYS (continued}
RAY TRACHEIDS

In the higher Coniferae the medullary ray is distinguished
by the presence of an element which differs materially in its
structure from the associated parenchyma cells. These elements
have been designated as ray tracheids (13, 491-492). Their struc-
ture is so peculiar, and they present such important relations
to classification and development that a somewhat detailed
account of them is necessary, to some extent in recapitulation of
well-known observations (13, 461 ; 21, 13 ; 82).

As stated by De Bary, the ray tracheid resembles the paren-
chyma cells, from which they differ, however, in the presence
of bordered pits on all their walls. Furthermore such pits not
only differ materially in form and size from the bordered pits
of adjacent parenchyma cells, but they are always much smaller
than the pits of those wood tracheids on which they border.
Such tracheids are invariable features of the ray in all the higher
Coniferae from Tsuga and Pseudotsuga to Finns, to the extent
of 25 per cent of the investigated genera. In Juniperus they
occur very rarely, being found, so far as I am aware, in only one
species (J. nana) out of a total of eleven, and they are so sparingly
developed as to readily escape observation. In Thuya they are
to be met with in T. japonica, likewise in a rudimentary state of
development. Out of nine species of Cupressus they occur only
in C. nootkatensis. Of the ten investigated species of Abies they
are found only in A. balsamea. In commenting upon this fact
many years since (13, 490), it was also pointed out that among
European species A. excelsa is similarly exceptional, but no
attempt has been made to interpret the significance of such facts.

88

MEDULLARY RAYS 89

In Thuya, Cupressus, and Abies the tracheids are strictly mar-
ginal in the composite rays, forming the entire structure in rays
only one or two elements high. This relation obtains in all the
higher Coniferae in the first instance ; but in Larix, Picea, and
Finns, where there is a notable increase in numbers, they also
become interspersed with the parenchyma cells and eventually
predominate over them, a feature which is especially character-
istic of the hard pines. Efforts have been made to show that in
all such cases the two kinds of elements succeed one another in
a definite order from above downward, or the reverse, but our
studies have failed to show that this is capable of practical ap-
plication to the purposes of classification or even of phylogeny
(13, 491). The great fact of importance for our present purpose,
however, and one which stands out with much prominence, is that
the ray tracheids are not a structural feature of the more primi-
tive Coniferales, but only of the higher types, such as Picea and
Pinus. Furthermore the primitive position for these structures
is in the one- or two-celled rays, or correspondingly in the margins
of the composite rays.

In Thuya and Cupressus the tracheids appear to stand by them-
selves, and they exhibit no special relations to the parenchyma
elements which would permit of inferences as to their possible
origin. In the genus Pinus, on the other hand, where the rela-
tions are somewhat complex, evidence does appear of such a
nature as to suggest their derivation. In Pinus inops, P. Torrey-
ana, P. pungens, P. clausa, P. taeda, P. palustris, and P. cubensis we
frequently find thick-walled parenchyma cells and characteris-
tic ray tracheids conterminous with one another. This does not
mean a simple association, since nearly all such cases, as typ-
ically presented by P. palustris, also show a graduated structure
of such a nature as to confirm the belief that the one passes into
the other by structural gradations. That such is the case can-
not be doubted, and if further confirmation were needed, it is
afforded by the precisely parallel relations to be met with in the
formation of resin cells and resin canals. A further fact of much
significance from the standpoint of development is that such

90 ANATOMY OF THE GYMNOSPERMS

interchangeable relations are peculiar to the highest types of the
genus Finns. But we may ask, What is the function of these
structures which make their appearance only in the higher Coni-
ferae ? What is the proper significance of their appearance there,
and do any other plants offer parallel examples ?

In the so-called medullary rays of Lepidodendron selaginoides
(81, 141) there are numerous reticulated or spiral elements which
are undoubtedly of the nature of tracheids, and they may beheld
to represent the ancestral form of the ray tracheids in the Coniferae,
toward which they bear the same relation that exists between
the spiral protoxylem element and the characteristic wood tracheid
with bordered pits. From this it is apparent that the ray tracheid
of Pinus or Tsuga represents a primitive structure which reappears
in response to conditions of growth and structural alterations of
such a nature as to demand the interposition of more simple,
because more primitive, elements for the proper performance of
necessary functional activities. These activities, in the case of
Lepidodendron, are probably expressed in the radial distribution
of water (81, 141), and we are no doubt correct in assuming
similar activities to be carried on in the higher Coniferae. In all
those species which present the primitive structure of the thin-
walled ray cells, both fossil and recent, there are no tracheids to
be found. As a tendency to thickening of the wall arises, there
is also developed a sporadic tendency to the development of ray
tracheids, as in Thuya and Cupressus. It is also a noteworthy
fact that simultaneously with a general thickening of all the cell
walls throughout the ray, as in the genus Tsuga, ray tracheids
become a constant and prominent structural feature. This rela-
tion exists in Pseudotsuga, Larix, Picea, and Pinus, and it is a
remarkable fact that as the type of organization advances, and
the structural modifications of the wall become more profound,
the tracheids gain steadily in numbers and importance until they
finally replace the parenchyma cells more or less completely.
Such facts serve to direct attention to the idea that by such pro-
gressive alteration the ray cells gradually lose their normal
functional powers with respect to the radial distribution of water,

MEDULLARY RAYS 91

•

and under such circumstances it is imperatively demanded that
this deficiency should be met through some other structures.
Under these circumstances two alternatives are possible : first,
that the thick-walled and useless cells should return to their
primitive condition in opposition to the general course of devel-
opment, and once more resume their appropriate functions. Such
structural reductions do in reality occur in these very cases, as
shown in Pinus taeda, etc., but it is to be observed that they are of
the nature of a growth which has been arrested at such an early
stage as to be devoid of many of the normal structural features.
Furthermore it would be difficult, if not impossible, to obtain evi-
dence from other plants in support of a hypothesis of this nature.
It is true that in the case of girdled pines the heartwood may
resume an activity long since lost, and thus take upon itself once
more the function of the sapwood, and also to some extent
the function of the bark ; but such renewed functional power
does not in any way involve structural modifications of existing
elements, and cases of this sort cannot be cited in support of the
hypothesis. It is therefore fair to conclude that such structural
reduction and restoration of functional activity are accompanied
by a partial diversion of energy to the preponderant tracheids.

The second alternative permits us to consider that in the
ordinary course of development the ray cells gradually lose their
functional activity as a result of extreme structural modification,
and that this loss of power cannot be restored, even though the
wall may return to a primitive condition of structure through
various phases of atrophy. In accordance with this idea the
tracheid would be introduced as the most natural because the
original medium for such activities as are centered in the ray,
and it would therefore acquire additional importance both nu-
merically and functionally in direct proportion to the loss of
power experienced by the parenchyma cells. This appears to be
a reasonable interpretation, and in the light of observed facts
it would seem to be the correct one.

A structural feature of great importance in the ray tracheid
appears in certain inequalities of the upper and lower walls, which

92 ANATOMY OF THE GYMNOSPERMS

take the form of teethlike projections into the cavity (fig. 26).
In what may be regarded as the most highly developed tracheids
the teeth project across the cell cavity until they meet and
coalesce, thereby forming a more or less definite reticulation,
which gives to the tracheid a very characteristic appearance.
As seen in tangential section, such reticulations often appear as
narrow bands crossing the cavity from side to side, thus giving
the cell a varying aspect. Such dentate and reticulated tracheids
are absolutely confined to the second section of the genus Pinus,
in which they constitute one of the most characteristic features
to the extent of 68.3 per cent of the species. A more detailed
analysis of this feature, as applied to the hard pines, is desirable.
In P. resinosa and P. Thunbergii the tracheids are simply dentate.
In six species, represented by P. Murrayana, the teeth extend into
definite reticulations confined to the summer wood ; but in six
other species, represented by P. Jeffreyi, such reticulations are
sparingly developed throughout the ray. In P. tseda a transitional
form appears. Typically this species shows the tracheids to be
sparingly reticulated, but occasionally they are strongly reticulated
throughout. This brings to mind the further fact that in all
species which are sparingly reticulated there is a marked tend-
ency to strong reticulation in the summer wood. In the thirteen
remaining species the tracheids are uniformly strongly reticu-
lated throughout the extent of the ray, and this feature attains
its highest expression in P. palustris and P. cubensis. It is there-
fore manifest that we have to deal here with a graduated develop-
ment of such a nature that the simply dentate tracheid is the
most rudimentary, while the strongly reticulated is of the most
advanced type of structure.

The value of the ray tracheid for taxonomic purposes depends
upon (i) its occurrence in certain genera, and (2) its structural
peculiarities. In the great majority of cases the simple wall of
the tracheid affords no basis of specific differentiation, but in the
various forms of dentate and reticulated walls of the second sec-
tion of Pinus it is of well-defined value in this respect. Pinus
resinosa, P. Thunbergii, and P. koraiensis are all characterized

MEDULLARY RAYS 93

by the occurrence of simple teeth, which are sometimes sparingly
developed. This feature is intimately associated with the occur-
rence of large, simple, and single pits on the lateral walls of the
ray cells. From this group P. densiflora may be differentiated by
the reticulations in the tracheids of the summer wood. Among
the hard pines P. taeda is distinguished by ray tracheids, which are
typically sparingly reticulated throughout, but on the other hand
P. palustris and P. cubensis, which probably represent the highest
types of the genus, are at once separated from all other species
by reason of the extent to which reticulations are developed.

The relations which the tracheids bear to the parenchyma
cells in the general composition of the ray also have an impor-
tant bearing upon specific differentiations. In the genus Tsuga
the tracheids are sometimes interspersed, affording the first
instance of a relation which later becomes most prominent in the
higher genera, and the same relation is also expressed in Pseudo-
tsuga and Larix. In Picea there is a somewhat stronger tendency
to an interspersal which is only expressed fully in Pinus. In the
soft pines eleven out of thirteen species show, as in the previ-
ous genera, that the tracheids, as a rule, are rarely interspersed ;
P. aristata forming a partial exception, as shown in a sparing in-
terspersal. P. monophylla and P. monticola, on the other hand,
show a strong interspersal of the tracheids, and in this respect
they approach the hard pines. In the latter group we again find
the first four species characterized by a rare interspersal ; but
passing on to the more highly developed species, such types as
P. clausa, P. palustris, and P. glabra show that the interspersed
tracheids are not only numerous but also that they eventually
become conspicuously predominant and often constitute the bulk
of the ray structure. It is evident, then, that such features pos-
sess an obvious value for diagnostic purposes, particularly in the
genus Pinus, where the variations are numerous, well defined,
and applicable to particular species or groups of species.

As displayed in tangential section, the medullary ray exhibits
two principal forms, each of which presents features of great
taxonomic and phylogenetic value. The type of structure which

94

ANATOMY OF THE GYMNOSPERMS

prevails, and which may be regarded as the fundamental form of

the ray, is that of from one to many cells superimposed in a single

series of varying height (fig. 27). Such one-
seriate rays are characteristic features of all the
investigated recent genera. In 30 per cent of
the genera there is a sporadic tendency to
a multiseriate form as expressed in the devel-
opment of rays which are two-seriate in part.
Such enlargement is not confined to any partic-
ular portion of the structure, and within the
limits of the same section it may arise at the cen-
ter or at either end. It is never found in Abies,
Picea, or Pinus,but it is met with in Pseudotsuga
macrocarpa, three species of Cupressus, two of
Juniperus, one each of Sequoia and Araucaria,
and two of Larix (figs. 27,
28). In Libocedrus such
tendency is much more pro-
nounced, and the rays may
be described as two- to
three-seriate in part.

This feature is of so
sporadic a nature that
existing species afford no
satisfactory evidence as to
its origin or significance,
but reference to Cordaites

tends to throw some light upon this somewhat

obscure problem. In fourteen species of Cor- FlG- 2iS- TAXUS BREVI-

. ^ FOLIA. Tangential

daites, three of which are European (28, 606- view of a meciuiiary
609), it is seen that the rays present four ray showing its two-
variants ranging from the strictly one-seriate "J**
form to one- to two-, rarely three-seriate.
The distribution is in the following percentage proportions :

1-2, rarely 3-seriate 2 1.4 per cent

FIG. 27. SEQUOIA
SEMPERVIRENS.
Tangential section
of a medullary ray
showing a typically
one-seriate ray of
broad form. X 280

1-2, seriate

14-3

2-seriate in part
I -seriate

50.0 per cent
14.3 " »

MEDULLARY RAYS

95

From this it would appear that Cordaites as a whole approaches
the primitive, multiseriate ray, such as may be found in the
Cycads, much more nearly than any of the existing species under
consideration, and from this point of view it becomes possible
to arrange a sequence showing the relative development in the
following terms: (i) Cordaites, (2) Libocedrus,
(3) all other genera, as enumerated above. The
evidence of fossil plants, however, shows that
caution must be exercised in our estimate / Q

of what constitutes the primitive ray. The
structure of Stigmaria shows a preponderance
of one-seriate medullary rays (81, 224), and
that such are primitive rays cannot well be
doubted. In general, however, we are prob-
ably not far from correct in the assumption
that the highest form of the ray is expressed
in its one-seriate character. Deviations from
this would then require to be interpreted as
vestigial features, which indicate a relatively
lower type of organization in direct propor-
tion to the increase of a tendency toward a

\ ™ I

multiseriate form. W/

In the majority of species the side walls of
the parenchyma cells are thick and traversed
by small pits. In the genus Pinus the wall
is commonly thin, and it closes the orifice of FlG- 29- PINUS RE-

FLEXA. Tangential

a very large pit on the wall of the adjacent section of a medui-
wood tracheid. This is notably true of the
soft pines, in which the side wall either pro-
jects as a convex membrane, or it is concave
and curves into the cell cavity. Such a feature is of very little
if any importance except in P. reflexa, where the thin side walls
almost invariably project so as to give the cells a correspond-
ingly inflated appearance (fig. 29). It is not only apparent in a
tangential section, but is very conspicuous in the transverse sec-
tion (fig. 1 8), where the inflated walls are seen to project into the

lary ray showing the
typically inflated
cells. X 300

96

ANATOMY OF THE GYMNOSPERMS

\0)

FlG. 30. PSEUDOTSUGA

DOUGLASII. Tangen-
tial section of a fusi-
form ray showing (a)
the typical resin ca-
nal with thick-walled
epithelium, but devoid
of thyloses. x 280

cavities of adjacent wood tracheids, thereby
giving to the ray a beaded appearance. As
an exceptional variation it possesses no ap-
parent significance with respect to questions
of descent.

The second form of the ray is that which
has been designated as fusiform in refer-
ence to its characteristic outline (44, 39).
Such rays occur in relatively few of the
existing genera to the extent of 20 per
cent. They occur typically in Pseudotsuga,
Larix, Picea, and Pinus, and they are thus
seen to be characteristic of the most ad-
vanced types. Among extinct species they
are unknown except in the case of Sequoia
Burgessii (46, 42-46) and S. Penhallowii of
Jeffrey (25, 321), in which they present a
remarkable exception to the general course
of development and structure of that genus.
The fusiform rays are peculiar in their
structural features. They vary greatly in
height as between different genera, and
such variations also occur within a given
genus, the extremes being met with in the
genus Pinus, where P. palustris and P. pon-
derosa present the antithetic relations.
In most cases they are much higher than
the one-seriate rays with which they are
associated, but this rule is subject to sev-
eral exceptions. They are always distin-
guished by a broadening of the central tract
by from two to several times the original
dimensions, thereby becoming more or
less multiseriate. These variations depend
upon the nature of the included structure,
which exhibits modifications directly related

MEDULLARY RAYS

97

O

FIG. 31,^. PINUS ALBICUALIS. Tan-
gential section of a fusiform ray
showing a typical resin canal with (a)
thyloses, and (f>) rather thick-walled
parenchyma, x 280; fi. PINUS PA-
LUSTRIS. Tangential section of afusi-
form ray in part showing thin-walled
parenchyma broken out. x 280

to progressive development of the genus. Such
broadening arises abruptly in Pseudotsuga,
Larix, and Picea, so that the terminals above
and below consist of a single series of cells
with the general structure of the one-seriate ray
(fig. 30). In Pinus the broadening is less ab-
rupt, diminishing in both direc-
tions somewhat gradually, thus
giving rise to a region of lenticu-
lar form which occupies upwards
of half the height of the ray, or
in some cases constitutes the
entire structure. From this it
follows that in such types as
P. palustris (fig. 3 i, B) the termi-
nals, which are often prolonged
to great length, may be linear
and one-seriate, while in P. pon-
derosa the whole ray is lenticular
in outline and the terminals con-
sist of only one or two limiting
tracheids (fig. 32). Within the
region of the central tract the
cells are all thick-walled in Pseu-
dotsuga, Larix, and Picea, but in
Pinus they are generally thin-
walled, and in the hard pines this
feature is emphasized by a degen-
eration of the tissue to such an
extent that it is readily broken
out in making sections, whence
it characteristically appears
either much broken up or entirely
wanting. The principal feature
of such rays, and the one which
determines their form, is the

98

ANATOMY OF THE GYMNOSPERMS

presence of a resin canal in each case. Such resin canals traverse

the ray continuously for its entire length.
They present the same details of structure
as the resin canals which lie within the
xylem. In Pseudotsuga, Larix, and Picea
the central canal is narrow, especially in
the first two genera, and the epithelium
consists of a single layer of thick-walled
cells. In Pseudotsuga and Larix (fig. 30)
thy loses are altogether wanting, but in
Picea they are of sporadic occurrence.
In Pinus (figs. 31 and 32), on the con-
trary, the canals are always distinguished
by their great breadth ; the epithelium is
composed of from one to several rows of
thin-walled cells, which are often resinous
and often much disorganized, while thy-
loses are an invariable feature of the
central canal.

b \\- K""^ A comparison of different genera and

species shows that there is a somewhat
striking variation in the number of one-
seriate rays (tangential) to a given area of
section. Such variations may arise within
narrow limits in the same species, accord-
ing to location and conditions of growth,
but apart from this there are somewhat
constant variations between different spe-
cies, which may be expressed by the use
of the relative terms "few" and "many."
No attempt has been made to define such
variations more exactly, but it is quite pos-
sible that a determination of the average
number to a square centimeter or other
convenient unit might disclose a somewhat greater differential
value than is at present apparent. A simple illustration will

c.

FIG. 32. PINUS CLAUSA.
Fusiform ray showing
(a) the resin canal with
thyloses; (/>) thin-walled
parenchyma cells; (c)
the terminals composed
of only one or two tra-
cheids. x 280

MEDULLARY RAYS

99

serve to afford an idea of the rather limited specific value of this
character. In Taxus cuspidata the rays are numerous, while in
the two remaining species they are relatively few. The same
feature applies to the differentiation of Torreya nucifera from the
other species of that genus. In Pinus clausa,
P. serotina, P. Murrayana, etc., the same rule
applies, but in all such cases it cannot be ac-
cepted as final.

The height of the ray is subject to such varia-
tions, even within the same species, that it can-
not be defined with sufficient accuracy to admit
of its application to classification in more than
a very general sense. It is true that the rays
of Gingko are always low, while those of Taxus
and Torreya are often high. In Juniperus
they are commonly low, while in Pinus they
range from low to very high. Such variations
do not possess sufficient constancy to admit
of either generic or specific application in the
strict sense, though they not infrequently serve
a useful purpose as controlling factors, and they
are therefore incorporated in all the diagno-
ses. Variations in breadth have a much more
definite value, since the element of constancy
is well defined. The genus Thuya (fig. 33)
may almost invariably be differentiated by this
feature. In Cupressus, C.thyoides may be dis- FIG. 33. THUYA

. , , , • -1 r U'l /- • GIGANTEA. Tan-

tmguished by a similar feature, while C. anzo-

nica and C. Goveniana are equally well indicated

by their great breadth. The same rule applies

also to Juniperus, Sequoia (fig. 27), Pinus, and

other genera, whence it appears that this feature

is of specific value. It is always associated with and dependent

upon the form of the component cells (tangential), which affords a

means of distinguishing genera and species with much directness.

The narrowly oblong cells of Thuya (fig. 33) serve to separate

Q
Q
Q
0

Q
ii

Q

0
Q
0

0

gential section of
a ray showing the
typically narrow
and oblong cells.
X 280

100 ANATOMY OF THE GYMNOSPERMS

this genus without difficulty, since a similar feature occurs but
rarely elsewhere, and then in such association as to make the
differentiation clear. In Juniperus the genus is separable into
four well-marked divisions: (i) round to oval or transversely
oval, (2) rays broad, the cells oval to round, chiefly round ;
(3) chiefly oval ; (4) rays narrow, the cells oblong to oval, chiefly
oblong. The broadly oval and thin-walled cells of Sequoia sepa-
rate it from associated genera. In Picea the genus may be sub-
divided according as the cells are (i) variable, round, oval, or
oblong; (2) equal and uniform, oblong or oval.1 Cupressus is
similarly separable into groups. But it is not difficult to separate
C. arizonica and C. Goveniana more specifically, by reason of
their broad rays and very conspicuously transversely oval cells,
from C. pisifera with its round or oval cells and C. thyoides with
its narrow, oblong, rarely oval cells. In the genus Pinus atten-
tion is at once directed to P. Murrayana by the conspicuously
round or transversely oval, very unequal, and variable cells.

The interspersal of the tracheids often imparts a characteristic
appearance to the tangential aspect of the ray, especially in the
genus Pinus, and more particularly among the hard pines. In
this group the tracheids present very variable forms and sizes.
In such types as P. glabra they are small, oval, or round, and
wherever they occur they give rise to a marked local contraction.
In P. palustris and P. cubensis they are commonly oblong and
not infrequently they become several times higher than broad.
As they are almost invariably narrower than the associated
parenchyma cells, they cause a local contraction which sometimes
extends over considerable distances. In P. palustris the predomi-
nance of the tracheids is carried so far that the rays are chiefly
composed of them, and it then becomes appropriate to apply
the term "interspersed" to the few parenchyma cells. In all
of the more highly organized rays of the hard pines the appear-
ance of the structure is so complex and variable that a proper

1 The term " equal " here applies to cells of the same ray which are of the same
width, " uniform " to the cells of all rays which are pretty constantly of one form,
the contrasting terms being " unequal" and "variable" respectively.

MEDULLARY RAYS

101

Generic.

diagnosis can be drawn only when we take cognizance of the
principal aspects presented, and these are sometimes as many
as four in number.

A consideration of the various structural features thus dis-
cussed in their relations to classification will show that no other
portion of the stem possesses so many elements of importance as
the medullary ray, which, in consequence, attains the highest
value in this respect and affords differential characters of wide
range, great prominence, and easy recognition, and is of primary
importance in the differentiation of groups, genera, and species ;
and, as a general summary, the utility of these characters for such
purposes is approximately indicated in the following tabulation :

1. Rays (tangential) of two kinds.

2. Ray tracheids.

3. Pits on the lateral walls of the ray cells simple or bordered.

4. Terminal walls of the ray cells thin and entire or locally

thickened.

5. Form and character of the ray cell (tangential).

6. Form and size of pits on the lateral walls of the ray cells.

7. Ray tracheids dentate or reticulated.

8. Direction and form of orifice of pits on the lateral walls of

ray cells.

9. Upper and lower walls of ray cells.

10. Ray tracheids interspersed or marginal.

11. Disposition of pits (radial).

12. The number of pits per tracheid.

The marginal cells of the ray- - that is, those which terminate
the ray above and below, as seen either in a radial or a tangential
section --are usually somewhat different from those which con-
stitute the bulk of the structure. This difference is expressed in
a tangential section by their greater height and relatively narrower
form. In a radial section it is expressed by the greater height?
the somewhat thinner walls, and the sinuous form of the latter as
they conform to the terminations of adjacent tracheids. In such
deviations from the usual characteristics of the ray cells it is
probable that those of the margin may be held to exhibit a tend-
ency to the formation of ray tracheids of which they would

- Specific.

102 ANATOMY OF THE GYMNOSPERMS

therefore be regarded as potential forms. This view gains
strength from the fact that the ray tracheids first appear in just
those situations ; that when they are sporadic, as in Abies bal-
samea, they are interspersed and conterminous with the marginal
cells ; that their external forms and general aspect are the same ;
and that when the tracheids are fully developed and become
constant features of the ray it is at the expense of the ordinary
marginal cells, which then disappear. Furthermore Jeffrey has
shown that in Sequoia Penhallowii (25), where the marginal cells
assume a very characteristic form, they are also interspersed in
the higher rays precisely as tracheids are in the rays of the higher
Coniferae. Another feature of these cells --to which Jeffrey
has directed attention in Sequoia Penhallowii - - is the presence of
numerous crystals. This is unique among the Sequoias, and it
is unknown in any other genus of the Coniferales except Abies,
where, as Jeffrey also shows, a similar deposit of crystals is to
be met with in A. concolor, A. grandis, A. bracteata, A. nobilis,
and A. magnifica ; but it is a feature of much more sporadic
occurrence, since large areas of these species show no crystals,
while in Sequoia Penhallowii they are exceedingly abundant.
Jeffrey correctly regards this as indicating a certain relationship
between these two genera (25), a connection, however, which is
also indicated by other structural features, as pointed out by
Penhallow some years since (44, 45).

CHAPTER VII

MEDULLARY RAYS (continued}
RELATIONS TO DEVELOPMENT

We are now in a position to determine the relations in which
the various structural features of the medullary ray stand to
development, and for this purpose it may be most convenient
to discuss them in that sequence which is apparently consonant
with the general order of evolution of the entire group.

It has been ascertained that bordered pits are characteristic
features of the lateral walls of the ray cell in 72.4 per cent of the
investigated species, and that in the remaining 2 7. 6 per cent, among
the higher types, simple pits predominate, but a closer scrutiny
of this latter group discloses some features of more than passing
interest. Reference to the table of anatomical data (Appendix A)
will show that the change from bordered to simple pits is entirely
confined to the genus Pinus, and that it does not arise abruptly
as if in response to some unusual condition whereby a profound
alteration in the usual course of development was induced ; but
it is effected by stages, showing that whatever influences were
brought to bear, they operated gradually through a somewhat
prolonged period of development, while here and there strong
tendencies to reversion were manifested, and that the alteration
was finally effected in a permanent way, only in the most highly
developed pines. Commencing with P. Lambertiana, it will be
observed that some species of the soft pines are characterized by
simple pits. Among the hard pines P. clausa and P. rigida have
bordered pits, while the six following species again show simple
pits. We next come to a group of four species, with one excep-
tion (P. Murrayana) Japanese, in which there is a mingling of
both bordered and simple pits, showing a decided persistency

103

104 ANATOMY OF THE GVMNOSPERMS

of the primitive character in the face of conditions which involve
a change. Following these are two species with simple pits, one
with transitional features, five with simple pits, one with bor-
dered pits, one with the transitional form, and the remaining six
species with simple pits only. It will therefore be seen that these
changes occur in waves, and that within the limits of forty-one
species there are three complete and six incomplete recurrent
phases. If we were arguing from purely theoretical grounds, all
of these species should be arranged in such order as to show (i)
bordered pits, (2) transitional forms, and (3) wholly simple pits,
and we should thereby gain a perfect developmental sequence.
But such a position would not be justified by other evidence of
an equally if not more weighty character, and it is our object
to interpret the facts as they are found. It has already been
shown that the occurrence of simple pits in the pines is conso-
nant with a higher type of development, and that the change is
not only accompanied by sporadic reversions or survivals, as one
may choose to regard them, but that the change as a whole is
a process of reduction. From this point of view, then, we must
regard the occurrence of bordered pits in P. clausa, P. rigida, and
P. pungens as pure survivals of a more primitive structure, --a
feature which is less perfectly expressed in such transitional forms
as P. koraiensis or P. mops. But a mere mingling of the two
kinds of pits in the same species is not the only evidence in this
direction. The mingling of simple and bordered pits does not
occur indiscriminately, but in accordance with a well-defined law
to the effect that the former are characteristic of the spring wood
throughout its entire extent, while the latter occur, if at all, only
in the summer wood, where they might be expected, since the
arrested development which might be complete in the case of
relatively thin-walled cells could be readily overcome in part in
walls of greater secondary growth. This in no way conflicts with
the observed fact that in the majority of cases the usual course
of development is such that the bordered pits of the spring wood
very commonly become reduced to simple pits in the summer
wood, in accordance with De Bary's law, as already stated in

MEDULLARY RAYS

105

application to other cases. Constancy in the structure of such
pits has been found to be characteristic of Cordaites, Gingko, the
Taxaceae, and all the lower forms of the Coniferae, from which
we may conclude that the bordered pit is essentially a primitive
character. On the other hand, variation is a well-marked feature
of the pit in the genus Pinus, as first expressed in the large oval
or squarish and open pits of P. resinosa or P. Thunbergii, and
as later appears with greater frequency in the smaller and very
inconstant pits of P. taeda or P. palustris. Such variations, then,
involving a gradual and complete transformation to the condition
of simple pits, are characteristic only of the more highly developed
pines, from which it may be concluded that it is a feature con-
sistent with a relatively high order of development in exact accord
with the principles governing parallel changes in the pits of the
wood tracheids. They are also in harmony with the well-known
principle that variation is always of a more simplified form in
primitive types, but that it tends to greater diversification with
advance in organization and general development, as a necessary
sequence to the adjustment of the organism to a wider and more
complex environment. Finally, it has been shown that the elimi-
nation of the bordered pit proceeds concurrently with the more
complete organization of the ray tracheids, in response to a sub-
stitution of functional activities between these structures and the
degenerate parenchyma cells. We may therefore conclude that
extreme variation in the character of the pit is an expression of a
higher type of development, and that from this standpoint such
structures have a definite value in solving questions of descent.
The terminal walls of the ray cells present three variants with
respect to secondary growth. All the more primitive Cordai-
tales and Coniferales are characterized by thin walls. Cupressus
and Juniperus are chiefly distinguished by their thin walls, which
are also locally thickened, a feature which has been shown to be
due to incipient secondary growth. But such alterations are
already foreshadowed in Libocedrus, where the local thickening
of the wall is of a sporadic nature. In Abies magnifica and A.
grandis there is a partial recurrence of thin and locally thickened

106 ANATOMY OF THE GVMNOSPERMS

walls, which is pretty fully expressed in A. concolor. A similar
recurrence is met with in Pseudotsuga macrocarpa, in Picea
polita, and in Pinus Parrayana, and it is also complete in thirteen
of the most highly developed species of Pinus, where the walls
have suffered extreme degeneration. Within the limits of Picea
(i) and the soft pines (5) there are six instances in all of spo-
radic and partial survival of the thin and locally thickened wall.
The first tendency to thick and strongly pitted walls is mani-
fested in five species of Juniperus, and such development is fully
expressed in what may be regarded as the three most highly
developed species. Thick walls are then fully characteristic of
Abies, - - with a partial reversion in A. concolor, - - of Tsuga,
Pseudotsuga Douglasii, and Picea, with the exception of P. polita,
five species of soft pines, and three species of hard pines. In
P. taeda and P. palustris the walls are so degenerate that their
structure cannot be satisfactorily determined, but they are pre-
sumably thin -walled.

From these facts it is manifest that the progressive thickening
of the terminal walls accords with the general course of devel-
opment, and once more making use of the principles already
applied to the pits on the lateral walls, we are brought to the
natural conclusion that (i) an increase in the thickness of the walls
is evidence of a higher type of organization, and (2) that the
sporadic recurrence of thin walls with local thickenings represents
the persistence of a primitive character.

Ray tracheids probably constitute one of the most valuable
of the structural elements as an indication of development. This
has its foundation (i) in the fact, previously shown, that they
arise as secondary structures from the parenchyma elements,
with which they exhibit interchangeable relations, in direct re-
sponse to the requirements of a higher degree of organization,
and (2) in their general relation to progressive development.
The complete absence of ray tracheids from the Cordaitales and
Gingkoales, as also from the Taxaceae and more primitive Coni-
ferae, while they are invariable features of the higher Coniferas,

MEDULLARY RAYS 107

in which they attain their most complete development, admits
of only one interpretation. The fact that they are exclusively
features of the Coniferae emphasizes their inferior value for de-
termining the derivation of that group, while it points to their
superior importance as a factor in the sequence of the various
coniferous genera. They occur sporadically in Thuya (i), Cu-
pressus (2), Juniperus (i), and Abies (i). They are prominent
features of Tsuga, Pseudotsuga, Larix, Picea, and Pinus. Their
invariable absence from Sequoia would appear to suggest that
this genus is more primitive than Thuya, but there are other
reasons which serve to suggest the opposite relation. Apart
from this exception, it will be seen that in accordance with the
relations exhibited in the table of anatomical data (Appendix A)
the genera enumerated form a continuous series, commencing
with those showing sporadic tracheids and ending with those in
which such structures attain their highest expression. From
this we are justified in the conclusion that the rare occurrence
of tracheids in Thuya, etc., is to be interpreted as the first evi-
dence of a tendency in development which is only fully realized
at a later period, and this appears to be justified by a closer
examination of the last five genera in this respect, since it is
found that in them the tracheids not only show a progressive
numerical development but their structure likewise becomes
more complicated in direct relation to the evolution of higher
types of genera and species. We must therefore look upon the
tracheids with their thin, simple walls as the primitive form,
while those with the strongest reticulations are of the highest
type, the two being united by a transitional form characterized
by the presence of simple teeth. The evidence at hand does
not appear to justify the idea that the various genera have been
segregated into small groups representing side lines of develop-
ment, but it rather favors the thought that each genus is in
itself a complete short line of descent, and that among these a
prominent parallelism has arisen in the tendency toward the
development of tracheids, — a tendency which has been carried
to completion in the case of only five of the series, and in such

108 ANATOMY OF THE GYMNOSPERMS

a way that in only a portion of one of these has that completion
reached its highest expression.

The occurrence of two kinds of parenchyma ray cells is an
exclusive feature of the genus Finns, and its value for phyloge-
netic purposes is strictly confined to the relations of the various
species of pines. The first appearance of this differentiation is
among the soft pines in P. aristata and P. edulis. It is to be
observed, however, that the thick-walled cells are always domi-
nant, the thin-walled cells being interspersed among and con-
terminous with them. No further evidence of such structural
alterations is to be noted until we reach the more highly devel-
oped representatives of the hard pines. Among these definite
transition forms occur in P. Murrayana, P. Coulteri, P. Jeffreyi,
P. virginiana, P. insignis, and P. cubensis, while in P. arizonica,
P. ponderosa, P. Sabiniana, P. pungens, etc., the original relations
are exactly reversed and the thick-walled cells show a diminish-
ing frequency until in P. glabra and P. taeda they are rarely met
with. Such facts give effective proof of the belief that struc-
tural alterations of this nature are not only evidences of the
highest type of development among the pines but also among
the Coniferales as a whole.

The invariable absence of the fusiform rays from all except
the four genera which attain the highest structural development,
and their constant occurrence in all the species of such genera,
presents an argument of great force as showing their relation
to the evolution of advanced types. There is here no evidence
of sporadic development, foreshadowing the general course of
evolution, but the fusiform rays with their resin canals appear
abruptly and permanently. Among fossil plants --except the
genus Pityoxylon, which, being essentially Pinus, falls under the
general rule - - there is no instance of such structures outside
of the four genera named, save in the case of the remarkable
Sequoia Burgessii, from the Lignite Tertiary (51, 42), and S. Pen-
hallowii of Jeffrey (25). As it will be necessary to further
discuss the essential structure of the fusiform ray, we need not
deal with it more in detail at the present moment.

CHAPTER VIII

WOOD PARENCHYMA

In our present studies we recognize as wood parenchyma all
those elements which, in association with tracheids, have their
major axes extended parallel with the principal axis of growth ;
and which, in accordance with accepted limitations, are charac-
terized by their more or less cylindrical form, abrupt termina-
tions, and relatively thin walls. Such elements do not occur in
wood of the Cordaitales, and they are infrequent in the Ging-
koales, but they are somewhat conspicuous features of the Coni-
ferales, where they acquire great prominence either because of
their peculiar contents or their association with somewhat highly
specialized tissues. They differ in their structure as in their
special functions, though in the main they are connected with
the production of resinous matter ; and inasmuch as their most
prominent feature is usually found in associated products of cel-
lular activity, it will be most convenient to discuss them under
specific names, which may serve to direct attention to their par-
ticular purposes in the plant economy. They may therefore be
classified as follows :

Wood parenchyma :

a. Crystallogenous idioblasts.

b. Resin cells.

CRYSTALLOGENOUS IDIOBLASTS

The investigations of Eichler (15, 35) show that in Gingko
the wood is characterized by the presence of wood-parenchyma
cells, which take the form of short idioblasts of lenticular form
in longitudinal section, and are distinguished by the storage of
crystals of calcium oxalate. Such structures are peculiar to this

109

I 10

ANATOMY OF THE GYMNOSPERMS

tr.

• -tr.w.

.fr.w.

genus, in which they form a specific character of definite value,
and it is therefore of importance that they should be described
somewhat in detail.

In a transverse section (plate 18) the idioblasts, recognizable
by their conspicuous crystals, may be seen scattered through
the entire section without special reference to either the spring
or the summer wood. Under a high degree of amplification it
will be seen that they are often single, but quite frequently they

are grouped in radial series
of two or three, in which case
one is generally much larger
than the others (fig. 34, a}.
The form is narrowed tangen-
tially and extended radially so
as to be approximately lenticu-
lar, and the cavity is usually
pretty well filled with a com-
pound crystalline mass. The
idioblast is situated in the
line of one of the radial rows
of tracheids, the continuity of
FIG. 34. GINGKO B i LOB A. «, trans- which it interrupts. It is usu-

verse section showing the occurrence a|Jy mucn larger than the ill-
and form of a crystallogenous idio- . . . , ,

blast;*, tangential section of the same, dividual wood tracheid, from

tr., tracheids; tr.-u>., tracheid walls; i., which it also differs ill the char-

idioblast; /«,., idioblast wall; cr., acter of the cell wall, which is
crystals. X 233

very thin and not infrequently

shows a want of continuity suggestive of obliteration in the course
of development. In a radial section the idioblasts are usually of
an isodiametric form, more rarely elongated longitudinally, and
the compound crystalline mass somewhat more than half fills the
cavity. In this section the walls are seen much better than in
any other, and the relations of the idioblasts to one another are
well exhibited. In a tangential section (fig. 34, b) the wall is also
well displayed. The individual idioblasts are lenticular in form
and the crystalline mass completely fills the cavity transversely,

RESIN CELLS I i i

but only about half fills it longitudinally. This section is the most
useful for displaying the relations of the idioblasts to the adjacent
tracheids, inasmuch as the limits of the walls of the latter are
much more clearly defined. As seen in the tangential section, the
idioblasts fall into a single longitudinal series, which may not
embrace more than two or three members, but more commonly
there are upwards of twenty-one in a series. Not infrequently
the chain of crystals will be found to be interrupted for some
little distance, but the continuity of the idioblasts will then be
seen to be uninterrupted through the development of cylindrical
elements of uniform but smaller diameter and devoid of crystals,
from which it would appear that the lenticular or rounded form,
as determined by the particular plane of section, is not the normal
form of the cell, but that such special form results from the
growth of the crystal, which must have been deposited when the
tissue was in a formative stage of development. This is made
apparent in another very striking manner. In any tangential
exposure of such a series it may be seen that the terminal mem-
ber does not necessarily occupy all the space between the walls
of adjacent tracheids. There is thus developed an intercellular
space of variable dimensions, which may be quite small or may
be so extensive as to suggest that the crystals were formed in
such spaces and not in closed cells. Such spaces are obviously
not the result of that splitting which is ordinarily incident to the
growth of tissues, but they clearly arise as a secondary effect
incident to the development of the crystalline mass and the
pressure of this latter upon the surrounding parts.

RESIN CELLS

In a large proportion of the Conif erales the wood is character-
ized by the presence of more or less numerous wood-parenchyma
cells. These are always distinguished by their cylindrical form
and transverse terminations. They are invariably associated
with the production of resin, either as entering into the com-
position of resin passages or as isolated cells. It is this latter

1 1 2 ANATOMY OF THE GYMNOSPERMS

group with which we are most particularly concerned at the
present moment, and as, with very few exceptions, they are
uniformly characterized by the presence of resin, which gives
them a distinctive appearance, I prefer to describe them as resin
cells rather than by the more commonly employed designation
of wood parenchyma, which conveys no suggestion of their
special function and most prominent feature.

The resin cells are found to be entirely wanting in those
species of Taxus (4) and Torreya (3) which are included in the
present studies. They do occur, however, in Podocarpus, where
they present the usual structural features, but they are there
remarkable for their number and the great abundance of massive
resin which they contain. This distribution in the Taxaceae does
not altogether accord with the conclusions of Eichler (15, 35),
who states that they occur very sparingly in the Taxaceae, but
makes no mention whatever of their presence in Podocarpus,
where they are much too prominent to escape even the most
casual observation.

In the Coniferac resin cells are characteristic of all genera
except Picea and Finns, where they are replaced by resin pas-
sages, of which they form essential parts. They are, therefore,
features in the wood structure of twelve genera, and they are
constant characteristics of all their species, with very few excep-
tions. Such exceptions apply exclusively to the genus Abies,
in which four species- -A. Fraseri, A. lasiocarpa, A. Veitchii,
and A. balsamea — are wholly devoid of such structures.

The recognition of the resin cells presents no difficulty in
the great majority of cases, because of the abundance and depth
of color of the resinous contents. This finds its most complete
expression in Taxodium, Sequoia, Cupressus, etc. In Abies, on
the other hand, where these cells have experienced extreme
numerical reduction, and where there also seems to be a cor-
responding reduction in their secretory power, it is impossible
to recognize them in this way. In such cases it is often pos-
sible to distinguish them by their slightly different form and
somewhat thinner walls as compared with the adjacent wood

RESIN CELLS

tracheids, by their situation slightly in advance of the outermost
row of summer wood tracheids, and most particularly by their
pitted terminal walls when the latter lie near the plane of sec-
tion. This last feature may also be relied upon in all other
cases when any element of doubt is involved (fig. 35). In longi-
tudinal section the characteristic form of the cell serves to dis-
tinguish it beyond all doubt, even in the absence of resinous
contents. Whether exposed in radial or tangential section the cell
has the form of a narrow cylinder upwards of 300 /JL in length,
and always several times longer than broad, except in cases where

)}
S.W.

FIG. 35. ABIES AMABILIS. Transverse section showing the position and structure
of the resin cells (r.c.) on the outer face of the summer wood. X 300

there is a definite tendency, through aggregation, to the forma-
tion of resin canals.

The resin cells sometimes occur in pairs, but more generally
as isolated structures separated by one or more tracheids. The
terminal walls are transverse and more or less strongly marked
with simple pits. The side walls, especially the radial, are pro-
vided with simple pits, though often few in number, and this
feature serves to a large extent to assist in their differentiation
from adjacent tracheids of similar form (fig. 36, c}. It neverthe-
less not infrequently happens that in transitional forms, such
as are met with in Sequoia sempervirens (fig. 36, c), bordered
pits occur on the lateral walls.

The resin is in all cases massive and often very abundant.
In such genera as Taxodium (plate 30) or Sequoia (plate 36) it

ANATOMY OF THE GYMNOSPERMS

FIG. 36. SEQUOIA SEM-
PERVIRENS. Radial
sections showing (</)
the form of the resin
cells and the associ-
ated parenchyma tra-
cheids; (/>) resin cells
from the spring wood
showing the form of

completely fills the entire cell cavity, but in Larix, Tsuga, and
Pseudotsuga it takes the form of a peripheral layer in imme-
diate contact with the inner face of the cell wall (plate 44).
The reduction thus indicated is, in some species, carried to
such an extent that the resin is barely recognizable, while in

Abies it is wholly wanting.

A relation of more than ordi-
nary interest is that of the resin
cells to certain forms
of tracheids. In Se-
quoia sempervirens it
commonly happens
that the resin cells
lie in immediate con-
tact with tracheids of
special form. These
structures are wholly
unlike the wood tra-
cheids among which
they are found, but
they are, in all essen-
tial respects, like the
tracheids of the med-
ullary rays. They
have the form of long,
cylindrical elements
with abrupt termina-

the resin ; (c) resin cells showing transitional tioilS and they thus
forms with bordered pits, x 200

bear an external re-
semblance in form to the wood-parenchyma cells with which
they are associated. They differ, however, in the distinguishing
presence of bordered pits upon their side and terminal walls
(fig. 37, a}. The relation of these two elements is nevertheless a
much more intimate one than is implied by mere association.
In Sequoia an interchangeable relation is manifested, as already
pointed out, in the occurrence of resin cells with bordered pits

RESIN CELLS

(fig. 36), while in Abies amabilis (fig. 37) resin cells and tra-
cheids also form a conterminous series. It is thus obvious that
we have here precisely the same interchangeable relations that
have been found to occur in the medullary rays, and it is evi-
dent the one element must arise through modification of the
other. The precise order of this sequence is not altogether clear
from the available data, but the fact that
ray tracheids are derived from their asso-
ciated parenchyma cells, and that in such
types as Podocarpus, Taxodium, etc., the
resin cells occur without tracheids, while
the latter do occur in Sequoia and espe-
cially in Abies, seems to justify the infer-
ence that here also they are derived forms,
having their origin substantially in special
modifications of the parenchyma elements.
In view of these relations it is necessary to
distinguish such elements as parenchyma
tracheids in order to establish their proper
identity and differentiate them from the
wood tracheids which have a wholly dif-
ferent origin, as well as from the ray
tracheids which have a wholly different
location.

chyma tracheids also serve a similar pur-
pose to the ray tracheids with respect to
the distribution of nutrient fluids. The
origin of the parenchyma tracheids as sug-
gested finds support in the statement of
Eichler (15) that the wood parenchyma arises through the activity
of the cambium cells, abundantly in the Cupressineae and Abie-
tinese, forming in exceptional cases the epithelium of the resin
canals, since it at the same time shows how the parenchyma
tracheids arise, and how they may be intimately connected with
the wood parenchyma ; but it finds additional support in a knowl-
edge of the genesis and structure of the resin passage.

ll

O

( c

c

n

£

0

c

i

©

0

0

©
©

O

y

\

c

k

F

A

FIG. 37. ABIES AMABILIS.
It is probable that the paren- Radial section showing

(a) the structure of the
parenchyma tracheids;
(t>) the structure of the
resin cells ; a and b being
normally conterminous.
X 200

Il6 ANATOMY OF THE GYMNOSPERMS

In Sequoia and Abies we have two genera which are remark-
able for their transitional forms of structure, affording a fairly
clear conception of the genesis of the resin passage. In each
case there is a well-defined tendency toward the aggregation of
the resin cells into compact groups which take the form of lon-
gitudinal strands, inclosed on all sides by the accompanying
parenchyma tracheids. Under such circumstances the individual
cells undergo a continual reduction in length until they eventu-
ally become but two or three times longer than broad, or they
may even become isodiametric. This change is not accompa-
nied by any alteration in the thickness of the walls in the earlier
stages of development, but as a result of such a shortening the
effect is to bring about the concentration of a greater number
of simple pits within a given area. Such cells, therefore, are
always more strongly pitted than those which are isolated and
of greater length. When aggregates of this sort have attained
to a certain degree of development a line of cleavage arises in
the center of the mass and results in the formation of an inter-
cellular space which, according to Eichler (15), always arises
schizogenously. This space is short and either isodiametric or
but little longer than broad, the length coinciding with the prin-
cipal axis of growth. Such cystlike reservoirs or sacs represent
the primitive form of the resin canal, and they are typically
developed in Sequoia, Abies, and Tsuga. They always form a
continuous series extending in a direction parallel with the axis
of growth ; but as the type of organization advances, they merge,
forming a continuous canal such as may be found typically in
Pseudotsuga or Pinus. From these statements, then, it is clear
that the parenchymatous resin cells undergo modification in two
directions, passing into parenchyma tracheids on the one hand,
and on the other becoming shorter and shorter, according to
conditions of aggregation, until they pass into short cells which
eventually constitute the epithelium structure of the somewhat
complicated resin passage, the latter thereby becoming the ex-
pression of a peculiar aggregation of resin cells. Whatever
the stage of development may be, the resin passage is always

RESIN CELLS 117

found to be composed of structural elements arranged in the
following order from without toward the center : (i) parenchyma
tracheids, (2) resin cells eventually forming an epithelium, and
(3) the central reservoir in the form of a cyst or canal. This
structure is fully exemplified in the genus Pinus, where the
highest form of development is attained.

While the occurrence of resin cells in particular genera is a
feature of great taxonomic value, their importance in this respect
is greatly emphasized by the particular form of their distribution
and the constant tendency they exhibit toward the formation
of definite aggregates. In Thujopsis (plate 24) and Crypto-
meria (plate 26) the resin cells are always scattered through-
out the entire transverse section, and they show no tendency to
the formation of aggregates. In Podocarpus, where there is a
notable increase in numbers, the same general law of segregation
prevails, but there is nevertheless a somewhat well-defined tend-
ency toward aggregation. In Thuya 66.6 per cent of the species
show definitely scattering cells, 33.3 per cent show the cells to
be scattering with a tendency toward a more compact dispo-
sition, while in 33.3 per cent the cells fall into well-defined aggre-
gates or an approximation to such an arrangement. The genus
Sequoia is characterized chiefly by the widely scattering distri-
bution of the resin cells (plate 36), but in S. sempervirens there
are individual cases in which there is also a definite aggregation
into groups. In Cupressus 53.9 per cent of the species are dis-
tinguished by the presence of widely scattering cells, which be-
come definitely arranged in zones in 38.4 per cent, and aggre-
gated into groups in 7.7 per cent of the species. It will be
observed here that this feature of distribution is, on the whole,
more pronounced in the relatively primitive genera, and that it
' diminishes in force in the genera of a relatively high order.

In Taxodium (plate 30) and Libocedrus (plate 32), both of
which are distinguished by the presence of very prominent resin
cells, these structures are disposed in well-defined zones which
are concentric with the growth rings and lie either in the spring or
summer wood, or in both. This is to be interpreted as a definite

Il8 ANATOMY OF THE GVMNOSPERMS

tendency to aggregation, which is nevertheless not fully expressed,
since in each case there are numbers of cells which are not zonal
in their distribution, but which conform to the law applicable to
Thujopsis and Podocarpus. In Juniperus the cells are typically
zonate, being also scattering in only one species. In Abies only
63.6 per cent of the species bear resin cells. These are neither
scattering nor zonate in the sense of the previous types, but it
is to be observed that in 50 per cent of such cases, or in 36.3
per cent of all species, they are aggregated in groups as a pre-
liminary step to the formation of resin passages. On the other
hand, 36.3 per cent of all species show the resin cells to be few,
inconspicuous, nonresinous, and scattered along the outer face
of the summer wood. This, for reasons which will appear more
fully later, is to be regarded as a phase in distribution leading
to the final obliteration of such structures, which is fully accom-
plished in 36.4 per cent of all the species as represented by
A. balsamea, A. Fraseri, A. lasiocarpa, A. Veitchii. This last
form of distribution is wholly typical of Tsuga (plate 44), in
which there are no other resin cells than those on the outer
face of the summer wood. Finally, in Picea and Pinus there are
no separate resin cells in any of the situations described, since
they have been completely replaced by highly organized resin
passages. It thus appears that the distribution of the resin cells
presents four variants which bear a direct relation to the organi-
zation of resin passages, as the latter eventually replace the
former. These facts will appear somewhat more clearly from the
summary in the table on opposite page.

From such data it is clear that the distribution of the resin
cells bears an important relation to the recognition of subgeneric
groups and even of species. But viewing these structures from
the broader standpoint of the Coniferales as a whole, it is obvious
that they must be placed among the structural elements which
belong to the first rank for taxonomic purposes.

We are now in a position to determine what relation, if any,
such resin-bearing elements bear to questions of phylogeny,
and we may first of all consider the resinous tracheids. These

RESIN CELLS

119

PERCENTAGE DISTRIBUTION OF RESIN CELLS

NUMBER
OF SPECIES

PER CENT OF
OCCURRENCE

SCATTER-
ING

IN ZONES

GROUPED

ON THE OUTER
FACE OF SUM-
MER WOOD

Gingko .

I

OOO.OO

Dammara .

I

OOO.OO

Araucaria

3

OOO.OO

Torreya .

3

OOO.OO

Taxus . .

4

OOO.OO

Thujopsis .

i

IOO.OO

IOO.OO

Cryptomeria

i

IOO.OO

IOO.OO

Podocarpus .

i

IOO.OO

IOO.OO

(100.00)

Thuya . .

2

66.600

1 = 3

IOO.OO

33-30

i

(33-3°)

Sequoia . .

2 — 2

IOO.OO

IOO.OO

I

50.00

Cupressus .

7

53-9°

5 = 9

IOO.OO

38.40

i

7.70

Taxodium .

i

IOO.OO

(100.00)

IOO.OO

Libocedrus .

i

IOO.OO

(100.00)

IOO.OO

Juniperus

ii = ii

IOO.OO

IOO.OO

i

I.IO

Abies . . .

4 = 7

100.00

36.30

5

45.50

Tsuga . .

2 = 5

IOO.OO

33-3°

5

IOO.OO

Pseudotsuga

2

IOO.OO

.

100.00

Larix .

4

IOO.OO

100.00

Picea . . .

10

OOO.OO

Pinus . . .

4i

OOO.OO

structures have been seen to be peculiar to Dammara, Araucaria,
and Abies, in which they occur only in certain species. In answer-
ing this question we cannot avail ourselves of evidence derived
from fossil plants, since it is, in such cases, of a negative char-
acter. Neither Cordaites nor Araucarioxylon affords definite
proof of the presence or absence of such structures, since they do
not appear in any of the published diagnoses, and our own studies
have not resulted in their recognition. If originally present, they

120 ANATOMY OF THE GYMNOSPERMS

must have been obliterated in the course of fossilization. \Ye
must therefore depend entirely upon such evidence as is afforded
by existing species. From this point of view it is obvious that
they furnish no evidence as to the origin of either of the three
genera in which they occur. It is, on the other hand, possible to
determine from other data that both Dammara and Araucaria are
much inferior to Abies in point of structural organization and
development, and from this we may be permitted to conclude
that the resin tracheids of Abies are vestigial forms of elements
which were typically developed in Dammara and Araucaria, and
possibly characteristic also of their progenitors. If such infer-
ences are to be regarded as justifiable, they go far to support
the idea of a common origin for all three genera, and they thus
lend force to conclusions which lead to the same result, but
upon the basis of independent data.

From a study of the distribution of the resin cells it is appar-
ent that they fall into four categories in which the typically
segregated cells may be held to represent the most primitive
form of disposition. This view is greatly strengthened by the
observation that in all such cases the resin cells are rarely if at
all accompanied by parenchyma tracheids, while the structure of
the cell is farthest removed from that which is found to enter
into the composition of resin passages, whence they are also to
be regarded as of a primitive character. This view is supported
by the observed fact that those genera and species in which such
segregations occur are also of a relatively primitive type. With
an advance in organization, there is a tendency to the formation
of aggregates as expressed in the zonal distribution of Taxodium,
Libocedrus, or Sequoia, where we also find the definite forma-
tion of groups of cells which later exhibit the initial stages in
the formation of a definite canal. But in Sequoia, as also in
Abies where similar changes take place, the more complete aggre-
gation of the cells is invariably accompanied by structural altera-
tions whereby they become greatly shortened and more strongly
pitted, while they are always accompanied by parenchyma tra-
cheids with which they are interchangeable. In this connection

RESIN CELLS 121

it is also to be noted that the aggregates in Sequoia, Abies,
and Larix, leading to the formation of resin sacs, are always dis-
posed in a zonal manner, conformably to the zonal disposition
of the separate elements, --a relation which is in direct harmony
with the view already advanced, that the zonal disposition of the
isolated cells is an advance upon the strictly segregated form,
and that it leads directly to the formation of resin passages.
Following upon the zonal distribution, a more complete aggre-
gation results in the formation of local groups of short resin
cells ultimately leading to the formation of a true resin canal.
Such a feature of distribution, occurring in genera which, from
other data, may be shown to be relatively high in development,
is in itself significant ; but we further find that the scattering,
zonal, and grouped forms bear such relations to one another
that the real succession is in the order already given. Thus
while both species of Sequoia are characterized by scattering
cells, S. sempervirens also shows them aggregated to form
groups and eventually imperfectly organized resin canals ; or,
in Cupressus, the transition is expressed in a more complete
form, involving all three modes of distribution. In Tsuga there
is an obvious tendency toward the elimination of the resin cells,
which are now greatly reduced in numbers and confined to the
outer face of the summer wood. In Abies a similar tendency is
also manifested, but it is expressed in a different way, and just
here we must note a fact of more than ordinary significance.
Resin cells are present on the outer face of the summer wood in
A. grandis, A. concolor, A. amabilis, and A. magnifica. Groups of
resin cells are present in A. nobilis, A. concolor, A. bracteata, and
A. firma, but it will be seen that in only one case-- A. concolor
— are the two forms of distribution presented in the same
species. This is in direct conformity with the idea that the resin
passage eventually displaces the resin cell, bringing about an
obliteration of the latter, and it goes far to support the idea that
with respect to these particular structures the genus Abies occu-
pies a transitional position, standing next to Picea and Pinus,
from both of which the resin cells have completely disappeared.

122 ANATOMY OF THE GYMNOSPERMS

Furthermore, from another point of view, the gradual replace-
ment of the resin cells appears to be indicated by a correspond-
ing reduction in the contained resin. Nowhere is the resin so
abundant in the resin cells as in those genera like Podocarpus
and Taxodium, which show no development of resin passages,
even in their most simple forms ; but with the development of
resin sacs, as in Abies or Sequoia, or of resin passages, as in
Larix and Pseudotsuga, there is a remarkable diminution of the
resin, apparently in direct response to its more ready production
by more specialized structures.

The genus Abies, then, appears to form a transition group,
having parallelisms with Dammara and Araucaria through the
occurrence of resin tracheids ; with Thuya, Cupressus, etc.,
through the survival of isolated resin cells approaching oblit-
eration ; with Tsuga, Larix, and Pseudotsuga through the devel-
opment of rudimentary resin canals leading to the formation of
definite resin passages ; and with Sequoia through the survival
of isolated resin cells and the development of rudimentary resin
canals. Through these parallelisms the connection appears to
be most direct with Sequoia, on the one hand, and with Tsuga,
on the other. This relation of Sequoia to Abies has been shown
by Penhallow on former occasions (59), and has more recently
been indicated in other ways by Jeffreys (24) ; but so far as the
present evidence is of value it would not permit us to infer that
Sequoia, Abies, and Tsuga form a continuous and conterminous
series in the order given, but rather that they represent sepa-
rate, though short, side lines of development, between which
the general sequence is manifested.

CHAPTER IX

RESIN PASSAGES

STRUCTURAL

Our studies of the resin cell have shown how peculiar aggre-
gates of these structures lead in a natural way to the organiza-
tion of resin passages, the structure of which it is now necessary
to discuss somewhat in detail, and in doing so it will be most
profitable to have reference to (i) the primitive form, (2) the
intermediate form, and (3) the advanced or fully organized form.

The primitive form of the resin passage is to be found in
Tsuga, Abies, and Sequoia, and inasmuch as within these genera
they exhibit differences in organization which correspond approxi-
mately to the sequence given, it will be necessary to discuss
them somewhat in detail, with special reference, however, to
Sequoia. This genus possesses special interest with respect to
the occurrence and organization of secretory reservoirs, since it
is in all probability not only the most ancient genus in which
such structures occur, but it is, so far as I am aware, the only
genus affording special data with respect to important varia-
tions of structure and mode of occurrence. Being also, on the
whole, the most primitive of the three genera, it may be dealt
with first.

In Sequoia sempervirens the secretory reservoirs occur in
rows within the initial layers of the spring wood,1 and they
therefore lie exactly on the outer face of the summer wood of
the previous year. Within this row the reservoirs are contigu-
ous, and in many cases they become confluent so as to form a

1 The apparent occurrence of these structures in the summer wood is due to the
presence of two growth rings of very unequal degree of development, the outermost
of which may have only one or two rows of tracheids in addition to the resin cysts.

123

124

ANATOMY OF THE GYMNOSPERMS

more or less extended and continuous compound reservoir, lying
tangentially. In their most rudimentary forms they present the
aspect of simple aggregates of resin cells without any differen-
tiation of a resin sac or of an epithelium. In a more advanced
stage of development there is produced a central cavity in the
form of an intercellular space (fig. 38, C.') which has obviously
originated schizogenously. About this the resin cells are gen-
erally flattened radially and disposed in such a manner as to
suggest the future development of a definite, limiting layer or

epithelium. In the

M'R' r\/fV completed form of the

£. E. :\\, structure the central

space has broadened
out and taken a cir-
cular form, assuming
the character of a defi-
nite cyst bounded by
as definite a limiting
epithelium in which
the cells are always
flattened radially and
disposed concentric-
ally (fig. 38, C.). Ex-
ternally to these cells
there may be a second
layer of similar resin

-4S.W

FIG. 38. SEQUOIA SEMPERVIRENS. Transverse sec-
tion showing two contiguous resin cysts : C., com-
pleted and with a normal epithelium (E.) ; C/, an
intercellular space as the rudiment of a cyst with
imperfectly developed epithelium; M.R., the
medullary ray ; S. II'., the summer wood, x 225

cells, constituting the outer epithelium, while the whole is inclosed
on three sides by a layer of parenchyma tracheids which are
exceedingly like the associated tracheids of the spring wood, but
from which they may usually be distinguished by (i) their greater
size and relatively thinner walls, and (2) the occurrence of bor-
dered pits on the tangential and terminal as well as upon the
radial walls. Such parenchyma tracheids never occur in the adja-
cent summer wood for very obvious reasons, but on the radially
opposite side of the reservoir they are very commonly flattened
radially (fig. 39), and they not infrequently present the same

RESIN PASSAGES

125

structural aspects as the epithelial cells. The interchangeable
relation between resin cell and parenchyma tracheid as already
shown would lead us to suspect a substitution in the composition
of the epithelium, and such substitution does actually occur, since
it is often to be noted that the second and third rows may be
made up, at least in part, of tracheids.

In a longitudinal radial section the reservoir is found to have
the form of a sac of varying form and size, but generally elongated

prt.

r.c

FIG. 39. SEQUOIA SEMPERVIRENS. Transverse section of a resin cyst showing
an associate resin cell (r.c.); the epithelium (ep.) ; the thyloses (///.), one of
which contains resin, and one of which is directly derived from an epithelium
cell ; the parenchyma (fr.t.). X 300

parallel with the axis of growth and completely closed at both
ends (fig. 40). The epithelium, which immediately defines the
limits of the sac, generally consists of short, cylindrical cells,
while in the second or outer layer the cells become much elon-
gated, being several times longer than broad. Beyond this, the
third layer consists of parenchyma tracheids, readily distinguish-
able whenever the terminal walls lie near the plane of section, or
otherwise recognizable, as already indicated. Certain deviations
from this typical structure require examination. The resin sacs

126

ANATOMY OF THE GYMNOSPERMS

are placed in vertical series of indeterminate extent, but at varying
intervals of such a nature that they may sometimes be separated
only by a rather thick wall of short resin cells. At other times
they are somewhat distant and separated by an extensive vertical
tract of resin cells. From this it is obvious that in any given

plane of section there
will be a great diversity
of aspects presented, but
in the main exhibiting
structural gradations in
the development of the
reservoir, as already re-
counted. In some cases
thick-walled cells of cir-
cular outline may be seen
S^^TS-^ in transverse section to

CD©

©0

c..

S.W.T

0
0

stand out from the gen-
eral line of the epithelium
and lie within the cavity
proper. More rarely such
cells are so multiplied as
to fill the entire cavity,
and they may themselves
be filled with granular
resin. Such features are
clearly defined (fig. 39),
and it is evident from the
way in which such cells
originate from the epithe-
lial cells that they are of
the nature of thyloses. A longitudinal section through such a
reservoir (fig. 41) shows how such thyloses occupy the entire
cavity of the cyst, while in other cases they may be purely local
(fig. 40). Among fossil Sequoias similar thyloses form a most
characteristic feature in the resin passages of the medullary rays
in S. Burgessii and S. Penhallowii.

FIG. 40. SEQUOIA SEMPERVIRENS. Radial sec-
tion of a resin cyst showing the epithelium
(ep.) ; the central cyst (c.) with a thylosis (///.) ;
parenchyma tracheids (pr.t.),a.nd a tracheid
of the spring wood (Sp. 71.). X 300

RESIN PASSAGES

127

In Tsuga caroliniana there are no secretory reservoirs, but
just in the region between the spring and summer wood of the
same growth ring there are peculiar
aggregates of resin cells of a more
or less rounded outline, forming a
continuous series of considerable
extent. An analysis of these aggre-
gates shows them to be composed of
thick-walled and rounded resin cells,
among which there may be a small
central, intercellular space without
any definite organization of epithe-
lium. In such aggregates the com-
ponent cells are far less resinous ep..
than the isolated resin cells of the
same section. The parenchyma tra- ep.-
cheids are not clearly distinguishable
from the associated wood tracheids.
In radial section the cells are seen
to be very variable, thick-walled, and
sometimes with more or less promi-
nent intercellular spaces. Between
the rays they are several times longer
than broad, but opposite the rays
they are short, cylindrical, and more
copiously pitted ; while sometimes
they may be seen to merge into ray
elements and thus to continue their
course at right angles to their pri-
mary direction. A careful compari- FIG. 41. SEQUOIA SEMPERVIRENS.

son Of these cell aggregates with Radial section of a resin cyst

showing the epithelium (<?/.) and

those of Sequoia and Abies leaves the thyioses (///.), which com-
little room for doubt as to their struc- Pletely fin the cyst' and several

.... of which are resinous. X 225

tural and functional identity, and we

cannot do otherwise than conclude that they represent the most

primitive structural condition which is capable of directly giving

128 ANATOMY OF THE GYMNOSPERMS

rise to definite cysts by central cleavage, and that such cysts
are precedent to the formation of canals.

In Tsuga Mertensiana the secretory reservoirs are disposed
like those of Sequoia, on the outer face of the summer wood,
where they form tangential series. They exhibit all the grada-
tions from simple cell aggregates without a central space to per-
fectly formed cysts with a definite epithelium. This latter is in
one, more rarely in two, rows, and it is composed of more or less
rounded or radially flattened elements. The parenchyma tracheids
are few in number, and they are not readily distinguishable from
the adjacent wood tracheids. In longitudinal section the reser-
voirs are variously rounded or oblong cysts, contiguous or isolated
and forming a longitudinal series. In their general form and
structure they are essentially the same as in Sequoia.

In the genus Abies secretory reservoirs occur in at least four
species, where they form more or less extensive tangential series,
within which they are usually contiguous and more or less con-
fluent. They present the same general variations in structural
organization as in Tsuga and Sequoia, but in A. concolor, and
less conspicuously in A. nobilis, they are often extended in a
radial direction so as to become narrowly oval or oblong and
several times longer than broad. The epithelium consists of a
well-defined structure composed of from one to three rows of cells.
The first row, immediately bordering upon the canal, consists of
rounded or oval and thick-walled cells, which are much smaller
than those of Sequoia and similar to those of Tsuga. They are
always characterized by an abundance of strongly defined, simple
pits, and many of them contain resin, which usually takes the
form of rounded granules of diverse sizes. The parenchyma
tracheids are so nearly like the accompanying wood tracheids as,
in some cases, to be separable with some difficulty, but they gen-
erally surround the resin sac, at least within the limits of the
spring wood, and they not infrequently replace the parenchyma
cells of the epithelium more or less completely. Not infrequently
they form somevvhat extended radial series from the epithelium
into the spring wood, as in Picea (fig. 43). In such cases they are

RESIN PASSAGES 129

usually recognizable by their rather unusual size and thinner
walls, and in addition they commonly show bordered pits on the
tangential walls. When the terminal wall lies sufficiently near
to the plane of section it shows from one to several rather large
bordered pits, and by this feature such tracheids may be located
with much certainty. Thyloses have been definitely noted only
in the case of A. concolor, in which species they are essentially of
the same general character as in Sequoia. They are thick-walled
and either isolated or so numerous as to fill the entire cyst. In
one case of contiguous cysts an epithelial cell was found to form
thyloses in both cysts, - - in the one case giving rise to an isolated
cell, in the other forming a tissue which nearly filled the entire
cavity.

In radial section the reservoirs are round or oblong cysts of
variable size, and they are either contiguous or distant. In the
former case they rarely or never become confluent, but they
maintain their separate identity, as in Sequoia and Tsuga. In
the latter case the intervening region is occupied by an aggre-
gate of resin cells in all essential respects like those in the same
regions of Sequoia and Tsuga Mertensiana, or like the aggre-
gates which are generally characteristic of Tsuga caroliniana.
The inner epithelium usually consists of short cylindrical and
strongly pitted cells, which in the second and third rows become
successively longer and less strongly pitted, so that those in the
outer row may be identical in form and markings with the isolated
resin cells. In the two outer rows the cells not infrequently
show bordered pits on their radial walls, thus presenting transi-
tional forms which gradually pass over into tracheids, and the
one then replaces the other. The parenchyma tracheids, which
are always most characteristic of the spring wood, are always
distinguished by the presence of large and prominent bordered
pits, but in addition they are sometimes broad and thin-walled
and lie in radial series.

From these facts it is clear that the secretory reservoirs of
the three genera in question always take the form of closed
sacs, which De Bary has already pointed out as a feature of

130 ANATOMY OF THE GYMNOSPERMS

certain Coniferas (13, 440), and in order to clearly differentiate
them from those which occur in the genus Finns I shall reserve
for all such cases the term resin cyst. While such cysts are
typically developed in the three genera named, they are also
features of Pseudotsuga, Larix, and Picea, --in fact, of all those
genera in which the epithelium is composed of thick-walled cells,
-but in these latter cases there is the additional feature that
such cysts are always accompanied by the occurrence of similar
structures in the medullary rays, and therefore they are asso-
ciated with fusiform rays. From these facts, then, it is obvious
that we have here a group of six genera all characterized by
the presence of structurally similar resin reservoirs, but sepa-
rable into two groups through the absence, on the one hand,
and presence, on the other, of fusiform rays. That such saclike
reservoirs represent the primitive form of the resin passage
scarcely admits of question when we observe the various transi-
tional forms which they present, and the relation which they bear
to the resin passages of Pinus, --a view which is strengthened
by the observation of De Bary (13, 443) that primitive forms of
the secretory reservoir occur in the pith of Gingko in the form
of elongated sacs.

De Bary has shown that (13, 440) the secretory passages
traverse the wood longitudinally, at first as prismatic tubes,
which usually acquire a round or elliptical transverse section. In
its strict sense, this statement is applicable exclusively to the
genus Pinus, but inasmuch as there are important structural
gradations whereby Pseudotsuga, Larix, and Picea represent an
intermediate type, while Pinus represents a completed type, it
will be necessary to compare them somewhat in detail. In the
genus Pinus, however, the secretory reservoir differs from that
of all other genera, in that it consists of a definite and continu-
ous canal of indeterminate length, and for the purpose of differ-
entiating it from other forms I shall reserve for it the appropriate
and long-used term resin passage.

In Pseudotsuga the resin cysts are always scattering, though
they frequently occur in tangentially extended groups of two or

RESIN PASSAGES 131

four contiguous or even coalescent reservoirs. The central canal,
which is usually small and not infrequently very narrow, is rather
more generally rounded than in previous types. The epithe-
lium is very clearly defined and consists of one to three rows of
thick-walled parenchyma cells, sometimes containing resin, the
first row of which are rather small and radially flattened, but
in P. macrocarpa they are rather thin-walled. In P. Douglasii
the epithelium is commonly extended on the two sides of the
resin canal in such a way as to form a tangentially elongated
tract which not infrequently extends beyond and involves neigh-
boring medullary rays. In P. macrocarpa, on the other hand,
the epithelium is concentric with the canal, thus forming a
tract of about equal thickness all around. Such a deviation as
is expressed in P. Douglasii constitutes the first evidence of a
tendency in development which is fully and frequently expressed
in Pinus. Thyloses are of infrequent occurrence, and appear
to be confined to P. macrocarpa where they are few in number
and generally rather thin-walled. Parenchyma tracheids are
usually not apparent in a transverse section. This results from
the frequent location of the resin passage in the summer wood,
which is not favorable to their development, and from the close
resemblance which they bear to the tracheids of the spring wood ;
and while such elements form an integral part of the resin cyst,
their particular disposition cannot be exactly defined, though
there is no good reason for supposing that they differ in this
respect from what may be observed in other cases. In a longi-
tudinal section the canal is found to be more or less continuous,
though it presents frequent constrictions and is thereby reduced
to very narrow dimensions, or it may even be discontinuous and
thereby form cysts. It is this feature which causes the canal to
exhibit such marked variations in size, when seen in transverse
section. The epithelial cells are narrowly cylindrical and rather
long and thick-walled, as well as somewhat strongly pitted. Out-
wardly they become much longer and relatively narrower, and
they eventually merge with the surrounding parenchyma tra-
cheids, by which they may also be replaced (fig. 42).

132

ANATOMY OF THE GYMNOSPERMS

In Larix the same features of contiguity and coalescence may
be observed, except that in L. occidentalis the resin passages
sometimes form into continuous zones of imperfectly organized
structures with the aspect presented in Tsuga Mertensiana. The
epithelium is always well defined (fig. 42), and it consists of
one, sometimes two, rows of cells. The cells of the first row are

small, very variable in form and
size, thick-walled, and more or
less strongly flattened radially.
They are also commonly resin-
ous and more or less strongly
pitted. When there is a sec-
ond row of epithelium the cells
are essentially like the wood
tracheids, and like the paren-
chyma tracheids, from which
they may be separated with
difficulty. The latter, there-
fore, which are absent from the
summer wood, can be distin-
guished from the elements of
the spring wood only when
the pits on the terminal walls

FIG. 42. LARIX OCCIDENTALIS. Trans- (fig. 42, pr.t.} are brought into
verse section from the inner spring vjew> or> more rarely, when the
wood showing a pair of resin passages . .

with the central canals (,-.) ; the thick- Plts on the tangential walls are
walled epithelium (<?/.) ; a parenchyma in evidence. Thyloses rarely

tracheid (fr.t.}, and the summer wood r

/ w i x 300 occur, and so far they have been

noted only in L. occidentalis,

where they are infrequent and thick-walled, and in L. americana,
where they are of rare occurrence and thin-walled. In longitu-
dinal section the central canal is always continuous, though con-
stricted at intervals, a feature in all essential respects the same
as in Pseudotsuga. Radially the first row of epithelial cells are
short cylindrical, or in L. occidentalis short fusiform, but there is
a graduated increase in length outwardly, so that in the second

s.w.;

'.W.

RESIN PASSAGES

133

prt.-

row, or in the third if present, they become narrow and very
long, and they eventually blend with the parenchyma tracheids
through intermediate forms with bordered pits. All of the epithe-
lial cells are thick-walled and strongly pitted, and they thus offer
a somewhat strong contrast to the rather thin-walled parenchyma
tracheids with bordered pits.

The resin passages of Picea differ from those of Pseudotsuga
and Larix in being more
strictly segregated, and in
consequence there is a con-
spicuous absence of contig-
uous structures, which may
nevertheless sometimes be
seen in P. nigra, and espe-
cially of coalescent forms.
They are usually narrow,
but well rounded or oval,
and there is far greater uni-
formity of structure and
form than in any of the pre-
ceding types. The epithe-
lium consists of one row,
one to two rows, or even
one to three rows of cells,—
differences which appar-
ently belong to particular
species, though no attempt
has been made to define
the precise limitations of
such features. The cells are generally small, round, or radially
flattened and thick-walled, though occasionally a cell may be
thin-walled, as in P. alba. In cases of thick-walled epithelium
the outermost cells merge with similar tracheids, from which
they are not readily distinguishable, while the general epithelium
becomes extended into a tangentially elongated tract, as in Pseu-
dotsuga Douglasii and Pinus. Occasionally thyloses have been

r

FIG. 43. PICEA ALBA. Transverse section of
a resin passage from the spring wood show-
ing the central canal (c.); the thick-walled
epithelium (t-'J>.), and the parenchyma tra-
cheids (pr.t.). x 300

134

ANATOMY OF THE GYMNOSPERMS

noted in P. nigra, P. pungcns, and P. sitchensis, but they are
always thin-walled. Parenchyma tracheids are not obvious in
the summer wood, but they are recognizable in the spring wood,
where they appear to replace the resin cells, though they are
apparently of much less frequent occurrence than in the genera
previously discussed. In P. alba, however (fig. 43, pr.t.), we
sometimes find a radial series of tracheids which also extends
laterally so as to form an inclosing layer. Longitudinally the
canal is continuous, but with more or less frequent constrictions,
as in Pseudotsuga and Larix. The epithelium consists of narrow
cylindrical and much-pitted cells, which increase in length in the
outer layers, where they become five to seven times longer than
broad, and finally merge with the parenchyma tracheids, which
replace them.

While the general composition of the resin passage in Pseu-
dotsuga, Larix, and Picea is the same as that of the resin cyst,
it is obvious that the frequent constrictions in the canal indicate
a partial survival of the cystic formation. We must, therefore,
regard these structures and the three genera to which they
belong as forming a transition group between the primitive
resin cyst, on the one hand, and the perfectly organized resin
passage of Pinus, with its canal of uniform width, on the other.

In the genus Pinus the resin passages show considerable vari-
ation in detail, but they all conform to the same structural type
(fig. 44). The central canal is broad and round, often very large,
and in longitudinal section it is a perfectly continuous passage
of uniform width. The epithelium consists of large but very vari-
able and thin- walled cells in from one to several rows. In the soft
pines it generally forms a concentric zone of uniform width, but
in several of the hard pines there is a marked tendency to exten-
sion in a tangential direction and the formation of rather exten-
sive eccentric tracts. In all of the pines there is a pronounced
tendency for the epithelial elements to become so thin-walled
that they are readily broken out in making sections, while in
the hard pines, as P. cubensis, P. taeda, P. pungens, etc., the
cells are often strongly resinous. In the outer epithelium the

RESIN PASSAGES

135

thin-walled elements may be associated with occasional thick-
walled elements with which they are interchangeable, precisely
as in the similar relations displayed by the medullary rays of
P. pungens and P. cubensis. In the same region also there is
a similar association with and transformation into parenchyma
tracheids, which also has its parallel in the medullary ray. Some-
what more specifically, special reference to two examples may

s.w-

SM

FIG. 44. PINUS REFLEXA. Transverse section of a resin passage from the inner
face of the spring wood showing the central canal (C.)\ the thin-walled and
resinous epithelium (ep.) \ the parenchyma tracheids (t.) ; the spring wood
(Sp.W.) and the summer wood (S. IF.) X 225

serve to illustrate the general nature of some of the more im-
portant variations. In longitudinal section the parenchyma tra-
cheids are usually of much greater length than the associated
parenchyma cells, with which they are parallel or conterminous,
and they occur in large numbers in P. Lambertiana. In P. reflexa
they are conterminous with parenchyma cells, which they finally
succeed, to be replaced in turn by thin-walled wood tracheids.
In P. Lambertiana they are always to be distinguished by the

136 ANATOMY OF THE GYMNOSPERMS

bordered pits on the radial, tangential, and terminal walls, while
in P. reflexa they are characterized by the large number of bor-
dered pits on the radial walls, with very few on the tangential
walls. In the former situation the pits are much smaller than
in adjacent wood tracheids. Together with adjacent wood tra-
cheids the parenchyma tracheids may be more or less involved
in bearing resin (P. Lambertiana), while finally, as exhibited in
transverse section, their numbers may be so large that they
form extensive areas about the resin passage (fig. 44). In such
a case the sequence of elements in transverse section would be :

1 . Canal with thyloses.

2. Thin-walled epithelium.

3. Epithelium and cylindrical parenchyma tracheids.

4. Parenchyma tracheids.

5. Wood tracheids with thin walls.

Thyloses are a constant feature in the structure of the resin
passages of Pinus (fig. 31, a). They are always thin-walled and
completely fill the canal. So constant are these features in
association with those previously recounted that they serve to
afford a ready means of accurately recognizing the genus under
all circumstances.

The general course of development thus outlined shows that
the parenchyma tracheid stands in such relation to the organiza-
tion of the resin passage that its more frequent occurrence is
directly correlated with a higher type of organization and devel-
opment in the plants to which they belong.

We are now in a position to present a general summary of
the relations which the resin cells bear to the organization of
the secretory reservoirs -- cysts and passages — and the position
which the latter occupy in the economy of the plant as follows :

1. Resin cells, which are of the nature of wood parenchyma, at first occur

as isolated structures filled with resin, but they show a definite tendency
to association and later form definite aggregates.

2. Parenchyma tracheids become associated with such aggregates for the

purpose of effecting a more complete nutrition of the secretory cells.

RESIN PASSAGES 137

3. Resin cells when aggregated beyond a certain point develop schizoge-

nous intercellular spaces, which form either central closed cysts or
central canals of indeterminate length.

4. The structure of the cyst or passage always presents the same sequence

of elements, and the work of the reservoir is then divided between

a. the tracheids, which provide nutrition for the secretory cells ;

b. the secretory cells or epithelium, in which the formation of the

resin takes place ;

c. the cyst or canal, which provides an outlet or storage reservoir for

the surplus product ;

d. the thyloses, which may impede the proper storage of the resin, or

which may individually serve the purpose of storage.

So long as the formation of resin is not excessive it is stored
in the cells where produced. This is true of all isolated resin
cells as well as of many which enter into the composition of
complex cysts and passages. When the resin is excessive, how-
ever, the surplus is excreted into specialized reservoirs of the
form of closed cysts or of canals, and we are led to interpret
the appearance of these structures in the higher Coniferae as a
response to such needs. The development of the resin passages
will thus be seen to stand in direct relation to the capacity of
the plant as a resin producer, --a fact which is otherwise appar-
ent from our knowledge of the general capacity of the different
genera as resin producers, and from a comparison of this feature
with their known position in the line of descent.

CHAPTER X

RESIN PASSAGES (continued)
DISTRIBUTION AND PHYLOGENY

Prantl (62, 37) states that resin passages occur in the wood
of "most Abietineae, namely, Pseudotsuga, Picea, Larix, Pinus,
and Abies firma." This statement requires some modification
in detail, especially with respect to the last-named genus, and
in order to make the results of the present studies clear it will
be expedient to discuss separately the distribution of the resin
cysts and the resin passages.

The first species to which our attention may be directed is
Tsuga Mertensiana. This is the only species of the genus in
which definite resin cysts are to be found. Such structures are
never numerous, and they take the form of short rows of con-
tiguous cysts in the initial layer of the summer wood of distant
growth rings. Longitudinally they have no definite limits, but
they appear to be extended for great distances, and probably
through the entire longitudinal growth of the season, at least.
There is no obvious alteration either in the position or volume
of the resinous contents of the isolated resin cells which lie on
the outer face of the summer wood. The constancy with which
these structures occur gives to them a definite value for the
recognition of the species, and permits us to differentiate it
from T. caroliniana on the one hand, and from the remaining
three species on the other.

In the genus Abies only four species out of eleven show
resin cysts. These are A. bracteata, A. nobilis, A. concolor,
and A. firma. Referring again to Prantl's observation (62, 37),
it must be pointed out that his statement with respect to the
occurrence of resin passages in A. firma requires modification in

138

RESIN PASSAGES 139

detail, in so far as these structures are not passages but cysts ;
while he also appears to have overlooked the occurrence of simi-
lar structures in the three other species mentioned. In all of
these cases the cysts are contiguous and disposed in tangential
rows of considerable length, either in the summer wood (A. con-
color and A. nobilis), in the outer spring wood (A. firma), or in
both the spring and summer wood (A. bracteata). Such varia-
tions appear to be of no specific value, conforming as they do
to similar variations in the zonate distribution of the resin cells.
It is found, however, that in only one case (A. concolor) are
these cysts associated with isolated resin cells. In the three
other cases the resin cells are entirely wanting, — a relation
which is strongly suggestive of their replacement by the cysts.

Sequoia sempervirens is the only species of that genus which
develops resin cysts in the secondary wood, though Jeffrey (24)
has shown that such structures are normal to the primary wood
zone of S. gigantea, and not elsewhere. As already shown, such
cysts are much more highly organized than those of either Tsuga
or Abies, though they are similarly contiguous and even coa-
lescent, and form extensive tangential rows in the initial layer of
the spring wood of distant growth rings. They form a much more
prominent feature than in any of the preceding species because
of their generally larger size and the greater extent of the series
in which they lie. Unlike Abies, however, there appears to be no
diminution either in the number or the extent of the prominent
resin cells, which are often intimately associated with the cysts.

The normal course of development for such cysts as are thus
described is subject to special alteration under conditions which
involve an unusual stimulus to growth, and under such circum-
stances they may become definitely associated with, or may
even be regarded as indicative of, pathological conditions. Thus
Anderson (1, 28-29) has shown that such cysts are definitely
developed in association with the formation of witches' brooms
in Abies firma. Under such circumstances the cysts become
much larger, more distant, and more numerous than in normal
growth, but they form well-defined tangential rows in the earlier

140

ANATOMY OF THE GYMNOSPERMS

spring wood of successive growth rings. In the development
of such secondary features the cysts manifestly exhibit a dis-
tinct approach to that higher type of structure and distribution
which is exhibited in Picea. In the following year Anderson
(2, 336) further showed that, while resin cysts are absent from
the normal wood of A. balsamea, they do arise under the influ-
ence of the special stimulus connected with the formation of
tumors produced by the action of yEcidium elatinum. He fur-
thermore points out that such cysts attain their greatest devel-
opment and largest number in the region of greatest stimulation,
i.e. in the middle of the tumor,1 decreasing above and below
until they eventually become pointed and finally disappear be-
tween four tracheids "which, in their meristematic condition, prob-
ably function as epithelial cells." It is unfortunate that the
histological details of these cysts and their endings are not given,
since such facts would serve to throw much light upon the rela-
tion of the cysts to similar structures in normal tissues, but
there is no reason to suppose that they differ in their essential
structure from those which occur in the normal tissues of the
same or other species. The tracheids above referred to are un-
doubtedly parenchyma tracheids, and it is probable that further
examination would show that they ultimately replace the resin
cells remaining over after the disappearance of the cyst proper.

Tubeuf has also shown (72, 44) that resin canals are irregu-
larly formed and greatly multiplied through the action of para-
sites, quoting the case cited by Hartig in which the resin canals
of the* spruce were found to be so numerous in trees attacked
by Agaricus melleus as to give rise to an abnormal production
of resin, which flows from the roots and characterizes the disease
called resin gland or resin flux. He also points out that a
similar flux occurs in the bark of the pine, due to the action of
Peridermium pini. The action is therefore developed in such
a way as to induce a greater activity in the formation of wood
parenchyma, which, in Juniperus communis, when attacked by

1 A precisely similar relation in development has been noted by Jeffrey (25)
in the case of Sequoia Penhallowii.

RESIN PASSAGES

141

Gymnosporangium clavariaeforme, often forms somewhat exten-
sive wedge-shaped masses projecting between the rows of tra-
cheids (72, 388). A close comparison of such a tissue with that
of the resin cysts of Abies shows that the two are essentially
the same, and we must therefore conclude that the cell aggre-
gates which precede the formation of resin cysts in Sequoia,
Abies, etc., are also to be found in Juniperus as a consequence
of injury effected by parasitic growths.

More recently Jeffrey (24) has contributed an important paper
on the anatomy of Sequoia, in which he brings out several facts
of considerable value. He shows that resin cysts may arise in
the roots of Abies balsamea which have been injured, while they
may also be produced experimentally by injury, thus confirming
the observations of Anderson that they may be traumatic in
their origin. The most significant facts, however, relate to the
normal occurrence of such cysts in Sequoia. He shows in the
first instance that they are absent from the wood of the first
year's growth in S. sempervirens, while they are present for the
same period of growth in S. gigantea, though absent from the
growth of later years. In both species they arise in the earlier
spring wood. In the case of S. Penhallowii from the Miocene
the same author directs attention (25) to the occurrence of resin
passages in both a radial and longitudinal direction, and estab-
lishes important relations between them. The somewhat strict
localization of the latter and their obvious connection with injury
in well-defined instances leads him to the conclusion that they
are wholly traumatic. This rule he also applies to all cases of
tangentially disposed resin cysts or resin passages such as occur
in Sequoia sempervirens, thereby making it include all similar
cases in the various species of Abies and Tsuga.

Some years since, De Bary (13, 490-495) formulated the law
that "resin canals occur in the ligneous bundles of the same
Abietineas which possess horizontal canals in the medullary
rays." This is a law of very great constancy in all those cases
in which a canal proper is developed, though it fails in such
cases of resin cysts as occur in Abies and Tsuga (59). It also

142 ANATOMY OF THE GYMNOSPERMS

fails in the case of Sequoia sempervirens and S. Langsdorfii (46),
and it likewise appears to fail in the case of S. Burgessii, but in
this latter case it is possible that there is the same peculiarity of
distribution which Jeffrey has observed in S. Penhallowii, accord-
ing to which local areas may be devoid of longitudinal canals
while radial ones may be present.

As presented by existing species, Pseudotsuga, Larix, Picea,
and Pinus, without exception, show resin passages in both the
radial and longitudinal positions. In transverse section they are
scattered throughout, sometimes appearing chiefly in the sum-
mer wood, sometimes chiefly in the spring wood, or again about
equally in the two regions, and they rarely conform to the pre-
cise law stated by De Bary (13, 495) that " they lie scattering
in a ring in the external region of every annular layer." The
constancy of their occurrence in the four genera mentioned in-
volves very few features which call for special comment. In
Pseudotsuga and Larix the resin passages are scattering. They
sometimes unite in pairs so as to form short tangential series,
and they thus approach the type of Tsuga or Abies, while yet
again they may become definitely isolated and scattering, thereby
approaching the distribution of Picea and Pinus. In Larix occi-
dentalis the tendency to a primitive form of distribution is ex-
pressed in the formation of a tangential zone essentially similar
to that of Tsuga Mertensiana. In both Pseudotsuga and Larix
there is an obliteration of resin cells from all parts of the struc-
ture except the extreme outer face of the summer wood. In
Picea, however, without exception, there is a complete oblitera-
tion of all resin cells except such as enter into the structure of
the resin passages, and this is directly correlated with a higher
type of structure in such passages.

In the genus Pinus, as already shown, the resin passage
reaches the highest degree of organization in all respects. It
shows little if any tendency to those primitive associations which
are expressed in the formation of tangential series, while it has
entirely replaced the isolated resin cells, which are never to be
found in that genus.

RESIN PASSAGES

If, then, we ask what value such structures have for taxo-
nomic purposes, we find them to be of well-defined importance.
It has already appeared that in Tsuga the occurrence of resin
cysts is of well-defined value for specific differentiation, and the
same rule is also applicable to Sequoia sempervirens and to four
species of Abies. In the higher Abietineae, inclusive of Pseu-
dotsuga, Larix, Picea, and Pinus, the invariable association of
resin passages in the wood and in the medullary rays not only
serves to separate these genera from all those in which resin cysts
only may occur, but it also differentiates them absolutely from
all the remaining genera. Such association, therefore, constitutes
a feature of great value. More particularly, the thin-walled
epithelium of Pinus at once separates that genus from the other
three, which are invariably characterized by thick-walled epithe-
lium. Such generic differentiations are greatly emphasized by
the occurrence of thyloses. These are typically developed in
Pinus, where they are always thin-walled and almost invariably
present. They are, therefore, of definite value as supplementing
other features previously described. In the other genera, how-
ever, their presence in either the cyst or the resin passage,
where they are generally thick-walled, is of so sporadic a nature
as to give them no definite value, and we therefore find that for
specific diagnoses such structures may be neglected.

We are now in a position to present an answer to the ques-
tion, How are the resin passages related to the phylogeny of
the Coniferales? In order to present an intelligent answer to
this question, it will be necessary to recall the facts already
discussed in connection with the resin cells, and bring them
into relation with our discussion of the resin passages.

In the genus Sequoia it has been shown that the general
course of development of the resin cells is essentially the same
as in Cupressus, etc., while it has also been shown that the genus
presents in other respects a somewhat remarkable deviation.
Of the two existing species both show the distribution of the
resin cells to be of the typically primitive form, i.e. scattering.
Nevertheless there are also in Sequoia sempervirens definitely

144 ANATOMY OF THE GYMNOSPERMS

organized resin cysts, but without exhibiting the transitional
form of a zonate disposition. Among fossil representatives Pen-
hallow (46, 41) has shown precisely the same feature to be
present in S. Langsdorfii.1. This is the less remarkable, how-
ever, because that species is undoubtedly the ancestral form of,
and practically identical with, S. sempervirens. The fact made
clear by Jeffrey (24, 457) that resin cysts occur in the first
annual ring of vigorous branches of adult trees, as well as in
the roots of S. gigantea, also tends to make it apparent that the
genus presents a very striking advance upon even the type
exhibited by Juniperus, since the aggregation of resin cells and
the formation of cysts from them has arisen abruptly, and with-
out the transitional forms presented by Juniperus and Taxodium.
While, therefore, Sequoia is obviously related to Thuya and
Cupressus, on the one hand, it is, on the other hand, related to
such types as Abies.2 In this sense it may be regarded as the
terminal member of a developmental series embracing the Taxo-
diinae, Cupressineae, Taxoideae, as follows :

1 . Taxus and Torreya. 6. Thuya.

2. Thujopsis. 7. Libocedrus.

3. Cryptomeria. 8. Taxodium.

4. Podocarpus. 9. Juniperus.

5. Cupressus. 10. Sequoia.

In the Abietineae a new series is presented. This is not in
any sense strictly conterminous with the first, but the two appear
to make a fault, as it were, whereby there is a lateral displace-
ment, but of such a nature that Sequoia still serves as the con-
necting link. Within the eleven species of Abies investigated
three important phases are presented, - - (i) resin cells scattering
on the outer face of the summer wood, (2) resin cells grouped
and forming cysts, and (3) resin cells entirely wanting. Viewing
these phases in the order given, it is to be observed that in those

1 While Jeffrey has shown (25) that in S. Penhallowii the resin cells are nor-
mally confined to the outer face of the summer wood.

2 This latter relation has been recently emphasized by Jeffrey (25) through
studies relating to S. Penhallowii, and it is in direct confirmation of conclusions
already reached by Penhallow (44) on the basis of other data.

RESIN PASSAGES

four species which develop cysts only one shows isolated resin
cells, and it is probably correct to interpret the variations noted
as expressions of developmental phases in such a way that the
occurrence of cysts represents the highest position. The genus
Tsuga is closely related to Abies in the occurrence of isolated
resin cells on the outer face of the summer wood, as also in the
formation of resin cysts, but it obviously occupies an inferior
position because (i) of the greater abundance of resin in the
individual cells, and (2) the occurrence of definite aggregates of
resin cells without the formation of cysts. This series is directly
extended by those genera in which definite resin passages re-
place the simple cysts, since the latter are convertible into the
former by easy and natural transitions. Both Pseudotsuga and
Larix occupy equivalent positions because they not only present
resin passages of an equal degree of development, but they also
show a survival of the isolated resin cells on the outer face of
the summer wood. Their affinities are therefore directly with
Abies and Tsuga on the lower side, but on the upper side their
alliance is with Picea, which presents a very similar though
somewhat higher organization of the resin passage and a com-
plete obliteration of the isolated resin cell. Yet again, the
structure of the resin passage in Picea at once connects that
genus with Pinus in which the most complete development is
attained, and it therefore terminates the series upwardly.

Having special reference to the particular forms of the secre-
tory reservoirs, and leaving out of account all other considera-
tions than their particular evolution, it is possible to indicate
the general sequence of the genera, and, to a more limited
extent, of their species, as follows :

i. Tsuga caro- 2. Abies bracteata. 3. Sequoia.

liniana. Abies firma. 4. Pseudotsuga and Larix.

Tsuga Mer- Abies nobilis. 5. Picea.

tensiana. Abies concolor. 6. Pinus.

From this it is manifest that Sequoia is superior to Tsuga and
Abies, but inferior to Pseudotsuga, Larix, etc. But if we now
view the general phylogeny with reference to the entire course

146 ANATOMY OF THE GYMNOSPERMS

of development of the resin cells and the resin passages, the rela-
tions just explained must be modified with reference to the partic-
ular position of Sequoia, and the sequence would then become :

1. Thujopsis and 5. Libocedrus. 10. Abies.

Cryptomeria. 6. Taxodium. 11. Pseudotsuga and

2. Podocarpus. 7- Juniperus. Larix.

3. Cupressus. 8. Sequoia. 12. Picea.

4. Thuya. 9. Tsuga. 13. Pinus.

But it may assist in the general argument to view this ques-
tion from another standpoint. Regarding the resin cells and the
secretory reservoirs as falling within a definite series, we may
apply to the various forms of distribution, and to the various
grades of resin reservoirs, arbitrary values of such a nature as
to represent our conception of their relative positions in the scale
of development as expressed by percentages, thus :

Resin cells scattering 25.0%

Resin cells zonate 37-5

*Resin cells grouped 50.0

Resin cells on the outer face of the summer wood, as in

Pseudotsuga and Larix 12.5

Resin cells on the outer face of the summer wood, as in

Abies (partial only) 5.0

Resin cells wholly wanting o.o

f Resin cysts, as in Tsuga, Abies, and Sequoia 70.0

Resin passages with constrictions, as in Pseudotsuga, Larix,

and Picea 80.0

Resin passages without constrictions and of the highest type

of organization, as in Pinus 100.0

We obviously have two subordinate series here, which for
convenience may be regarded as conterminous, but which, as
already shown, are "faulted" in such a way that the grouped
resin cells (*) and the resin cysts (f) jointly represent the point
of divergence for two separate courses of development, the
latter continuing upward, while the former descend and thereby
represent degradation. These features are best exhibited graph-
ically, and the accompanying curves clearly show how, on the
one hand, resin cysts and resin passages directly result from

IOO

75

5°

25

C urve

Curv

r R<

u

sn

fo A Resin

\

es

Cells

7

(D

(*!

FIG. 45. Curve showing the approximate development of resin passages
and the corresponding obliteration of resin cells

147

148 ANATOMY OF THE GYMNOSPERMS

special modification of cell aggregates, while, on the other hand,
from the same starting point, there arises a course of degrada-
tion which finally results in the complete obliteration of the
resin cell as an independent structure.

The facts thus far set forth have thrown important light upon
the general course of development of certain anatomical features,
and they also show the general course of development for genera
and species with reference to particular structures. They do not,
however, convey any information with respect to the origin of
the phylum as a whole, or the relations of the particular genera
and species from the standpoint of collective data, and such a
discussion will be more appropriately reserved for the general
summary. There is, however, one feature arising out of recent
investigations which calls for consideration at this point, since
certain of the conclusions reached are not in harmony with
our own, the divergence of opinion indicated being the result
of different methods of interpretation.

Jeffrey states (24, 447, 457) that all such resin cysts as
occur in Sequoia sempervirens and Abies are of a traumatic
nature, and therefore pathological. To this category he would
also doubtless assign the corresponding structures of Tsuga.
This opinion appears to be shared by Anderson (1, 2), and it
is also apparently supported by Pierce (60). Both Jeffrey and
Anderson show that the development of such cysts is sometimes
definitely associated with the production of tumors through the
operation of parasites, and that they may also be induced by
wounds experimentally produced. The facts they cite show con-
clusively that resin cysts may and often do arise traumatically,
and such is unquestionably true of Sequoia Penhallowii, as shown
by Jeffrey (25) within the limits of our present knowledge of
that species, but in such cases they lie outside the usual course
of development.

The occurrence of resin passages in the fundamental tissue
of the Coniferales is a well-known fact, as pointed out by De Bary
(13, 441) many years since, when he summarized the general
facts in the statement that " all investigated species of Coniferae,

RESIN PASSAGES

J49

with the single exception of Taxus, have resin passages or resin
reservoirs, which vary in distribution and number according
to the species." This statement would include the leaves and
bark, and sometimes even the pith of species which produce
neither isolated resin cells nor resin reservoirs of any kind in
the xylem tissue of the stem. It directs attention somewhat
forcibly to the fact that while the occurrence of resin reservoirs
in the fundamental tissue is a legitimate inheritance of the
mucilage canals of the Eusporangiate ferns and the Cycado-
filices, as also later of the resin cells of Cordaitales, the xylem
structure is the very last to receive the impress of such a course
of development ; and it is therefore in nowise surprising that
the resin passages do not appear there until a very late period
of development, and that their organization can even then be
brought about only through a somewhat prolonged series of
changes which are initiated by the occurrence of isolated resin
cells, much as the formation of mucilage canals may be traced
back to specialized cells which separately have the same func-
tion in the Eusporangiate ferns.

The local occurrence of resin passages in the xylem of the
floral axis in no way invalidates the obvious conclusions to be
drawn from these statements, since it may be readily accounted
for in other ways. In a structure so unresponsive to influences
which would induce profound alterations as the xylem, it is to
be expected that important structural changes could be effected
only after a prolonged interval during which the fixation of any
particular character would be preceded by a period of sporadic
development, within which such character would be liable to
recur under special conditions; and as such conditions are obvi-
ously of fundamental importance, we may inquire somewhat
more fully into their nature and results.

The statement of Prantl (62, 35), that "Those genera which
are devoid of resin passages in the wood of young and vigorous
growth later produce single parenchyma elements in the wood
which contain resin," requires some modification in view of what
Jeffrey has shown in the case of Sequoia and Abies, as well as

150 ANATOMY OF THE GYMNOSPERMS

what has been shown in the course of the present studies, and
in its more comprehensive and exact form it should read, " Those
genera which are usually devoid of resin passages in the wood,
but some species of which may nevertheless contain resin cysts
in the young and vigorous growth, later produce single paren-
chyma elements in the wood which contain resin."

Taken by itself, this statement as applied to Sequoia and
Abies might be held to indicate that the growth of the first year
represents the most stable structural region of the entire stem,
in the sense that it embodies characters which are most fully
established, and that it will therefore embrace elements which
may be eliminated from the older parts, or which may be
replaced there by degenerate forms only. From this point of
view it would be necessary to regard the complex resin passage
as the primitive form of structure from which the cysts, groups
of cells, and isolated resin cells have been derived by a process
of progressive degradation. This view appears to have been
adopted by Jeffrey (24, 454), who supports his position by citing
the occurrence of resin passages in the vascular structure of
the peduncle of certain fossil Cycads, interpreting this to mean
that such structures represent a survival of features which have
been obliterated from the structure of the stem. Such a view
does not seem to be in harmony with the facts which our own
studies have brought out, to the effect that resin passages of
the type found in the xylem structure are in no sense primitive
or vestigial, since they are wholly wanting in the primitive gym-
nosperms, and their organization does not arise until a very late
period in the evolution of the higher forms. If our interpretation
of observed facts is correct, as applied to the origin of the resin
passages, it shows as clearly as one could well expect a pro-
gressive development from the isolated resin cell through various
phases of aggregation to the highest form of structure as found
in Pinus. That there is such a series cannot be doubted, and
we must interpret it in one of two ways, - - either as progressive
evolution or as progressive degeneration. To us the arguments
all seem to be very emphatic with respect to lending support to

RESIN PASSAGES 151

the former view, most especially as all anatomical data confirm
the relative positions of the genera as determined by the devel-
opment of the resin passage. But assuming for the moment
that the latter view is the correct one, let us see where it would
lead us. It would, first of all, necessitate a direct reversal of the
structural sequence, and this in turn would impose the necessity
of placing the genus Pinus at the bottom of the scale, while
those genera, like Taxus, Torreya, Dammara, etc., which have
no resin cells even, would be at the top. I venture to suggest
that such a proposition would meet with instant opposition, even
from the advocates of the idea that the resin passage has pre-
ceded the other forms of resin-bearing structures. The whole
question appears to turn upon our recognition of what consti-
tutes the most impressionable portions of the stem structure,
and therefore the regions within which structural changes are
initiated. In this connection the evidence of both paleobotany
and recent botany brings out certain facts with great force and
throws them into strong relief. They are as follows :

1. The mucilage canals of the Eusporangiate ferns may be
regarded as the ancestral forms of the resin passages among the
higher plants, but they are obviously the successors of, as they
are derived from aggregates of, mucilage sacs as simple paren-
chyma cells.

2. Resin passages are wholly unknown in the wood of the
stem of ferns, the Cycadofilices, the Cycads, Cordaites, or
Araucarioxylon.

3. Resin cells are known and are abundant in the pith and
bark of Cordaites, but they are absent from its wood.

4. Resin passages are known in the bark and in the pith of the
Cycadacese, of Dammara and Araucaria, and of the Coniferales in
general. They also occur in the wood of the peduncles of Sequoia
and in the xylem of the first year's growth of vigorous shoots in
Sequoia and Abies. They likewise occur in the leaves generally.

5. In Sequoia Burgessii, from the Eocene, resin passages
occur in the medullary rays, but they do not traverse the wood
longitudinally, though isolated resin cells do occur there.

152 ANATOMY OF THE GYMNOSPERMS

From this it would seem that the fundamental tissue is the
most impressionable with respect to the development of these
structures, and that after it we have in the same order the
peduncle of the inflorescences and the wood of the young shoots,
to which latter category would also belong the development of
resin passages in fasciated stems, and such a sequence is pre-
cisely what we should expect from our knowledge of the relation
which the fundamental tissue bears to other structures. Accord-
ing to this conception the resin passages may appear in any part
of the woody structure where growth is sufficiently vigorous,
but such appearance would be temporary and indicative only
of a future course of development which has not as yet become
sufficiently well impressed upon the organism to form a perma-
nent feature of it. In other words, the tissue exhibits what in
other cases would be termed "sports." Such structural fore-
casts are well known and of frequent occurrence. As applied
to the development of tissues, no better example is afforded than
that shown by the central strand of mosses, which is generally
accepted as prophetic of the future vascular system in the spo-
rophyte, and they serve to suggest that the law of mutation as
proposed by De Vries finds expression in the evolution of internal
structures as well as in the development of external forms. Such
cases as Sequoia gigantea, which shows resin cysts in the wood
of the first year and nowhere else, being replaced later by resin
cells, appear to us to show that young and vigorous growth in
general, and therefore the growth ring of the first year, consti-
tutes a transitional zone within which many changes of structure
wholly apart from the strictly normal may arise ; and such a
law would similarly be applicable to the wood of peduncles.
This feature is manifested in the structure of the medullary ray,
the character of the tracheids as exhibited in transverse section,
the genesis of the bordered pits from spiral tracheids, and, in all
probability, also in the formation of resin passages in Sequoia
and Abies, as noted by Jeffrey.

Changes of this nature are to be regarded as tendencies in
development in the direction of higher types of structure, whereby

RESIN PASSAGES

153

potentialities assume a more or less definite form. From this it
may be assumed that the primary growth ring is a zone within
which sporadic characters are common, but it is only in the later
rings that the various anatomical characters become permanently
developed and properly express the normal features of structure
and development.

The considerations dealt with here, as well as in previous
chapters, lead us to give renewed emphasis to a view which
has been expressed elsewhere, and which finds justification in
many ways, not only in the gymnosperms but in the Salicaceae
and in Catalpa among the angiosperms, to the effect that inas-
much as the physiological activity of the plant is directly asso-
ciated with and dependent upon conditions of internal structure,
variations in the internal anatomy are to be regarded as of
primary importance, and such changes are no doubt established
or may be established considerably in advance of corresponding
alterations in the external character of the vegetative or even
of the reproductive organs. From this point of view questions
of internal structure must always have precedence over those of
external morphology in questions of classification.

CHAPTER XI

GENERAL PHYLOGENY

The results to which we are now brought are based entirely
upon developmental phases in anatomical elements of the vas-
cular cylinder. While our studies lead to certain definite con-
clusions, we do not in any sense regard these as final, but only
as affording one step in the solution of a question which must
be viewed not only from the broader standpoint of more extended
anatomical data but also from that of physiology as well, although
we feel disposed to insist that the final answer will be found to
rest chiefly upon an anatomical basis. That there may be room
for a different interpretation of the facts here recorded is quite
possible, since Dr. Jeffrey has recently permitted me to exam-
ine the manuscript of an important contribution to our knowl-
edge of the Abietineae, in which he brings out very significant
facts, which suggest that the group is of a much more primitive
character than has hitherto been supposed or than is indicated
by our own studies. It is therefore of importance that final
judgment should be suspended until the results of these various
studies, as well as those of Coulter, Chamberlain, and Ferguson,
all directed to the same end but prosecuted along somewhat
different lines, can be brought together and coordinated. It is
in this sense that the following conclusions are offered.

In discussing the phylogeny of the higher gymnosperms
three subordinate phyla must be taken into consideration in the
following order: (i) Cordaitales, (2) Gingkoales, (3) Coniferales.

Regarding the Cordaitales as the most primitive gymnosper-
mous stock of which we have present knowledge, it is possible to
trace its origin to the Cycadofilices. The genera Lyginodendron,
Heterangium, and Calamopitys present many structural features
which are common to all, and which not only establish their

GENERAL PHYLOGENY 155

relation to the Cycadean line of descent but also offer many
suggestions of that course of development which is realized in
the higher Coniferales. They therefore constitute the real start-
ing point for two lines of descent, the first of which embraces
the Cycadales. At the present moment we have little or nothing
to do with this beyond establishing its probable relation to the
other gymnosperms. The second line emerges in a type of plants
having characteristics distinctly allied to those of the Coniferae,
and it is this line of descent with which we are now chiefly con-
cerned. It is now possible to define the origin of this phylum
somewhat more exactly than Coulter has done (11, 12), since
there is good reason to believe that it emerges from the Cycado-
filices through Poroxylon. Scott (81, 398) has already pointed
out the relations of this genus to the Cycadofilices and the
Cycadaceae on the one hand, and to Cordaites on the other, so
clearly as to remove the necessity for detailed discussion at this
time, beyond giving emphasis to one or two important structural
relations. In Calamopitys saturni it has been noted that the most
primitive distribution of the bordered pits upon both the radial
and tangential walls is represented in the protoxylem structure.
Such distribution, however, undergoes rapid modification where-
by it is wholly limited to the radial walls in the secondary wood.
A similar limitation appears in other somewhat closely related
genera, and it is fully expressed in Poroxylon, where the multi-
seriate disposition and hexagonal form are typically preserved,
though there is at the same time a tendency to segregation to
such an extent that the pits sometimes become round. In this
it is possible to notice the first indication of a character which,
while infrequent, is nevertheless occasionally expressed among
the Cordaitales, though it is generally characteristic of the related
phyla, Gingkoales and Coniferales.

Among the Cordaitales there is but one genus (Cordaites) which
we have heretofore been accustomed to associate with that phylum,
and, so far as our present knowledge goes, it undoubtedly stands
in the closest relations to Poroxylon. It is, however, improbable
that the two were in any sense conterminous, and it is altogether

156 ANATOMY OF THE GYMNOSPERMS

probable that there may have been some one or more intermediate
forms of which we have no present knowledge. Our present
studies, on the other hand, show clearly that we must bring into
this phylum two other genera of an obviously higher degree
of development, but which have commonly been ranked with
the Abietineas and which, according to Eichler (15), occupy the
highest position in the scale. This position is untenable upon
anatomical grounds which give us reason to believe that Dam-
mara and Araucaria (including, of course, Araucarioxylon) are
not only inferior to the Coniferales as a whole but that they are
also distinctly Cordaitean. Accepting this view and the fact
that Dammara is the inferior genus, the sequence would place
Cordaites at the base and Araucaria at the top, with Walchia as
the immediately ancestral form of the latter. This relation is not
only natural but it is justified on anatomical grounds.

The tendency to segregation of the bordered pits, as exhibited
by Poroxylon, suggests the relation of this genus to others in
which such a feature is fully expressed, and it thereby forms the
basal member of another series. From the opposite point of view
it has been shown that the occurrence of two-seriate pits in Pinus
and others of the Coniferales, as well as in Gingko, points to a com-
mon origin for such genera in a type with multiseriate hexagonal
pits, and that both Dammara and Araucaria must likewise center
in the same generalized form. This gradual convergence is justi-
fied on other grounds, and the genus Poroxylon among known
forms most nearly fulfils the requirements of the case. We may
therefore look upon it as lying between the Cycadofilices and all
the higher gymnosperms, giving rise to two lines of descent, the
first of which embraces the Cordaitales, as already described, while
the second shortly divides once more. This secondary division
gives rise on the one side to the Gingkoales, and on the other to
the Coniferales. The anatomical data already discussed, when
viewed collectively, show that the general sequence within the lat-
ter would be (i) the Taxoideae, (2) the Taxodiinae, (3) the Cupres-
sineae, (4) Abies, (5) Tsuga, (6) Pseudotsuga, (7) Larix, (8) Picea,
and (9) Pinus, of which one division, (II), represents the highest

GENERAL PHYLOGENY 157

type of development. With respect to the precise position of
Sequoia in particular, its relation to Abies on the one hand, and
to such genera as Thuya and Cupressus on the other, cannot be
taken, in the present state of our knowledge, to indicate its origin
from or its ancestry to either of them. The facts derived from
anatomy, however, do indicate a more or less common origin for all
four genera, and from this point of view, taking into account the
peculiar features exhibited by Sequoia, they would seem to justify
the idea that that genus represents a short side line of develop-
ment, which does not lead to the evolution of other types, but
terminates in S. gigantea after a comparatively brief period. The
sequence of species for each genus cannot always be determined
with a full measure of satisfaction, and these difficulties may pos-
sibly be made clear by reference to the succession of the two
species of Sequoia, which is difficult to determine on purely ana-
tomical grounds, but the general tendency of the facts already
recited is to give to S. sempervirens the more primitive posi-
tion,--a view which is sustained by its paleontological history.
The relations brought out in the foregoing studies, and the
reasons for the conclusions reached, may be made more obvious,
without the tedious method of a detailed discussion, by refer-
ence to the accompanying table of anatomical data (Appendix A),
which substantially summarizes all the results derived from the
study of particular structures. In preparing this table the various
anatomical features have been chosen with reference to (i) the
constancy of their occurrence, (2) their structural prominence,
and (3) their obvious relation to diagnostic purposes. In their
horizontal extension an attempt has been made to arrange them
in accordance with the law of frequency, as well as with reference
to their relation to development, in such wise that while the spiral
tracheid is assumed to be the most primitive type of the vascular
structure, the presence of two kinds of cells in the medullary ray
may be held to express the highest form of development. To
the members of the series so constituted we may then assign
arbitrary values in arithmetical sequence from one to seventeen;
while those subordinate characters which are represented by

158 ANATOMY OF THE GYMNOSPERMS

different forms of distribution may be regarded as forming a
second series similarly valued. Any primitive or other character
which has become obliterated through development may be held
to retain its original value with respect to the general course of
such development, and it is always indicated by — . Vestigial
structures occurring sporadically are designated by i, and to
them one half the value of the fully developed character is
assigned. All normal features are designated by x, which
becomes x + when they show development toward the next
higher form, or x — when they show a definite tendency to degen-
eration. Sporadic characters which are obviously in the line of
development are indicated by o, but they are assigned only
half values. On this basis it is possible to arrange a sequence of
genera and species in such a manner as to exhibit a progressive
development from the simple Dammara, with a minimum of char-
acteristics, to the complex Pinus, in which the greatest number
of anatomical features is involved. Furthermore through such a
series it is possible to determine the relative position of the vari-
ous genera by percentage values, and it gives the most valuable
insight into the approximate relations of the various members
within the general line of descent. Such relations are determined
not only for each anatomical character but also for the collective
characters. Reducing these facts to a graphic form, the accom-
panying curves will assist in making the relations more clear,
especially in emphasizing the general course of development, and,
in their final form, they are best expressed by a biological tree. A
figure of this sort is difficult to construct, and there is no agree-
ment among investigators as to the particular form it should take.
While the figures in common use indicate a certain relationship
in descent, they completely fail to convey any impression of the
way in which the succession arises, and they furnish no indica-
tion of possible gaps. They therefore constitute a very poor
working basis.

In teaching I have long been accustomed to compare the
various lines of descent among plants with the branchings of
a deliquescent tree, since it has always seemed reasonable to

GENERAL PHYLOGENY

159

suppose that the laws which govern the branching of a. limb,
which give rise to all the varying forms of arrested development,
and which thereby determine a particular modification of the
figure which would otherwise result from unmodified growth,
must be equally applicable to the general evolution of the higher
forms of plants from a common ancestral type. In endeavor-
ing to secure a natural growth which would best express all the

IOO

12345

7 8 9 10 ii 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

FIG. 46. Curves for sequence of genera and frequency of anatomical characters
of the Cordaitales, Gingkoales, and Coniferales : A, sequence of genera;
B, specific characters ; C, generic characters

conditions involved, the branching system of the Norway maple
(Acer platanoides) seems best suited to an illustration of all these
phases of terminal growth, suppression, and relations of successive
members which we conceive to be represented in the development
of plant phyla, inasmuch as it conveys the idea of succession
through lateral members in such a way as to indicate the chief
line of descent. The branch of the Norway maple, when of vigor-
ous growth, is a monopodium, and it is obvious that such would

160 ANATOMY OF THE GYMNOSPERMS

not answer the object in view, since its most prominent feature
would suggest the idea of a continuous series of conterminous
members, from which lateral members would arise at intervals.
There is no evidence that any phylum represents such a series ;
on the contrary, there is every reason to believe that such
relations do not exist among the various groups of plants.

In those branches of the Norway maple which exhibit slow
growth various forms of arrested development are manifested.
These take the form of atrophied buds, or of branches in all
stages of development, and there thus arises a modified monopo-
dium which eventually becomes, in many cases at least, a true
sympodium. In comparing this with the monopodial branch of
vigorous growth, it appears that the alterations involve more
than mere suppression. In the monopodium the average angle
of divergence for the lateral members is 45.3 degrees, while for the
derived form it is 34. i degrees. The latter will be seen to com-
pletely fulfil all conditions with respect to the development of
a phylum, even to indicating the position of missing members.
In the construction of this figure an attempt has been made to
show all normally developed buds (O) and their relative dimen-
sions ; atrophied buds (o), the position of which is recognizable ; and
atrophied branches (Y) which are still visible, but it is obvious
that the figure does not show many members all evidence of the
former existence of which has completely disappeared. Selecting
from this we obtain the accompanying figure, which embodies
our final conclusions as to the general succession of the different
gymnosperms, and from it we may gather that the highest repre-
sentative, Pinus, is the terminal member in the main line of
descent from the Cycadofilices through Poroxylon, while from
such a central line both the Cordaitales and Gingkoales have
been given off as side lines.

The general results of these investigations serve to confirm in
a very striking manner the probable monophyletic origin of the
gymnosperms, as already expressed by Coulter (11), while they
also show that the real transition ground, at least for all but the
Cycadaceae, was probably represented by Poroxylon, as indicated
by Scott (81).

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161

• CHAPTER XII

DURABILITY OF WOODS AND THEIR PRESERVATION

AS FOSSILS

One of the most important questions which enters into the
consideration of those who are called upon to employ timbers for
the various constructive purposes to which they are adapted, is
their ability to resist decay in its various forms, or their dura-
bility. Different species of woods vary widely in this respect, as
may be readily ascertained by consulting the data collected by
Professor C. S. Sargent in his Tenth Census Report upon the
Forest Resources of the United States, and as appears in the sec-
ond part of the present work. In general terms it is probably true
that the more resinous woods are more durable than those which
are less resinous, this being the direct result of the preservative
action of the resinous material, which is in itself highly resistant
to decay, and which further acts through its somewhat well-
defined antiseptic properties and therefore behaves toward the
general structure as a natural preservative, while it also excludes
water from the interior parts and thus tends to limit the opera-
tions of fungi. Thus it may be stated broadly that the resinous
conifers as a whole are more durable than the nonresinous
woods of the higher angiosperms. Or among the conifers them-
selves the hard pines are more durable than the soft pines, as
may be seen by a comparison of the southern pine (Finns palus-
tris) with the white pine (Pinus strobus). But apart from the
presence of resin, which may be localized or distributed through-
out the entire cellulose skeleton, it is altogether probable that the
durability depends to a very large extent upon inherent proper-
ties of the cell membranes which have become variously modified
in the course of growth and thus adapted to this end. Thus it has
already appeared (Chapter III, p. 48) that while the unmodified

162

DURABILITY OF WOODS 163

cellulose contains approximately 44 per cent of carbon, the lig-
nified tissues contain upwards of 68 per cent of this element.
From this we are led to conclude that tissues yield to or resist
decay just in proportion to the extent of such modifications,
which are to be regarded as of a protective character. If this
principle be extended to lignified tissues in general, we must then
admit that since the extent and quality of the lignification do
not develop equally in all species, these latter must exhibit corre-
sponding differences with respect to their ability to resist the
disintegration attending what is commonly called decay, whether
such decay arises primarily as a process of slow oxidation, or
whether it is initiated through the operation of active enzymes.
The general law thus stated has an illustration in a very striking
instance of the relation which the special character of the cell
wall bears to agents promotive of decay, as recorded by von
Schrenk (68, 49), who shows that while Polyporus versicolor
readily attacks the living catalpa tree and produces widespread
decay, there is no fungus which will attack the timber when once
it has been cut and seasoned, — a fact which serves to explain the
astonishing durability of this wood in spite of its great porosity.
Another factor of great importance is to be found in the con-
ditions which immediately surround a given timber, since it is a
well-known fact that the same species of wood does not exhibit
the same degree of durability under all conditions. Thus wood
in a well-drained and well-aerated soil will have a much longer
term of life than it would in a wet and badly aerated soil. Or,
again, the same difference would hold true as between a com-
paratively sterile soil and one which is rich in organic compounds.
The life of a timber in salt water is far greater than in fresh
water, or even than in well-drained soil, owing to the specially
preservative action of the salt ; while the durability may be
indefinitely prolonged if the wood be hermetically sealed in an
impervious matrix such as clay. These differences are readily
susceptible of an explanation by reference to the relation which
the various media bear to the growth of fungi and bacteria, since
we recognize in these two groups of plants the active agents

1 64 ANATOMY OF THE GYMNOSPERMS

which constitute the source of decay. It is not our purpose to
discuss the particular mode of action of these organisms at the
present moment, since that is more appropriately reserved for
a subsequent chapter, but a few concrete examples will serve to
indicate somewhat more exactly the relative durability of certain
species under widely different conditions.

One of the most instructive examples to which our attention
has been drawn, not only because of the very perfect state of
preservation but also because of the great length of time the
wood has resisted the action of decay, is to be found in Sequoia
Penhallowii, as recorded by Jeffrey (25). The wood in question,
representing a large fragment of a tree at least six feet in
diameter, presents the external aspects of a recently cut piece
taken from an existing tree. It is of Miocene age, and was
obtained from the Sierra Nevada Mountains on the line of the
Central Pacific Railway, under sixty feet of conglomerate, where
it was located in the auriferous gravels. No difficulty was ex-
perienced in making sections of this wood for the microscope, no
more than would be encountered in wood taken from an exist-
ing tree, since it was very slightly silicified. A microscopic
examination shows the structure to be most beautifully and per-
fectly preserved in all its details ; while several beautifully pre-
pared sections, for which I am indebted to the courtesy of
Dr. Jeffrey, also make it evident, from the complete absence of
fungus mycelia, that these latter had not found their way into
the tissues at any time during the long burial of the tree. The
special interest of this wood centers in the fact that, so far as I
am aware, there is no other example of an uninfiltrated and
unaltered wood from so ancient a formation.

More recent Tertiary strata afford numerous examples of a
similar character. The Pleistocene in particular has furnished
many instances of the most perfect conditions of preservation,
chiefly of woods which, under ordinary circumstances, would be
regarded as "durable." In 1898 Professor A. P. Coleman of To-
ronto obtained from the Pleistocene clays of the Don valley, at that
place, a specimen of the common red cedar (Juniperus virginiana)

DURABILITY OF WOODS 165

which exhibited all the external features of that species, includ-
ing the characteristic color and fibrous bark (48, 562). When
cut with a saw the well-known odor was given off somewhat
freely. Under the microscope the structure was found to exhibit
no evidence of alteration, while there was seen to be only a
limited development of mycelial filaments, - - not as much as
may often be found in badly seasoned logs. This condition of
preservation is to be ascribed chiefly, no doubt, to the fact that
the wood was hermetically sealed in an impervious clay which
completely excluded all fungi and inhibited further growth of
those originally present. This explanation appears the more
probable from the fact that leaves of the Vallisneria spiralis,
embedded in the same clays, show all the details of the original
structure when freshly exposed, and it is only upon subsequent
dessication that disorganization takes place.

Juniperus calif ornica from the interglacial deposits of Hum-
boldt County, California (46), offers a very similar though much
more instructive example of preservation through long periods
of time. This wood was obtained from two localities, in the one
case occurring in blue, sandy silt under one hundred and fifty
feet of local debris, while in the other case it was embedded
in blue, slaty muck under fifty to sixty feet of local debris. A
microscopic examination showed that the structure contains very
few mycelial filaments, in fact only slightly more than in the
Don specimen of Juniperus virginiana. The structure of the
tissues is well preserved and gives no evidence of that oblitera-
tion of parts which usually accompanies the operation of fungi
and bacteria, whence we may correctly infer that such organisms
were not operative. It was nevertheless found that the tissues
did not offer the normal amount of resistance to the action of the
knife in cutting sections, the result being a localized fragmenta-
tion. The material was only very slightly silicified and there was
no difficulty in the removal of the mineral matter, but the entire
structure presented unusual thickening of the cell walls, such
as would arise through the action of strong alkali. Alterations
of this character are not infrequent among fossil plants, most

1 66 ANATOMY OF THE GYMNOSPERMS

particularly among those which are eventually silicified, and in
the present instance they serve to explain the mechanical weak-
ness of the tissue, the cellulose substance of which has undergone
a gradual molecular alteration consequent upon the action of an
alkaline solution - - possibly of a hot spring - - which has been
continued indefinitely.

The Douglas fir is regarded as one of the most durable of
woods, and it is not surprising to find instances of its perfect
preservation under very adverse circumstances. Specimens of
Pseudotsuga macrocarpa, from the same beds as the Californian
juniper already described, exhibit the same absence of special
silicification, but they differ in a much more marked development
of fungus mycelia, and in a somewhat extreme alteration through
the action of free alkali, which has been carried so far that in the
summer wood the cell cavities are largely obliterated, while
the thinner-walled tissue of the spring wood shows definite col-
lapse. Apart from this there is no evidence of the removal of
parts through the action of decay, and we may conclude that
the fungus present had not produced any specific effect. Yet
another illustration is afforded by Pseudotsuga Douglasii from
Mystic Lake at Bozeman, Montana, where it was found under
eight feet of the old lake-bed deposit, which antedates a well-
defined and superimposed glacial deposit. The age of this for-
mation is open to discussion, as it may represent local glaciation
of recent date, while there is also a possibility that it may be
synchronous with the continental interglacial period, since the
absence of the tree from the same locality at the present day
leads us to suppose that its removal occurred in the time of
general glaciation, as may be inferred from other evidence (46).
In its external aspects the wood presents a remarkably perfect
state of preservation, exhibiting all the features of grain and
other structural details, even to an exhibition of the bordered
pits, which may be readily determined with a hand lens of mod-
erate power. Furthermore it was wholly free from infiltrated
mineral matter and was readily softened in boiling water so that
sections could be cut with the greatest ease. Internally the

DURABILITY OF WOODS 167

structure was found to be most perfectly preserved in all its
details, showing no evidences of decay and a remarkable freedom
from fungus mycelia, from which we may conclude that the tree
was not only buried but practically hermetically sealed up-
possibly by the operation of an avalanche - - before an oppor-
tunity for the action of fungi and the operations of decay was
possible.

The genus Picea is a widely distributed type in the Pleistocene
deposits, particularly in Canada. A large amount of material
has been obtained from the Pleistocene clays of the Don valley
at Toronto and elsewhere, and it affords an excellent index of
the durability of the wood under such conditions. All of the
material has been found to be devoid of silicification or other
mineralization, and it presents somewhat diversified aspects with
respect to conditions of preservation. P. alba, of the Scarbor-
ough period, although the wood is fairly well preserved as a
whole and readily admits of a determination of the species, shows
a great abundance of fungus mycelia. Wherever this is to be
found there is a marked alteration in the structure of the cell
wall, involving a breaking down of the secondary layer, as usu-
ally occurs under such circumstances, this disintegration being
always most marked in those regions where the mycelium is
most abundant. In this case the relation of the fungus to the
changes noted is very obvious.

Picea nigra from the Don deposits is in some cases so well
preserved as to permit of a determination of the species with-
out difficulty, while in other cases the decay has progressed so
far as to render identification impossible. Fungus mycelia are
always present and they clearly constitute the active agents
of decay. The widely different conditions of preservation here
represented suggest the operation of specific causes wholly
apart from the inherent qualities of durability which the wood
naturally possesses. These are to be sought for in two direc-
tions,--either in local conditions of preservation, as varying
permeability of the soil, or in the conditions of decay established
prior to entombment. All of the material has been derived from

1 68 ANATOMY OF THE GVMNOSPERMS

a compact clay, which offers a practically air-tight matrix of
essentially the same physical character in all cases. It therefore
seems improbable that local variations of the inclosing material
could have been so different as to give rise to the diverse aspects
of decay noted, though such may have been a factor of secondary
importance. The fact that under essentially the same conditions
some specimens were well preserved while others were badly
decayed, at once directs attention to the probable operation of
antecedent causes. It is quite obvious that trees which eventu-
ally become fossilized are neither of the same age when they fall
nor are they in the same condition of soundness. Some may be
quite sound, while others may be infested with fungi, and the living
tree may therefore present the somewhat advanced progress of
decay. But the fossils of the Don deposits are obviously fragments
of trees which had been brought, through the agency of water, to
the places where found, and it is quite clear that while some of the
trees may have been speedily buried others were no doubt a
long time in the water before being inclosed in the sedimentary
deposits. Decay would have an opportunity for extended devel-
opment under such conditions, and it would even continue for
an indefinite period after entombment. On the other hand, the
rapid entombment of a vigorous tree in which decay had not
yet made its appearance might involve the inhibition of fungoid
growth. On this hypothesis, which seems to present the prefer-
able alternative, it is possible to satisfactorily account for the
varied states of preservation noted, as arising under essentially
uniform conditions.

The common larch (Larix americana) is another wood of very
widespread occurrence throughout the Pleistocene deposits. Two
widely separated localities may be selected as affording exam-
ples of its preservation. At Dahlonega, Georgia, this species has
been found in the black clays, which are to be regarded as prob-
ably synchronous with and equivalent to the Pleistocene deposits
of more northern localities (51). The material was found to be
wholly free from impregnation with mineral matter, but it exhib-
ited the somewhat extreme effects of advanced decay with the

DURABILITY OF WOODS 169

subsequent operation of pressure,1 so that it was with some diffi-
culty that sections were made which would show structure.
The entire structure showed abundant fungus mycelia, while
the walls of the tracheids had suffered such reduction under the
operation of decay that the secondary walls were largely removed
with a corresponding obliteration of structural markings, and the
whole fabric was reduced to a compressed and greatly modified
skeleton consisting of the primary cell walls. Numerous speci-
mens from the Don valley show that while some are full of fun-
gus hyphae and present a correspondingly advanced state of decay,
others from precisely the same locality show a total absence of
all fungoid growths and a completeness of structural details
which leaves nothing to be desired by way of comparison with
recently cut material. Here it is still more evident that the
explanation applied to Picea nigra is not only applicable in this
case also, but that it affords a correct insight into the reason
for the various conditions of preservation of wood which, when
embedded in clay, is practically imperishable. A more recent
example of the larch may serve to lend emphasis to these con-
clusions, and it is of particular interest because it embodies the
changes which may arise in the course of practical use. In the
Peter Redpath Museum of McGill College there is a specimen
of an old aqueduct log which was laid down in the early days of
Montreal. The old and long-forgotten pipes were uncovered in
the course of excavations for a new water main on St. Paul
Street. They were about one foot in diameter, with a two-inch
bore. According to a communication in one of the daily papers,
the pipes were laid about eighty years previous, but were in
use for only a short time. An examination showed that when
the pipes were recovered they were practically sound, with the
exception of the superficial layers, which had so far yielded to
decay as to be in process of removal, and the external form had
thereby suffered some alteration. A microscopic examination
showed the structure to be so perfectly preserved as to admit of

1 Recent studies indicate that the amount of pressure required to produce
such results need not be very great, probably less than one hundred pounds.

7o

ANATOMY OF THE GYMNOSPERMS

identification without any question, and there was but slight evi-
dence of the operation of decay, a fact which goes far to support
the hypothesis already discussed, that if the wood is sound when
buried in a compact and air-tight matrix, its decay depends
essentially upon that which had been initiated before inclosure,
and that otherwise there is essentially no change.

Upon assuming charge of the office of governor of Montreal
in 1642, Maisonneuve constructed a palisaded fort near the
present location of the customhouse. In 1890, in the course
of excavations in that locality, the workmen uncovered hewn
timbers which were held to represent a portion of the palisade
of the old fort. A specimen of one of these may now be seen
in the museum of the Natural History Society of Montreal. It
represents the wood of the common red pine (Pinus resinosa).
Externally the wood has all the aspects of a recently cut log, a
state of preservation which is amply supported by microscopical
examination, from which we learn that there is very little myce-
lium present, and that the structure is as perfect as if taken
from a tree of present growth, notwithstanding its probable
burial for two and one-half centuries.

Data of a more recent character with respect to the duration
of timbers used for constructive purposes may be derived from
actual experience. Thus Dudley has found that when the yellow
pine (Pinus palustris) is employed in the ground or used as ties,
it very quickly decays, being destroyed by the action of Len-
tinus lepideus, Fr., although the wood is very durable under
conditions of comparative dryness (14). In the case of ties from
the Panama railway, he also points out that they were useless
in two years, while similar ties employed in the southern states
lasted from four to six years, and in the middle states they
lasted from five to eight years, showing very clearly the influ-
ence of varying climatic conditions, particularly with respect to
the relative humidity and temperature. According to the same
authority, cedar ties (Cupressus thyoides) will last from eight
to ten years, even when not wholly sound at the time of laying,
while hemlock ties (Tsuga canadensis) have a life of only four

DURABILITY OF WOODS 171

years. The relation of special conditions of moisture is further
exhibited in these cases in the fact that ties which were perfectly
sound on the exposed sides are very often found to be in an
advanced state of decay throughout the buried parts. Mutilation
is an important factor in the introduction of decay, and Dudley
has shown (14) that where spikes have been driven into the ties,
and where the structure has thereby suffered mechanical altera-
tion, decay finds an opportunity for speedy entrance into the
interior tissues, which it rapidly permeates and destroys. This
relation of cause and effect is in perfect harmony with what
has long been known to occur in living trees where broken or
badly amputated limbs afford an opportunity for fungi to pene-
trate and destroy otherwise healthy tissues.

The preceding considerations have directed attention to the
fact that coniferous woods may be preserved indefinitely, pro-
vided they are completely excluded from fresh supplies of free
oxygen and are maintained under conditions of low tempera-
ture,--in other words, hermetically sealed in an impervious
medium. While we are thus in a position to understand the
conditions under which a very large proportion of woods are
preserved as fossils in the more recent geological strata, no
explanation is offered which will adequately account for the
mode of preservation of the large number of plants met with
in the older rocks, even as far back as the Devonian and
Silurian, and it is desirable that examples of these should be
passed in review. In this connection four principal forms of
preservation may be noted, -- (i) carbonization, (2) silicification,
(3) calcification, and (4) pyritization.

Carbonization. This form of preservation is essentially char-
acteristic of plants derived from the coal measures, and it is
represented by coal itself. It depends essentially upon a gradual
withdrawal of the elements of water from the original cellulose
substance, whereby a relative excess of carbon is developed. It
is a change which takes place under exclusion of air, and it is
no doubt facilitated by the action of heat and possibly also of
pressure. It is obvious, however, from the nature of the changes

172 ANATOMY OF THE GYMNOSPERMS

involved, that they not only proceed very slowly, but that it is
possible to find plant remains which present different stages of
the process, as represented by the various forms of peat, brown
coal, soft coal, and anthracite. Being determined by the with-
drawal of hydrogen and oxygen from the original tissues, these
alterations must arise very unequally in different parts of the
plant body, as determined by the character of the tissue involved
and the relative percentage of carbon originally present in the
cellulose substance. In the progress of such changes, gases
constitute some of the most abundant and conspicuous end
products. While under ordinary circumstances they may be lib-
erated continuously, they may be stored under favorable condi-
tions, to be liberated in great volume at a later period. Thus
it has been shown, as the result of recent observations (88),
that where plant remains accumulate in large quantities, sul-
phureted hydrogen together with the light carbureted and
phosphurcted hydrogen arise. The two latter, being subject
to spontaneous combustion, take fire upon coming in con-
tact with the air, and, setting fire to the associated sulphurated
hydrogen, an extensive conflagration may result. Phenomena of
this kind on a large scale rarely come within the observation of
man, but that such have been observed affords abundant ground
for the belief that many forest fires of obscure origin are to be
accounted for in this way. Thus, once more comparing the per-
centage composition of the principal cellulose modifications, it
is found that normal cellulose contains 44 per cent of carbon,
lignin about 62 per cent, while cork contains upwards of 74 per
cent. In accordance with this principle it will be found that
wood tissue becomes carbonized sooner than the softer parts of
the structure, which may already have disappeared through the
operation of decay, or the highly carbonaceous cork tissue of
the bark may be converted into a structureless mass of carbon,
while yet the less carbonaceous wood tissue is preserved in all
its details. It is thus possible, in a silicified wood, to recognize
and define the general limits of the bark by the carbonized layer
which oftentimes forms the outer portion of a fossil wood.

DURABILITY OF WOODS 173

Carbonization necessarily involves a more or less profound
obliteration of structural details. This is especially true in those
cases in which an absence of infiltrated mineral matter has pre-
vented a retention of the original structural details, and where
pressure in conjunction with heat, as in hard coal, has pro-
duced a secondary effect. From this point of view it is true
that a highly carbonized cortex rarely presents any structural
details. Lignites and some of the softer coals not infrequently
present well-defined structure, but the same cannot be expected
of the hard coals, in which extreme alteration has been effected.
In many cases, such as may be found in the Devonian and later
formations, carbonization is joined to silicification or calcification
and gives rise to resultant forms of preservation, which will be
discussed more fully and with more propriety in the next chapter;
but attention may be directed to the general fact that where
carbonization operates by itself the fossil acquires an opacity
which renders it very difficult to determine details, while the
structure also becomes so friable as to make special methods of
section cutting imperative.

Silicification. This is by far the most common form in which
the stems of plants are preserved in the older rocks. It depends
upon the slow infiltration of a solution of an alkaline silicate into
the tissues, whereby the entire structure eventually becomes con-
verted into a mass of silica, as in the trees of the petrified for-
ests of Arizona, or as may be seen in some of the larger algae,
such as Nematophycus from the Devonian. According to the
rate of infiltration, relatively to the operation of decay, all struc-
tural details may be observed. Under ordinary circumstances,
however, such a method of preservation is one of the most
advantageous for the purposes of scientific study, because of
the transparency of the mass and the permanent form of the
material.

Calcification. This form of mineralization is much less com-
mon than silicification, with which it may be combined. In
some cases, however, calcite constitutes the entire mass of the
infiltrated material, as in the case of Osmundites skidegatensis

174

ANATOMY OF THE GYMNOSPERMS

from the Cretaceous of the Queen Charlotte Islands, which, as
shown on a former occasion (56), contains at least 70 per cent
of calcium carbonate. The general effect of this form of pres-
ervation upon the structure is substantially the same as in
silicification.

Pyritization. A still less common form of preservation is that
which involves a replacement of the silica or calcite of the pre-
vious forms by crystalline sulphide of iron. This is a feature
more or less common to fossils from the older formations, which
always involves a complete obliteration of structural details,
though in rare cases the more general features may be seen
when viewed by reflected light. Plants presenting this form
of preservation are among the least valuable for purposes of
scientific study.

CHAPTER XIII

DECAY: ITS MODE OF ACTION AND EFFECTS

In discussing the operation of decay in the woody tissue of
a stem, it will be desirable to have reference to (i) the nature
of the active agents, (2) the conditions under which they flour-
ish, (3) their mode of operation, and (4) their effects upon the
structure and mode of preservation.

i. The nature of the active agents. Decay has its origin in the
growth of certain plants of a low degree of organization, which,
through their ability to seek food supplies either in living or
dead organic bodies, produce such an unusual course of develop-
ment as to effect an actual disorganization of the tissues, as
expressed in decay. To understand fully the nature and mode
of operation of these plants, it will be necessary to briefly pass
in review their essential characteristics.

Among the lower forms of plants we recognize two somewhat
nearly related groups, which present many features in common,
both with respect to their influence upon the promotion of dis-
ease and decay and to their general habits of life, but which
nevertheless differ very materially in their structure and the
details of their life history. The first group embraces what are
known as the Bacteria, - - plants characterized by their unicel-
lular structure, which rarely assumes a filamentous form, and
by the fact that while they may and frequently do propagate
through the medium of spores, they more commonly multiply
by simple fission, in consequence of which they are designated
the fission fungi or Schizomycetes . Their life history is very
simple, and the incomplete cycle, which is wholly devoid of a
sexual phase, is repeated at very frequent intervals, so that they
multiply with enormous rapidity. The nutrition of the bacteria
is derived by a process of direct absorption from the surrounding

175

I 76 ANATOMY OF THE GYMNOSPERMS

medium without the development of specialized organs for that
purpose. Owing to their minute size they are readily distrib-
uted by even slight currents of air, from which they eventually
settle as constituents of dust. Their spores offer a remarkable
degree of resistance to ordinary conditions, whereby they may
survive a most adverse environment for prolonged periods, and
again produce the vegetative form when favorable conditions
are once more established. It will thus be observed that the
growth and operation of such plants is not necessarily continu-
ous, but that their action may be intermittent or periodic, as
determined by the special circumstances under which they are
placed. In any event, the characteristics noted favor, in an
exceptionally high degree, the wide prevalence of the effects of
which they are the immediate cause. It would be out of place
here to enter upon a detailed discussion of these effects, and it
will suffice to direct attention to the very general relation of
these plants to the production of disease in both plants and
animals, while their relation to the disorganization of organic tis-
sues is exemplified in the various processes of maceration which
constitute so essential a feature in many important industrial
processes.

The second group of plants includes the Fungi, - - plants
distinguished by their somewhat higher degree of organization
and the development of specialized organs. They are generally
multicellular, and the plant body, or mycelium, is in the form of
a septate, or nonseptate and branching, microscopic filament,
which is capable of very rapid extension, and which may also
bring about a vegetative propagation by simple subdivision. At
certain stages of its growth, as also under special conditions of
moisture and temperature, the mycelium gives rise to asexual
reproductive bodies, or spores. Such spores are very minute,
and are composed each of a single cell. They may or may not
arise through the medium of a sexual process, the fungi exhibit-
ing a great diversity in this respect, a discussion of which is
unnecessary at this time. The spores are generally produced
in vast numbers ; they are most readily distributed by the wind

DECAY 177

or even by slight movements of the air ; their extreme buoy-
ancy keeps them afloat for prolonged periods, though they
eventually settle as one of the ordinary constituents of dust ;
they offer a high degree of resistance to deleterious influences,
and are thus capable of bridging over critical periods, at the end
of which they may germinate with great freedom. It will thus
be seen that through such spores it is possible for the fungi to
develop wherever and whenever favorable conditions are met
with. The life history of the fungi is usually much longer and
more complex than that of the bacteria, and while the life cycle
often involves both a sexual and an asexual phase, the former
may not appear throughout a very much prolonged period of
development, within which the plant may nevertheless extend
with great rapidity and produce all the characteristic effects
of its growth.

Both the bacteria and the fungi are characterized by the ab-
sence of a green pigment, or chlorophyll, and their consequent
inability to produce carbon compounds from the carbon dioxide
of the atmosphere as a source of energy. With the exception of
a few of the bacteria, the energy of all these plants depends
entirely upon the oxidation of carbon compounds previously
formed and accumulated by some other organisms, primarily
those which contain chlorophyll. It is therefore imperative that
such compounds should be derived directly from the nutrient
fluids of a living organism, or /tost, upon which the parasite
feeds ; or that it should be obtained as one of the products of a
decay induced by the fungus or bacillus which thereby becomes
a saprophyte. From the nature of their process of nutrition,
saprophytes are generally found within the body upon which
they act, and they are thus endophytic. This is particularly
true of the bacteria. The more highly organized fungi may
live chiefly upon the surface of the body (epiphytic), sending
the branches of their mycelium (the hypha) into the interior
parts, where they develop specialized feeding branches (Jiaus-
toria), which arise wherever food supplies are to be met with.
Or, again, endophytic forms may reach the surface only at certain

178 ANATOMY OF THE GYMNOSPERMS

periods of development and under special conditions of environ-
ment, when they become recognizable without the aid of the
microscope by reason of their characteristic fruiting structures.
It is further true that in these two groups of plants there is
a more or less variable relation toward the source of food supply.
This is expressed by the classification long since adopted by
De Bary (83), and now generally used with slight modifica-
tions, who recognized :

1. True or obligate saprophytes: those which obtain their food supplies
from the products of organic decay under all circumstances.

2. Partial or facitltath'e saprophytes : those which usually complete the
life cycle as true saprophytes, but which, under special circumstances, may
more or less completely but temporarily become parasites.

3. True or obligate parasites : plants which invariably derive their nutri-
tion directly from the nutritive materials of living organisms.

4. Partial or facultative parasites: those which, under special circum-
stances, may become saprophytes, though ordinarily completing the life
cycle as true parasites.

Among the very large number of parasites and saprophytes
which attack timber, either living or dead, it will be found that
within certain limits there is a more or less well-defined relation
to the organism affected, whereby it is characterized by the
growth of special forms. The number of species peculiar to a
given tree will be found to vary somewhat widely, and this will
in turn be influenced within the limits of a particular species of
tree by conditions of environment. Thus von Schrenk (68, 49)
shows that the wood of Catalpa speciosa is injuriously affected
by only two fungi, and the same is likewise true of the red cedar
(Juniperus virginiana); but Dudley (14) points to the fact that
no less than eighteen species of fungi infest the wood of the
hemlock (Tsuga canadensis), of which nine are Polypori and six
Agarics. Again, it is a well-known fact that other fungi, such as
dry rot (Merulius lachrymans), are not selective in any particu-
lar sense, but by reason of their very cosmopolitan habits they
grow within any wood, provided the external conditions of warmth
and moisture are favorable. It by no means follows from the

DECAY 1 79

above statement that all the fungi found in a particular wood
either produce the same or even similar diseases, that they are
equally active, or that they operate under all conditions ; and it
will suffice in this connection to again direct attention to the
results obtained by von Schrenk in the case of the hardy Catalpa,
with respect to which he shows that soft rot produced by Poly-
porus versicolor (L.), Fr., rapidly destroys the heartwood, while
the brown rot induced by Polyporus catalpae, von Schr., operates
throughout the trunk near its base ; and yet again, while these
two diseases produce specific and distinct effects in the living
tree (68), there is as yet no fungus known which will grow in
the tissue of the catalpa wood after it has been cut and dried, -
a fact which readily explains the remarkable durability of this
wood and its adaptation to purposes where freedom from decay
is a first consideration.

2. Conditions under which they flourish. In entering upon a
discussion of the conditions under which fungi operate in plant
tissues, we must assume, as is in reality true in all cases, that
the latter contain an appreciable amount of material which may
be utilized by the fungus for the purposes of its own nutrition.
Such food material is always presented by the cellulose sub-
stance of the cell wall, which is thereby broken down and grad-
ually removed, though this does not occur usually until other
and more available forms of food material have been exhausted.
In the second place, the nutrient material stored by the plant
for its own sustenance, such as the starches and sugars, are
readily attacked by fungi, and so long as they last the invading
organism confines its operations chiefly to those regions and
particular cells in which such storage is most marked. Apart
from such conditions of food supply, which must be held to be
of fundamental importance and to be a constant factor under
all circumstances, air, temperature, and moisture must also be
regarded as essential though variable factors which operate as
the real determinants in the growth of the invading organism.

The active growth of all plants demands an abundant supply
of oxygen. In the vast majority of cases this gas is derived

iSo ANATOMY OF THE GYMNOSPERMS

directly from the air, or indirectly through the medium of the
surrounding fluid, such as water, in which the organism may be
growing. Such ae robes cannot exist when the supply of oxy-
gen from either of the sources indicated is cut off, since their
respiratory function is inhibited and all dependent activities
necessarily cease. It is true that some plants, such as certain of
the bacteria, cannot live under such conditions of free aeration, in-
asmuch as they have become adapted to obtaining their oxygen
from the products of organic decomposition, and any access of
air or free oxygen at once inhibits their growth. Such anaerobes
form a comparatively small but none the less exceedingly im-
portant group of plants, and it is a knowledge of these differences
in the life history of the organism which enables us to gain an
intelligent insight into the operation of the various forms of
organic decay. It may be stated, then, that the fungi in general
cannot grow except under conditions which afford a free supply
of oxygen, and this fact supplies the basic principle on which to
found methods for retarding or permanently arresting the oper-
ation of fungi. But it will be found in practice that this is
further dependent upon the remaining factors of warmth and
moisture. In the preceding chapter it has been shown that the
spores of fungi, as also those of the bacteria, are capable of enter-
ing upon a resting state whereby they become capable of resist-
ing very adverse influences, but that they are also capable of
once more germinating, sometimes after the lapse of several
years, when again brought under favorable conditions. These
conditions are (i) a suitable temperature, and (2) an abundance
of moisture. The consideration of a few special cases will per-
mit of a clearer conception of the nature and operation of these
conditions.

That all fungi arc not equally affected by the same degree of
heat and cold is one of the elementary facts of plant physiology,
while it is also equally well known that the same plant will be
variously affected according to the special condition of growth
in which it is brought under the action of varying temperatures.
These facts are probably illustrated among the bacteria in a

DECAY

181

more prominent way than in any other group of plants, though
the general relations also hold true for all the higher fungi.
Thus among the bacteria certain forms have been known to
survive a temperature of - 10° C., or even - - 100° C. when the
cold is applied for a short time only. On the other hand, Bacil-
lus thermophilus thrives vigorously at a temperature of 70° C.,
while the spores of the common hay bacillus (B. subtilis), which
are destroyed when heated in their nutrient solutions to temper-
atures exceeding 100° C., are nevertheless capable of resisting
upwards of 120° C. of dry heat. From these and similar well-
known examples it may be concluded that the specific effect of
varying temperatures is due to the amount of water present in
the albuminoid protoplasm, --a conclusion in accord with the
reduction of water which is known to take place in a cell when
it passes from the active vegetative to the resting state, in which
form it manifests its highest powers of resistance to extreme
conditions of temperature. This principle finds its further illus-
tration in the fact that the vegetative cells of fungi, which con-
tain a maximum of water and are adjusted to certain conditions
of temperature, may be readily killed by dryness, for which pur-
pose desiccation at the ordinary temperature is often sufficient.
Broadly speaking, the bacteria cannot survive a temperature
exceeding 50° to 60° C., and in this connection a statement of
the three critical points in temperature for a few well-known
forms, as given by Warming, may be instructive :

MINIMUM

OPTIMUM

MAXIMUM

Hay bacillus (B subtilis) ....

6°

70°

50°

I c

2O— 2 S

4-3

* j

Cholera bacillus (Spirillum cholerae-asiaticas)

8

37

40

Tubercle bacillus (B. tuberculosis) ....

28

37-33

42

Turning our attention to the fungi, which are more immedi-
ately concerned in the destruction of timber, we find that with
the exception of certain specialized forms the three critical points
in temperature may be stated as minimum, i° to 2° C. ; optimum,

1 82 ANATOMY OF THE GYMNOSPERMS

20° C. ; maximum, 40° C. The relation of moisture and heat
to continued life conforms to the same principle as stated
for the bacilli, namely, that the spores of Penicillium glaucum
and Rhizopus nigricans rarely germinate if exposed for one or
two hours to air which has been heated to a temperature of 70°
to 80° C., while they are entirely destroyed at 82° to 84° C. On
the other hand, spores which have been heated in their own
nutrient fluids to a temperature of 54° or 55° C. completely
lose all power of germination (84, 725).

Although but little is as yet known respecting the life history
of the fungi, and especially the particular conditions under which
the germination of the spores occurs, the foregoing facts direct
attention to the great diversity and wide range of the conditions
involved for different species. Fortunately the researches of
Hartig have made it possible to gain an insight of a more exact
character into the operations of one of the most destructive fungi
known, the dry rot (Merulius lachrymans), a short account of
which may serve as a working basis for all fungi.

The spores of dry rot germinate on the surface of damp
timber, and the growing plant quickly penetrates the tissue ;
but the germination of the spores demands certain conditions
which are fulfilled by the presence of alkaline products, particu-
larly those which are ammoniacal. It will therefore be found
that locations where there is bad drainage, especially in cellars
and stables where ammoniacal products are likely to be abun-
dant, offer exceptionally favorable situations for its development.
When the plant has once entered upon its course of growth its
extension is very rapid, and it thrives wherever the air is con-
fined, warm, and damp, though it is well known that air, i.e.
air which is freely circulating and which contains a much lower
percentage of moisture, will cause the death of the plant in one
or two days, except in deeply seated parts. From this point
of view it may be observed that the disease is readily propa-
gated in badly ventilated cellars or in confined areas where air
does not freely circulate and there is a tendency to the collec-
tion of moisture. Thus in the construction of the MacDonald

DECAY 183

Engineering Building at McGill University use was made of
very fine timbers of Douglas fir as supporting beams to carry
the heavy floors of the upper stories. These were seated in
cast-iron, flanged bed plates. Within a few years, in the room
used as a hydraulic laboratory, the timbers had developed dry
rot, which extended upwards from the base for a distance of
about one foot. The obvious cause was to be found in the con-
fined air and in the accumulation of moisture condensed from
the atmosphere of the room. In another case brought to my
notice the heavy oak roof timbers of a large building developed
an extensive growth of dry rot. Upon examination it was found
that the air of the low attic was confined and no circulation was
possible. Openings were at once made at opposite ends and a
free circulation established. The difficulty was speedily removed,
and there has been no recurrence of the trouble within a period
of about fifteen years.

Our knowledge of the way in which and the conditions under
which dry rot operates makes it possible to apply effective reme-
dial measures with intelligence. These measures involve :

1. Complete ventilation.

2. Removal of all sources of alkaline and particularly of ammoniacal
products.

3. A complete removal of all diseased wood.

4. Treatment with some fungicide, such as cupric sulphate, if the condi-
tions are such as to make other remedies in any way ineffective.

Finally, the observations of Dudley (14, 44), that fungi do
not penetrate cedar ties unless there is a good supply of air,
and that when the latter is cut off the growth stops, once
more direct attention to the nature of the effective prevent-
ive measures.

From these considerations it becomes obvious that for fungi in
general higher temperatures offer correspondingly more favor-
able conditions for growth, which is also accelerated by an in-
crease of moisture, both operating within certain well-defined
limits. And we may further conclude that preventive measures
will be most effective under those conditions which involve low

1 84 ANATOMY OF THE GYMNOSPERMS

temperature, an absence of moisture, and, if possible, a complete
exclusion of oxygen.

3. Their mode of operation. The mycelium, or plant body,
of the fungus consists of a very slender thread which is about
7 //, or less in diameter. Comparing this with the normal phys-
ical openings in the tissue of coniferous woods, it is found to be
only one fourth the size of the cavity of the tracheid (28 /x) of
the spring wood, while it is but little smaller than the average
tracheid cavity of the inner summer wood (10 /x), and twice as
large as the cavities of the tracheids last formed (3.5 /u) in the
wood of Juniperus virginiana. Within this same species it is
but little smaller than the tangential diameter of the ray cell
(8.7 n), while it is about twice as large as the average pore of
the bordered pit (3.5 /LA). Red cedar was selected for compari-
son for the reason that the structural features referred to are
relatively small and they represent what is common to a number
of species, such as those of Torreya and Taxus. But it must be
remembered that in the majority of coniferous woods the open-
ings referred to are far larger, and they would therefore offer
correspondingly more favorable conditions for free development
of the mycelium. From these facts it is not difficult to perceive
that when spores germinate on the surface of a timber, on a
wounded surface, or in a crack, the growing plant at once finds
ready access to the interior parts through the natural channels
afforded by relatively large openings in the tissue. Such entrance
will be greatly facilitated in proportion as the surface is rougher
or the tissue is in any way lacerated, since such laceration not
only increases the size and number of the initial openings but
is also a factor which contributes to more speedy disorganization
of the organic substance of the cell wall. From this it is evident
that the stumps of branches which have been left in a ragged
condition either through wind pruning or through the careless
operations of the forester must afford conditions highly favor-
able to the operation of decay. Or yet again, when felled timber
cracks in the process of drying before it is rafted, the cracks
offer inviting places for the lodgment of fungus spores, especially

DECAY 185

those of the Polypori, which abound in the forests. The sub-
sequent immersion of the logs as they are floated to the mill
causes the cracks to close and favors the development of the
spores in the interior of the log. The relatively small amount
of fungus developed under such circumstances lies dormant and
is widely distributed wherever the prepared lumber is used for
constructive purposes. If such boards should be employed in
damp and close situations, such as a cellar or poorly ventilated
basement, the fungus will find most congenial conditions for
renewed and vigorous growth, and all the characteristic phe-
nomena of dry rot will be manifested. An instance of this kind
came under my observation some two years since in a city house,
where the wainscoting of the basement dining room was once
removed ; but as the fungus again appeared within a short time
and attacked the entire sheathing, the tenants sought safety in
removal to another and better constructed house. A second
case of the same sort was brought to a conclusion during the
past summer. As a precautionary measure, about a year ago
the infected woodwork was all removed and the surrounding
walls were cleaned as thoroughly as possible, the surfaces being
washed with a solution of cupric sulphate. Eventually, it being
found impossible to check the trouble without much more exten-
sive repairs than the landlord was willing to make, the tenant
brought suit and secured damages.

When the fungus has once been established through any of
the means described, and the conditions continue favorable, it
extends with great rapidity in all directions from the original
center, being guided in the course it takes by conditions of nutri-
tion rather than the path of least resistance, carrying with it all
the characteristic features of disease and decomposition. Wher-
ever there is room for expansion, as in seasoning cracks or in
the cavities arising through its own operations, the mycelium
increases greatly and gives rise to massive developments of
various forms. Thus in the white rot of the red cedar, caused by
Polyporus juniperinus, von Schrenk has shown that the cavities
arising through the action of the fungus are lined with a felt

1 86 ANATOMY OF THE GYMNOSPERMS

of soft brown mycelium, which often assumes very fantastic
shapes (69, IO).

In the diffusion of a fungus through woody tissue two impor-
tant features may be noted : (i) the extent and direction of
development are determined in the first instance by the distribu-
tion of food materials ; (2) the distribution and progress of the
mycelium are independent of the presence of physical openings
in the structure. A few specific illustrations may serve to make
these statements clear. No matter what particular channels
may have permitted the mycelium to gain access to the interior,
its development appears to arise chiefly and first of all in the
medullary rays. The mycelium extends in the general direction
of the ray structure and therefore at right angles to the principal
lines of structure for the wood as a whole, filling the individual
cells with loosely felted masses of brown hyphae, from which are
developed short and variously divided branches. These latter
are particularly connected with the absorption of food substances,
and they are appropriately known as haustoria. It very fre-
quently happens that such growths of mycelium may be nearly
or altogether confined to the structure of the ray, the adjacent
tracheids being wholly devoid of them ; or there may be local
areas within which the mycelia extend vertically upward and
downward from the ray, invading the neighboring tracheids,
through which they extend for long distances. These facts
suggest that the medullary ray may offer more favorable condi-
tions for development than other parts of the structure, and
they make it desirable to examine its structural features some-
what more closely from this point of view.

An examination of a medullary ray as exposed in radial sec-
tion shows that the upper, lower, and side walls -- particularly
the latter --are provided with definite pits, through which it
would be possible for the fungus to pass into adjacent cells with
very little opposition. But such favorable conditions are obvi-
ously not taken advantage of to any great extent, since neigh-
boring tracheids often remain quite free from the mycelium
while the ray cells are crowded with it. This would seem to

DECAY 187

imply that there is some special property in the ray itself which
favors a more vigorous growth there, and serves to retain the
fungus in that particular locality. The terminal walls, as in
Abies, Larix, Picea, etc., are perforated with numerous pits, which
would offer a somewhat easy path for the radial extension of the
fungus. But such openings fail to satisfy the conditions and
explain the great abundance of mycelium found in the rays,
since the terminal walls of the Cupressinese are not pitted but
present a blank wall to the further progress of the fungus.
Furthermore it may be shown, as will appear very shortly, that
physical openings offer no determining influence upon the direc-
tion of growth of the mycelium, which continues in the originally
selected course without respect to the structural characteristics
of that which may lie in its path. From these facts, then, it
would seem that the structure of the ray does not afford an
adequate explanation of the observed phenomena.

The medullary ray constitutes perhaps the most important
structural region within the vascular cylinder with respect to
the accumulation of reserve food. This is deposited in the form
of starch and other easily assimilated products, and it is their
presence in relative excess which undoubtedly determines the
abundant development and localization of the mycelia within
such regions in the first instance. If this hypothesis be regarded
as a correct one, then it is possible to see how the mycelia gain
access to other structures exactly in accordance with its require-
ments and the possibilities of finding fresh stores of food mate-
rial, which may be held to appear in diminishing quantities as
successive areas are entered, until, the more available forms of
food having been exhausted, the cellulose fabric itself is attacked,
and with its disintegration the characteristic features in the
operation of the fungus are expressed in recognizable form. In
confirmation of the view thus expressed, it will be found to be
very generally true that next to the medullary ray the greatest
development of the mycelium takes place in the tracheids and
resin passages, which they traverse in a longitudinal direction
(plate 9). In this case it is possible that the opportunities for

1 88

ANATOMY OF THE GYMNOSPERMS

free growth afforded by the long cavity of the <tracheid or resin
passage may serve somewhat to influence the direction of growth
as the fungus searches for food, although, as in the previous
case, it cannot be regarded as a determining factor of primary
importance, inasmuch as there is a constant tendency to the
formation of branches which traverse the wood at right angles
to the walls. The third phase in distribution is established when
the vertical strands give rise to hyphae, which are developed at
right angles to the original course, and which then traverse

the tissue at right angles to the principal
lines of structure (plate 10).

It might be supposed that the course
of the fungus would be determined by
the presence of physical openings in the
walls of the tracheids, and that the myce-
lium would therefore follow an irregular
course leading it through the various bor-
dered pits, which, as previously shown,
offer ample opportunities for such pas-

FlG. 48. PlNUS RESINOSA. 011 • •

Radial section showing sa£e- Such> however, is in no sense the
the progress of a fungus case. In fig. 48 a radial section of the red

mycelium across the line in£ (pjnus reginosa) shows dearl

of structure, and its pene-

that the growth of the fungus is wholly
independent of physical openings of any
kind, otherwise it would take advantage of
those which lie in its immediate neighborhood. On the contrary,
its course does not deviate from the original direction established
at the point of emergence from the main filament. Whenever
in its progress the mycelium comes in contact with the cell
wall, its enzyme attacks the latter, and by solution establishes
an opening through which the fungus passes. It will be noted,
nevertheless, that the resistance offered by the wall is sufficient
to bring about a great reduction of the mycelium, which is always
much less than the normal diameter within the limits of the
wall. In thin-walled cells, where little resistance is offered, the
opening thus established is commonly larger than the mycelium,

tration of the cell wall,
independently of the
presence of pits, x 350

DECAY 189

which then has a perfectly free passage ; but in all highly
lignified tissues, and more particularly those in which secondary
growth of the wall is excessive, such contraction is always exhib-
ited. This action of the mycelium in perforating the cellulose
wall is by no means exceptional or peculiar to the fungi, since it
appears in a variety of forms throughout the plant world and
constitutes a well-known process in the liberation of spores from
the mother cell, as well as in the progress of the pollen tube
through the structure of the style.

It now remains to inquire somewhat more particularly into
the specific action of fungi as expressed in

4. Their effects upon the structure and their relation to forms
of preservation in fossil plants. While the general course of the
physical changes in decaying wood is fairly well known, there
are many features which demand more thorough and extended
study. This is particularly true of the changes which arise in
the cellulose and eventually resolve it into its proximate ele-
ments, whereby the chemistry of decay is recognized as one of
the most obscure problems with which the plant physiologist
has to deal. Nevertheless reference to the well-known reactions
for cellulose, as already given (p. 49), enables us to form some con-
ception of the nature of these changes, since those which pro-
ceed from the action of fungi are in many respects parallel with
those obtained through the action of reagents. The alterations
accomplished by the latter, either through the action of an acid
or of an oxidizing body, are brought about in the fungi by the
action of special ferment secretions included under the general
name of enzymes. But here it is to be noted that each fungus
behaves in a way peculiar to itself, and gives rise to specific
effects which cannot be associated with other fungi. These
differences may be reduced in the first instance to two groups,
in the first of which the action is primarily upon the intercellu-
lar substance, whereby the latter is destroyed with a separation
of the secondary walls from one another ; in the second place
the action is upon the secondary walls, which are largely removed
with the production of a skeleton composed of the primary

I go ANATOMY OF THE GYMNOSPERMS

walls. The specific action in such cases is probably one of
hydrolysis, whereby the cellulose is resolved into soluble prod-
ucts of the general nature of glucose, and the results are pre-
cisely parallel with those produced by Mangin's maceration or
by strong sulphuric acid. But such changes should be studied
through the records of special cases. Tubeuf (72, 38-39) has
shown that Trametes pini acts in the first instance upon the
more highly lignified portions of the wall. The first effects of its
operations, therefore, are expressed in the solution and removal
of the primary wall, while the secondary and tertiary walls
remain behind as a skeleton, which may eventually become
corroded and disappear after prolonged action.

Precisely the same action has been reported more recently by
von Schrenk as developed in the white rot of the red cedar
through the action of Polyporus juniperinus, von Schr. (69,
9-10). The holes produced in the trunk of the tree through
the action of this fungus often contain as much as three hun-
dred grams of the cellulose fiber. On the other hand, the same
author shows that in the red or brown rot of the same tree
numerous pockets are formed in the wood. These are occupied
by metamorphosed wood tissue which has cracked by shrinkage
so as to form small cubes adhering to the walls of the pockets.
An examination of such brown material shows it to be the resi-
due of the original structure after elimination of the cellulose,
the action involving a reduction of the cell wall by solution of
the less lignified parts, thus reducing the original structure
to the primary cell wall. Here again the action is seen to be
exactly contrary to that of the previous case, since, while in the
white rot the soluble substance, or hadromal of Czapek, is all
removed, leaving the cellulose behind, in the brown rot the cel-
lulose is removed, leaving behind a residue which von Schrenk
has been able to identify with the so-called hadromal.

By the same authority identical changes have also been shown
to arise from the action of Polyporus versicolor in producing
the soft rot of Catalpa speciosa (68, 50-52). Tubeuf has also
directed attention to the fact that the same general changes may

DECAY 191

arise in other conifers through the action of Polyporus vaporarius,
P. Schweinitzii, and P. sulphureus, one of their characteristic
results being expressed in a breaking up of the cell wall into
a series of spiral fibers corresponding to the original striation.
This feature of decay is very commonly expressed in macerated
woods among existing species, and it is exemplified in a very
striking manner by Pseudotsuga miocena from the Miocene of
Oregon (plate n).

Whatever particular form the decay effected by fungi may
take, it is no doubt correct to say that the disorganization of
the cellulose is due in general terms, and in the first instance
at least, to a process of hydrolysis. From this point of view it
is possible to satisfactorily explain the varying degrees of resist-
ance offered by tissues of different degrees of modification,
since it will be observed that the decay acts inversely as the
amount of carbon present, wherefore the unmodified walls are
the first to be acted upon, the cork and cutin the last.

The changes thus noted as arising through the action of fungi
have a more or less profound effect upon the degree of perfec-
tion with which structural details are retained when the plant
eventually becomes silicified or calcified and is converted into
the condition of a fossil. It has been shown that even when
present in the tissue, the destructive effects of the fungus may
be inhibited by the exclusion of oxygen, with the result that
the structure is preserved in a most perfect manner through
indefinite periods of time, and without the subsequent infiltra-
tion of mineral matter. Most commonly the wood exhibits the
effects of more or less extended decay, which, in the majority of
cases, shows a removal of the secondary wall and the formation
of a thin-walled skeleton, which readily collapses and thus gives
rise to extended distortion of the whole structure, whereby it
becomes exceedingly difficult to recognize even the genus. If
these changes proceed simultaneously with the infiltration of
mineral matter, the latter may eventually replace the former to
such an extent that while the lines of structure are preserved,
they are but faintly defined by thin lines of finely granulated

1 92 ANATOMY OF THE GYMNOSPERMS

matter representing the carbon residue of the original structure.
Such a condition is presented in various species of Cupress-
oxylon and Pityoxylon from the Permian and Cretaceous of
Kansas (45, 76-77). Eventually, as so commonly expressed in
specimens from the petrified forests of Arizona, the silica may
entirely replace the organic matter with an absolute obliteration
of all structural details. Such alterations are necessarily regional
and local, as determined by the more or less energetic action of
the fungus and the progress of infiltration, of which two factors
it is the necessary resultant.

A peculiar combination of decay and infiltration may, under
other circumstances, give rise to a false structure which bears
no relation whatever to the normal. This has been recognized
by Penhallow on former occasions (57, 1 17, and 58, 25) in the case
of the so-called Celluloxylon primsevum of Dawson, which he
has shown to be nothing more than peculiarly altered forms of
Nematophycus Logani and N. crassus. No similar instance has
yet been recorded for the vascular plants, and it would almost
seem as if the alterations noted were to be specially identified
with the more resistant forms of marine algae. The peculiar
changes observed in these plants were of such a nature as to
give rise to tissuelike figures, which, under a low power, present
the precise aspects of a coarse parenchyma tissue in process
of decay. Such appearances led the late Sir William Dawson
to recognize in Celluloxylon primaevum a distinct type of plant,
though it was subsequently shown that the appearances were
wholly due to highly altered forms of Nematophycus. The effect
arises from the fact that the carbon residue, the decay of which
has already been carried to an extreme point, is in a finely gran-
ulated form, which admits of very ready redistribution. The
crystallization of the infiltrated silica at such a time supplies
exactly the necessary conditions for such redistribution. Under
these circumstances the carbon particles arrange themselves
upon the surfaces of the crystals without any reference to the
original lines of structure, but in such a way as to produce
definite figures of the size of the silicious crystals.

NORTH AMERICAN GYMNOSPERMS

PART II- -SYSTEMATIC

NOTE

Genera and species which are also represented in the fossil state are

indicated by *.
Genera and species which are exclusively found in the fossil state are

indicated by * *.

PART II— SYSTEMATIC

SYNOPSIS OF GENERA FOR THE CORDAITALES,
GINGKOALES, AND CONIFERALES

A. Resin passages and fusiform rays present.

I. Fusiform rays narrow, the terminals chiefly long and abruptly linear ;
the cells rather small and thick-walled. Resin passages with thick-
walled epithelium and chiefly without thyloses.

Tracheids (radial) with spirals, at least in the spring wood.

Resin cells scattering on the outer face of the summer wood.

18. Pseudotsuga (p. 271).
Tracheids wholly without spirals.

Pits on the tangential walls of the summer tracheids.

Resin cells present but scattering on the outer face of the summer wood.

19. Larix (p. 276).
Resin cells wholly wanting.

20. Picea (p. 281).

II. Fusiform rays (tangential) chiefly broad, the cells large, the resin
passages broad with thin-walled epithelium and strongly developed
thyloses.

Tracheids wholly without spirals.
Resin cells wholly wanting.

Pits on the tangential walls of the summer tracheids.
Ray tracheids not dentate.

21. Pinus (Section I, p. 305).

Pits on the tangential walls of the summer tracheids usually wanting.
Ray tracheids dentate.

21. Pinus (Section II, p. 318).

III. Fusiform rays (tangential) wholly wanting. Resin passages (trans-
verse) when present usually in compact rows on the outer face of
the summer wood of distant growth rings, imperfectly formed.

Resin cells prominent.

Pits on the lateral walls of the ray cells usually with a conspicuous border,
the orifice very large, oblong, the pits very prominent.

13. Sequoia sempervirens (p. 224).

Pits on the lateral walls of the ray cells very small, with a narrowly oblong
orifice. Terminal walls of the ray cells strongly pitted.

17. Tsuga Mertensiana (p. 270).

Resin cells remote and more or less obscure on the outer face of the summer wood
or wholly wanting.

'95

196 ANATOMY OF THE GYMNOSPERMS

Pits on the lateral walls of the ray cells small, simple, elliptical.
Terminal walls of the ray cells more or less strongly pitted.

1 6. Abies (p. 253).

B. Resin passages and fusiform rays wholly wanting.

I. Tracheids (radial or tangential) bearing thin spiral bands in 1-4 series.

Ray cells (tangential) narrowly oblong.

Tracheids (transverse) chiefly thick-walled and variable, the lumens usually
conspicuously rounded, the structure somewhat compact (except T. flori-
dana), the spirals rather close.

6. Taxus (p. 212).
Ray cells (tangential) broad, oval, or oblong.

Tracheids (transverse) large, chiefly squarish, and rather thin-walled, the
structure rather open throughout, the spirals rather open.

5. Torreya (p. 210).
II. Tracheids (radial or tangential) wholly devoid of spirals.

1. Wood nonresinous, commonly bearing idioblasts with sphere

crystals; the tracheids of 2 kinds (transverse).

4. Gingko (p. 209).

2. Wood resinous, devoid of crystal-bearing idioblasts ; the tracheids

(transverse) all of i kind.

Resin cells (transverse) prominent and in more or less conspicuous, tangential
bands, sometimes of distant growth rings or again widely scattering.
Terminal walls of the ray cells entire, straight, more rarely curved.

Pits on the lateral walls of the ray cells large, with a distinct border.
Resin cells distinctly zonate.

Pits on the lateral walls of the ray cells round, the narrowly
oblong orifice distinctly diagonal, the border very prominent.

10. Taxodium (p. 217).
Resin cells scattering.

Pits on the lateral walls of the ray cells oval, the oblong or len-
ticular orifice usually parallel with the cell axis, the border
often narrow, sometimes obscure.

13. Sequoia (p. 223).
Terminal walls of the ray cells sparingly pitted.

Pits on the lateral walls of the ray cells wholly simple or with an incon-
spicuous border, chiefly small.

Rays (tangential) broad, very sparingly resinous, often 2-seriate at
least in part.

11. Libocedrus (p. 219).

Pits on the lateral walls of the ray cells distinctly bordered.

Rays (tangential) usually rather narrow, more or less strongly resin-
ous, i -seriate.

15. Juniperus (p. 244).

Terminal walls of the ray cells entire or locally thickened, usually much curved,
sometimes straight.

SYNOPSIS OF GENERA 197

Resin cells (transverse) rarely in bands, chiefly widely scattering, some-
times \vanting.

Ray cells (tangential) narrowly oblong.

12. Thuya (p. 220).

Ray cells (tangential) rather broad, the cells round, oval or trans-
versely oval, rarely oblong.

Summer wood usually thin and of open structure.

Pits on the tangential walls of the summer tracheids usually
large and open, prominent.

Rays (tangential) not very numerous.

14. Cupressus (p. 228).
Rays (tangential) very numerous.

9. Podocarpus (p. 216).

Pits on the tangential walls of the summer tracheids very
flat and not very prominent.

7. Thujopsis (p. 215).

Summer wood dense, the spring wood open, thin-walled.

8. Cryptomeria (p. 216).
Terminal walls of the ray cells thick, more or less coarsely pitted.

Resin cells (transverse) not very prominent, remote, and more or less
obscure on the outer face of the summer wood, sometimes wholly
wanting (Abies).

Rays (radial) without tracheids (rarely present in A. balsamea).

16. Abies (p. 253).

Resin cells (transverse) rather prominent, more or less numerous on the
outer face of the summer wood, rarely zonate.
Rays (radial) with conspicuous tracheids.

17. Tsuga (p. 265).

Resin cells (transverse) entirely wanting, being sometimes replaced by resinous
tracheids which are chiefly located along the medullary rays, or sometimes
scattering.

Bordered pits multiseriate, hexagonal.

Resin when present contained in tracheids (transverse) and forming plates
(radial) simulating Sanio's bands, or opposite rays (tangential).
Growth rings not determinable.

Tracheids (transverse) chiefly equal and in very regular radial rows.

1. Cordaites (p. 198).

Tracheids (transverse) very unequal and in irregular, radial rows.

3. Araucaria (p. 203).
Growth rings obvious, but poorly defined.

2. Dammara (p. 203).
Bordered pits in i row.

Resin when present contained in tracheids (transverse) and forming plates
(radial) simulating Sanio's bands, or opposite rays (tangential).
Growth rings not very well developed.

3. Araucaria Bidwillii (p. 205).
Resin when present massive (radial), not in plates.

Growth rings very prominent and well defined.

16. Abies (p. 253).

198 ANATOMY OF THE GYMNOSPERMS

I. CORDAITALES

Growth rings rarely well defined. Wood more or less resinous, but devoid
of specialized resin cells or resin reservoirs. Medullary rays all of one kind.
Bordered pits on the radial walls of the tracheids, hexagonal and multiseriate.

1. * * CORDAITES, U.NGER. PLATES 12 AND 13

Transverse. Pith of the Sternbergia type, the cells large, thin-walled, often
resinous. Growth rings, when present, obscure, rarely somewhat conspic-
uous. Specialized resin cells and canals wholly wanting except in the
bark, where they take the form of tubular, branching canals without epi-
thelium, extending in the general direction of the stem-axis. Tracheids
in regular, radial rows, conspicuously squarish, and often resin bearing.

Radial. Elements of the protoxylem spiral and scalariform, and often show-
ing a graduated transition into tracheids with bordered pits. Tracheids
with hexagonal, bordered pits throughout, on their radial walls only,
in 1-5 rows. Ray cells usually of one kind only; the upper and lower
walls thin and not pitted ; the terminal walls thin, not pitted, generally
curved ; the lateral walls with bordered pits.

Tangential. Medullary rays rather numerous, i -seriate or often 2-seriate in
part.

This genus is wholly extinct and occurs only in Paleozoic strata. For a
more detailed account of the thirteen known North American species,
see Penhallow, North American Species of Dado.rylon, Trans. R. S. C.,
VI, iv, 51-97, 1901.

SYNOPSIS OF SPECIES

The following synopsis is given provisionally as an aid to identification of
the various species, without implying the absolute value of the differential
characters.

I. Growth rings present

1. C. pennsylvanicum.

II. Growth rings obscure or obsolete
A. Ray elements of two kinds, tracheids and parenchyma

Bordered pits in 2-3, rarely 4, rows.

Ray cells (tangential) oval or oblong, often narrow.

2. C. Clarkei.

B. Ray elements of one kind only

Bordered pits in groups of 6-13.

Pits on the lateral walls of the ray cells 3-6, chiefly 4, per tracheid.

3. C. Newberryi.

CORDAITES 199

Bordered pits in one row, compressed.

Ray cells (tangential) broad, round, or squarish.

4. C. recentium.
Bordered pits in 1-3, chiefly 2, rows.

Ray cells (tangential) broadly oval.
Ray cells about 31-57 p. broad.

5. C. hamiltonense.
Ray cells about 28-37 p. broad.

Pits on the lateral walls of the ray cells about 1-4 per tracheid.

6. C. illinoisense.
Ray cells (tangential) oval or round.

Pits on the lateral walls of the ray cells i-S, chiefly 2-3, per
tracheid.

7. C. materioide.
Ray cells not determinable.

8. C. annulatum.
Bordered pits in 2-5 rows.

Ray cells (tangential) oval or oblong.

Pits on the lateral walls of the ray cells 2-4, chiefly 4, per tracheid.

9. C. ouangondianum.

Pits on the lateral walls of the ray cells 4-10, chiefly 6, per tracheid.

10. C. acadianum.
Ray cells (tangential) broad or squarish.

Pits on the lateral walls of the ray cells 2 per tracheid.

11. C. ohioense.
Ray cells (tangential) oval or round.

Pits on the lateral walls of the ray cells 1-5, chiefly 1-2, per

tracheid.

12. C. materiarium.

Bordered pits in 5 rows.

13. C. Hallii.

1. C. pennsylvanicum, Dn.

Transverse. Tracheids 44 x 44 /A broad, the walls 6.7 p. thick. Growth rings
present, the summer wood about 8 tracheids thick, the tracheids about
12.5 p. radially, the walls 3.1 p. thick. Resin passages and resin cells
wanting.

Radial. Ray cells all of one kind, conspicuously but gradually narrower
toward the ends, equal to about 3 tracheids ; the lateral walls with
round or oval pits, about 2-3 per tracheid.

Tangential. Rays medium, broad, the cells round or transversely oval, vari-
able, 25-31 p. broad.

The Carboniferous at Pittsville, Pennsylvania.

200 ANATOMY OF THE GYMNOSPERMS

2. C. Clarkei, l)n.

Transverse. Growth rings obscure or entirely wanting. The tracheids about
41 x49 /LI broad, their walls 12.5 p. thick.

Radial. Bordered pits numerous throughout the tracheids, in 2-3, more
rarely in 4, rows. The elements of the medullary rays of two kinds ; the
parenchyma cells thin-walled and devoid of pits, about equal to 3
tracheids; the ray tracheids long, interspersed, and bearing on their
lateral upper and lower walls numerous crowded, bordered pits.

Tangential. Rays very variable, commonly i -seriate but sometimes 2-seriate
in part ; the tracheids usually distinguished by their narrow form and
pitted walls.

Hamilton Group, Ithaca, New York.

3. C. Newberryi, (Dn.) Knowlton

Transverse. Tracheids about 44 x 55 p., the walls about 12.5 p,, thick.

Radial. Ray cells resinous and starch bearing, long and narrow, about equal
to 3-7 tracheids, the ends conspicuously narrower; the pits on the
lateral walls 3-6, chiefly 4, per tracheid, the slitlike orifice nearly the
full diameter of the pit. Bordered pits numerous, round, about 9.3 p.
broad, distributed in radially disposed groups of about 6-13; the ori-
fice diagonal, nearly the diameter of the pit.

Tangential. Rays of medium height, i-, 2-, or rarely 3-seriate in part ; 24-55
p. broad, the oval or round cells all thin-walled.

Hamilton Group (Middle Devonian) of Ohio (Newberry) ; Carboniferous of
Ohio (Claypole).

4. C. recentium, Dn.

Transverse. Tracheids 47 x 53 p, broad, the walls much reduced by decay.

Radial. Ray cells all of one kind, about equal to 2 tracheids ; the lateral
walls with round pits about i (?) per tracheid ; the cells conspicuously
narrower at the ends. Bordered pits in a single row, compact, large,
compressed, and transversely oval or oblong, 15.6 x 22 p., the orifice
very variable from oblong to round, often eccentric, but typically round
and central. When distant the pits are round and smaller.

Tangential. Rays medium, i-seriate or 2-seriate, the very broad cells 41 p.,
thin-walled, round, and squarish.

The Permian or Permocarboniferous of Prince Edward Island.

5. C. hamiltonense, Penh.

Transverse. Tracheids very variable, growth rings obscure.

Radial. Structure of the medullary rays not determinable. Bordered pits

hexagonal, in 2 rows throughout.

Tangential. Rays numerous and variable, 31-57 P- broad; the cells very
'variable in form and size, thin-walled, often broader than high, chiefly
i-seriate, often more or less 2-seriate.

Genesee shales (Hamilton Group) of Ontario County, New York.

CORDAITES 201

6. C. illinoisense, Dn.

Transverse. Tracheids 47x47^ broad, the walls 9.3 p. thick.

Radial. Ray cells straight or abruptly narrowed at the ends, equal to 3-4

tracheids ; the lateral walls show no recognizable structure. Bordered

pits in 1-3, chiefly 2, rows, hexagonal, 12.5 p. broad.
Tangential. Rays numerous, i-seriate or 2-seriate in part, the broadly oval,

thin-walled cells 28 p. broad.

Chase Formation (Permian) of Chase County, Kansas ; the Coal Measures of
Rock Island, Illinois, and Boonsboro, Iowa (?).

7. C. materioide, Dn.

Transverse. Tracheids about 56x56 p. broad, the walls 12.5 p. thick.

Scattering tracheids contain resin.
Radial. Ray cells straight or somewhat contracted at the ends ; the pits on

the lateral walls oval, narrowly bordered, i-S, chiefly 2-3, per tracheid ;

the lenticular or oblong orifice nearly equal to the diameter of the pit.

Bordered pits hexagonal, in 1-3, chiefly 2, rows.
Tangential. Rays i-seriate or sometimes 2-seriate in part, upwards of 35 cells

high; the oval or round cells 25-31 p. broad.

Douglas Mine, Grand Lake, and Mirimichi, New Brunswick ; Port Hood and
Mabou, Cape Breton; Joggins, Nova Scotia.

8. C. annulatum, Dn.

Transverse. Structure much altered by decay, extensive areas being com-
pletely carbonized and consolidated to coal. The tracheids are about
34 x 44 p, broad, the walls much attenuated by decay.

Radial. Structure of the rays not determinable. Bordered pits hexagonal,
9.5 p. broad, in 2-3, chiefly 2, rows.

Tangential. The structure is too much altered by decay and pressure to
make the details obvious.

Middle Carboniferous, Joggins, Nova Scotia

9. C. ouangondianum, Dn.

Transverse. Tracheids about 47x56^ broad, the walls 9.3 p, thick. Growth

rings none.
Radial. Bordered pits numerous throughout the tracheids, in 2-4, chiefly 3,

rows, about 12 p. broad. Ray cells equal to about 3-4 tracheids; the

lateral walls with oval pits, 2-4, chiefly 4, per tracheid and disposed in

radial series.
Tangential. Rays of medium height, i-seriate or 2-seriate in part, the oval

cells chiefly about 25-37 p. broad.

Middle Devonian of New Brunswick.

202 ANATOMY OF THE GYMNOSPERMS

10. C. acadianum, Dn.

Transverse. The large tracheids are about 62x62 p. broad, the walls 9.5 p.

thick. Scattering tracheids show resinous contents.
Radial. Ray cells often somewhat abruptly contracted at the ends, equal to

2-4 tracheids; the lateral walls with numerous round or oval pits, 4-10

per tracheid, chiefly about 6, the border often very narrow, the oblong

orifice three fourths the diameter of the pit. Bordered pits numerous,

hexagonal, 12.5-16 fj. broad, crowded in 2-5 rows.
Tangential. Rays very variable, ranging upwards of 60 cells high, resinous,

more or less 2-seriate throughout, the oval or oblong cells 17-31 p.

broad.

Middle Coal Measures, Joggins, Nova Scotia; Port Hood, Mira, and Glace
Bay, Cape Breton ; Dorchester, New Brunswick ; St. George's Bay,
Newfoundland.

11. C. ohioense, Dn.

Trans-verse. Tracheids 47 x 56 p. broad, the walls 12.5 p, thick.

Radial. Ray cells chiefly short, about equal to 2 tracheids, straight, or
somewhat abruptly contracted at the ends ; the pits on the lateral walls
oval, with a prominent border, apparently 2 per tracheid, but not
exactly determinable on account of extended decay. Bordered pits in
3-4 rows, sometimes 2 rows throughout the tracheid, hexagonal, about
12.5 p, broad.

Tangential. Rays numerous, upwards of 25 cells high; broad, about 41 p.,
conspicuously squarish, i- or often 2-seriate or 3-seriate in part.

New Lisbon, Ohio.

12. C. materiarium, Dn.

Transverse. Tracheids 45 x 75 p. broad, the walls 7.8 p. thick. Scattering
tracheids show resinous matter.

Radial. Ray cells straight, somewhat narrowed at the ends, equal to about
2-6 tracheids ; the pits on the lateral walls large, oval, round, or oblong,
narrowly or even obscurely bordered, 1-5, chiefly 1-2, per tracheid.
Bordered pits numerous throughout the tracheids, chiefly in 2, some-
times in 3-4, rows, hexagonal, or, when more distant, oval, about 12.5 p.
broad.

Tangential. Rays i-seriate or 2-seriate in part, upwards of 40 cells high, the
oval or round cells 17-35 f broad.

Holmes County, Ohio (Newberry) ; Upper Coal Measures of Malagash,
Pictou, Joggins, Belen, and Cambon, Nova Scotia ; St. George's Bay, New-
foundland ; Mirimichi, New Brunswick ; Glace Bay, Cape Breton ; Marion
County, Illinois.

13. C. Halli, Dn.

" Wood cells very large, with 5 rows of contiguous, alternate, hexagonal
areoles. Medullary rays frequent, and with as many as 30 rows of cells
superimposed " (Dawson).

Middle Devonian of Ontario County, New York.

ARAUCARIA

2. *DAMMARA,J LAMB. PLATES 14 AND 1 5

203

Transverse. Growth rings more or less clearly defined. Resin-bearing

tracheids more or less prominent.
Radial. Rays wholly devoid of tracheids. Bordered pits hexagonal in 1-3

rows. Spiral tracheids wanting.
Tangential. Medullary rays all of one kind and i-seriate, usually composed

of broad cells.

1. D. australis, Steud.
Kanrie. Coiudie Pine

Transverse. Growth rings very variable and usually poorly defined. Summer
wood thin, often obscure, the structure open but the tracheids thick-
walled, passing gradually into the spring wood. Spring wood of large,
thickish-walled, very variable tracheids with distinctly rounded lumens.
Resinous tracheids rather numerous, not very prominent, generally in
rows on either side of the medullary rays. Medullary rays prominent,
rather resinous, i cell wide, not numerous, distant 2-27 rows of
tracheids.

Radial. Medullary rays devoid of tracheids ; the resinous cells strongly
contracted at the ends, equal to about 5 spring tracheids ; the upper
and lower walls thin and not pitted ; the terminal walls thin and entire,
not locally thickened ; the lateral walls with round, bordered pits and a
diagonal, lenticular orifice, 2-6 per tracheid. Wood tracheids usually
radially thickened opposite the medullary rays, with the development of
resinous plates simulating Sanio's bands. Bordered pits hexagonal,
chiefly in 2, or more rarely 1-3, rows. Pits on the tangential walls of
the summer tracheids very numerous, large, and prominent.

Tangential. Fusiform rays wholly wanting. The resinous rays strictly
i-seriate, the cells very broad, unequal, oval or transversely oval, the
thin walls often broken out.

3. * ARAUCARIA, Juss. PLATES 16 AND 17

Transverse. Growth rings not determinable, or at most poorly defined.
Resin passages and specialized resin cells entirely wanting. Resin-
bearing tracheids more or less prominent.

Radial. Rays wholly devoid of tracheids. Bordered pits usually hexagonal,
multiseriate. Spiral tracheids wholly wanting.

Tangential. Fusiform rays wholly wanting.

1 The genus Protodammara has been created by Hollick and Jeffrey for the
reception of certain cretaceous cones, but at present it does not contain any wood.

204 ANATOMY OF THE GYMNOSPERMS

SYNOPSIS OF SPECIES
I. ARAUCARIA

Existing species confined to the southern hemisphere and unknown in the
fossil state.

A. Growth rings obscure or wanting

Bordered pits in 1-3 rows, hexagonal.

Resin-bearing tracheids (radial) wanting.

1 . A. Cunninghamii

Resin-bearing tracheids (radial) numerous, the resin in thick plates like
Sanio's bands.

2. A. excelsa

B. Growth rings obvious

Bordered pits crowded in i row, more or less rounded, not strictly hexagonal.
Rays (radial) locally and strongly resinous, the lateral walls at such
points with sieve-plate structure.

3. A. Bidwillii

II. * * ARAUCARIOXYLON

Extinct species occurring in Mesozoic and Tertiary strata, the remains
being usually silicified or calcified.

A. Growth rings obscure or wanting

Bordered pits in 1-3 rows.

4. * * A. Woodworthi.
Bordered pits in 1-2 rows.

5. * * A. virginianum.
Bordered pits chiefly in i row.

Growth rings wholly wanting.

6. * * A. Prosseri.
Growth rings present but obscure.

7. * * A. arizonicum.

B. Growth rings obvious
Bordered pits in 1-2 rows.

8. * * A. Hoppertonas.
Bordered pits chiefly in i row.

9. * * A. Edvardianum.

Araucarioxylon obscurum of Knowlton {Mesozoic Floras of the United
States, p. 418) does not belong here at all, but is cited now for future
reference.

ARAUCARIA 205

1. A. Cunninghamii, Sweet.

Moreton Bay Pine. Hoop Pine. Colonial Pine. Coorong. Cumburizi. Coonam

Transverse. Growth rings not clearly discernible ; tracheids very unequal in
irregular, radial rows, round-hexagonal, the walls medium ; the structure
open throughout. Resinous tracheids few, widely scattering. Medullary
rays prominent, somewhat resinous, broad, i cell wide, distant 2-23
tracheids.

Radial. Ray cells conspicuously contracted at the ends, often very unequal,
about equal to i o tracheids ; the upper and lower walls thin and not
pitted ; the terminal walls thin, commonly curved, not pitted or locally
thickened ; the lateral walls with pits having an obscure border and a slit-
like orifice, numerous, 3-8 per tracheid. Bordered pits in 1-2 or 3
rows, compact, compressed, hexagonal. Pits on the tangential walls of
the summer tracheids wanting.

Tangential. Rays numerous, low to medium, resinous ; sometimes 2-seriate
in part ; the cells very large, unequal, oval or transversely oval, the
walls thin.

2. A. excelsa, R. Br.

Norfolk Island Pine

Transverse. Growth rings not determinable ; the unequal tracheids in
irregular, radial rows, round-hexagonal, the walls medium, the structure
open throughout. Resin-bearing tracheids in small, scattered groups, or
in rows parallel with the rays on either side. Rays prominent, broad,
somewhat resinous, i cell wide, distant 2-21 rows of tracheids.

Radial. Ray cells conspicuously contracted at the ends, equal to 6-8
tracheids ; the upper and lower walls thin, entire ; the terminal walls
thin, not pitted ; the lateral walls with round, bordered pits having a
slitlike orifice, about 3-6 per tracheid. Resin-bearing tracheids numer-
ous, the resin in thick plates simulating Sanio's bands in the vicinity of
rays. Bordered pits in 1-2 rows, compact, hexagonal.

Tangential. Rays medium, numerous, broad ; the cells oval or squarish,
thin-walled, unequal, the thin walls commonly broken down ; i -seriate.

3. A. Bidwillii, Hook.
Bunya-Bimya

Transverse. Growth rings broad but poorly defined by a slightly more open
structure in the early spring wood ; the structure rather dense through-
out, the unequal tracheids thick-walled, round-hexagonal. Medullary
rays not very prominent, locally very resinous, i cell wide, distant 4—45
rows of tracheids.

Radial. Ray cells rather high and short, equal to upwards of 5 tracheids ;
distant cells strongly resinous ; conspicuously contracted at the ends ;
the upper and lower walls very thin and entire ; the terminal walls thin,
entire, commonly curved ; the lateral walls with obscurely margined
pits ; the orifice linear or slitlike, diagonal, 3-7 per tracheid, in the very
high, marginal cells forming high, vertical series. Where resin is

206 ANATOMY OF THE GYMNOSPERMS

deposited the lateral walls of groups of cells bear numerous rounded
pits, giving a sieve-plate structure. Bordered pits crowded in i row,
more or less rounded, not hexagonal, as broad as the narrow tracheids.
Pits on the tangential walls of the summer wood wanting.
Tangential. Rays low, only a few cells high, numerous, resinous ; the cells
oval, broad, thin-walled, strictly i-seriate.
%

4. * * A. Woodworthi, Kn.

" Transverse. Annual ring very obscure and not visible to the naked eye, but
on examination under the microscope it is found to be present and to
consist of only 2 or 3 slightly smaller and thicker-walled cells. The
wood cells are only moderately thick-walled and are quite uniform
in size.

" Radial. This section shows to the best advantage the character of the wood.
The wood cells are shown to be long, sharp pointed, and to be provided
with usually 2 rows of bordered pits, although cells are common on
which there is but a single series. Cells on which there are 3 rows of
pits are much rarer. When in a single row the pits are contiguous and
but slightly modified in shape by pressure. When the pits are in 2 rows
they usually occupy the center of the cell and are contiguous and
slightly hexagonal ; but occasionally the 2 rows may be slightly sep-
arated and then may have the characters of the single rows. When
there are 3 rows of pits they are close together and markedly hexagonal.
The average diameter of the pits is about o.o 1 5 mm., and that of the
inner pore about 0.003 or 0.004 rnrn. The medullary rays, as seen in
this section, are short-celled, each cell being about as long as the width
of 2^ wood cells. They are without markings or pits of any kind, so
far as can be made out.

" Tangential. Owing to pressure in this direction the section is somewhat
distorted and does not show clearly the relative abundance of the rays.
The number of cells entering into the composition of the rays, however,
shows satisfactorily. It is found that they are in a single vertical series
of 1-12 cells, the usual number being 3 or 4" (Knowlton).

Material silicified. Specimen from a large, prostrate trunk 20 feet or more

in length and over 4 feet in diameter.
Richmond Basin (Trias) south of Mosley Junction, Chesterfield County,

Virginia (Knowlton).

5. * * A. virginianum, Kn.

" Transverse. Growth rings not obvious to the naked eye, but apparent
microscopically. The line of demarcation consists of only 3 or 4 rows
of slightly smaller and thicker-walled cells. [Growth rings obscure,
D.P.I'.] Tracheids prominent, with thick walls. The individual cells
have a diameter of 0.051 mm., the average being about 0.0375111111.
They are arranged in radial rows, which are most pronounced in prox-
imity to the medullary rays.

" Radial. The radial walls are the only ones bearing bordered pits. The
number of rows varies, even on the same cell, from 1-2. When there is
but i row they occupy the center of the cell and are in contact. They

ARAUCARIOXYLON 207

are then nearly circular in outline and have a diameter of o.oi 7-0.02 mm.
When there are 2 rows they are in contact and alternate with each
other, and have a nearly regular, hexagonal outline. These hexagonal
pits have a diameter of o.oi6-.o2i mm. The inner pore is very small,
being only about .002 5-. 003 mm. in diameter.

" Tangential. The rays are single and range from 1-27 cells in height, the
average number being about 10-12" (Knowlton).

Material silicified. Specimen represented by a small fragment.
From the Potomac Formation at Taylorsville, Virginia (Knowlton).

6. * * A. Prosseri, Penh.

Transverse. Tracheids in regular radial rows, squarish, 39 x 42 p broad ;
the walls 6.2 p. thick. Resin cells and special resin passages wholly
wanting. No evidence of growth rings in a radial extent of 22 mm.

Radial. Ray cells all of one kind, straight or narrower at the ends, equal to
3-9 tracheids ; the upper and lower walls thin and devoid of pits ; the
terminal walls thin, not pitted, curved ; the lateral walls show no struc-
ture through extreme alteration. Bordered pits not clearly determinable,
but probably round and in i row.

Tangential. Rays numerous, chiefly low ; the cells broad, round, about 31 ^
wide.

Material silicified.

The Cheyenne (Comanche Cretaceous) of the bluff west of Sun City, Medi-
cine Lodge River, Baker County, Kansas, 1897 (Prosser).

7. * * A. arizonicum, Kn.

" Transverse. Annual rings not apparent to the naked eye, but under the
microscope observed to be present, the yearly growths being separated
by a layer of 2-5 tangentially compressed cells ; the tracheids in this
section are observed to have moderately thick cell walls, and to be
separated by small intercellular spaces. The largest cells observed have
a diameter of .055 mm. and the smallest of about .020 mm., the average
being about .040 mm.

" Radial. As seen in this section the tracheids are observed to be long, and
to be provided with numerous pores. These pores or bordered pits
are usually arranged in a single series, and number 40-80 or more on
each cell. Usually they touch each other slightly, but sometimes they
become a trifle compressed by actual contact. When these pores are
arranged in 2 series they alternate and are slightly, if at all, angled by
mutual pressure. The pores are rather large, the average diameter for
the outer circle being about .02 mm., that for the inner .0040 mm. The
medullary rays are composed of short, thin-walled cells, which, in some
instances, seem to have been provided with small, oval pores. They are
difficult of demonstration, and it is possible that the granular contents
of the cells may give the appearance of exterior markings.

" Tangential. This section demonstrates the presence of pores or bordered
p'its on the tangential walls, a circumstance of infrequent occurrence

208 ANATOMY OF THE GYMNOSPERMS

in the genus Araucarioxylon. They are much smaller than the pores
on the radial walls, and are in a single or rarely in 2 series. The pores
are always separated from each other, sometimes widely so. The diame-
ter of the outer circle is about .0075 mm., and that of the inner about
.0027 mm. The medullary rays are numerous and range in height from
1-22 cells. It is possible that in some rare cases they may be in 2
series, but this is certainly not commonly the case. No resin ducts
have been detected in any of the sections, their absence being a well-
known character of the genus" (Knowlton).

Material silicified. Specimens are represented by fragments of trunks
upwards of 20 inches in length and 1 3 inches in diameter.

Triassic or Lower Jurassic near Fort Wingate, New Mexico ; Lithodendron
Creek (Cretaceous?) and Chalcedony Park, Arizona (Knowlton).

8. * * A. Hoppertonae, Kn.

" Transverse. Annual rings very distinct, of 4-8 rows of very thick-walled
fall wood. The spring wood is made up of very large though thick-
walled cells, which begin very abruptly at the fall wood. The cells
gradually decrease in size until the last 5-8 rows of cells are very thick.

" Radial. As the material has been very finely preserved, this section shows
remarkably well. The wide cells of the spring wood are provided with
usually 2 longitudinal rows of hexagonal pores, which quite cover the
walls. Occasionally, in cells of unusual width, the pores, while in 2
series, are only slightly compressed. Usually when but i row is present
they are hexagonal and occupy the center of the cell. The inner pores
in these punctations are relatively small and slightly elongated in a
direction at right angles to the cells. The medullary rays as seen in
this section are short, covering the width usually of 4 or 5 wood cells,
although occasionally longer and covering as many as 8 cells. They
are provided with a single row of bordered pores so arranged that i
comes over each wood cell, or occasionally there may be 2 over a wood
cell. The inner pore is minute.

" Tangential. The medullary rays as seen in this section are quite numer-
ous, in a single series of from 3 to sometimes as many as 15 superim-
posed cells. The wood cells as seen in this section do not seem to
have been provided with punctations or other markings" (Knowlton).

Material silicified.

Cretaceous formation of the Black Hills, Cycad bed 2 miles southeast of
Minnekahta Station, South Dakota (Knowlton).

9. * * A. Edvardianum, Dn.

" Trunks with distinct rings of growth, and with a central pith not
observed to have transverse laminae. Wood cells with i or rarely 2 rows
of contiguous, hexagonal areolas. Medullary rays simple, infrequent, with
2-10 rows of cells superimposed" (Dawson).

Triassic of Prince Edward Island (Dawson).

GINGKO 209

II. GINGKOALES

Wood nonresinous, the tracheids of two kinds, interspersed. Wood paren-
chyma present and forming idioblasts containing sphere crystals.

1. * GINGKO, KAMPF. PLATES 18 AND 19

Transverse. Growth rings broad. The summer wood thin ; the structure
chiefly open throughout ; tracheids chiefly squarish and large, with
smaller, thicker-walled tracheids interspersed. Resin passages and resin
cells wholly wanting. Crystal-bearing idioblasts rather numerous.

Radial. Medullary rays devoid of tracheids. Terminal walls of the ray cells
very thin and not pitted. Bordered pits in 1-2 series. Spiral tracheids
wholly wanting.

Tangential. Fusiform rays wholly wanting. Ray cells rather broad and
thin-walled.

1. G. biloba, Linn.
Maidenhair Tree. Salisbitria. Gingko. Jap. = Icho

Transverse. Growth rings very broad, the summer wood very narrow and of
open structure, passing gradually into the spring wood. Spring wood
open, the tracheids large, squarish, very unequal, somewhat thin-walled,
with which are interspersed less numerous, much smaller, rounded, and
thick-walled tracheids. Idioblasts containing sphere crystals somewhat
numerous. Medullary rays prominent, slightly resinous, i cell broad,
distant 2-10, more rarely 15, rows of tracheids.

Radial. Cells of the medullary rays conspicuously contracted at the ends,
locally somewhat resinous, equal to about 5-7 spring tracheids; the
upper and lower walls very thin and not pitted ; the terminal walls very
thin, not pitted or locally thickened, chiefly straight ; the lateral walls
with oval, bordered pits having a narrowly oval or oblong orifice, about
1-4, or, in the marginal cells, 7, per tracheid. Bordered pits very numer-
ous in the broader tracheids, where they are compressed vertically and
crowded in i row, or more generally in pairs, forming 2 compact series;
in the narrower tracheids few, round, distant, and often wanting. Pits
on the tangential walls of the summer tracheids numerous, large, and
open. Idioblasts round or oblong, i sphere crystal to each ; scattering
or often in vertical series.

Tangential. Fusiform rays wholly wanting. Rays strictly i-seriate, low to
medium ; the cells rather broad, oval, thin-walled, somewhat variable.
Idioblasts oblong, in vertical series.

Native of Japan, now widely distributed through cultivation in similar
climates.

2. * * G. pusilla, Dn.

Transverse. Growth rings obvious, the spring wood passing gradually into
the not strongly denned summer wood ; tracheids in regular radial
rows, very uniform, those of the spring wood about 22 x 21 p., the walls
5.3 fj., thick. Medullary rays very narrow.

210 ANATOMY OF THE GYMNOSPERMS

Radial. Medullary rays very low, the cells straight, about 1 7 fj. high, equal
to about 5 tracheids ; the upper and lower walls thin and not pitted ;
the terminal walls thin, straight, and devoid of pits ; the lateral walls
with large (?) pits, i per tracheid. Bordered pits on the radial walls of
the tracheids not recognizable.

Tangential. Medullary rays 1-3, more rarely 4, cells high, about 8.7 p.
broad.

Material calcined.

Upper Cretaceous of Port McNeil, Vancouver Island, and Upper Creta-
ceous of Cumshava Inlet, Queen Charlotte Islands.

III. CONIFERALES

Wood more or less resinous, often characterized by the presence of
specialized resin cells, cysts, or passages. Tracheids (transverse) in radial
rows, bearing on their radial walls, as also on the tangential walls of the sum-
mer tracheids, round or elliptical, often distant, bordered pits in 1-3 series.

1. TORREYA, ARNOTT. PLATES 20 AND 21

Transverse. Growth rings rather thin, often variable ; tracheids rather
large, chiefly squarish, the structure generally open throughout. Sum-
mer wood usually very thin. Resin cells and resin passages wholly
wanting.

Radial. Ray cells very long, the tracheids of the wood with rather open
spirals in 2-4 series.

Tangential. Ray cells large, broadly oval or oblong. Fusiform rays wholly
wanting.

SYNOPSIS OF SPECIES

A. Summer wood thin, of 2-4 tracheids or more, often double ; the
structure of the growth ring very open throughout

Tracheids large, distinctly squarish.
Spirals in 2 series.

1. T. taxifolia.

B. Summer wood thin but sometimes equal to the spring wood

Tracheids very unequal, not conspicuously squarish, chiefly hexagonal,
often in very irregular rows.

Spirals imperfectly 2-4 seriate, often very incomplete.

2. T. californica.
Spirals in double, triple, or quadruple series.

3. T. nucifera.

TORREYA 211

1. T. taxifolia, Arnott
Stinking Cedar. Savin

Transverse. Growth rings variable, 1.5-3 mm. thick. Summer wood of 2-4
or more tracheids, usually very thin, often double and passing gradually
into the spring wood ; spring tracheids squarish and in regular rows,
rather uniform. Structure of the growth ring open throughout. Medul-
lary rays somewhat prominent, i cell wide, distant 2-9, rarely 16, rows
of tracheids.

Radial. Ray cells straight ; the upper and lower walls thick, conspicuously
pitted, uniform ; the terminal walls thin and entire, sometimes curved ;
the lateral walls with small, round, but variable pits with a distinct
border, the orifice very narrow, 2-5 per tracheid. Bordered pits in I
or 2 rows. Pits on the tangential walls of the summer tracheids obscure.
Spirals of the tracheids in 2 series, distant 5-30 p, very flat, the angle
70.4°, compact and finally vestigial in the summer wood.

Tangential. Rays medium, the cells rather small, oval, or oblong, thick-
walled.

Very durable in the soil.

Relative specific gravity 0.5145

Approximate fuel value 51 .08

Coefficient of elasticity in kilograms on millimeters. . . 821.

Ultimate transverse strength in kilograms 378.

Ultimate resistance to longitudinal crushing in kilograms 7364.

Resistance to indentation to 1.27 mm. in kilograms . . . 2523.
(Sargent)

Western Florida.

2. T. californica, Torr.

Stinking Cedar. California Nutmeg

Transverse. Growth rings 1.5-2.5 mm. broad. Summer wood thin, some-
times one fourth to one half the spring wood into which it passes
gradually. Structure of the growth rings rather open throughout,
the tracheids somewhat rounded and in more or less irregular rows.
Medullary rays rather prominent, i cell wide, distant 2-14 rows of
tracheids.

Radial. Ray cells straight ; the upper and lower walls rather thin, con-
spicuously double and frequently pitted ; the terminal walls very thin
and entire ; the lateral walls with rather variable, round, bordered
pits, i-6 per tracheid, the orifice very narrow. Bordered pits usually
somewhat distant, elliptical, in i row, sometimes in pairs. Pits on
the tangential walls of the summer tracheids small and obscure.
Spirals of the tracheids high, often very incompletely developed,
imperfectly 2-4 seriate, distant 5-125 //, or more, the angle 46.2°, in
the summer wood obscure and finally obsolete.

Tangential. Rays medium to low, the cells large, rather thin-walled.

212 ANATOMY OF THE GYMNOSPERMS

Very durable in the soil.

Relative specific gravity 0.4760

Approximate fuel value 46.96

Coefficient of elasticity in kilograms on millimeters . . 401.

Ultimate transverse strength in kilograms 249.

Ultimate resistance to longitudinal crushing in kilograms 5625.

Resistance to indentation to 1.27 mm. in kilograms . . 1962.
(Sargent)

Mendocino County, California, and along the western slope of the Sierra
Nevadas to Tulare County, at elevations of 3000-5000 feet (Sargent).

3. T. nucifera, Sieb. et Zucc.

Jap. — Kaya

Transverse. Growth rings rather narrow ; the tracheids of the spring wood
large, often distinctly squarish, passing gradually into the conspicuous
but narrow summer wood of about 10 tracheids, which again becomes
equal to the spring wood. Medullary rays prominent, i cell wide, dis-
tant 2-1 o rows of tracheids.

Radial. Cells of the medullary rays not contracted at the ends, equal to
about 6 tracheids ; the upper and lower walls medium, remotely and
obscurely pitted; the terminal walls thin, not pitted or locally thick-
ened, diagonal or straight, rarely curved ; the lateral walls with small,
conspicuously bordered, oval pits with a diagonal, linear-oblong ori-
fice, about 2-6, or, in the summer wood, i per tracheid. Bordered
pits in i series, or in pairs, forming 2 imperfect series, distant,
the outer margin rather obscure, the orifice lenticular and diagonal
throughout. Pits on the tangential walls of the summer wood wholly
wanting. Spirals of the tracheids prominent, distant 5-25 yu., in double,
triple, or quadruple series, the angle 70.5°, in the summer wood
becoming vestigial in the outer tracheids.

Tangential. Rays numerous, low to medium, the walls of the cells rather
thick. Pits on the tangential walls of the summer wood wanting.

Japan.

2. * TAXUS, TOURN. PLATES 22 AND 23

Transverse. Growth rings variable, often unconformable. The summer
wood dense and conspicuous, though often very thin ; the tracheids
small throughout and more or less rounded, the structure somewhat
dense or more rarely open (T. floridana), with large and squarish
tracheids. Resin passages and resin cells wholly wanting.

Radial. Spirals of the tracheids rather close, 2-, rarely 3-seriate.

Tangential. Ray cells narrowly oblong. Fusiform rays wholly wanting.

SYNOPSIS OF SPECIES

A. Tracheids small, rounded, thick-walled
Rays low, i -seriate.

Growth rings variable, sometimes double.

2. * T. canadensis, Willd.

TAXUS 2 1 3

Rays chiefly high, 1-2 seriate.
Growth rings usually broad.

3. T. brevifolia, Nutt.

B. Tracheids medium, rather thick-walled
Rays medium.

Growth rings usually rather broad.

4. T. cuspidata, Sieb. et Zucc.

C. Tracheids large, the structure open

Rays chiefly high.

i. T. floridana, Nutt.

1. T. floridana, Nutt.
Yew

Transverse. Growth rings medium, irregularly eccentric. Summer wood
very thin, upwards of 10 tracheids thick, rarely double, open ; the
tracheids unequal in irregular rows with more or less conspicuous
intercellular spaces ; transition to the spring wood gradual. Medul-
lary rays prominent, I cell wide, distant l-io rows of tracheids.

Radial. Ray cells straight, rather narrow ; the upper and lower walls
entire, more or less sinuately unequal ; the terminal walls thin and
not pitted ; the lateral walls with somewhat conspicuously bordered
oval or rounded pits, the orifice lenticular, diagonal, chiefly 1-2,
more rarely 3, or, in the marginal cells, 4 per tracheid. Bordered pits
very scattering except at the ends of tracheids, where they become
more or less 2-rowed. Pits on the tangential walls of the summer
wood small, often very distant, the orifice bell-shaped. Spirals of
the tracheids prominent, rather flat, 2-seriate, distant 7.5-20 ft, rarely
more, the angle 78.4°, wanting in the outer summer wood.

Tangential. Rays medium to high, the cells very narrowly oval to oblong.

Western Florida.

2. * T. canadensis, Willd.

American Yew. Ground Hemlock

Transverse. Growth rings narrow and variable, often unconformable.
Summer wood variable, now thin and abruptly passing into the
spring wood, or thickish and finally equal to the spring wood into
which it gradually passes ; rather dense. Spring wood more open, the
tracheids small throughout and thick-walled but distinctly rounded
and variable. Medullary rays i cell wide, not very prominent, dis-
tant 2-15 tracheids.

Radial. Ray cells equal to about 5 spring tracheids ; the upper and lower
walls rather thin, uniform, entire, or remotely pitted ; the terminal walls
thin and entire, often curved ; the lateral walls with round, bordered
pits, 1-2 per tracheid. Bordered pits small, round. Pits on the tangen-
tial walls of the summer wood very numerous but small and obscure.
Spirals of the tracheids very prominent, 2-3 seriate, distant 7.5-15 /*>
the angle 72.4°, conspicuous throughout the summer wood.

Tangential. Rays very low, the cells rather thick-walled.

214 ANATOMY OF THE GYMNOSPERMS

Damp woodlands from Newfoundland westward to Lake Winnipeg and
Minnesota, northward to York Factory, and southward to New Jersey
or along the Alleghenies to Virginia.

The Pleistocene of the Don River, Toronto ; Solsgirth and Heart Hill,
Rolling River, Manitoba, and Fort Madison, Iowa ; Cape Breton and
Bloomington, Illinois. An abundantly represented and widely dis-
tributed species in the northern United States and southern Canada.

3. T. brevifolia, Nutt.

Yeiv. Western

Transverse. Growth rings thick, upwards of 2-3 mm. Summer wood
dense, about equal to the spring wood into which it passes very
gradually. Spring wood open, the tracheids in regular rows, rather
uniform, not much rounded. Medullary rays I cell wide, distant
about 1-17 rows of tracheids.

Radial. Ray cells very long ; the upper and lower walls thickish, unequal,
conspicuously double, entire or distantly pitted ; the terminals walls
thin and entire ; the lateral walls with round, conspicuously bordered
pits, chiefly 2, more rarely 4, per tracheid, the narrow diagonal orifice
equal to the outer ring. Bordered pits round or elliptical. Pits on
the tangential walls of the summer tracheids numerous but very small
and obscure. Spirals of the tracheids prominent, 2-seriate, distant
7.5-20 fj., rarely more, the angle 63.0°, vestigial in the summer wood.

Tangential. Rays commonly high, the cells thick-walled.

Very durable in the soil.

Relative specific gravity ........... 0.6391

Approximate fuel value ............ 63.78

Coefficient of elasticity in kilograms on millimeters . . 761.

Ultimate transverse strength in kilograms ..... 460.

Ultimate resistance to longitudinal crushing in kilograms 7734.

Resistance to indentation to 1.27 mm. in kilograms . . 4223.
(Sargent)

Vancouver Island and adjacent mainland and on the lower Skeena
(Macoun) ; sparingly in the Queen Charlotte Islands (Dawson) ; south-
ward through the coast ranges of British Columbia, Washington, and
Oregon, the western slopes of the Rocky Mountains in Montana, and
through the California coast ranges to Monterey and the southern slopes
of the Sierra Nevadas to latitude 37° N. (Sargent).

4. T. cuspidata, Sieb. et Zucc.
Yew. Jap. = Araragi

Transverse. Growth rings rather broad. Summer wood prominent, about
one fourth the spring wood into which it passes gradually. Spring
wood somewhat open, the tracheids distinctly hexagonal, rather

THUJOPSIS 2 1 5

uniform and thin-walled. Bordered pits on the tangential walls of the
summer tracheids few and obscure. Medullary rays prominent, I cell
wide, distant about 2-10 tracheids.

Radial. Cells of the medullary rays not much contracted at the ends;
the upper and lower walls rather thin, but very unequal and obscurely
pitted ; the terminal walls thin, often obscure, not pitted or locally
thickened, diagonal and chiefly straight ; the lateral walls with con-
spicuously bordered pits, oval, with a diagonal, lenticular-oblong
orifice, chiefly 2 per tracheid in radial series, equal to about 4-9
tracheids. Bordered pits round, about two thirds the width of the
tracheid, in open rows, the orifice round, concentric, in the summer
wood becoming lenticular, diagonal. Pits on the tangential walls of
the summer tracheids distant, rather obscure. Spirals of the tracheids
2-seriate, distant 12.5-25 p., the angle 66.1°, vestigial in the summer
wood.

Tangential. Bordered pits on the tangential walls of the summer tra-
cheids not very numerous, in distant groups. Rays low to high,
numerous.

3. THUJOPSIS, SIEB. ET Zucc. PLATES 24 AND 25

Transverse. Growth rings usually very narrow. Resin passages wholly
wanting. Resin cells not numerous but prominent, rarely zonate.

Radial. Ray tracheids wholly wanting. Bordered pits generally rather
numerous, in i row. Tracheids wholly without spirals.

Tangential. Fusiform rays wholly wanting, the i-seriate rays low, resinous.

1. T. dolabrata, Sieb. et Zucc.

Jap. = Hiba

Transverse. Growth rings very narrow and variable. Summer wood
rather open, sometimes dense, thin, of 2-10 tracheids, the transition
to the spring wood rather gradual. Spring wood very open, the
tracheids large, squarish-hexagonal, in very regular rows, uniform,
very thin-walled. Resin cells very prominent, not numerous, scatter-
ing throughout the growth ring, not obviously zonate. Medullary
rays prominent and resinous, not numerous, i cell wide, distant 2-12
or sometimes 16 rows of tracheids.

Radial. Rays somewhat resinous. The cells conspicuously contracted at
the ends, equal to 5-6 spring tracheids ; the upper and lower walls
thick, sparingly pitted ; the terminal walls thin, often curved, not
pitted or locally thickened ; the lateral walls with small, obscurely
bordered pits, the large orifice broadly lenticular or oval, about 1-2
per tracheid. Bordered pits round or elliptical, nearly as broad as
the tracheid, rather numerous, in i row. Pits on the tangential walls
of the summer tracheids few, very flat, and rather obscure. Resin cells
15-25 //, wide, chiefly 225 p. long.

Tangential. Rays low, not very broad, resinous ; the cells oval or oblong,
rarely round, rather thick-walled, i-seriate.

216 ANATOMY OF THE GYMNOSPERMS

4. CRYPTOMERIA, DON. PLATES 26 AND 27

Transverse. Growth rings medium, with a dense summer wood and open

spring wood. Resin passages wholly wanting. Resin cells prominent

and scattering.
Radial. Rays wholly devoid of tracheids ; the cells sparingly, if at all,

resinous; the terminal walls thin and not pitted or locally thickened.

Bordered pits in i row, much less than the diameter of the tracheid.
Tangential. Fusiform rays wholly wanting. Cells of the i -seriate rays rather

broad, round.

1. C. japonica, Don.
Cryptomeria. Jap- = Sugi

Transverse. Growth rings medium, rather uniform. The summer wood
prominent, about one fourth the spring wood into which it passes
rather abruptly, the structure dense. Spring wood very open, the
large tracheids hexagonal, uniformly thin-walled. Resin cells promi-
nent and scattering, chiefly confined to the summer wood and the
late spring wood, the resin filling the cells. Medullary rays some-
what prominent, distant 2-14, more rarely 20, rows of tracheids.

Radial. Ray cells more or less contracted at the ends, equal to 5-9 spring
tracheids ; the upper and lower walls rather thick, uniform, distantly
pitted ; the terminal walls thin, not pitted or locally thickened,
straight or curved ; the lateral walls with round, obscurely bordered
pits, 1-2 in radial series or in the marginal cells 3-5 per tracheid.
Bordered pits one half the diameter of the tracheid, in i row, round,
the orifice round ; in the summer wood small, becoming obscure or
entirely wanting, the orifice a slit. Pits on the tangential walls of the
summer tracheids small but numerous. Resin cells upwards of 20 p.
wide and upwards of 400 //. long.

Tangential. Rays all i -seriate, rarely 2-seriate in part ; low, the cells round,
rather thick-walled, uniform.

5. PODOCARPUS, L'HER. PLATES 28 AND 29

Transverse. Growth rings very variable, either very narrow or very broad.
Summer wood very thin and not clearly distinguishable from the
spring wood. Structure open, tracheids of the spring wood large,
squarish. Resin passages wholly wanting. Resin cells numerous,
scattering, rarely zonate.

Radial. Ray tracheids wholly wanting. Bordered pits small, distant in
i row. Spiral tracheids wholly wanting.

Tangential. Fusiform rays wholly wanting. Ray cells oval or round,
thick-walled.

1. P. macrophylla, Don.

Jap. = Maki

Transverse. Growth rings very variable and narrow, or again broad. The
summer wood very thin and not very different, of 2-4 tracheids and
passing imperceptibly into the spring wood. Tracheids of the spring

TAXODIUM 2 1 7

wood chiefly rectangular, rather uniform, and somewhat thick-walled.
Resin cells very numerous, the resin chiefly in a peripheral layer ;
scattering throughout the growth ring or occasionally becoming more
or less zonate. Medullary rays prominent, numerous, and i cell wide,
distant 2-9 rows of tracheids.

Radial. Medullary rays conspicuously resinous, numerous ; the cells not
much contracted at the ends, equal to about 6 tracheids. The upper
and lower walls thickish, unequal, irregularly and often distantly
pitted, the pits rather broad ; the terminal walls thin, not pitted or
locally thickened, chiefly strongly curved ; the lateral walls with small,
rather obscure, oval pits, 1-2 per tracheid, the orifice narrowly lenticu-
lar, often slitlike. Resin cells very numerous, upwards of 20 p. wide and
200 p. long. Bordered pits small, round, distant in i row. Pits on the
tangential walls of the summer wood numerous, conspicuous, open.

Tangential. The I -seriate rays very numerous, medium ; the oval or round
cells somewhat thick-walled, rarely in pairs.

6. * TAXODIUM, RICH. PLATES 30 AND 31

Transverse. The summer wood of the usually broad growth rings much
less than the spring wood. Resin passages wholly wanting. Resin
cells numerous and prominent, either scattering or zonate.

Radial. Rays wholly without tracheids, the cells commonly contracted at
the ends. Tracheids wholly without spirals.

Tangential. Fusiform rays wholly wanting, the cells of the i-seriate rays
broadly oval.

SYNOPSIS OF SPECIES

Resin cells large, numerous, more or less distinctly zonate.

Pits on the lateral walls of the rays cells 1-4, more rarely 7, per tra-
cheid, the lenticular orifice narrow.

Bordered pits numerous, often paired, or in the earlier spring
wood imperfectly 2-rowed.

1. * T. distichum.

Resin cells obscure and forming an open zone on the inner face of the
summer wood.

Pits on the lateral walls of the ray cells about 2-3 per tracheid in
radial series.

Bordered pits numerous, in the earlier spring wood crowded into 2-3
compact rows, but becoming 2-rowed toward the summer wood.

2. * * T. laramianum.

1. * T. distichum, Rich.

Bald Cypress. Deciduous Cypress

Transverse. Growth rings usually very broad. The dense and conspicu-
ous summer wood often double or treble ; transition to the spring

218 ANATOMY OF THE GYMNOSPERMS

wood somewhat gradual. Spring wood very open ; the tracheids
very large, thin-walled, hexagonal, rather uniform. Resin cells numer-
ous, large, not strongly resinous, distinctly zonate or sometimes scat-
tering throughout the growth ring. Medullary rays prominent but
sparingly resinous, distant 2-8 or more rarely 13 rows of tracheids,
I cell wide.

Radial. Ray cells sparingly resinous, usually more or less contracted at
the ends, equal to 3-5 spring tracheids ; the upper and lower walls
thickish, rather unequal and entire or distantly and often imperfectly
pitted ; the terminal walls thin, sometimes obscure, often curved, not
pitted or locally thickened ; the lateral walls with prominent and con-
spicuously bordered pits, round, 1-4, or more rarely 7, per tracheid,
the very narrow, lenticular orifice often as long as the outer limits
of the pit. Bordered pits chiefly elliptical, numerous, variable, often
paired and in the earlier spring wood becoming imperfectly 2-seriate.
Pits on the tangential walls of the summer tracheids very numerous,
not very large. Resin cells sparingly resinous, 25 p, wide, chiefly
140 n. long, but ranging upwards of 310 /x.

Tangential. Rays numerous, medium to high, very sparingly resinous ; the
round or oval cells rather broad and thick-walled, rarely in pairs.

Wood very durable in the soil and of great economic value.

Relative specific gravity °-4543

Approximate fuel value 45-24

Coefficient of elasticity in kilograms on millimeters . . . 1032.

Ultimate transverse strength in kilograms 291.

Ultimate resistance to longitudinal crushing in kilograms . 6771.

Resistance to indentation to 1.27 mm. in kilograms . . 1166.
(Sargent)

Material silicified.

Delaware to Florida and westward through the Gulf States to Texas; north-
ward through Tennessee, Kentucky, and southern Missouri to southern
Illinois and Indiana (Sargent).

This well-known Tertiary plant, chiefly represented by its foliage and fruit,
is known through its woody structure in only one instance, occurring in
the Eocene of the Porcupine Creek and Great Valley groups.

2. * * T. laramianum, Penh.

Transverse. Growth rings prominent, rather broad. Summer wood promi-
nent, upwards of 17 tracheids thick and passing somewhat gradually
into the broad spring wood. Spring tracheids large, squarish-hex-
agonal, thin-walled, uniform in regular rows. Resin cells obscure and
forming an open zone on the inner face of the summer wood. Resin
passages wholly wanting. Medullary rays numerous, narrow, distant
about 2-8 rows of tracheids.

Radial. Medullary rays wholly devoid of tracheids. Ray cells straight,
equal to about 3 tracheids ; the upper and lower walls rather thick

LIBOCEDRUS 219

and sparingly pitted ; the terminal walls straight or diagonal, some-
times curved, entire ; the lateral walls with oval or rounded pits, about
2-3 per tracheid in radial series. Bordered pits numerous, but becom-
ing 2-rowed toward the summer wood, though distinctly crowded into
2-3 compact rows in the earlier spring tracheids. Resin cells not
conspicuous.

Tangential. Resin cells conspicuous but not numerous, about 3 times
longer than broad. Medullary rays rather numerous and narrow,
often very high, strictly i-seriate ; the cells oval, more rarely round
in the low rays.

Material silicified.

A distinctive species occurring in the Laramie (Eocene) at Cochrane,
Alberta.

7. LIBOCEDRUS, ENDL. PLATES 32 AND 33

Transverse. The thin and rather dense summer wood usually showing a

more dense median layer. Resin passages wholly wanting. Resin

cells numerous and conspicuously zonate.
Radial. Rays wholly without tracheids. The terminal walls of the ray

cells straight or curved, entire, locally thickened or even coarsely

pitted. Tracheids wholly without spirals.
Tangential. Fusiform rays wholly wanting, the rays strictly of one kind.

1. L. decurrens, Torn

White Cedar. Bastard Cedar. Post Cedar. Incense Cedar

Transverse. Growth rings broad. The dense summer wood rather thin
and composed of 8-14 tracheids, often more or less double ; the tran-
sition from the spring wood gradual. Spring tracheids in regular
rows, uniform, squarish, large and thin-walled, the structure open.
Resin cells numerous, prominent, large, in a very broad band or
scattering through the late spring wood. Medullary rays prominent,
numerous, resinous, i cell wide; distant 2-8, rarely 15, rows of
tracheids.

Radial. Ray cells sparingly resinous, more or less contracted at the ends,
equal to about 4-8 spring tracheids ; the upper and lower walls medium
and entire, or again distantly and often imperfectly pitted ; the ter-
minal walls thin, straight, or curved and locally thickened or even
coarsely pitted ; the lateral walls with small, narrowly bordered, oval
pits with a lenticular, diagonal orifice, 1-4 per tracheid. Bordered
pits in i row, sometimes in pairs, numerous. Pits on the tangential
walls of the summer tracheids numerous and large, extending almost
through the entire zone. Resin cells 20-30 p. wide, chiefly 175-225 p.
long, less commonly upwards of 475 p..

Tangential. Rays very variable, often 2-3 seriate at the center or near
one end, sparingly resinous, rather broad ; the cells round or oval,
uniform, the walls medium.

220 ANATOMY OF THE GYMNOSPERMS

A lar^e tree 30-40 m. in height, with a trunk 1.20-2.10 m. in diameter.
The light, soft wood is very durable in contact with the soil.

Relative specific gravity 0.4017

Approximate relative fuel value ... 40.14

Coefficient of elasticity, in kilograms on millimeters . . 847.
Ultimate transverse strength in kilograms 291.

Ultimate resistance to longitudinal crushing in kilograms 7446.

Resistance to indentation to 1.27 mm. in kilograms . . 1561.
(Sargent)

Santian river, Oregon ; southward along the western slopes of the Cas-
cade and Sierra Nevada mountains at elevations of 3000-8500 feet,
thence through California Coast Range to the San Bernardino and Cayu-
maca mountains (Sargent).

8. * THUYA, TOURN. PLATES 34 AND 35

Transverse. Summer wood thin and dense. Resin passages wholly want-
ing. Resin cells more or less prominent, but often widely scattering.
Tracheids chiefly large and thin-walled, squarish.

Radial. Ray tracheids wholly wanting except in T. japonica. Ray cells
usually conspicuously contracted at the ends ; the terminal walls thin
and not pitted or locally thickened, usually much curved. Tracheids
wholly without spirals.

Tangential. Fusiform rays wholly wanting. Ordinary rays narrow, medium
'to low, strictly i-seriate, the cells chiefly narrowly oval to oblong.

SYNOPSIS OF SPECIES

Pits on the lateral walls of the ray cells 1-2, or in the marginal cells and
low rays upwards of 8 per tracheid.

Pits on the tangential walls of the summer wood confined to the
outermost wall.

3. T. japonica, Max.

Pits on the lateral walls of the ray cells 1-4, or in the marginal cells and
low rays 6 per tracheid.

Pits on the tangential walls of the summer wood not confined to the
outermost tracheid wall.

1. T. gigantea, Nutt.

Pits on the lateral walls of the ray cells 1-4, or in the marginal cells and
low rays 7 per tracheid.

Pits on the tangential walls of the summer wood confined to the
outermost tracheid wall.

2. * T. occidentalis, Linn.

THUYA 221

1. T. gigantea, Nutt.
Red Cedar. Canoe Cedar. Western White Cedar

Transverse. Growth rings usually broad. Summer wood prominent and
upwards of 14 tracheids thick, the transition to the spring wood
gradual. Spring wood open, the thin-walled tracheids squarish-
hexagonal, rather uniform, in regular rows. Resin cells usually in a
single narrow band in the summer wood of distant growth rings, thus
often apparently wanting. Medullary rays somewhat resinous, i cell
wide, distant 2-20 tracheids.

Radial. Rays devoid of tracheids, somewhat resinous. Ray cells con-
spicuously contracted at the ends ; the upper and lower walls thick-
ish and entire or remotely pitted ; the terminal walls thin, generally
curved, not pitted or locally thickened ; the lateral walls with small,
oval pits with a lenticular or oval orifice, 1-4, or in the marginal
cells and low rays 6 per tracheid. Bordered pits round, in one row,
sometimes in pairs. Pits on the tangential walls of the summer wood
small, conspicuous, often remote, not confined to the outermost wall.
Resin cells about 15 /j. wide, 60-255 /x long, very variable, thin-walled.

Tangential. Rays medium, narrow, the cells oblong.

A light, soft, and rather brittle wood which is very durable in the soil.

Relative specific gravity 0.3796

Approximate relative fuel value 37-9°

Coefficient of elasticity in kilograms on millimeters . . 1034.

Ultimate transverse strength in kilograms 319.

Ultimate resistance to longitudinal crushing in kilograms 7197.

Resistance to indentation to 1.27 mm. in kilograms . . 1114.
(Sargent)

Alaska, southward through the coast ranges of British Columbia, where
it attains to an altitude upwards of 6000 feet, often attaining a height
of 150 feet and a diameter of more than 10 feet (Macoun); thence
through Washington, Oregon, and California, as far as Mendocino
County, and eastward through Washington and Idaho to northern
Montana (Sargent).

2. * T. occidentalis, Linn.
White Cedar. Arbor Vita

Transverse. Growth rings chiefly broad but variable. Summer wood very
thin, of 2-6 or upwards of 14 tracheids, the structure very open, the
tracheids large and squarish-hexagonal, in regular rows, rather uni-
form, thin-walled. Resin cells few and widely scattering, often appar-
ently wanting, or sometimes distantly zonate in the spring wood.
Medullary rays not prominent, i cell wide, distant 2-15 tracheids.

Radial. Rays devoid of tracheids, sparingly, if at all, resinous. Ray cells
more or less contracted at the ends; the upper and lower walls
medium, with conspicuous though often distant pits ; the terminal
walls thin, often strongly curved, not pitted or locally thickened;

222 ANATOMY OF THE GYMNOSPERMS

the upper and lower walls medium, with conspicuous, though often
distant, simple pits ; the lateral walls with small, oval pits with an
oval or lenticular, rather large, orifice, 1-4, or in the marginal cells
and low rays 7 per tracheid. Bordered pits elliptical in one row, some-
times in pairs, those of the summer wood finally obscure and wanting.
Pits on the tangential walls of the summer wood small, often obscure,
frequently very distant and confined to the outermost tracheid wall.
Resin cells 15-40 p. wide.
Tangential. Rays low and narrow, the cells uniformly narrow, oblong.

A tree 12-18 m. in height and 1.20-1.50 m. in diameter, producing a light,
soft, and very durable wood.

Relative specific gravity 0.3164

Approximate relative fuel value 3r-53

Coefficient of elasticity in kilograms on millimeters . . 533.

Ultimate transverse strength in kilograms 219.

Ultimate resistance to longitudinal crushing in kilograms 4903.

Resistance to indentation to 1.27 mm. in kilograms . . 957.
(Sargent)

Rare in Nova Scotia; abundant in New Brunswick, Quebec, and Ontario,
and northward to Hudson's Bay ; westward to Lake Winnipeg and the
mouth of the Saskatchewan in latitude 53° 30' N. (Macoun); southward
to New Jersey and through the Alleghenies to North Carolina (Britton) ;
thence westward through New York and Pennsylvania to central Michi-
gan, northern Illinois, and central Minnesota (Sargent).

This species is a well-defined and somewhat abundant constituent of the
Pleistocene flora in the Don Valley at Toronto, and the Leda clays of
Montreal ; Leda River, Manitoba, and Marietta, Ohio. An undescribed
species of Thuya also occurs in the Lignite Tertiary, Saskatchewan,
probably of the Porcupine Creek and Great Valley groups.

3. T. japonica, Max.

Jap. = Xedziiko

Transverse. Growth rings rather narrow, variable ; the prominent summer
wood very narrow, of about 6 tracheids, or again upwards of 16 tra-
cheids, rather dense, the transition to the spring wood gradual. The
broad spring wood open ; the tracheids rather large, conspicuously
hexagonal, very thin-walled, in regular rows, uniform. Resin cells
prominent and dark, few and widely scattering, chiefly in the summer
wood. Medullary rays not prominent, sparingly resinous, i cell wide,
narrow, distant 2-18 tracheids.

Radial. Rays very sparingly resinous, rarely with tracheids. Cells chiefly
straight, the upper and lower walls rather thin, uniform, and fre-
quently pitted ; the terminal walls thin, very commonly curved, not

SEQUOIA 223

pitted or locally thickened; the lateral walls with small, oval pits,
the orifice broadly lenticular, 1-2 or in the marginal cells and low
rays upwards of 8 per tracheid. Bordered pits elliptical in one row,
sometimes in pairs, numerous, about one half the diameter of the
tracheid. Pits on the tangential walls of the summer wood confined
to the outermost wall, not large, flat, rather numerous, often obscure.
Resin cells few, 12.5 p. wide, about 135 ^ long.

Tangential. Rays low to medium, very narrow, strictly i -seriate ; the cells
uniform, thin-walled, oblong.

9. * SEQUOIA, ENDL. PLATES 36 AND 37

Trans-verse. Growth rings chiefly narrow, the usually thin summer wood
distinct. Resin cysts when present forming a continuous row on the
outer face of distant growth rings. Tracheids large, thin-walled,
square. Resin cells scattering, chiefly in the spring wood, or more
rarely wholly in the summer wood (S. Penhallowii).

Radial. Rays without tracheids, but the marginal cells sometimes crystal-
logenous (S. Penhallowii). Pits of the ray cells with a narrow border,
the orifice commonly parallel with the cell axis. Pits often occur on
the tangential walls of both spring and summer tracheids. Terminal
walls of the ray cells rarely, if at all, pitted, except in S. Penhallowii.
Tracheids wholly without spirals. Radial resin passages wanting
except in S. Burgessii and S. Penhallowii, when they contain promi-
nent thyloses.

Tangential. Fusiform rays usually wanting, or present in S. Burgessii and
S. Penhallowii.

SYNOPSIS OF SPECIES

Resin passages wholly wanting.

Resin cells more or less numerous and scattering throughout the
growth ring.

Bordered pits large, oval, conspicuously in 1-2 rows.

Ray cells (tangential) of the spring wood very large and
broad, squarish.

Pits on the lateral walls of the rays cells 2-6 per
tracheid.

1. S. sempervirens.
Bordered pits in i or sometimes 2 rows.

Ray cells (tangential) large, broad, squarish, or as often
transversely oblong.

5. * * S. magnifica.
Ray cells (tangential) broadly oval or round.

Pits on the lateral walls of the ray cells 1-2, or rarely
3-4, per tracheid.

2. S. gigantea.

224 ANATOMY OF THE GYMNOSPERMS

Resin cells on the outer face of the summer wood only.
Bordered pits not definitely seriate.

Pits on the lateral walls of the ray cells i-seriate in the cen-
tral, 2-3 seriate in the marginal cells which are crystal-
logenous.

6. * * S. Penhallowii.
Resin passages present on the outer face of the summer wood.

Resin cells more or less numerous and scattering throughout the
growth ring.

Bordered pits in 1-2 rows.

Ray cells (tangential) very large and broad, squarish.

Pits on the lateral walls of the ray cells 2-6 per tracheid.

i. S. sempervirens.
Ray cells (tangential) oval or round.

Pits on the lateral walls of the ray cells obliterated.

3. * * S. Langsdorfii.
Resin passages (radial only) with thyloses.

Resin cells somewhat numerous, scattering throughout the growth
ring but most abundant on the outer face of the summer wood.
Bordered pits in 1-2 rows.

Marginal ray cells not crystallogenous.

4. * * S. Burgessii.

Resin passages (traumatic) present, both vertically and radially.
Resin cells on the outer face of the summer wood only.
Bordered pits not definitely seriate.

Pits on the lateral walls of the ray cells i-seriate in the
central, 2-3 seriate in the marginal cells which are crystal-
logenous.

6. * * S. Penhallowii.

1. S. sempervirens, Endl.
Redwood

Transverse. Summer wood very prominent, of 3-11 tracheids, or upwards
of one third the spring wood ; the structure often very open, or when
dense sometimes double. Spring wood very open, the large, squarish,
or hexagonal tracheids often radially elongated, the walls thin ; tran-
sition to the summer wood rather abrupt. Resin cysts contiguous
and coalescent and forming an extended tangential series in the
initial growth of the spring wood, of distant growth rings. Resin
cells rather abundant, very prominent and dark, rather large, scatter-
ing through the spring wood. Tracheids rather uniform in very
irregular rows. Medullary rays broad, prominent, i cell wide, distant
1-12, mpre rarely 20, rows of tracheids.

SEQUOIA 225

Radial. Ray cells straight or rarely contracted at the ends, somewhat
resinous, equal to about 4 spring tracheids ; the upper and lower
walls thin, rather uniform, rarely pitted ; the terminal walls very thin,
straight or curved, and not pitted ; the lateral walls with large, oval,
narrowly bordered pits 2-6 per tracheid, the round or broadly oblong
orifice either parallel with or diagonal to the cell axis. Bordered pits
conspicuously in 1-2 rows, elliptical. Pits on the tangential walls of
the summer wood numerous, small, the orifice broadly trumpet-shaped
or bell-shaped ; the pits on the tangential walls of the spring wood
large, sometimes rather abundant. Resin cells rather numerous,
30-40 p. wide, 175-480 (j. long.

Tangential. Rays medium to high, often more or less 2-seriate ; the cells
very large and broadly oval, those in the center commonly conspicu-
ously squarish.

Wood very durable in contact with the soil and of great economic value.
Trees 61-92 m. in height and 2.40-7 m. in diameter.

Relative specific gravity 0.4208

Approximate relative fuel value 42.02

Coefficient of elasticity in kilograms on millimeters . . 676.

Ultimate transverse strength in kilograms 255.

Ultimate resistance to longitudinal crushing in kilograms 6656.

Resistance to indentation to 1.27 mm. in kilograms . . 1242.
(Sargent)

From the northern borders of California southward through the coast
ranges to near the southern boundary of Monterey County (Sargent).

2. S. gigantea, Decaisne
Big Tree

Transverse. Summer wood very thin, of 2-6 tracheids, the transition to
the spring wood usually abrupt. Spring tracheids large, open, thin-
walled, uniform, squarish, in regular rows. Resin cells not very numer-
ous, but large and prominent, scattering. Medullary rays not very
prominent, rather numerous, i cell wide; distant 2-14, rarely 25, rows
of tracheids.

Radial. Ray cells usually somewhat contracted at the ends, equal to 6-8
spring tracheids, chiefly resinous throughout ; the upper and lower
walls thin and entire or distantly pitted, unequal ; the terminal walls
thin, straight or curved, not pitted or locally thickened ; the lateral
walls with oval and commonly narrowly bordered pits, the broadly
oblong orifice equal to the outer limits of the pit and chiefly parallel
to the cell axis, 1-2, or more rarely 3-4, per tracheid. Bordered pits
in one or two rows, elliptical, the orifice large, elliptical. Pits on the
tangential walls of the summer wood prominent and frequent ; on
the tangential walls of the spring wood prominent but rare. Resin
cells few, about 20 yu. wide and 140-325 ^ long, chiefly about 250 p..

Tangential. Rays chiefly low to medium, the large cells broadly oval or
round, thin-walled.

226 ANATOMY OF THE GYMNOSPERMS

A light, soft wood remarkable for its durability in the soil. The tree is the
largest produced by American forests, attaining a height of 79-119 m.
and a diameter of 6-1 1 m.

Relative specific gravity 0.2882

Approximate relative fuel value 28.67

Coefficient of elasticity in kilograms on millimeters . . 451.

Ultimate transverse strength in kilograms 196.

Ultimate resistance to longitudinal crushing in kilograms 6210.

Resistance to indentation to 1.27 mm. in kilograms . . 1091.
(Sargent)

Western slopes of the Sierra Nevada Mountains, California, from Placer
County south to Deer Creek on the southern borders of Tulare County
(Sargent).

3. * * S. Langsdorfii (Brongn), Heer.

Transverse. Growth rings medium, strongly defined. Tracheids of the
spring wood squarish, large, 52 x 52 p., the walls 14 p. thick. Summer
wood of 3-6 tracheids in thickness, the transition from the spring
wood rather abrupt. Resin cells rather numerous throughout the
growth ring and scattering. Resin passages usually absent, but occa-
sionally appearing in a rudimentary form on the outer face of the
summer wood.

Radial. Medullary rays devoid of tracheids ; the parenchyma cells equal
to about 4 tracheids, somewhat constricted at the ends ; the upper and
lower walls thin and entire ; the terminal walls not pitted, straight or
curved ; the lateral walls with no recognizable structural details.

Tangential. Medullary rays i -seriate or rarely 2-seriate in part, the oval
or round cells about 31.5 p. broad.

This very widely distributed and well-known Cretaceous and Tertiary plant,
which is chiefly represented by foliage and fruit, is apparently repre-
sented also by the woody stem in the Lignite Tertiary of the Porcupine
Creek and Great Valley groups in Saskatchewan. Reference of the
wood to this species is, however, made provisionally, as the evidence is
not such as to warrant an absolute decision. The occurrence of the
genus in this locality, however, indicates that it at one time occupied
the present prairie region in preglacial times, and that its recession to its
present narrow limits probably occurred as the result of glacial action.

4. * * S. Burgessii, Penh.

Transverse. Growth rings chiefly narrow but variable, the rather narrow
but variable summer wood dense, the transition from the spring wood
abrupt. Tracheids of the spring wood large, squarish, and thin-walled.
Resin canals wholly wanting. Resin cells numerous throughout the
growth ring, but especially on the outer face of the summer wood :
with dark, massive resin. Medullary rays chiefly i cell wide, occa-
sionally broader and bearing a resin canal with large thyloses.

SEQUOIA 227

Radial. Bordered pits large, in 1-2 rows. Medullary rays often with a
large resin passage bearing thyloses ; the cells all of one kind ; the
upper and lower walls thin and much altered by decay ; the lateral
walls devoid of recognizable markings.

Tangential. Ordinary rays i- or sometimes 2-seriate in part ; the fusiform
rays with large resin passages containing thyloses.

An exceedingly well-characterized species from the Eocene of the Porcu-
pine Creek and Great Valley groups.

5. * * S. magnifica, Knowlton

"Trunks often of great size, 6-10 feet in diameter, 30 feet high as now
preserved, bark when present 5 or 6 inches in thickness ; annual rings
very distinct, 2-3 mm. broad."

" Transverse. In this section the structure appears beautifully preserved.
The rings are rather narrow, being only 2 or 3 mm. broad, or often
only i mm. They are very sharply demarked, even to the naked eye.
Under the microscope the rings are found to consist of a band of
thick-walled cells that is never more than 15 rows of cells deep and
often reduced to 2 or 3 rows. The cells composing the spring and
summer wood are of uniform size and inclined to hexagonal in shape.
Those of the fall wood are, of course, compressed.

" The resin cells are numerous and may be readily distinguished
by the dark contents. They occur mainly in the spring and summer
wood.

" The medullary rays seen in this section are long, straight, and
separated by usually about 3 rows of wood cells."

"Radial. This section is the least satisfactory of all. The wood cells
show well under the microscope, but their markings are very obscure.
By prolonged search it is made out that the pits are in i row, or some-
times 2 parallel rows. They are small, as far as can be made out,
and are too obscure for satisfactory measurement.

" The rays are composed of long, unmarked cells."

" Tangential. This section is very satisfactory. The wood cells are long
and unmarked. The resin ducts are numerous, but scattered, the
cells being twice or three times as long as wide. In many cases they
are filled with or contain masses of dark material, representing the
resin now turned to a carbonaceous mass.

" The medullary rays are composed of i , or in some cases of a
partially double, series of 2 to about 25 superimposed cells. They
are large and quite thick-walled. The average number of cells in
each ray is about 12" (Knowlton).

According to Professor F. H. Knowlton, this species can hardly be dis-
tinguished from the existing S. sempervirens, of which he considers it
to be the ancestral form.

Tertiary of the Yellowstone National Park, at Specimen Ridge, Fossil'
Forest at head of Crystal Creek, Fossil Forest on Cache Creek, etc.
(Knowlton).

228 ANATOMY OF THE GYMNOSPERMS

6. * * S. Penhallowii, Jeffrey

" Transverse. Rings of growth rather narrow, with sharply marked but thin
summer wood. Rings regular, or if varying in thickness, varying uni-
formly and without violent transitions except as the result of injury.
Resin canals present in both the vertical and horizontal planes appar-
ently only as the result of injury. The resin canals when present
surrounded by resin cells, containing dark brown resin. Resin cells
inconspicuous and confined to the face of the summer wood, except
in the case of injury, where they may be present throughout the zone
of annual growth. Tracheids of the spring wood very large and with
pits on the radial walls only. Tracheids of the summer wood with
tangential pits."

"Radial. Rays without tracheidal cells, but with distinctly differentiated
marginal cells. Lateral pits of the ray cells elliptical, bordered, larger
in the marginal cells. Rows of pits single in the central cells of the
ray and 2-3 seriate in the marginal cells. Medullary ray cells covering
1-4 tracheids, the central ones resiniferous, the marginal generally
empty, sometimes containing large clinorhombic crystals inclosed in
cysts derived from the cell walls. Marginal cells with undulating free
border, deeper than central cells. End walls of the cells of the medul-
lary rays very strongly pitted. Longitudinal walls of ray cells also
pitted and rather thick. Rays contain resin canals in the case of
injury, which take their origin from similar vertical canals running in
the wood. Resin canals of the rays sometimes ending blindly and
sometimes in a more external series of vertical canals, often extending
through many annual rings, varying greatly in size and frequently
occluded by thyloses. Spring tracheids generally with 2 rows of oppo-
site pits, which often alternate in the ends."

" Tangential. Rays of one kind only in uninjured parts of the wood. Fusi-
form rays present with linear rays in the case of injury and varying
greatly in size. Fusiform rays, when present, generally with central
resin canal, which is often occluded by thyloses. Linear rays varying
greatly in depth. No pits on the tangential walls of the spring tra-
cheids. Pits on the tangential walls of the summer tracheids numer-
ous, generally not in rows " (Jeffrey).

Material but slightly silicified and showing little alteration through decay.

From a waterworn fragment of a trunk originally 6 feet or more in

diameter.
Miocene(P), from Tunnel No. i, Central Pacific Railway, at Blue Gap,

Sierra Nevada Mountains (Jeffrey).

10. * CUPRESSUS, TOURN. PLATES 38 AND 39

Transverse. Summer wood usually very thin, often barely distinguishable,
the structure of the growth ring open throughout. Resin passages
wholly wanting. Resin cells prominent, rather numerous in bands,
scattering or even apparently wanting.

CUPRESSUS 229

Radial. Rays chiefly without trachcids. Terminal walls of the ray cells thin
and entire, very commonly curved, often locally thickened. Tracheids
wholly without spirals.

Tangential. Fusiform rays wholly wanting. Ray cells chiefly broad, oval, or
even transversely oval ; the rays sometimes 2-seriate in part.

SYNOPSIS OF SPECIES

A. * CHAM/ECYPARIS

Existing Species

1. Pits on the tangential walls of the summer tracheids flat,

small, obscure, or at least not prominent
Ray cells (tangential) round or oval.
Ray tracheids absent.

Tracheids more or less conspicuously rounded throughout.
Ray cells (radial) straight, sparingly resinous.

Pits on the lateral walls of the ray cells 2, in radial
series, or in the marginal cells 6, per tracheid.

5. C. obtusa.
Tracheids distinctly squarish, large, the structure open.

Pits on the lateral walls of the ray cells 2-4, rarely 8, per

tracheid.

2. C. Lawsoniana.

Pits on the lateral walls of the ray cells 2, in radial series,

or 6, per tracheid.

3. C. pisifera.

Ray tracheids present in the low rays.

Tracheids distinctly squarish, or again rounded and thick-walled,
the structure variable, either open or somewhat dense.

Pits on the lateral walls of the ray cells 1-4 per tracheid.
Tracheids (transverse) commonly in very irregular rows.

4. C. nootkatensis.
Ray cells (tangential) narrow, oblong, more rarely oval.

Tracheids distinctly squarish, in regular rows, the structure open.

Pits on the lateral walls of the ray cells 1-2, or in the marginal
cells and low rays upwards of 6, per tracheid.

i. C. thyoides.

B. CUPRESSUS

Existing Species

2. Pits on the tangential walls of the summer tracheids chiefly

large and open
Ray cells (tangential) round or oval, more rarely transversely oval.

230 ANATOMY OF THE GYMNOSPERMS

Tracheids more or less conspicuously rounded throughout.

Ray cells (radial) somewhat contracted at the ends, strongly
resinous.

Pits on the lateral walls of the ray cells 1-2, rarely 4, per
tracheid.

6. C. macrocarpa.
Tracheids barely if at all rounded.

Ray cells (radial) contracted at the ends, more or less resinous.
Pits on the lateral walls of the ray cells 1-2, rarely 3, per
tracheid.

8. C. Macnabiana.
Ray cells (tangential) chiefly transversely oval.

Tracheids more or less rounded throughout.

Ray cells (radial) somewhat contracted at the ends, barely resinous.
Pits on the lateral walls of the ray cells 1-2, more rarely 4, per
tracheid.

7. C. arizonica.
Tracheids squarish, the structure open throughout.

Ray cells (radial) strongly fusiform, generally resinous.

Pits on the lateral walls of the ray cells 1-2 per tracheid.

9. C. Goveniana.

C. * * CUPRESSOXYLON (Cupressinoxylon)
Extinct Species

Tracheids of the spring wood distinctly rounded.
Bordered pits obliterated by decay.

Medullary rays (tangential) 1-3 seriate, the round, thin-walled
cells 47 fj. broad.

10. C. cheyennense.
Bordered pits in i row, distant, round.

Pits on the lateral walls of the ray cells 1-2, chiefly 2, per
tracheid.

Rays (tangential) numerous, the variable cells chiefly broad,
oval, or round, sometimes transversely oval.

1 1 . C. macrocarpoides.

Bordered pits large, in i row, or often in pairs, and in larger tracheids
becoming more or less 2-rowed.

Pits on the lateral walls of the ray cells 1-2 per tracheid.

Medullary rays (tangential) i- seriate, the round cells 19 p
broad.

12. C. comanchense.

CUPRESSUS 231

Tracheids of the spring wood squarish-hexagonal.
Bordered pits round, distant, in i row.

13. C. pulchellum.

14. C. arkansanum.

Bordered pits large, in i row, often in pairs, the latter sometimes so
approximated as to make the pits more or less 2-rowed.

Pits on the lateral walls of the ray cells 1-2, in vertical series, or
in marginal cells and low rays 4, per tracheid.

15. C. Dawsoni.

Pits on the lateral walls of the ray cells obliterated.

16. C. Wardi.

Pits on the lateral walls of the ray cells minute, round.

Medullary rays (tangential) small, the cells small, oblong,
15-iyx 10 p..

17. C. columbianum.
Bordered pits conspicuously in 2 rows.

Pits on the lateral walls of the ray cells obliterated.
Growth rings obscure.

1 8. C. elongatum.
Growth rings sharply denned.

Tracheids of the earlier spring wood very large and
thin-walled.

19. C. glasgowi.
Bordered pits in 2, or sometimes 3, rows.

Pits on the lateral walls of the ray cells with large, oval pits
1-3 per tracheid.

20. C. McGeei.

Pits on the lateral walls of the ray cells 3 per tracheid.

21. C. Calli.

A. CHA1VLECYPARIS

1. * C. thyoides, Linn.

White Cedar

Transverse. Growth rings thin, variable, the structure open throughout.
The summer wood chiefly thin, of 2-6 tracheids, the transition to the
spring wood rather abrupt, or sometimes thicker and not clearly sepa-
rable from the spring wood. Spring tracheids large, conspicuously
squarish, uniform, in regular rows, in small stems and branches often
much elongated radially, the walls not very thin. Resin cells widely
scattering and often apparently wanting ; when in bands, often giving
the appearance of secondary growth rings, chiefly in or near the sum-
mer wood. Medullary rays not very prominent or resinous, i cell
wide, distant 2-12 tracheids.

232 ANATOMY OF THE GYMNOSPERMS

/\<i(fiti/. Ray trachcids chiefly narrow, very unequal, often high, sometimes
present, then rather abundant and composing the entire ray when of
I or 2 cells only, usually absent from the higher rays. Medullary
rays contracted at the ends ; the upper and lower walls medium to
thick, unequal, frequently pitted or again entire or distantly pitted ;
the terminal walls thin, often curved and locally thickened ; the lateral
walls with round or oval pits, the orifice lenticular, 1-2, or in the
marginal cells and low rays, 6, per tracheid. Pits on the tangential
walls of the summer tracheids very small and often obscure. Bor-
dered pits round or elliptical in i row, or in radially broad tracheids
in 2 rows. Resin cells not numerous, 20-25 /j. wide, 150-175 /x
long.

Tangential. Rays medium, wholly I -seriate ; the cells narrow, oblong.

Wood very light and soft, but very durable in the soil.

Relative specific gravity • . . . . 0.3322

Approximate relative fuel value 33-12

Coefficient of elasticity in kilograms on millimeters . . 404.

Ultimate transverse strength in kilograms 194.

Ultimate resistance to longitudinal crushing in kilograms 4149.

Resistance to indentation to 1.27 mm. in kilograms . . 1074.
(Sargent)

Cape Breton Island and near Halifax (Macoun) ; southern Maine, south-
ward along the coast to Florida, thence westward along the Gulf coast
to Pearl River, Mississippi (Sargent).

The Pleistocene deposits of the Don Valley, Toronto. Material not pet-
rified, but often showing the effects of advanced decay.

2. C. Lawsoniana, A. Murr.

Port Orford Cedar. Oregon Cedar. White Cedar. Lawson's Cypress.

Ginger Pine

Transverse. Growth rings very narrow, variable, the structure very open
throughout. Summer wood very thin, of 1-5 tracheids, sometimes
double and then upwards of 14 tracheids, the transition to the spring
wood gradual. Spring tracheids very large, squarish-hexagonal, thin-
walled, in very regular rows, uniform. Resin cells prominent, large,
usuallj^widely scattering and not numerous, or again numerous within
narrow zones in the summer wood. Medullary rays resinous, rather
prominent and numerous, i cell wide, distant 1-9 or 12 tracheids.

Radial. Ray tracheids wholly wanting. The straight or somewhat con-
tracted ray cells rather resinous, equal to 3-12 spring tracheids; the
upper and lower walls variable, often strongly thickened toward the
ends of the cells, not obviously pitted ; the terminal walls thickish,
chiefly straight, not pitted or locally thickened ; the lateral walls with
small bordered pits with a narrow orifice, 1-4, or more rarely upwards
of 8, per tracheid and chiefly in vertical rows. Bordered pits in i
row, sometimes in 2 rows, round. Pits on the tangential walls of the

CUPRESSUS 233

summer tracheicls small, rarely large, not numerous. Resin cells not
numerous, 20-25 /* wide, 150-200 /j. long, chiefly about 175 /u,.
Tangential. Rays medium, wholly i-seriate ; the cells broadly oblong or
oval, sometimes round, the walls thick.

A light, hard, and strong wood which is very durable in the soil.

Relative specific gravity 0.4621

Approximate relative fuel value 46.16

Coefficient of elasticity in kilograms on millimeters . . 1217.

Ultimate transverse strength in kilograms 379.

Ultimate resistance to longitudinal crushing in kilograms 7435.

Resistance to indentation to 1.27 mm. in kilograms . . 1317.
(Sargent)

Oregon, not more than thirty miles from the coast ; valley of the upper
Sacramento River, California (Sargent).

3. C. pisifera, Sieb. et Zucc.
Jap. = Saivara

Transverse, Growth rings narrow, uniform ; the usually dense and very
narrow summer wood of 3-5 tracheids, the transition to the spring
wood somewhat abrupt ; the spring wood open, the large, squarish-
hexagonal tracheids in very regular rows, uniform, rather thin-walled.
Resin cells few, dark, and prominent, zonate in the summer wood.
Medullary rays not prominent, I cell wide, narrow, distant 2-17
tracheids.

Radial. Rays devoid of tracheids, nonresinous, the cells contracted at
the ends, equal to 5-6 spring tracheids : the upper and lower walls
thin, rather unequal, not obviously pitted ; the terminal walls thin,
chiefly curved, not pitted or locally thickened ; the lateral walls with
oval, bordered pits, chiefly 2 per tracheid in radial series, or in the
marginal cells and low rays smaller and upwards of 6 per tracheid.
Bordered pits elliptical, large, rather numerous in i row or sometimes
in pairs. Pits on the tangential walls of the summer tracheids rather
few, small, flat, and inconspicuous. Resin cells few in the summer
wood, 12.5-20 /A wide, 170-250 ju, long.

Tangential. Rays low to medium, narrow, nonresinous ; the cells rather
variable from oblong to oval or round, chiefly rather oblong, rarely
if ever in pairs.

4. C. nootkatensis, Lam.

Yellow Cypress. Sitka Cypress

Transverse. Growth rings unequal. Summer wood very thin, of 2-6
tracheids, the transition to the spring wood gradual. Spring tracheids
chiefly large, but very variable and often in irregular rows, squarish
Resin cells prominent and rather numerous, either scattering or com-
pressed into narrow bands in both the spring and summer wood.
Medullary rays resinous, prominent, i cell wide, distant about 2-17
tracheids.

234

ANATOMY OF THE GYMNOSPERMS

Radial '. Ray tracheids chiefly short and broad ; chiefly or wholly confined
to rays i or 2 cells high, then constituting the entire ray, not very
numerous. Kay cells somewhat resinous, more or less conspicuously
contracted at the ends, equal to 4-9 spring tracheids ; the upper and
lower walls thick and entire or distantly pitted ; the terminal walls
thin and locally thickened; the lateral walls with rather small pits
with a lenticular orifice often parallel with the cell axis, 1-4 per
tracheid. Bordered pits round or elliptical in i row, somewhat distant ;
the round orifice often very variable, much enlarged, eccentric,
irregular in outline or even wanting, the pits then presenting a vari-
able aspect which at once serves to define the species. Pits on the tan-
gential walls of the summer tracheids few, often obscure. Resin cells
few, about 20 p. wide and 100-175 /u, long, rarely upwards of 270 /t.

Tangential. Rays low, narrow, and i-seriate, sometimes 2-seriate in part ;
'the cells narrowly elliptical or broadly oval, sometimes transversely
oval or oblong, much enlarged.

This is the most variable species of Cupressus, and it is chiefly remarkable
for the variable character of the summer wood, the irregular disposition
of the tracheids (transverse), the often very numerous resin cells, and
the peculiarly imperfect bordered pits which at once separate it from
all other species. It may show deviation from the normal in (i) the
absence of resin cells ; (2) the form of the tracheids, which are some-
times round with thick walls, even in the same section, thus giving rise
to (3) a variable structure of the wood which is in some rings rather
dense throughout.

A large tree of great economic importance with a height of 30-38 m. and
a diameter of 1.20-1.80 m. Wood light, hard, and very durable.

Relative specific gravity 0.4782

Approximate relative fuel value 47.66

Coefficient of elasticity in kilograms on millimeters . . 1029.

Ultimate transverse strength in kilograms 342.

Ultimate resistance to longitudinal crushing in kilograms 7281.

Resistance to indentation to 1.27 mm. in kilograms . . 1618.
(Sargent)

Interior of Vancouver Island ; British Columbia, near the coast, where
it reaches sea level in the northern portions, and thence to Alaska
(Macoun) ; southward through the Cascade Mountains of Washington
and Oregon, where it is seldom found below an elevation of 5000 feet
(Sargent).

5. C. obtusa, Sieb. et Zucc.

Jap. — II i n ok i

Transverse. Growth rings broad. Summer wood chiefly rather thin, some-
times double, rather open but passing very gradually into the broad
spring wood from which it is not clearly separable. Tracheids of the
spring wood round-hexagonal, thickish-walled, not very large, the

CUPRESSUS 235

structure not very open. Resin cells prominent, dark, not very large
or numerous, rather scattering or again zonate in both spring and
summer woods. Medullary rays not prominent or numerous, rather
narrow and i cell wide, distant 1-23 tracheids.

Radial. Medullary rays devoid of tracheids, sparingly resinous, the cells
straight and equal to 5-10 spring tracheids; the upper and lower
walls thickish, sinuately unequal, not obviously pitted ; the terminal
walls thin, curved or straight, not pitted or locally thickened ; the
lateral walls with oval, bordered pits, chiefly i, or in the marginal
cells 2, per tracheid, the orifice lenticular-oblong. Bordered pits
round or elliptical, rather distant in i row, usually less than one half
the diameter of the tracheid. Pits on the tangential walls of the
summer tracheids not very numerous, small, flat, obscure. Resin
cells few, 15-25 /j, wide, 150-210 p. long, chiefly about 150 /x.

Tangential. Rays medium, narrow ; the uniformly oval, nonresinous cells
rarely if ever in pairs.

B. CUPRESSUS

6. C. macrocarpa, Gordon

Monterey Cypress

Transverse. Growth rings usually broad. Summer wood very thin, of 6-8
tracheids, and passing gradually into the spring wood from which it
is not always clearly separable. Spring wood very broad, the tra-
cheids uniform, rather large, rounded-hexagonal, the walls rather
thick. Resin cells prominent and widely scattering or somewhat
zonate in the summer wood. Medullary rays prominent, resinous,
broad, i cell wide, distant 2-12, rarely 33, tracheids.

Radial. Rays devoid of tracheids and resinous throughout. Cells more or
less contracted at the ends, equal to 4-6 spring tracheids ; the upper
and lower walls variable and not obviously pitted ; the terminal walls
thin, often curved, locally thickened ; the lateral walls with rather
large bordered pits with large, lenticular, or oblong orifices, 1-2, or in
the low rays 4, per tracheid. Bordered pits round or elliptical, some-
times in pairs. Pits on the tangential walls of the summer tracheids
numerous, large, and open. Resin cells not numerous, 20-25 P- wide,
40-65 p. long, chiefly about 50 p..

Tangential. Rays medium, sometimes 2-seriate in part, the cells broadly
often transversely oval, thick-walled.

This species is usually recognized by the very large, bordered pits on the
tangential walls of the summer tracheids. In transverse section the
summer wood commonly presents somewhat strong variations in speci-
mens from different individuals.

Wood heavy, hard, strong, and very durable. Trees upward of 21 m. in
height and i .80 m. in diameter.

Relative specific gravity 0.6261

(Sargent)

California (Sargent).

236 ANATOMY OF THE GYMNOSPERMS

7. C. arizonica, Greene
Cypress

Transverse. Growth rings medium, rather uniform. Summer wood very
thin, upwards of 6 tracheids, and passing very gradually into the
spring wood. The very broad spring wood somewhat open, the very
variable tracheids chiefly squarish-hexagonal, the walls not thin.
Resin cells numerous and prominent, narrowly zonate in both the
spring and summer woods, sometimes in groups of larger and thicker-
walled cells, showing a tendency to the formation of resin canals.
Medullary rays rather prominent, somewhat resinous, rather numerous
and broad, i cell wide, distant 2-10 tracheids.

Radial. Rays devoid of tracheids and sparingly resinous, the cells con-
spicuously contracted at the ends, equal to about 6-9 spring tracheids ;
the terminal walls chiefly straight, sparingly and locally thickened ; the
upper and lower walls medium to thick, not obviously pitted ; the lat-
eral walls with round or oval pits 1-2, or in the marginal cells 4, per
tracheid. Bordered pits round or elliptical, rather numerous, in i row.
Pits on the tangential walls of the summer tracheids rather numer-
ous and large, open. Resin cells not numerous, 15-20 yu, wide, 120-
250 /along, chiefly about 200 p.; sometimes in multiple series of much
broader, very variable, often isodiametric and thick-walled cells, show-
ing a strong tendency to the formation of resin canals.

Tangential. Rays medium, the cells broad, more or less resinous, trans-
'versely oval, or in the low rays vertically oval.

Wood soft, light, and coarse grained.

Relative specific gravity 0.4843

(Sargent)

San Francisco Mountains of New Mexico and Arizona, where the tree
forms extensive forests on the northern slopes of the mountains at eleva-
tions of 5000-8000 feet ; Santa Catalina and Santa Rita mountains of
Arizona ; on the Sierra Madre and Guadeloupe Island, Mexico (Sargent).

8. C. Macnabiana, A. Murr.
Cypress

Transverse. Growth rings medium, uniform. Summer wood very thin, of
about 3-5 tracheids, open, the transition to the spring wood gradual.
The broad spring wood rather open, the tracheids conspicuously hex-
agonal, rather uniform, the walls medium. Resin cells prominent, not
numerous, widely scattering throughout the growth ring. Medullary
rays prominent, somewhat resinous, i cell wide, distant i-io, rarely
14, tracheids.

Radial. Rays wholly devoid of tracheids, more or less resinous throughout,
individual cells often strongly so. The cells somewhat contracted at
the ends, equal to 4-5 spring tracheids ; the upper and lower walls
medium, unequal, entire, or sparingly pitted ; the terminal walls thin and

CUPRESSUS

237

chiefly straight, locally thickened ; the lateral walls with oval or round
bordered pits, orifice lenticular, 1-2, or in the marginal cells rarely 3,
per tracheid. Bordered pits rather numerous in i row, elliptical, the
orifice large. Pits on the tangential walls of the summer tracheids
rather numerous and large, the orifice bell-shaped, not very open.
Resin cells not numerous, 12.5-25 or sometimes 35 p. broad, 210-
310 p. long, chiefly about 250 /x.
Tangential. Rays low, the cells broad, oval, or round, often resinous.

A small tree of the mountains of Lake County, California (Sargent).

9. C. Goveniana, Gordon

Cypress

Transverse. Growth rings variable. Summer wood very thin, of 2-6
tracheids ; the transition to the spring wood gradual. Spring wood
very open, the tracheids large and squarish, in regular rows, rather
uniform and thin-walled. Resin cells abundant and prominent, in
narrow but well-defined zones, sometimes forming rather extended
radial series, i to 3 cells wide, of broader and thicker-walled cells.
Medullary rays rather numerous but not very resinous or prominent,
i cell wide, distant 2-8, rarely 15, tracheids.

Radial. Rays devoid of tracheids, more or less resinous. Ray cells con-
spicuously narrower at the ends, equal to 3-8 spring tracheids, becom-
ing shorter in the summer wood ; the upper and lower walls medium,
entire or distantly pitted ; the terminal walls thin, often locally thick-
ened ; the lateral walls with round or oval pits having large, round or
oval openings, 1-2, or in the marginal cells 4, per tracheid. Bordered
pits elliptical, sometimes round in I row, becoming much more dis-
tant and smaller toward the summer wood. Pits on the tangential
walls of the summer tracheids rather numerous, prominent, chiefly
large and open. Resin cells rather abundant, 10-20 p, wide, 185-375 fj.
long, chiefly about 225 //, ; sometimes in radially wide, multiple series
of broad and short, thick-walled cells.

Tangential. Rays low and broad, sometimes 2-seriate in part ; the cells
thick-walled, chiefly transversely oval.

This species is largely distinguished by the smaller pits on the lateral walls
of the strongly contracted ray cells, and by the transversely oval ray cells
as shown in tangential section.

A small tree furnishing a light, soft wood.

Relative specific gravity 0.4689

Approximate relative fuel value 46.68

Coefficient of elasticity in kilograms on millimeters . . 499.

Ultimate transverse strength in kilograms 230.

Ultimate resistance to longitudinal crushing in kilograms 5742.

Resistance to indentation to 1.27 mm. in kilograms . . 2852.
(Sargent)

Humboldt County, California, south along the coast, and through the coast
ranges into southern California (Sargent).

238 ANATOMY OF THE GYMNOSPERMS

C. ** CUPRESSOXYLON (Cupressinoxylon)

Extinct Species Only
10. * * C. cheyennense, Penh.

Transverse. Tracheids in regular, radial rows, rather uniform, roundish,
about 62x62 /j. broad; the walls 15.5 p. thick. Resin passages and
special resin cells wanting. Growth rings apparent, very broad ; in a
radial extent of 20 mm., 2 growth rings of an equal thickness of
10 mm. are represented. The summer wood conspicuous, about 3-4
cells thick, the tracheids about 29 x 38 p. broad, the tangential walls
about 15.5 p. thick.

Radial. Ray cells all of one kind, straight ; the upper and lower walls thin
and not pitted ; the terminal walls thin and not pitted, straight or
curved ; the lateral walls showing no structure which has been oblit-
erated by decay ; the cells 3-5 tracheids long.

Tangential. Rays numerous, medium, 1-3 seriate ; the cells round, thin-
walled, 47 /A broad.

Material silicified. Specimens represented by small portions of stem.
From the Cheyenne Formation (Comanche Cretaceous), east of Stokes Hill,
Kiowa and Baker County line, Kansas (Prosser).

11. ** C. macrocarpoides, Penh.

Transverse. Growth rings rather broad. Tracheids of the spring wood
round but thin-walled through the obvious effects of decay ; rather
uniform in regular rows, and passing gradually into the rather thin but
conspicuous summer wood. Resin passages wholly wanting. Resin
cells not recognizable. Medullary rays prominent, often 2 cells wide,
distant 1-6 rows of tracheids.

Radial. Medullary rays wholly devoid of tracheids. Ray cells more or less
conspicuously contracted at the ends, equal to about 6 spring tracheids;
the upper and lower walls rather thin and sparingly pitted ; the termi-
nal walls chiefly straight, sometimes curved, not pitted or obviously
thickened locally; the lateral walls with oval or round pits, 1-2, chiefly
2, per tracheid. Bordered pits in i row, chiefly distant, round. Pits
on the tangential walls of the summer wood not recognizable. Resin
cells present on the outer face of the summer wood (?), 30 p. wide and
125 /Along.

Tangential. Fusiform rays wholly wanting. Ordinary rays numerous, low
to high, often more or less 2-seriate, rarely 3-seriate in part ; the cells
variable, chiefly broad, oval or round, or sometimes transversely oval.
Resin cells rather numerous, usually very long, the resin scattering in
small globules.

Material silicified.

Cretaceous near Medicine Hat, Alberta ; Tertiary of Kettle River, near
Midway, British Columbia.

CUPRESSOXYLON

12. * * C. comanchense, Penh.

239

Transverse. Tracheids in regular, radial rows, rounded, very uniform, 44 x
44 //, broad, the walls 12.5 /u. thick. Growth rings prominent, about 10
in a radial extent of 22 mm. ; the summer wood thin, composed of 2-4
rows of tracheids, the latter about 22 p. wide, the walls 12.5 ^ thick.
Resin passages and resin cells wholly wanting. Worm burrows are fre-
quent and show copious exudation of resin, which has often preserved
the adjacent structure from decay.

Radial. Ray cells of one kind only, straight ; the upper and lower walls
thin and not pitted ; the terminal walls thin, not pitted, chiefly curved ;
the lateral walls with oval, bordered pits, about 1-2 per tracheid, the
oblong or broadly lenticular orifice nearly as long as the pit ; the cells
equal to about 4 tracheids. Bordered pits round, large, 1 9 /x broad;
in i or sometimes 2 rows, the orifice round.

Tangential. Rays i -seriate, the cells thin-walled, round, 19 p. broad.

Material silicified. Specimens represented by small fragments of a stem.
Comanche Cretaceous (?) northwest of Ashland, Clark County, Kansas
(Prosser).

13. ** C. pulchellum, Knowlton

" Transverse. The pith is well preserved and consists, when viewed under
the microscope, of numerous large, rather thick-walled cells with an
elliptic or nearly circular outline. The larger cells, which have a
diameter of .05-. 08 mm., occupy the center, from which they de-
crease in size and pass more or less gradually into the medullary
rays. The rays are very numerous and pass in nearly a straight line to
the circumference. No trace of bark remains. The tracheids are
arranged with great regularity in radial rows, and are remarkable for
their small size, particularly where they are in contact with the pith.
As the medullary rays diverge, new layers of tracheids are intercalated
to fill up the space. The line of demarcation between the annual
layers is generally well defined, the fall wood consisting of 5-8 com-
pressed cells in each radial row. The spring wood consists of much
larger cells, which have a diameter of .025-. 035 mm. These cells are
more nearly hexagonal than the others, and, decreasing gradually in
size, pass into the next ring of fall wood.

" Radial. In this section the tracheids are seen to be long and provided
with a single longitudinal row of bordered pits, which have an average
outer diameter of .01 7-. 021 mm. The inner circle of the pits is rather
small, with a diameter of .005-. 006 mm. The medullary rays are
cut up into comparatively short cells, each one covering the space
of five or six of the tracheids ; markings seem to be absent from
the walls of the rays, but the real state of affairs may be masked by the
petrifying material, which has evidently somewhat disorganized the
original structure. The resin ducts (cells) are numerous. These con-
sist of a chain of short, regular cells, which are slightly constricted at
the ends. The individual cells are .08-. 15 mm. in length, and are
usually filled with minute globules of darker matter.

240 ANATOMY OF THE GYMNOSPERMS

" Tangential. The medullary rays are very abundant. They are always
simple and consist of a single layer, which ranges from i to 15 cells
in height, the average being about 7 or 8. The tracheids do not show
bordered pits on the tangential walls, a fact of considerable impor-
tance " (Knowlton).

Remains silicified.

From the Potomac Formation at Spring Hill, Virginia (Knowlton).

14. * * C. arkansanum, Knowlton

" Transverse. The annual ring is either entirely absent or so obscured by
the mass of crushed cells as to be indistinguishable. In a single,
exceptionally well-preserved spot the tracheids are seen to be arranged
in nearly uniform radial rows, there being generally about 3 or 4 rows
between 2 medullary rays. The rays are abundant and consist of a
single cell.

'•'•Radial. The tracheids are rather thick-walled and provided with a single
row of pits. The pits are rather distant, the outer circle having a diam-
eter of .oii-.oi45 mm., and the inner a diameter of .oo28-.oo48 mm.
The medullary rays are abundant, and usually only a single series thick,
although a few may be found with 2 series of cells in the center.

" Tangential. The material is not sufficiently well preserved to determine
the medullary rays satisfactorily" (Knowlton).

Remains silicified.

From the Tertiary deposits (Orange sands) of Poinsett County, Arkansas
(Knowlton).

15. * * C. Dawsoni, Penh.

Transverse. Growth rings variable, chiefly medium to broad. Tracheids
of the spring wood large, thin-walled, conspicuously squarish, and
passing gradually into the usually thin but rather prominent summer
wood, which may occasionally become thicker and without definite
internal demarcation. Resin passages wholly wanting. Resin cells
numerous and conspicuous throughout the growth ring, often in more
or less prominent, tangential row. Medullary rays prominent, resin-
ous, i cell wide but rather broad, distant 2-9 rows of tracheids.

Radial. Medullary rays devoid of tracheids. Ray cells resinous, contracted
at the ends, equal to 5-6 spring tracheids ; the upper and lower walls
thin and sparingly pitted ; the terminal walls straight, or sometimes
strongly curved, not pitted or locally thickened ; the lateral walls
with round or oval pits, 1-2 per tracheid in vertical series, or in
marginal cells and low rays, or over very broad tracheids, becoming 4
per tracheid. Bordered pits large, in I row, often more or less in pairs,
and so, over broad tracheids, becoming more or less 2-rowed. Resin
cells numerous, 35-40 /j. wide, 200 p. long.

Tangential. Medullary rays of one kind only and i -seriate; the cells
rarely in pairs, large, thin-walled, oval or oblong, usually broad, and
often becoming transversely oval in all except the terminal cells.
Resin cells as in the radial section.

CUPRESSOXYLON 241

Material silicified.

Eocene of the Great Valley and Porcupine Creek groups, the province of

Saskatchewan ; Cretaceous of the south Saskatchewan near Medicine

Hat, Alberta.

16. C. Wardi, Knowlton

" Transverse. Material too fragmentary and too poorly preserved to show
the annual rings to the naked eye, but they are apparent under the
microscope. The fall wood consists of 3-6 or 3-8 compressed cells
in radial rows. The spring wood contains some very large cells, with
a diameter in some instances of .062 mm. The number of cells in
each row of tracheids varies according to the width of the annual
ring, there being frequently as much as 100. Large intercellular
spaces occur, especially where additional rows of tracheids have been
introduced.

" Radial. Tracheids provided in i row, or, in some instances, with 2 lon-
gitudinal rows of bordered pits. They occupy the center of the cell,
and are in close relations, almost touching in some cases. The larger
have a diameter of .02 mm., and the smaller a diameter of .015 mm.
The medullary rays consist of typical parenchymatous tissue. The
individual cells are short, covering a width of 4-8 tracheids. Pits on
the lateral walls of the rays not observable, possibly due to the poor
state of preservation. The resin ducts (cells) are not very numerous.
They are of nearly the same size and shape as the tracheids, and in
fact look very much like tracheids with transverse partitions. They
are almost always empty.

" Tangential. The tracheids are not provided with pits on the tangential
walls, or at least none have been detected. The medullary rays in
many cases are 2 cells broad, and, as indicated, 1-35 cells high.
The individual cells of the rays have a diameter of .OI7-.O3 mm."
(Knowlton).

Material silicified. Specimens represented by small fragments only.
From the Potomac Formation on the line of the Baltimore and Ohio Rail-
road, between Montello and Rives Station, D.C. (Knowlton).

17. C. columbianum, Knowlton

" Transverse. The annual ring is very indistinct, although not entirely
absent, as slight traces of it are to be observed among a mass of
crushed cells. Tracheids in very regular, radial rows, and remarkable
for their nearly uniform size and thick walls. The larger cells are
about .05 mm. in diameter, the smaller .03 -.04 mm. in diameter.
The medullary rays are not abundant and appear very narrow.

"Radial. The tracheids are thick-walled and covered with I, or rarely
2, rows of bordered pits, which are rather small. The larger pits
have a diameter of .015 mm. and the smaller a diameter of only
.01 mm. The rays consist of long cells, in some cases provided with
minute, round punctations. The resin ducts (cells) are numerous.
In most cases they consist of a regular chain of short, constricted
cells. In some cases they contain small globules of resinous matter.

242 ANATOMY OF THE GYMNOSPERMS

" Tangential. The medullary rays have very small cells which have a
long diameter of .ois-.oiy mm. and a short diameter of only .01 mm.
The walls of the tracheids are so thick and the rays so small that
the walls between which they appear are but slightly bulged. The
tracheids do not exhibit pits on the tangential walls" (Knowlton).

Remains silicified. The specimen is represented by numerous fragments

of stem, upwards of 25 cm. in length.
The Potomac Formation of Dutch Gap and Nebasco Creek, Virginia

(Knowlton).

18. C. elongatum, Knowlton

" Transverse. Annual rings apparent to the naked eye, but faint, i-6mm.
broad. The layer of the fall wood is narrow, consisting of only 6-10
rows of flattened and thick-walled cells. The cells of the spring and
summer wood are much larger and rectangular in outline. Their
radial diameter is as great as .105 mm. in some cases, while the tan-
gential diameter is only .035-. 04 mm. The average size is about
.07 mm. in long, and .O3-.O5 mm. in short, diameter. The medullary
rays are observed to be numerous. The largest cells are in contact
with the medullary rays.

"Radial. The wood cells or tracheids appear broad and thick-walled, and
to be provided with 2 rows of very large pits which nearly touch in
the center, and are in contact with the walls on the outside. The
diameter of the outer circle is .02 mm., that of the inner circle
.oo4-.oo6 mm. They are rarely in a single row when they occupy
the center of the cell. The resin ducts consist of a chain of short
cells, the contents of which are not preserved. Medullary rays abun-
dant; individual cells long, covering the width of 6 or 8 tracheids;
thin-walled. They seem not to have been provided with pits or
markings.

" Tangential. Medullary rays in a single series, and rarely of 1-44 super-
imposed cells. It is not common to find rays with less than 5 cells or
more than 30, the average being about 10-25. No pits on the walls
of the tracheids" (Knowlton).

Remains silicified. Specimen represented by a log about 30 feet long in

a clay soil.
From the Laramie of Tiger Buttes, Dawson County, Montana (Knowlton).

19. C. glasgowi, Knowlton

" Transverse. Annual rings very sharply marked, 3-4! mm. broad. Under
the microscope the cells are shown to be arranged in strict radial
rows, and in the band of summer wood consist of a layer of
18-30 cells more or less completely lignified. In the outer layers
of this lignified band of fall wood the lumen of the cells is reduced
to a minimum. The lumen is in the form of an ellipse, of which the
long diameter is less than .01 mm. and the short diameter about
.005 mm. In the immediately following layer of spring wood the
cells are very large and thin-walled, measuring .08 mm. in long, and

CUPRESSOXYLON 243

.05 mm. in short, diameter. In the summer wood the cells become
smaller and more nearly hexagonal in outline, and pass abruptly into
the band of fall wood.

'•'•Radial. In this section, as in the transverse, the demarcation between
fall and spring wood is very clearly marked. The walls of the cells
in the spring and summer wood are the only ones provided with bor-
dered pits, and in these they seem not to have been very abundant,
or at least are not preserved in a manner capable of demonstration.
These pits are usually arranged in 2 parallel rows, although in some
cases there is but i row, when it occupies the center of the cell. The
pits are large, and when in 2 rows take up nearly the entire width
of the cell. The diameter of the outer circle is in extreme cases
fully .025 mm., the average being about .02 mm. ; the diameter of the
inner circle is only .oo25-.oc>4 mm. The medullary rays are observed
to be numerous, with the individual cells very long. The latter are
not, however, very high, and they are thin-walled. The pits on the
lateral walls are not recognizable. The resin ducts are moderately
numerous. They are composed of a chain of short, thin-walled cells
.15-. 25 mm. in length, and are partially filled with a dark mass repre-
senting the resin.

" Tangential. In this section the medullary rays are observed to be com-
posed of a single series of cells which ranges from 3 to 30 in number.
It is rare, however, to find them with as few as 3 or as many as 30
cells, the average number being from 8 to 15. Bordered pits have
not been observed in this section" (Knowlton).

Material silicified.

Cretaceous (?) of Emmet County, Iowa (Knowlton).

20. C. McGeei, Knowlton

" Transverse. The tracheids are arranged in strictly radial rows. The
annual ring is broad, consisting in some cases of as many as 50 or
60 of the larger, and 10-16 of the smaller, thick-walled cells. The
larger cells are mostly quadrangular in outline and have a diameter in
some instances of .08 mm., the average being about .068 mm. The
cells of the fall wood have very thick walls and are much flattened.
Intercellular spaces are frequently observed, particularly where ad-
ditional rows of tracheids have been intercalated. The medullary rays
are moderately numerous.

" Radial. The large size of the tracheids is very clearly shown, and they
make up the bulk of the section. The tracheids of the fall wood are,
of course, much smaller, and are covered with but a single row of
pits. The bordered pits are very close together on the summer wood,
and are always in 2, and in some exceptionally large cells, in 3 rows.
They are also very large, the outer circle having a diameter of .02—
.025 mm., and the inner of .005— .008 mm. The walls of the medul-
lary rays are marked by large, oval pores, from I to 3 of which
occupy the width of a single wood cell. The resin ducts consist of
a chain of short, small, thin-walled cells, which now contain a small
quantity of granular matter, representing probably drops of resin.

244 ANATOMY OF THE GYMNOSPERMS

The individual cells have a length of .12-. 25 mm., and a diameter of
about .05 mm., slightly less, it will be observed, than the tracheids
among which they run.

" Tangential. The medullary rays are always simple ; that is, they consist
of but a single row of cells, which varies from 2 to 49 cells in height.
The tracheids are provided on the tangential walls with a few scattered,
bordered pits. These have a diameter of .oi6-.o2i mm." (Knowlton).

Remains silicified. Specimens represented by a trunk nearly 40 feet long

and almost 2 feet in diameter.
Potomac Formation at Washington, D.C. (Knowlton).

21. C. Calli, Knowlton

" Transverse. The annual rings are very distinct, being marked by a
layer of fall wood 6-15 or more cells in thickness. These cells are
very thick-walled, the lumen being reduced to a mere line. The cells
of the spring wood are very large and begin abruptly at the ring, and
gradually diminish in size until they reach and pass into the fall wood.
The medullary rays as seen in this section are numerous and are sepa-
rated by 2-4 rows of tracheids.

'•'•Radial. In the spring and summer wood the tracheids are very broad
and provided with 2-3 rows of regularly and closely packed bor-
dered pits. These pits have an average diameter of .012 mm. and an
average inner diameter of .003 mm. The medullary rays are thin-
walled and in some cases, at least, provided with pits, of which there
are usually 3 in thickness of each tracheid. The resin tubes consist of
a chain of short, rectangular cells; they are moderately numerous.

" Tangential. The medullary rays are arranged in a single series of super-
imposed cells, which varies from 2 to 25, the ordinary number being
6-15. The tracheids are not provided with pits on the tangential
walls" (Knowlton).

Remains silicified.

From the Tertiary clays of Greene County, Arkansas (Knowlton).

11. * JUNIPERUS, Lixx. PLATES 40 AND 41

Transverse. Growth rings generally narrow, often unconformable and
coalescent on the narrow side ; the summer wood usually thin but
dense. Resin passages wholly wanting. Resin cells rather numerous,
prominent, and chiefly in tangential bands, often giving rise to the
appearance of secondary growth rings.

Radial. The numerous and often very resinous rays chiefly without tra-
cheids. Ray cells with thin and entire or sometimes coarsely pitted
terminal walls ; the lateral walls with bordered pits. Bordered pits
round or oval, chiefly in i row, generally numerous. Tracheids wholly
without spirals.

Tangential. Fusiform rays wholly wanting. Ordinary rays I -seriate, some-
times 2-seriate in part, the cells oval, chiefly broad.

JUNIPKRUS 245

SYNOPSIS OF SPECIES

i . Ray cells (tangential) oval to round or transversely oval,

resinous, conspicuously broad
Ray cells (radial) resinous throughout.

4. * J. californica.

Ray cells (radial) locally resinous. Rays usually higher (tangential) than
in No. 4

5. J. utahensis.

2. Rays (tangential) rather broad, the cells oval to round, chiefly

round, sometimes in pairs, resinous
Bordered pits (radial) numerous, usually more or less distant.

Rays (tangential) rather high, more or less 2-seriate or the cells in
pairs ; the cells chiefly very round, rarely transversely oval.

9. J. pachyphlasa.

Rays (tangential) low, the cells rarely in pairs, round to oval, not trans-
versely oval

1. * J. virginiana.

Bordered pits (radial) numerous, usually crowded into compact series.
Rays (tangential) with conspicuously and uniformly rounded cells.

10. J. monosperma.

3. Ray cells (tangential) chiefly oval, the rays low, barely resinous
Summer wood of 2-4, rarely of 10, tracheids.

Pits on the lateral walls of the ray cells chiefly 2 per tracheid.

1 1. J. occidentalis.
Summer wood conspicuously thicker.

Pits on the lateral walls of the ray cells 1-4 per tracheid.

6. J. sabinoides.

4. Rays (tangential) narrow, the cells oblong to oval, chiefly oblong
Pits on the lateral walls of the ray cells chiefly 2 per tracheid, Ray cells
resinous.

Terminal walls of the ray cells strongly pitted.
Rays with narrow tracheids.

7. J. communis.
Terminal walls of the ray cells thin and not pitted.

Rays without tracheids.

3. J. rigida.

Pits on the lateral walls of the ray cells large, 2-4 per tracheid, obscurely

and irregularly bordered.

2. J. nana.

Pits on the lateral walls of the ray cells not very large, chiefly 4 per
tracheid. Ray cells sparingly resinous.

8. J. sabina.

246 ANATOMY OF THE GYMNOSPERMS

1. * J. virginiana, Linn.

Red Cedar. Savin

Transverse. Growth rings usually broad, often double or treble. The thin
summer wood rather open and passing gradually into the broad spring
wood. Spring wood rather open, the tracheids variable with medium
walls, in regular rows. Resin cells rather small and usually disposed
in 1-2 open bands chiefly in the spring wood. Medullary rays not
very prominent or resinous, rather numerous, i cell wide, distant
2-13 tracheids.

Radial. Ray cells not very resinous, equal to 5-10 spring tracheids; the
upper and lower walls rather thick, unequal and remotely pitted ;
the terminal walls thin, straight, and entire, rarely curved or locally
thickened ; the lateral walls with small, chiefly bordered pits 6 /j.
broad, chiefly 2, more rarely 4, per tracheid, the orifice narrow,
linear-oblong. Bordered pits round, in I row, sometimes in pairs,
the orifice rather large. Pits on the tangential walls of the summer
tracheids numerous, flat. Resin cells about 20 /j. broad, 100—150 p.
long.

Tangential. Rays sometimes 2-seriate in part, low ; the cells small, nar-
rowly oval to round, chiefly round, thick-walled, resinous.

A tree 20-30 m. high, with a trunk .60-1.35 m. in diameter. Wood light,
soft, not strong, brittle, very close and straight grained, compact, easily
worked, very durable in contact with the soil, odorous.

Relative specific gravity 0.4926

Approximate relative fuel value 49. u

Coefficient of elasticity in kilograms on millimeters . . 670.

Ultimate transverse strength in kilograms 316.

Ultimate resistance to longitudinal crushing in kilograms 6750.

Resistance to indentation to 1.27 mm. in kilograms . . . 2376.
(Sargent)

Nova Scotia ; uncommon about Ottawa, but becoming more common
westward throughout Ontario, abundant at Bay of Quinte, thence south-
ward, crossing the St. Lawrence River midway between Montreal and
Lake Ontario (Macoun); southward from New Brunswick to Tampa
Bay, Florida ; westward through Texas, Nebraska, Kansas, and Okla-
homa to the looth parallel, thence north to northern Michigan, Wiscon-
sin, and Minnesota ; in the Pacific region through the mountains of
Colorado and British Columbia to Vancouver Island (Sargent).

Pleistocene of the Don Valley, Toronto.

Material not petrified, but remarkably well preserved in its natural state,
and exhibiting the characteristic odor when cut.

JUNIPERUS 247

2. J. nana, Willd.

Common Juniper

Transverse. Growth rings very variable and unconformable, the tracheids
very small throughout. Summer wood thin, of 3-6 tracheids, rather
open, often double, the transition from the spring wood gradual.
Spring wood broad, the tracheids squarish-hexagonal, not very uni-
form, small, the walls medium, the general density varying greatly in
different rings. Medullary rays inconspicuous, i cell wide, distant 2-10
rows of tracheids. Resin cells numerous, prominent, distinctly zonate.

Radial. Rays very sparingly, if at all, resinous throughout, wholly devoid
of tracheids. Ray cells variable in height, chiefly straight or becom-
ing contracted in the summer wood, equal to 7-8 spring tracheids ;
the upper and lower walls thin, with broad, unequal, and usually
rather distant pits ; the terminal walls thin, often curved, entire or
locally thickened ; the lateral walls with large, very prominent, oval
pits with an obscure and unequal border, 2-4, or in the summer wood
2, per tracheid. Bordered pits numerous, large, as broad as the tra-
cheid, in i row. Pits on the tangential walls of the summer tracheids
numerous, large, and open. Resin cells 20 /A wide, about 165 p. long.

Tangential. Rays rather numerous, low to medium ; the cells equal, rather
uniform and oblong, sometimes oval, the walls thin.

Of uncertain range in the northern parts of the continent ; Lake Mistas-
sini ; the Shickshock Mountains, Gaspe; Bow River, Alberta; Rocky
Mountains from Silver City westward to the summit of the Selkirks in
latitude 51°; also the south and north Kootenay passes (Macoun);
Labrador southward to Massachusetts and New York, thence westward
to Michigan, Colorado, and Utah (Britton).

3. J. rigida, Sieb. et Zucc.
Jap. = Muro

Transverse. Growth rings broad, the structure rather open throughout.
Summer wood very thin, of 3-4 tracheids, the transition from the
spring wood rather gradual. Spring tracheids conspicuously hex-
agonal, rather thin-walled, uniform in regular rows. Medullary rays
not very prominent or resinous, I cell wide, distant 2-12 rows of
tracheids, more rarely 32. Resin cells prominent, usually distant in
very narrow zones of occasional growth rings.

Radial. Rays somewhat resinous throughout, devoid of tracheids. Ray
cells chiefly straight or somewhat contracted in the summer wood ;
the upper and lower walls medium, unequal, distinctly perforate with
broad and unequal pits ; the terminal walls thin, often curved, entire
or locally thickened ; the lateral walls with rather large, oval, nar-
rowly bordered pits, the broadly lenticular orifice becoming oblong
in the summer wood, 1-2, or in the marginal cells 4, per tracheid.
Bordered pits round, somewhat distant in i row, not very numerous.

248 ANATOMY OF THE GYMNOSPERMS

Pits on the tangential walls of the summer tracheids rather numerous
but not very large or prominent. Resin cells few, 15 p. wide, 185—
240 p, long.

Tangential. Kays somewhat numerous, medium ; the cells chiefly equal,
rather uniform, oblong, more rarely oval and broader.

4. * J. californica, Carr.
Juniper

Transverse. Growth rings variable, more or less eccentric and often
coalescent. Summer wood thin, chiefly of 3-6 tracheids, not very
dense, passing somewhat abruptly into the broad spring wood.
Spring wood rather open, the tracheids squarish, the walls medium.
Resin cells numerous and conspicuous, chiefly in broad, open bands.
Medullary rays very prominent and resinous, i cell wide, distant
2-1 I, rarely 17, tracheids.

Radial. Ray cells very resinous, more or less contracted at the ends,
equal to 5-7 spring tracheids ; the upper and lower walls medium
and entire or remotely pitted, becoming conspicuously thicker at the
ends of the cells ; the terminal walls thin, curved and entire or
straight, locally thickened or even coarsely pitted ; the lateral walls
with oblong pits, chiefly i, or in the marginal cells and low rays 2-4,
per tracheid. Bordered pits broadly elliptical, rather numerous, the
orifice rather large. Pits on the tangential walls of the summer tra-
cheids numerous and prominent, rather large, the orifice bell-shaped.
Resin cells about 12.5-20/4 wide, and many times longer, upwards

Of 215 /A.

Tangential. Rays low and rather broad, very resinous, the cells from nar-
rowly oval in the lowest rays to round or more rarely transversely
oval, chiefly round.

A small tree rarely 6-9 m. high, with a trunk .3o-.6o m. in diameter.
Wood light, soft, very close grained and compact, very durable in contact
with the soil.

Relative specific gravity 0.6282

Percentage of ash residue 0.73

(Sargent)

Dry slopes and plains of the lower Sacramento River, southward through
the California coast ranges to Lower California ; spreading inland along
the coast mountains to their union with the Sierra Nevada, through
which it ranges northward as far as Kernville, descending to 2600 feet ;
desert slopes of Tehachapi Mountains, and abundant on the northern
foothills and on the seaward slopes of the San Jacinto and Cuyamaca
ranges (Sargent).

From the Quaternary deposits (lowan ?) of the Klamath River, Orleans,
Humboldt County, California, in blue, sandy silt at a depth of 150 feet.
Material very slightly silicified and in a good state of preservation.

JUNIPERUS 249

5. J. utahensis, Lemm.

Juniper

Transverse. Growth rings very variable, chiefly thin. Summer wood very
thin, of 2-4 tracheids, the transition to the spring wood somewhat
abrupt. Spring wood rather open, the tracheids uniform, squarish-
hexagonal, often radially compressed, rather large, the walls medium.
Resin cells numerous, conspicuous, in very open bands in both the
spring and summer wood. Medullary rays very prominent and resin-
ous, broad, i cell wide, distant 2-8, more rarely 12, tracheids.

Radial. Ray cells more conspicuously contracted at the ends and dis-
tinctly less resinous than in the preceding, the resin chiefly in terminal
masses, equal to 6-10 spring tracheids; the upper and lower walls
not conspicuously thickened at the ends of the cells, thickish, rather
uniform, obscurely pitted, if at all ; the terminal walls often curved
and coarsely pitted ; the lateral walls with oblong pits, often with an
obscure border, chiefly 1-2, or in the lowest rays 4, per tracheid.
Pits on the tangential walls of the summer tracheids very numerous
and large, but less open and prominent than in J. californica. Resin
cells about 15 //. wide, very long, — 150 /A or upwards of 285 /u., — not
strongly resinous.

Tangential. Rays somewhat resinous, the cells thick-walled, chiefly trans-
versely oval or oblong, usually broader than in No. 4 and much
shortened vertically.

A small tree 6-9 m. high, with a trunk .60-. 90 m. in diameter. Wood
light, soft, close grained, compact, very durable in contact with the soil.

Relative specific gravity 0.5522

Percentage of ash residue 0.75

(Sargent)

Western base of Wasatch Mountains, Utah, to eastern California and
south through the Great Basin to southern California ; the San Fran-
cisco Mountains of eastern Arizona (Sargent).

6. J. sabinoides, Neds.

Cedar. Rock Cedar

Transverse. Growth rings very variable. Summer wood rather dense and
composed of small tracheids, often double, chiefly much less than the
spring wood, into which it passes gradually and which it sometimes
equals. Spring wood chiefly somewhat open, but the demarcation
from the summer wood obscure. Resin cells numerous, not very
resinous or prominent, usually in somewhat compact zones, chiefly of
the summer wood. Medullary rays not very prominent, i cell wide,
distant 2-8, rarely 1 2, rows of tracheids.

Radial. Ray cells rather resinous, equal to 5-10 spring tracheids; the
upper and lower walls rather thick, variable, frequently pitted ; the
terminal walls thin and not pitted except in the marginal cells ;

250 ANATOMY OF THE (rVMNOSPERMS

the lateral walls with 1-4 pits per tracheid. Bordered pits numerous,
in I row, round or vertically compressed in compact rows, the len-
ticular orifice large. Pits on the tangential walls of the summer
tracheids numerous and prominent. Resin cells not very numerous,
15-20 p. wide and 150-275 //, long.

Tangential. Rays usually very low, the cells oval to oblong, not broad,
chiefly oval, barely resinous.

A tree 11-15 m. in height, with a trunk upwards of .30 m. in diameter.
Wood light, hard, not strong, very close grained, compact, very durable
in contact with the soil.

Relative specific gravity 0.6907

Percentage of ash residue 0.47

Approximate relative fuel value 68.75

Coefficient of elasticity in kilograms on millimeters . . 734.

Ultimate transverse strength in kilograms 200.

Ultimate resistance to longitudinal crushing in kilograms 8505.

Resistance to indentation to 1.27 mm. in kilograms . . 4464.
(Sargent)

Valley of the Colorado River, western Texas (Sargent).

7. J. communis, Linn.
Juniper. Ground Cedar

Transverse. Growth rings medium, very variable. The chiefly thin and
dense summer wood often double, sometimes equal to the spring
wood, into which it passes very gradually, the line of demarcation
obscure. Tracheids of the usually broad spring wood small. Resin
cells rather numerous, usually not very prominent, in 1-3 very narrow
zones in each growth ring, the contiguous tracheids rarely becom-
ing resinous so as to form a strongly resinous zone. Medullary
rays numerous, i cell wide, distant 2-8, or more rarely 10, rows of
tracheids.

Radial. Rays uniformly resinous throughout, tracheids occasionally pres-
ent and marginal. Ray cells somewhat contracted at the ends, equal
to 5-6 spring tracheids ; the upper and lower walls thick, unequal,
rather frequently pitted ; the terminal walls thin, entire, locally thick-
ened or sometimes coarsely pitted ; the lateral walls with unequally
bordered, oval pits having a large, lenticular orifice, 1-2 per tracheid.
Pits on the tangential walls of the summer tracheids rather numerous,
not very large or prominent. Resin cells 12.5-15 /j. wide, 125-200/11
long. Bordered pits round, equal to the tracheid, in i row, rather
distant, or when more crowded becoming elliptical.

Tangential. Rays numerous, low, narrow, resinous ; the oblong cells thick-
walled.

A prostrate shrub with ascending branches, forming dense mats upwards
of 5-7 m. in diameter and 1-1.30 m. high.

JUNIPERUS 251

From Labrador to the Pacific (Macoun) ; southward to New Jersey and
Pennsylvania; westward to Michigan and western Nebraska, thence
southward through the Rocky Mountains to New Mexico (Britton).

8. J. sabina, Linn.
Shrubby Red Cedar

Transverse. Growth rings unequal, often coalescent on the narrower side.
The thin summer wood of 3-8 tracheids, rarely forming the entire
ring, in the broader rings becoming double or treble. Spring wood
open, the tracheids large and thin-walled. Resin cells not very numer-
ous or prominent, chiefly narrowly zonate in the spring wood, often
showing extensive but local aggregations when they become large,
rounded and loosely grouped in irregular masses with the partial
formation of resin canals. Medullary rays inconspicuous, distant
2-25, rarely 37, tracheids.

Radial. Ray cells very sparingly resinous, chiefly straight, equal to about
5 spring tracheids ; the upper and lower walls thin and entire or with
rather distant pits ; the terminal walls thin and locally thickened or
coarsely pitted ; the lateral walls with rather prominent pits with a
broadly lenticular or oval orifice, the border rather obscure, 1-2,
chiefly 4, per tracheid. Bordered pits numerous, as broad as the tra-
cheids, generally elliptical in I compact row, the orifice large. Pits
on the tangential walls of the summer tracheids somewhat numerous
and prominent. Resin cells about 15 p. wide, 125-150 p. long.

Tangential. Rays all narrow, the cells chiefly narrowly oval to oblong, the
"walls thin, variable ; when of a single cell, the latter is high, lenticular.

A depressed, usually procumbent shrub, seldom more than 1.20 m.
high (Britton).

On exposed slopes and river banks from Anticosti, Nova Scotia, New
Brunswick, Quebec, and Ontario, across the prairie region to the sum-
mit of the Rocky Mountains at Kicking Horse Pass (Macoun); from
Maine, westward through New York, Minnesota, and Montana (Britton).

9. J. pachyphlaea, Torr.

Juniper. Checkered-Barked Juniper

Transverse. Growth rings very narrow and unequal, eccentric. Summer
wood dense and thin, of 2-6 tracheids, the transition to the spring
wood somewhat gradual. Spring wood somewhat open, the tracheids
in regular rows. Resin cells numerous, chiefly in the spring wood,
irregularly zonate. Medullary rays very prominent and resinous, i
cell wide, broad, distant 2-8 tracheids.

Radial. The resinous ray cells equal to 4-13 spring tracheids; the upper
and lower walls medium to thick, entire or remotely pitted ; the ter-
minal walls strongly pitted ; the lateral walls with rather conspicuous,
lenticular pits about 1-2, more rarely 4, per tracheid. Bordered pits

252 ANATOMY OF THE GYMNOSPERMS

round, numerous, becoming very small and obscure in the summer
wood, the round orifice becoming lenticular towards the summer wood.
Tits on the tangential walls of the summer tracheids numerous, medium,
flat. Resin cells about 20 p. wide, 165-400 /x long.

Tangential. Rays medium, often 2-seriate in part, the cells broadly oval or
round, rather thick-walled.

A tree 6-15 m. high and .60 m. in diameter.

Wood light, soft, not strong, brittle, very close grained, compact, suscep-
tible of a fine polish.

Relative specific gravity 0.5829

Percentage of ash residue o. 1 1

(Sargent)

Mountains of western Texas, southern New Mexico, and Arizona south of
latitude 34°; southward into Mexico (Sargent).

10. J. monosperma, Sarg.

Juniper

Transverse. Growth rings chiefly broad, very variable. The prominent
but usually very thin summer wood dense, of 3-7 tracheids, often
double ; the transition from the spring wood somewhat gradual. Spring
wood somewhat dense, the tracheids variable. Resin cells very prom-
inent and resinous, numerous, in compact zones chiefly in the spring
wood. Medullary rays very numerous and prominent, broad, i cell
wide, distant i-io rows of tracheids.

Radial. Ray cells resinous throughout, more or less conspicuously con-
tracted at the ends, equal to 6-8 spring tracheids ; the upper and lower
walls thick, rather uniform, frequently pitted ; the terminal walls
coarsely pitted; the lateral walls with small, round, bordered pits with
a lenticular-oblong but small orifice, chiefly 2, but in low rays and
marginal cells often upwards of 6, per tracheid. Bordered pits numer-
ous and in I compact row, round or vertically compressed, nearly
as broad as the tracheid. Pits on the tangential walls of the summer
tracheids very numerous but small. Resin cells about 15 p. wide, 200 p.
and upwards long.

Tangential. Rays numerous, resinous, low ; the broad cells oval or round,
somewhat uniform.

A stunted tree 6-9 m. high, and a trunk upwards of .60 m. in diameter.

Relative specific gravity 0.7119

Percentage of ash residue 0.78

(Sargent)

Gravelly slopes between 3500 and 7000 feet elevation, eastern base of
Pikes Peak, to the mountains of western Texas ; through New Mexico
and southern Arizona to southern California (Sargent).

ABIES 253

11. J. occidentalis, Hook.

Juniper

Trans-verse. Growth rings usually very narrow ; the dense summer wood of
2-4, rarely 10, tracheids, passing rather abruptly into the rather open
spring wood ; the tracheids small and thick-walled. Spring wood
rather open, but the tracheids rather small and usually much rounded.
Resin cells abundant and prominent, chiefly in the summer and outer
spring wood, in open or compact zones. Medullary rays numerous,
rather prominent, not very resinous, i cell wide, distant 2-8, rarely
13, rows of tracheids.

Radial. Ray cells very sparingly resinous, usually straight or somewhat
contracted at the ends, equal to 4-6 spring tracheids ; the upper and
lower walls thickish, entire or distantly pitted ; the terminal walls
strongly pitted ; the lateral walls with small, oval, bordered pits, the
orifice oblong, 1-3, more rarely 4, per tracheid throughout. Bordered
pits round, numerous, in i row, becoming obscure or wanting in the
summer wood. Pits on the tangential walls of the summer tracheids
numerous, but usually small and often obscure. Resin cells numerous,
20 p. wide, 140-275 p. long.

Tangential. Rays generally low, of a few cells only ; the cells round to
oblong, not very broad, chiefly oval.

A tree 6-15 m. high, with a trunk 1.20-2.10 m. in diameter ; often becoming

a low, much-branched shrub.
Wood light, soft, very close grained, compact, very durable in contact with

the soil.

Relative specific gravity 0.5765

Percentage of ash residue 0.12

(Sargent)

Dry, rocky ridges and prairies of the Blue Mountains and high prairies of
eastern Washington and Oregon ; the Cascade Mountains of Oregon ; the
valley of the Klamath River, California, and south along the high ridges
of the Sierra Nevada Mountains at elevations of 7000-10,000 feet, to
the San Bernardino Mountains (Sargent).

12. * ABIES, LINK. PLATES 42 AND 43

Transverse. Growth rings usually broad with no very clear demarcation
between the spring and summer woods. Resin passages sometimes
present and then imperfectly organized, usually in somewhat distant
growth rings. Resin cells, when present, remote and inconspicuous
on the outer face of the summer wood.

Radial. Ray tracheids not present (except A. balsamea). The terminal
walls of the ray cells usually strongly pitted, especially in the summer
wood. Tracheids wholly without spirals.

Tangential. Fusiform rays wholly wanting. Rays narrow, strictly r-seriate.

254

ANATOMY OF THE GYMNOSPERMS

SYNOPSIS OF SPECIES

i. Resin passages present but imperfectly developed1

Ray cells (tangential) all broad, oval, or round.

Pits on the lateral walls of the ray cells 1-3, rarely 4, per tracheid.
Tracheids in regular rows.

Resin cells on the outer face of the summer wood.

10. A. concolor.

Resin cells wanting.

8. A. bracteata.

Pits on the lateral walls of the ray cells chiefly 2, rarely 3-4, per tracheid.
Tracheids in regular rows.

Resin cells wanting.

9. A. nobilis.

Ray cells uniformly narrow, oblong.

Pits on the lateral walls of the ray cells obscurely bordered, greatly
reduced or wanting in the summer wood, 1-4, or in the marginal
cells 6, per tracheid.

Resin cells wanting.

1 1. A. firma.

2. Resin passages wholly wanting

Ray tracheids present, few.

Resin cells (transverse) wanting.

Ray cells (tangential) uniformly narrow, oblong.

Pits on the lateral walls of the ray cells i -4, rarely 8, per tracheid.

4. * A. balsamea.
Ray tracheids wholly wanting.
Resin cells wanting.

Ray cells (tangential) uniformly narrow.

Pits on the lateral walls of the ray cells 1-4, rarely 8, per tracheid.

4. * A. balsamea.

Pits on the lateral walls of the ray cells obscurely bor-
dered, greatly reduced or wanting in the summer wood,
1-4, or in the marginal cells 6, per tracheid.

1 1 . A. firma.

Pits on the lateral walls of the ray cells more or less obvi-
ously bordered, especially in the summer wood, chiefly 2 per

tracheid.

i. A. Fraseri.

Ray cells (tangential) variable, from round or oval to narrowly
oblong.

1 Species included in this section should also be looked for under the second
section with the same differentiation.

ABIKS 255

Pits on the lateral walls of the ray cells 1-4, in the mar-
ginal cells rarely 5, per tracheid.

Upper and lower walls of the ray cells strongly pitted
throughout.

2. A. lasiocarpa.

Pits on the lateral walls of the ray cells 1-2, or in the mar-
ginal cells upwards of 4, per tracheid.

Upper and lower walls of the ray cells sparingly pitted
in the spring wood.

3. A. Veitchii.

Resin cells scattering on the outer face of the summer wood.
Ray cells broad (tangential), oval to round.

Pits on the lateral walls of the ray cells small, round, or
oval, at first obscurely bordered, but toward the summer
wood with a distinct border and narrow orifice.

Pits on the lateral walls of the ray cells i -4, soon becoming
2, and in the summer wood i,per tracheid throughout.
Upper and lower walls of the ray cells thin, not
obviously pitted.

Ray cells (tangential) very broad and large.

7. A. grandis.

Pits on the lateral walls of the ray cells 1-2, rarely 3,
or in the marginal cells sometimes 5, per tracheid.
Upper and lower walls of the ray cells thick, un-
equal, coarsely but very unequally pitted.

Ray cells (tangential) chiefly oval, rarely in
pairs.

6. A. amabilis.

Pits on the lateral walls of the ray cells chiefly 2, more
rarely i or 4, or in the summer wood i, per tracheid
throughout.

Upper and lower walls of the ray cells unequal,
strongly but imperfectly pitted throughout.

Ray cells (tangential) round or oval, not very
large.

5. A. magnifica.

1. A. Fraseri, Poir.
Balsam. She Balsam

Trans-verse. Growth rings rather thin, variable, the structure open through-
out. Summer wood very thin, of 2-6 tracheids, passing gradually
into the spring wood. Spring tracheids rather large and thin-walled,

256 ANATOMY OF THE GYMNOSPERMS

squarish, uniform, in very regular rows. Resin cells none. Resin-
bearing tracheids few, rather prominent, scattering through the sum-
mer wood, more rarely in the spring wood. Medullary rays somewhat
resinous and prominent, i cell wide, distant 2-15 rows of tracheids.

Radial. Medullary rays sparingly resinous throughout, wholly devoid of
tracheids. Ray cells straight, or in the summer wood contracted at
the ends, equal to 7-8 spring tracheids ; the upper and lower walls
medium, unequal, somewhat distantly and imperfectly pitted in the
spring wood, but strongly pitted in the summer wood ; the terminal
walls strongly pitted ; the lateral walls with small pits which become
conspicuously bordered in the summer wood where the orifice is
reduced to a slit and the pit is round, 1-2, chiefly 2, or in the marginal
cells 2-4, per tracheid. Resin-bearing tracheids not numerous, the
resin sometimes massive in the summer wood, but forming a periph-
eral layer in the spring wood. Bordered pits elliptical, in i row or
sometimes in pairs. Pits on the tangential walls of the summer
tracheids somewhat numerous but small and flat.

Tangential. Rays small to medium, the cells narrow, rather uniform, oval
to oblong.

A tree 18-24 m. high and upwards of .60 m. in diameter.
Wood very light, soft, not strong, coarse grained, compact.

Relative specific gravity 0.3565

Percentage of ash residue 0.54

Approximate relative fuel value 35-46

Coefficient of elasticity in kilograms on millimeters . . . 972.

Ultimate transverse strength in kilograms 273.

Ultimate resistance to longitudinal crushing in kilograms . 5557.

Resistance to indentation to 1.27 mm. in kilograms . . 1048.
(Sargent)

High mountains of North Carolina and Tennessee, forming somewhat
extensive forests on moist slopes between 5000 and 6500 feet (Sargent).

2. A. lasiocarpa, Nutt.

Mountain Balsam. Balsam Fir

Transverse. Growth rings narrow, uniform, the structure open throughout.
Summer wood very thin, rarely upwards of 14 tracheids, the transition
to the spring wood gradual. Spring wood of large, squarish tracheids
with rather thin walls, uniform in regular rows. Resin cells and resin-
ous tracheids wholly wanting. Medullary rays not prominent, barely
if at all resinous, i cell wide, distant 2-8, more rarely 15, tracheids.

Radial. Rays very sparingly resinous, wholly devoid of tracheids. Ray
cells more or less conspicuously contracted at the ends, equal to about
7 spring tracheids ; the upper and lower walls thick, unequal, and
strongly pitted throughout ; the terminal walls thin, often devoid of
pits ; the lateral walls with obscurely bordered pits, the large orifice
lenticular, variable, 1-4, or in the marginal cells rarely 5, per tracheid,
and distinctly bordered, in the summer wood reduced to i per tracheid

ABIES

257

and distinctly bordered. Bordered pits elliptical, in i row, nearly
the diameter of the tracheid. Pits on the tangential walls of the
summer tracheids rather numerous, not very large. Resin cells and
resinous tracheids wholly wanting.

Tangential. Rays medium, the cells variable, from round or broadly oval
to narrowly oblong.

A tree 20-40 m. high, with a trunk upwards of .60 m. in diameter.
Wood very light, soft, not strong, rather close grained, compact.

Relative specific gravity 0.3476

Percentage of ash residue 0.44

Approximate relative fuel value 34-6 1

Coefficient of elasticity in kilograms on millimeters . . 762.

Ultimate transverse strength in kilograms 202.

Ultimate resistance to longitudinal crushing in kilograms 4829.

Resistance to indentation to 1.27 mm. in kilograms . . 1015.
(Sargent)

Summit of House Mountain, south of Lesser Slave Lake ; abundant in
Bow River Pass on mountain slopes 5000-7000 feet elevation, extend-
ing on the line of the Central Pacific Railroad from Castle Mountain
to Selkirk Summit ; abundantly in the Gold and Selkirk ranges, and in
the Rocky Mountain region east of McLeod's Lake ; elsewhere in the
northern portion of the interior plateau it occurs in scattering groves,
generally in localities nearly reaching or surpassing 4000 feet, but even
in low valleys in the eastern portion of the coast ranges ; damp situations
in the country between Lesser Slave Lake and the Athabasca River ;
high, cool valleys in the Rocky Mountains, southward to the 49th par-
allel, reaching upward to the timber line (Macoun) ; valley of the Stakhin
River in Alaska, in latitude 60° N. ; through the Blue Mountains of
Oregon and the ranges of Idaho, Montana, Wyoming, Utah, and Col-
orado ; on mountain slopes and canons from 4000 (British Columbia)
to 12,000 feet (Colorado); rarely forming the prevailing forest growth
(Sargent).

3. A. Veitchii, Lindl.

Jap. — Shirabe

Transverse. Growth rings very variable, often very narrow. Summer wood
prominent but very narrow, of 3-5 squarish tracheids, the structure
open, or again broad and somewhat exceeding the spring wood, with
the structure rather open but the tracheids strongly rounded ; transition
to the spring wood gradual. Spring wood open, the tracheids rather
large, squarish, and thin-walled, uniform in regular rows. Resin cells
and resinous tracheids wanting. Medullary rays not prominent, i cell
wide, distant 1-20 rows of tracheids.

Radial. Rays somewhat resinous in part, and wholly devoid of tracheids.
Ray cells chiefly straight, equal to 7-8 spring tracheids, or in the

258 ANATOMY OF THE GYMNOSPERMS

summer wood becoming very much shorter ; the upper and lower walls
medium, unequal, the narrow pits not very numerous, except in the
summer wood, often imperfectly formed ; the terminal walls closely
pitted, becoming more prominent in the summer wood ; the lateral
walls with narrowly bordered oval pits, 1-2, or in the marginal cells
upwards of 4, per tracheid, the orifice broadly lenticular or oval. Bor-
dered pits round or elliptical, numerous in i row, variable, but chiefly
two thirds the diameter of the tracheid, the large orifice round. Pits on
the tangential walls of the summer tracheids few, small, rather open.
Resin cells and resinous tracheids wholly wanting.

Tangential. Rays not very numerous, medium to high, somewhat resinous,
strictly i -seriate ; the cells somewhat unequal and variable, chiefly
round or oval, sometimes oblong.

4. * A. balsamea, Mill.
Balsam Fir. Balm-of-Gilead Fir. Canada Balsam Fir

Transverse. Growth rings thick. Summer wood thin, open, passing very
gradually into the spring wood. Spring wood very open, the large
tracheids squarish-hexagonal, thin-walled, uniform in regular rows.
Resin cells wanting. Medullary rays not numerous or prominent,
i cell wide, distant 2-8, rarely 12, rows of tracheids.

Radial. Ray tracheids few, narrow, and very unequal ; the rays barely
resinous. Ray cells conspicuously contracted at the ends and equal
to 2-6 spring tracheids ; the upper and lower walls medium, unequal,
somewhat distantly and finely, but often imperfectly, pitted ; the ter-
minal walls coarsely pitted, especially in the summer wood ; the lateral
walls with small, round or oval pits, 2-4, more rarely upwards of 8, per
tracheid. Bordered pits elliptical, large, one half the diameter of the
tracheid, chiefly rather scattering, in i row or often in pairs, and
more or less imperfectly 2-rowed. Pits on the tangential walls of the
summer wood not numerous, chiefly quite small.

Tangential. Rays medium, the cells narrow, uniform, oval to oblong.

A tree 21-27 m. high, with a trunk upwards of .60 m. in diameter.
Wood very light, soft, not strong, coarse grained, compact, not durable.

Relative specific gravity 0.3819

Percentage of ash residue 0.45

Approximate relative fuel value 38.02

Coefficient of elasticity in kilograms on millimeters . . 819.

Ultimate transverse strength in kilograms 220.

Ultimate resistance to longitudinal crushing in kilograms 5851.

Resistance to indentation to 1.27 mm. in kilograms . . 1202.
(Sargent)

Abundant in swamps throughout the eastern provinces of Canada, north-
ward to James Bay and westward to the Athabasca River in latitude 58°
(Macoun) ; southward through the northern United States to Pennsyl-
vania, and along the Allegheny Mountains to the high peaks of Virginia ;

ABIES

259

westward through central Michigan and Minnesota and northward along

the eastern slope of the Rocky Mountains (Sargent).
Pleistocene of the Scarborough Period at Scarborough, Ontario.
Material altered by decay, but otherwise in original condition and not

petrified.

5. A. magnifica, A. Murr.

Red Fir

Transverse. Growth rings rather broad. The summer wood upwards of
one third the growth ring, the structure open throughout, but the most
recent tracheids much compressed radially, transition to the spring
wood very gradual. Spring wood open, the large, conspicuously
squarish tracheids uniform in very regular rows, thin-walled. Resin
cells present on the outer face of the summer wood, where they are to
be distinguished by their thin walls and somewhat advanced position.
Medullary rays prominent, sparingly resinous, i cell wide, distant 2-10
rows of tracheids.

Radial. Rays sparingly resinous throughout and wholly devoid of tracheids.
Ray cells straight throughout, equal to 7-9 spring tracheids, becoming
much shorter in the summer wood ; the upper and lower walls thick,
unequal, and strongly but imperfectly pitted throughout ; the terminal
walls sparingly pitted in the spring wood, but becoming strongly pitted
in the summer wood ; the lateral walls with small, obscurely bordered
pits, at length becoming conspicuous and round with a prominent
border and slitlike orifice toward the summer wood, chiefly 2, more
rarely i or 4, in the summer wood reduced to i, per tracheid through-
out. Bordered pits in i row, elliptical, becoming much smaller
toward the summer wood, where the round orifice becomes narrow
and prolonged, coalescing to form spiral striations. Pits on the tan-
gential walls of the summer tracheids numerous but flat and small,
sometimes present on the tangential walls of the earliest spring
tracheids. Resin cells few, on the outer face of the summer wood,
nonresinous and distinguished by the transverse septa without bor-
dered pits; narrow and very long, usually about 20-25 /x wide,
350-435 p or more long.

Tangential. Rays high, occasionally 2-seriate in part, the cells uniformly
broad, round, and large or oval, sometimes sparingly resinous.

A large tree 61-76 m. high, with a trunk 2.40-3 m. in diameter.
Wood light, soft, not strong, rather close grained, compact, satiny, durable
in contact with the soil, liable to twist and warp in seasoning.

Relative specific gravity 0.4701

Percentage of ash residue 0.30

Approximate relative fuel value 46.87

Coefficient of elasticity in kilograms on millimeters . . 662.

Ultimate transverse strength in kilograms 299.

Ultimate resistance to longitudinal crushing in kilograms 6963.

Resistance to indentation to 1.27 mm. in kilograms . . 1545.
(Sargent)

260 ANATOMY OF THE GYMNOSPERMS

California, Mt. Shasta, south along the western slopes of the Sierra Nevadas
to Kern County; forming extensive forests between 4900 and 8000 feet
elevation ; becoming less common south of Mt. Shasta, and reaching an
extreme elevation of 10,000 feet (Sargent).

6. A. amabilis, Forbes
While Fir

Transverse. Growth rings narrow, the structure usually very open through-
out. Summer wood upwards of one half the spring wood, into which
it passes very gradually. Spring tracheids large, thin-walled, very
squarish, and uniform in regular rows. Resin cells few and widely
scattering on the outer face of the summer wood, where they may be
distinguished by (i) the sieve-plate structure of the terminal wall, and
(2) their often advanced position. Medullary rays rather prominent,
not resinous, i cell wide, numerous, distant 2—9 rows of tracheids.

Radial. Rays nonresinous, wholly devoid of tracheids. Ray cells chiefly
straight except in the summer wood, equal to 3-7 spring tracheids,
becoming much shorter in the summer wood ; the upper and lower
walls thick, unequal, and coarsely but very unequally pitted through-
out ; the terminal walls strongly pitted throughout ; the lateral walls
with small, round or oval pits, which toward the summer wood show a
prominent and broad border, and the broadly lenticular orifice becomes
reduced to a slit, 1-2, rarely 3, or in the marginal cells sometimes 5,
per tracheid. Bordered pits in i row, sometimes in pairs, variable,
elliptical. Pits on the tangential walls of the summer tracheids
numerous and rather small, but broadly lenticular, open. Resin cells
frequently present on the outer face of the summer wood, sometimes
conterminous with similar tracheids ; usually very narrow and long,
12.5-25 fj, wide, and upwards of 600 p. long.

Tangential. Rays medium to high, the cells uniform, chiefly oval, more
rarely round or narrowly oval, sometimes in pairs.

A tree 30-45 m. high, with a trunk upwards of 1.20 m. in diameter.
Wood light, hard, not strong, close grained, compact.

Relative specific gravity 0.4228

Percentage of ash residue 0.23

Approximate relative fuel value 42.18

Coefficient of elasticity in kilograms on millimeters . . 1260.

Ultimate transverse strength in kilograms 338.

Ultimate resistance to longitudinal crushing in kilograms 7480.

Resistance to indentation to 1.27 mm. in kilograms . . 1029.
(Sargent)

Valley of the Fraser River and probably farther north ; south along the
Cascade Mountains of Washington and Oregon (Sargent).

ABIES 26l

7. A. grandis, Lindl.

ll'hilc Fir

Transverse. Growth rings usually very broad, the structure rather open
throughout. Summer wood prominent, upwards of one eighth to one
fourth the very broad spring wood, into which it passes gradually,
the tracheids very unequal. Spring tracheids very large, thin-walled,
hexagonal, in regular rows, rather uniform. Resin cells few and scat-
tering on the outer face of the summer wood, nonresinous, distinguished
by (i) the sieve-plate structure of the terminal walls, and (2) their
somewhat advanced position. Resin-bearing tracheids more or less
numerous and scattering through the summer wood. Resin passages
wholly wanting. Medullary rays rather prominent and resinous, espe-
cially in the summer wood, i cell wide, distant 2-8, or rarely 10-12,
rows of tracheids.

Radial. Rays more or less resinous throughout. Ray cells straight, becom-
ing contracted at the ends in the summer wood, equal to 4-6 spring
tracheids ; the upper and lower walls thin and entire or sparingly and
imperfectly pitted ; the terminal walls at first barely if at all pitted,
but at length coarsely pitted in the summer wood ; the lateral walls
with prominent but small oval pits, with an obscure border, the latter
becoming prominent toward the summer wood, where the broadly len-
ticular orifice becomes oblong, 1-2 throughout, or more rarely 4-6 in
the marginal cells. Bordered pits rather numerous in i row, ellip-
tical but variable, the orifice large. Resin-bearing tracheids rather
numerous and chiefly in contact with the rays, very resinous. Resin
cells on the outer face of the summer wood rather prominent, long,
and narrow, nonresinous, about equal to 20 /x wide and 135-310 /u,
long. Pits on the tangential walls of the summer tracheids somewhat
numerous, rather small and flat.

Tangential. Rays rather numerous, low to high, broad, the rather large
cells more or less unequal, chiefly broadly oval, often squarish, fre-
quently resinous.

A tree 61-92 m. high, with a trunk .90-1.50 m. in diameter.
Wood light, soft, not strong, coarse grained, compact.

Relative specific gravity Q-3545

Percentage of ash residue 0.49

Approximate relative fuel value 35-°8

Coefficient of elasticity in kilograms on millimeters . . 958.

Ultimate transverse strength in kilograms 211.

Ultimate resistance to longitudinal crushing in kilograms 6255.

Resistance to indentation to 1.27 mm. in kilograms . . 810.
(Sargent)

Vancouver Island, south to Mendocino County, California, near the coast ;
interior valleys of western Washington and Oregon, south to the Umpqua
River, Cascade Mountains below 4000 feet elevation ; Blue Mountains of
Oregon ; Bitter Root Mountains of Idaho ; western slopes of the Rocky
Mountains of northern Montana (Sargent).

262 ANATOMY OF THE GYMNOSPERMS

8. A. bracteata, Nutt.

Sih'er I-'ir

Transverse. Growth rings broad. Summer wood prominent, dense, one
third the spring wood, into which it passes somewhat gradually. Spring
wood rather open, the tracheids large and thin-walled, squarish-hex-
agonal, rather uniform in regular rows. Resinous tracheids wholly
wanting. Resin cells sometimes present and then forming imperfectly
organized resin canals in a somewhat continuous zone, within or near
the summer wood of distant growth rings. Medullary rays prominent
and somewhat resinous, especially in the summer wood, i cell wide.

Radial. Rays somewhat resinous throughout, especially in the summer
wood, wholly devoid of tracheids. Ray cells straight or barely fusi-
form except in the summer wood, where they are strongly contracted
at the ends ; equal to about 5 spring tracheids ; the upper and lower
walls rather thin, unequal, rather distantly pitted except in the sum-
mer wood, where the pits are numerous, or again in the spring wood
locally numerous ; the terminal walls thin, often devoid of pits except
in the summer wood ; the lateral walls with prominent, round or
broadly oval pits, chiefly 1-3, or in the marginal cells 4, per tracheid.
Bordered pits numerous, chiefly elliptical in i row, or often in pairs
so that they become more or less 2-rowed. Pits on the tangential
walls of the summer wood numerous and extending well into the
interior. Resin cells short-cylindrical, united to form short resin sacs
on the outer face of the summer wood.

Tangential. Rays medium to high ; the cells chiefly broad, oval, often
resinous and sometimes in pairs of much smaller cells.

A tree 41-61 m. in height and with a trunk .90-1.20 m. in diameter.
Wood heavy, not hard, coarse grained, compact.

Relative specific gravity 0.6783

Percentage of ash residue 2.04

(Sargent)

Santa Lucia Mountains of California, from the northern boundary of
San Luis Obispo County, about 40 miles northward ; on moist, cold soil,
occupying four or five canons at 3000-6000 feet elevation, generally west
of the summit of the range (Sargent).

9. A. nobilis, Lindl.
Red Fir. Larch

Transverse. Growth rings rather broad. The summer wood prominent,
broad, upwards of one half the spring wood, the structure chiefly
open, but becoming rather dense on the outer face of the growth ring;
transition to the spring wood gradual. Spring tracheids rather large
and thin-walled, squarish-hexagonal, toward the summer wood becom-
ing unequal and in more or less irregular rows. Resin cells localized

ABIKS 263

to form imperfect resin canals in a more or less continuous zone in
the summer wood of distant growth rings. Medullary rays prominent,
somewhat resinous, i cell wide, distant 1-8 rows of tracheids.

Radial. Rays more or less resinous throughout, wholly devoid of tra-
cheids. Ray cells chiefly straight, becoming conspicuously fusiform
in the summer wood, equal to about 8-u spring tracheids ; the upper
and lower walls medium, unequal, more or less strongly pitted through-
out ; the terminal walls strongly pitted ; the lateral walls with round
or oval, conspicuously bordered pits, the orifice lenticular or oblong,
1-2, or in the marginal cells rarely 3-4, per tracheid. Bordered pits
in i row, sometimes in pairs, round, the orifice large. Pits on the
tangential walls of the summer tracheids minute. Resin cells, when
present, short-cylindrical and united to form short resin sacs within
the summer wood of distant growth rings.

Tangential. Rays medium to high, the cells often resinous, chiefly broad
but variable from round to oval and oblong, unequal, often in pairs.

A large tree 61-92 m. high, with a trunk 2.40-3 m. in diameter.
Wood light, hard, strong, rather close grained, compact.

Relative specific gravity 0.4561

Percentage of ash residue 0.34

Approximate relative fuel value 45-46

Coefficient of elasticity in kilograms on millimeters . . 1277.

Ultimate transverse strength in kilograms 368.

Ultimate resistance to longitudinal crushing in kilograms 7256.

Resistance to indentation to 1.27 mm. in kilograms . . 1917.
(Sargent)

Oregon, Cascade Mountains from the Columbia River south to the valley
of the upper Rogue River, and along the summits of the Coast Range
from the Columbia to the Nestucca River (Sargent).

10. A. concolor, Lindl. and Gordon
White Fir. Balsam Fir

Transverse. Growth rings broad, the structure rather open throughout.
Summer wood prominent, thin, upwards of one third the spring wood,
into which it passes very gradually. Spring tracheids medium, squar-
ish, thin-walled, and uniform in somewhat regular rows. Resin pas-
sages prominent and rather numerous but imperfectly formed, very
variable, and often large, forming more or less continuous series
within the summer wood, often of distant growth rings. Resin cells
few, nonresinous, distant on the outer face of the summer wood and
distinguished by (i) the sieve-plate structure of the terminal wall, and
(2) their somewhat advanced position. Medullary rays rather promi-
nent and somewhat resinous, especially in the summer wood ; i cell
wide, distant 2-7, rarely 10, rows of tracheids.

Radial. Rays somewhat resinous, especially in the summer wood. Ray
cells conspicuously contracted at the ends throughout and equal to

264 ANATOMY OF THE GYMNOSPERMS

6-11 spring tracheids, becoming shorter in the summer wood: the
upper and lower walls rather thick, unequal, and conspicuously pitted
throughout ; the terminal walls rather sparingly pitted, especially in
the spring wood ; the lateral walls with round or elliptical, small,
obscurely bordered pits, which become distinctly bordered toward the
summer wood, where the broadly lenticular orifice becomes oblong
or finally slitlike, 1-3 per tracheid throughout the spring wood, becom-
ing i in the summer wood. Bordered pits rather numerous in i row,
elliptical or round. Pits on the tangential walls of the summer tra-
cheids rather numerous but not very large, flat. Pits rarely on the
tangential walls of the earlier spring tracheids. Resin cells rarely to
be seen. Resin passages imperfectly formed of short, cylindrical resin
cells, in interrupted series.

Tangential. Rays numerous, medium to high, not very broad ; the cells
chiefly uniform, oval, sometimes round or oblong, rarely large.

A tree 30-40 m. in height, with a trunk 1.20-1.50 m. in diameter.
Wood very light, soft, not strong, coarse grained, compact.

Relative specific gravity ........... 0.3638

Percentage of ash residue ........... 0.85

Approximate relative fuel value ......... 36.07

Coefficient of elasticity in kilograms on millimeters . . 909.
Ultimate transverse strength in kilograms ..... 300.

Ultimate resistance to longitudinal crushing in kilograms 6237.

Resistance to indentation to 1.27 mm. in kilograms . . 1248.
(Sargent)

Moist slopes and canons between 3000 and 9000 feet elevation, reach-
ing its greatest development in the California Sierras ; northern slopes
of the Siskiyou Mountains of Oregon ; south along the western slope of
the Sierra Nevadas to San Bernardino and San Jacinto Mountains of
California ; the high mountains of Arizona to the Mogollon Mountains
of New Mexico ; northward to Pikes Peak and the Wasatch Moun-
tains of Utah (Sargent).

11. A. firma, Sieb. et Zucc.

Jap. — j

Transverse. Growth rings broad, the dense summer wood about one
fourth the spring wood, into which it passes gradually. Spring wood
open, the tracheids thin-walled, in very regular rows, uniform, large.
Resin cells and resinous tracheids wanting. Medullary rays rather
prominent and sparingly resinous, I cell wide, distant 2-10 rows of
tracheids. Resin canals present but imperfectly organized, forming
local or sometimes extensive tangential rows on the outer face of the
summer wood of distant growth rings.

Radial. Medullary rays sparingly resinous, devoid of tracheids. Ray
cells straight, equal to 5-10 spring tracheids, in the summer wood
becoming much shorter and distinctly fusiform ; the upper and lower

TSUGA 265

walls medium, unequal, very sparingly pitted, in the summer wood
becoming conspicuously thicker and strongly pitted ; the terminal
walls coarsely pitted, when seen in plan like a sieve plate ; the lateral
walls with obscurely bordered pits, 1-4, or in the marginal cells and
low rays upwards of 6, per tracheid, becoming reduced toward the
summer wood, where they are only i or entirely wanting. Bordered
pits numerous, elliptical, usually less than half the tracheid, in i row
or often in pairs and imperfectly 2-rowed. Pits on the tangential
walls of the summer tracheids not very numerous, rather small.
Resin cells and resinous tracheids wanting.

Tangential. Rays medium to high, sparingly resinous, narrow, strictly
i-seriate ; the cells uniform, oblong, rarely oval.

13. TSUGA, CARR. PLATES 44 AND 45

Transverse. Growth rings usually thin, the summer wood prominent, usu-
ally dense. Resin passages rarely present (T. heterophylla) and
then imperfectly organized. Resin cells scattering on the outer face
of the summer wood and distinguished by (i) their resinous contents,
(2) their somewhat advanced position, (3) their thinner walls, and
(4) the sieve-plate structure of the terminal walls ; rarely numerous
and zonate in the spring or summer wood. Resinous tracheids wanting
(except in T. Mertensiana).

Radial. Ray tracheids usually prominent, sometimes interspersed, usually
marginal. Ray cells usually resinous, more or less contracted at the
ends, the terminal walls strongly pitted. Tracheids wholly without
spirals.

Tangential. Fusiform rays wholly wanting. Ray cells rarely in pairs, not
broad, chiefly oval or round.

*
SYNOPSIS OF SPECIES

Bordered pits in 2 rows.

Resin passages wholly wanting, the prominent resin cells scattering
on the outer face of the summer wood.

Pits on the lateral walls of the ray cells 2-4, or in the summer
wood 1-2, per tracheid.

i. T. canadensis.
Bordered pits in i row.

Resin passages present but imperfectly formed, in more or less con-
tinuous series, the resin cells scattering on the outer face of the
summer wood.

Pits on the lateral walls of the ray cells 1-2, rarely 3, per
tracheid.

Spring tracheids very large and uniform, distinctly 4-sided,

the walls thin.

5. T. Mertensiana.

266 ANATOMY OF THE GYMNOSPERMS

Resin passages not present.

Resin cells scattering on the outer face of the summer wood.

Pits on the lateral walls of the ray cells 2-4, or in the sum-
mer wood 1-2, per tracheid ; the resin cells prominent,

resinous.

1. T. canadensis.

Pits on the lateral walls of the ray cells 1-2, rarely 3, per
tracheid.

Spring tracheids very large and uniform, conspicuously
4-sided, the walls thin.

5. T. Mertensiana.

Pits on the lateral walls of the ray cells very variable, at
first 5, soon uniformly 2, and finally I, per tracheid.
Spring tracheids squarish-hexagonal.

2. T. Sieboldii.

Resin cells on the outer face of the summer wood and also often
zonate in the spring or summer wood.
Resinous tracheids wanting.

Pits on the lateral walls of the ray cells 2-6, finally i,
per tracheid.

3. T. caroliniana.

Resinous tracheids in groups or radial series in contact with
the rays.

Pits on the lateral walls of the ray cells 1-4, chiefly 2,
and finally i, per tracheid, the orifice finally becom-
ing a prolonged slit.

4. T. Pattoniana.

1. T. canadensis, Carr.
Hemlock

Transverse. Growth rings thin, variable. The thin and dense summer
wood prominent, equal to about one fourth to one half the spring
wood, from which the transition is abrupt. Spring wood very open,
the large and very thin-walled tracheids conspicuously squarish, often
elongated radially, very uniform and in regular rows. Resin cells
prominent, resinous, not very numerous. Medullary rays very promi-
nent, somewhat resinous, i cell wide, distant 2-10 rows of tracheids.

Radial. Rays uniformly somewhat resinous throughout, the tracheids
often interspersed. Ray cells somewhat contracted at the ends, equal
to 3-5 spring tracheids ; the upper and lower walls medium, unequal,
very irregularly and often imperfectly, sometimes very sparingly,
pitted ; the terminal walls not very strongly pitted except in the
summer wood ; the lateral walls with small, oval pits, at first with
a very narrow border, which becomes more pronounced toward the

TSUGA 267

summer wood, the lenticular orifice becoming oblong, 2-4, or in the
summer wood 1-2, per tracheid. Bordered pits round or elliptical in
1-2 rows, more rarely in i row only, the orifice large. Pits on tin-
tangential walls of the summer wood rather numerous, prominent,
flat. Resin cells 15 p. wide, 165-240 p. long.

Tangential. Rays numerous, low to high, not very broad, usually con-
stricted at the position of the frequent narrow and oblong tracheids ;
the parenchyma cells rather equal and chiefly narrowly oval to
oblong, sometimes broadly oval.

A tree 21-33 m- high and with a trunk .90-1.15 m. in diameter.

Wood light, soft, not strong, brittle, coarse, crooked grained, difficult to

work, liable to wind shake and splinter, not durable (Sargent).
This wood is of great value for construction purposes, where it is to be

constantly submerged in water, when it possesses elements of great

durability (Bovey).

Relative specific gravity 0.4239

Percentage of ash residue 0.46

Approximate relative fuel value 42.20

Coefficient of elasticity in kilograms on millimeters . . 900.

Ultimate transverse strength in kilograms 307.

Ultimate resistance to longitudinal crushing in kilograms 6142.

Resistance to indentation to 1.27 mm. in kilograms . . 1314.
(Sargent)

According to the results obtained by Dr. Bovey in the testing laboratories
of McGill University, the following data may be given:

Coefficient of strength in pounds per square inch for :

Bending 5000

Torsion 8000

Compression 3200

Shear 380

Weight of i cubic foot 33

Abundant on cold soils, Nova Scotia and New Brunswick, and throughout
Quebec and Ontario ; northward from Quebec to the northern end of
Lake Temiscaming, thence to the eastern extremity of Lake Superior at
Agawa (Macoun) ; through the northern United States to Newcastle
County, Delaware, and along the Allegheny Mountains to Clear Creek
Falls, Winston County, Alabama ; southeastern Michigan and central
Wisconsin (Sargent).

2. T. Sieboldii, Carr.

Jap. = Tsuga

Transverse. Growth rings narrow, uniform, the prominent summer wood
dense, about one fourth to one half the spring wood, from which the
transition is gradual. Spring tracheids squarish-hexagonal, rather

268 ANATOMY OF THE GYMNOSPERMS

thin-walled, uniform in regular rows. Medullary rays not very numer-
ous, resinous, prominent, and distant 2-10 rows of tracheids. Resin
cells somewhat distant on the outer face of the summer wood, but
readily recognizable.

Radial. Rays somewhat resinous throughout, the tracheids wholly marginal.
Ray cells chiefly straight except in the summer wood ; the upper and
lower walls medium, unequal, strongly pitted, especially in the summer
wood ; the terminal walls strongly pitted ; the lateral walls with very
small, oval, bordered pits with a lenticular orifice, which soon becomes
oblong and narrow, at first very variable and upwards of 5, soon uni-
formly 2, and in the summer wood i, per tracheid. Bordered pits
numerous, round or elliptical, in i row, sometimes in pairs. Pits on
the tangential walls of the summer wood rather numerous and flat,
not very large. Resin cells 20 //, wide, 150-275 /A long.

Tangential. Rays medium, resinous, the cells unequal, chiefly broad but
variable, round or oval, more rarely oblong.

3. T. caroliniana, Engel.
Hemlock

Transverse. Growth rings medium, variable, the dense and prominent
summer wood composed of rather small and more or less rounded
tracheids, the transition from the spring wood rather abrupt, often
quite gradual, usually much less than, or again upwards of one half,
the spring wood. Spring tracheids rather large, uniform and thin-
walled in regular rows, usually elongated radially. Medullary rays
prominent, not very broad, i cell wide, distant 2-10 rows of tracheids.
Resin cells on the outer face of the summer wood prominent, resin-
ous, not very numerous, sometimes aggregated to form limited but
conspicuous and irregular layers on the inner face of the summer
wood.

Radial. Rays uniformly somewhat resinous throughout, the tracheids
prominent, sometimes interspersed. Ray cells not conspicuously con-
tracted at the ends except in the summer wood, equal to 6-8 spring
tracheids, becoming much shorter in the summer wood ; the upper
and lower walls medium, very sparingly pitted except in the outer
summer wood ; the terminal walls coarsely pitted throughout ; the
lateral walls with small, narrowly bordered pits, the orifice at first
lenticular, at length narrowly oblong, at first 2-6, finally reduced to
i, per tracheid in the summer wood. Bordered pits round or elliptical,
very numerous, usually as broad as the tracheid, in I compact row.
Pits on the tangential walls of the summer tracheids numerous but
small and not very prominent. Resin cells on the outer face of the
summer wood 15 /JL wide, 185-310 p. long; those on the inner face
very short and cylindrical, irregular and unequal, and forming a con-
tinuous series without canals.

Tangential. Rays rather numerous, medium, narrow, resinous, sometimes
constricted by the occasional and narrow, oblong tracheids ; the cells
somewhat unequal, chiefly oblong but rather variable, and sometimes
becoming oval.

TSUGA 269

A small tree 12-15 m- high, with a trunk .60-. 75 m. in diameter.
Wood light, soft, not strong, brittle, coarse grained.

Relative specific gravity 0.4275

Percentage of ash residue 0.40

Approximate relative fuel value 42.58

Coefficient of elasticity in kilograms on millimeters . . 713.

Ultimate transverse strength in kilograms 10,7.

Ultimate resistance to longitudinal crushing in kilograms 6450.

Resistance to indentation to 1.27 mm. in kilograms . . 1996.
(Sargent)

Dry, rocky ridges ; rare and local at elevations of 4000-5000 feet.

Southern Allegheny region ; Bluff Mountain, Pinnacle Mountain, New
River, Whitesides Mountain, and Devil's Court-House Peak, North Caro-
lina ; Saluda Mountain, Caesar's Head, South Carolina (Sargent).

4. T. Pattoniana, Se'nec.

Mountain Hemlock. Pattern Spruce

Transverse. Growth rings variable, chiefly rather narrow, the structure
usually open throughout. Summer wood very narrow, rather open,
the transition from the spring wood very gradual. Spring tracheids
rather large and thin-walled, conspicuously squarish, uniform, in
regular rows. Medullary rays numerous, broad, i cell wide, rather
prominent, distant 2-7 rows of tracheids. Resin passages sometimes
present though imperfectly formed, generally in a short zone on the
outer face of widely distant growth rings. Resin cells on the outer
face of the summer wood numerous, resinous, and prominent, some-
times aggregated to form distinct and rather broad zones. Resinous
tracheids often forming small groups or radial series in contact with
the rays.

Radial. Rays uniformly somewhat resinous throughout ; the ray tracheids
narrow, marginal, often locally wanting. Ray cells straight or some-
what contracted at the ends, equal to 10-15 spring tracheids; the
terminal walls sparingly pitted ; the upper and lower walls medium to
thick, rather strongly pitted, especially in the summer wood ; the
lateral walls with small, oval, at first narrowly bordered pits, the len-
ticular orifice at length oblong, 1-4, chiefly 2, per tracheid, becoming
i in the summer wood, where the orifice is a prolonged slit. Bordered
pits round or elliptical, chiefly somewhat distant in i row, large,
the round orifice large. Pits on the tangential walls of the summer
wood not very numerous, small, often remote and obscure. Resin
cells on the outer face of the summer wood 15-20 p. wide, 115-275 //,
long, chiefly about 150 p.. Resinous tracheids sometimes locally
numerous, the resin massive.

Tangential. Rays numerous, medium to high, somewhat resinous ; the cells
oblong-oval, more rarely oval, rather equal and uniform. Ray tra-
cheids very few, terminal, very often wanting.

2 ;o ANATOMY OF THE GYMNOSPERMS

An Alpine tree rarely 30 m. in height, with a trunk i .50-2. 10 m. in diameter.
Wood light, soft, not strong, close grained, satiny, susceptible of a good
polish.

Relative specific gravity 0.4454

Percentage of ash residue 0.44

Approximate relative fuel value 44-35

Coefficient of elasticity in kilograms on millimeters . . 775.

Ultimate transverse strength in kilograms 307.

Ultimate resistance to longitudinal crushing in kilograms 6074.

Resistance to indentation to 1.27 mm. in kilograms . . 1664.
(Sargent)

Dry slopes and ridges near the limits of tree growth, from 2700 feet in
British Columbia to 10,000 feet in Colorado.

Valley of the Fraser River, on Silver Mountain, Yale, and probably much
farther north (Macoun); south along the Cascade Mountains and the
California Sierras to the headwaters of the San Joaquin River ; east-
ward along the high mountains of northern Washington to the Cceur
d'Alene and Bitter Root mountains of Idaho, and the divide between
Thompson and Little Bitter Root creeks in northern Montana (Sargent).

5. T. Mertensiana, Carr.

Western Hemlock

Transverse. Growth rings thin, the prominent summer wood dense and
about equal to the spring wood, from which the transition is gradual.
Spring wood very open, the large and thin-walled tracheids conspic-
uously squarish, in very regular rows, uniform. Medullary rays very
prominent, resinous, rather broad, i cell wide, distant 1-9 rows of
tracheids. Resin cells very prominent and resinous, sometimes form-
ing short rows of imperfectly organized resin canals on the outer face
of the summer wood.

Radial. Rays uniformly somewhat resinous throughout, the tracheids very
unequal, short, sometimes obscure, not infrequently interspersed.
Ray cells narrow, conspicuously contracted at the ends, equal to 4-9
spring tracheids ; the upper and lower walls medium, unequal, rather
strongly pitted ; the terminal walls coarsely pitted ; the lateral walls
with small, conspicuously bordered oval pits with an oblong orifice,
1-2, rarely 3, per tracheid, becoming obscure in the summer wood.
Bordered pits round or elliptical in I row. Pits on the tangential
walls of the summer tracheids numerous but small and obscure.
Resin canals composed of short, cylindrical resin cells, which unite
to form disconnected passages. Resin cells very long and narrow,
about 15 fji wide and 150-385 /u, long.

Tangential. Rays rather numerous, medium to high, resinous, rather
broad, the somewhat thick-walled cells rather unequal and variable,
round or oval.

PSEUDOTSUGA 271

A large tree 30-61 m. high, with a trunk 1.20-3 m- in diametej.
Wood light, hard, not strong, rather close grained.

Relative specific gravity 0.5182

Percentage of ash residue 0.42

Approximate relative fuel value 51.61

Coefficient of elasticity in kilograms on millimeters . . 1375.

Ultimate transverse strength in kilograms 388.

Ultimate resistance to longitudinal crushing in kilograms 8747.

Resistance to indentation to 1.27 mm. in kilograms . . 1622.
(Sargent)

Low, moist bottoms and rocky ridges ; very common and reaching its
greatest development in western Oregon and Washington, often form-
ing extensive forests (Sargent); valley of the Columbia at Donald,
at 1000 feet elevation, thence westward to Stony Creek at 3500 feet,
thence the predominant tree to the Selkirk summit (Macoun); Alaska,
thence south along the islands and coast of British Columbia and
through the Rocky Mountains to the Bitter Root Mountains of Idaho ;
the western slopes of the Rocky Mountains of Montana ; through the
Cascade Mountains of southern Oregon and the coast ranges to Marin
County, California, between 1000 and 4000 feet elevation (Sargent).

14. * PSEUDOTSUGA, CARR. PLATES 46 AND 47

Transverse. Growth rings and summer wood very variable. Resin pas-
sages prominent and well formed without thyloses, but with thick-
walled epithelium. Resin cells more or less numerous on the outer
face of the summer wood, not very resinous, and usually distinguished
by their (i) thinner walls and somewhat advanced position, and (2)
by the sieve-plate structure of the terminal walls.

Radial. Ray tracheids present. Ray cells with thick and coarsely pitted
terminal walls. Wood tracheids always with flat and close spirals in
double series.

Tangential. Fusiform rays present, generally narrow, the central tract
composed of i small resin canal without thyloses, but with small and
thick-walled epithelium cells ; the ray cells thick-walled throughout.

SYNOPSIS OF SPECIES

Ray cells (tangential) distinctly oval or oblong.

Pits on the lateral walls of the ray cells small, round or oval, at first

3-7, soon 1-3, per tracheid.

1. * P. Douglasii.

Ray cells (tangential) broad, distinctly squarish, more rarely oval or round.
Pits on the lateral walls of the ray cells conspicuously larger than in
i, the orifice lenticular, 3-6 per tracheid.

2. P. macrocarpa.

272 ANATOMY OF THE GYMNOSPERMS

Ray cells oval or round (tangential).

Pits on the lateral walls of the ray cells 4 per tracheid.

3. ** P. miocena.

1. * P. Douglasii, Carr.
Yellviv Fir. Oregon Pine. Douglas Fir

Transverse. Growth rings very variable, and either very thin with a close,
compact grain, or very broad with a coarse, open grain. Summer
wood very variable, now barely distinguishable, or again upwards of
one half the spring wood, often hard and flinty ; transition from the
spring wood more or less abrupt. Spring tracheids large, thin-walled,
hexagonal, uniform in regular rows. Medullary rays prominent and
somewhat resinous, rather few, i cell wide, distant 2-13 rows of
tracheids. Resin passages rather few and widely scattering, chiefly
in the summer wood, the canal equal to about i or 2 tracheids.
Resin cells few and distant on the outer face of the summer wood,
not very prominent or resinous, chiefly distinguished by their position
and the sieve-plate structure of the terminal walls.

Radial. Rays sparingly resinous throughout, the tracheids prominent,
chiefly narrow and marginal, but sometimes interspersed. Ray cells
straight or somewhat contracted at the ends ; the upper and lower
walls thickish, irregularly and often imperfectly pitted ; the terminal
walls coarsely pitted; the lateral walls with small, elliptical pits, the
border narrow, the orifice lenticular, at first 3-7, soon becoming 1-3,
and- in the summer wood i, per tracheid. Pits on the tangential
walls of the summer tracheids wanting. Resin cells 15-25 p, wide,
125-225 p long. Bordered pits in i row, sometimes in pairs, gen-
erally elliptical, the orifice large. Spirals generally wanting in the
summer tracheids, the angle 82°.

Tangential. Fusiform rays with linear and unequal terminals. Ordinary
rays low to medium, the cells oval to oblong. Medullary ray cells all
thick-walled.

This species presents the most striking variations of any of the North
American Coniferae. These variations appear as follows:

1 . The growth rings occur in zones, between which there are pronounced
differences in the average thickness of the component rings (52).

2. The growth rings vary from several millimeters in thickness to less
than i mm. In this respect a distinction may be made between the
" fine-grained," in which the rings seldom exceed 2-2.5 rnm., usually being
much less, and the " coarse-grained " wood, in which the rings approx-
imate to 4 mm. in thickness ; the latter is further distinguished by its
coarse, open grain, and often very flinty summer wood, thus approximat-
ing to the " red fir," as represented by the next species.

3. The summer wood varies greatly, either in the same tree or in
different trees, being in one case barely if at all distinguishable ; or,
on the other hand, becoming very prominent, dark, dense and flinty,
and often equal to the spring wood.

PSEUDOTSUGA

273

4. The size of the tracheids and the volume of the lumen vary rela-
tively to the total area of the cross section, whereby in some cases the
summer wood presents a very dense structure, while in others it is com-
paratively open. The extreme variations observed in nine specimens from
different localities lie within the following limits :

Spring wood 24x43^-43x77^

Summer wood 18 x 27 /j. — 26 x 53 /x,

A large tree 61-92 m. high, with a trunk upwards of 3.66 m. in diameter.

Wood hard, strong, varying greatly with age and conditions of growth,
difficult to work, very durable (Sargent).

Two varieties are recognized : the " yellow fir," distinguished by its lighter
color and usually fine and compact grain ; and the " red fir," which
approximates to the characteristics of the next species and is distin-
guished by its darker red color, coarse grain, and flinty summer wood.
The former is of superior quality for constructive purposes. The great
strength and durability of this wood make it the most valuable species
of the Pacific region, and it is largely employed where these qualities,
joined to great size of timber, are required.

Relative specific gravity

Percentage of ash residue

Approximate relative fuel value

Coefficient of elasticity in kilograms on millimeters
Ultimate transverse strength in kilograms

0.5157
0.08

51-53
1283.

376.

Ultimate resistance to longitudinal crushing in kilograms 8289.
Resistance to indentation to 1.27 mm. in kilograms . . 1608.
(Sargent)

A comparison of these values with those given by Sargent for some of
the more commonly used oaks will serve to show the superior quality
of this timber, which has a higher coefficient of elasticity than our three
best native species.

COMPARATIVE STRENGTH OF OAKS AND DOUGLAS FIR

(After Sargent)

Coefficient of

Ultimate Resist-

Resistance to

Elasticity in Kil-

Ultimate Trans-

ance to Longi-

Indentation

ograms on

verse Strength

tudinal Crushing

to 1.27 mm. in

Millimeters

in Kilograms

in Kilograms

Kilograms

Pseudotsuga Douglasii

1283

376

8289

1608

White oak (Quercus alba)

971

386

8lS3

3338

Red oak (Quercus rubra)

"37

422

8172

2825

Live oak (Quercus virens)

1136

434

874S

5'85

274 ANATOMY OF THE (,YM NOSPKRMS

According to experiments reported by Dr. Bovey, as carried out in the
testing laboratories at McGill University, the following values may be
assigned to Douglas fir :

Specially selected wood, free from knots and cut out of the log at a
distance from the heart, gave

Coefficient of bending, pounds per square inch . . 9,000

Coefficient of elasticity in pounds 2,000,000

Weight per cubic foot 34

Ordinary first-quality wood gave

Coefficient of bending, pounds per square inch . . 6,000

Coefficient of elasticity in pounds 1,430,000

Weight per cubic foot 34

The Douglas fir often forms extensive forests to the almost complete
exclusion of other species, ranging from sea level to an elevation of
nearly 10,000 feet in Colorado, and reaching its greatest development
and value in Oregon and Washington (Sargent).

All parts of Vancouver Island with the exception of the exposed western
coast ; near the 49th parallel it ranges from the coast of the mainland
to the Rocky Mountains, where it occurs in a stunted form at eleva-
tions of 6000 feet ; on the eastern slopes of the Rocky Mountains,
from the 49th parallel northward through the Porcupine Hills to the
Bow River, where it reaches its eastern extension at Calgary; in
the interior of southern British Columbia it is generally confined to
the higher uplands between river valleys ; northward it descends to the
general level of the country (Macoun); mountain ranges of Washing-
ton, Oregon, and the California coast ranges and the Sierra Nevadas;
east to Montana, Wyoming, Colorado, and the Guadeloupe Moun-
tains of northern and eastern Arizona, and southward into Mexico
(Sargent).

This tree is known but sparingly in the fossil state, the only representa-
tive so far known having been derived from the glacial deposits at
Mystic Lake, near Bozeman, Montana. The age of these deposits
cannot be accurately determined from the present data, but they prob-
ably represent the result of glaciation which may have continued for
some time after the period of continental glaciation, and even until
quite recently. The tree is, however, now extinct in that locality, and
it is possible that its elimination may have been due to the same general
causes that brought about a withdrawal of Sequoia from the prairie
region during glacial time.

PSEUDOTSUGA 275

2. P. macrocarpa, Mayr.
Hemlock

Transverse. Growth rings broad, variable, the dense summer wood com-
posed of rather small, rounded tracheids in irregular rows, upwards
of one third the spring wood, from which the transition is gradual.
Spring tracheids rather large and squarish-hexagonal, the walls
medium, rather uniform in regular rows. Medullary rays promi-
nent and resinous, numerous and wide, chiefly i cell wide, distant
1-6 rows of tracheids. Resin passages numerous but scattering,
equal to about 2 tracheids. Resin cells numerous and prominent on
the outer face of the summer wood, and at once recognizable by
their color, position, and structure. Resinous tracheids sometimes
present and forming small groups or radial series in contact with the
rays.

Radial. Rays sparingly resinous throughout, the tracheids narrow, mar-
ginal, or sometimes interspersed. Ray cells straight or contracted at
the ends, equal to 6-10 spring tracheids; the upper and lower walls
medium, sparingly pitted except in the summer wood ; the terminal
walls chiefly rather thin and not very strongly pitted ; the lateral
walls with prominent and resinous pits conspicuously much larger
than in P. Douglasii, the border prominent, the orifice at first len-
ticular, at length oblong, at first 3-6 throughout the spring wood,
somewhat abruptly reduced to i per tracheid in the summer wood.
Bordered pits numerous in i row, strongly elliptical. Pits on the
tangential walls of the summer tracheids few, very small and obscure.
Resin cells upwards of 50 /u, wide and 135-300 p, long. Spirals more
or less obscure, often distant, finally vestigial and in the summer
wood wanting, the angle 70°.

Tangential. Fusiform rays lenticular or the terminals unequally linear,
narrow, the central tract with i small resin canal. Ordinary rays
sometimes 2-seriate in part, resinous, broad, medium to high ; the
cells often very unequal, rather uniform, squarish, more rarely oval
or round. Rays much more numerous than in P. Douglasii.

A tree 30-54 m. in height, with a trunk of 1.08 m. in diameter.

Wood heavy, hard, strong, cross grained, very durable, difficult to work.

Relative specific gravity 0.4563

Percentage of ash residue 0.08

Approximate relative fuel value 45-59

Coefficient of elasticity in kilograms on millimeters . . 1050.

Ultimate transverse strength in kilograms 361.

Ultimate resistance to longitudinal crushing in kilograms 7405.

Resistance to indentation to 1.27 mm. in kilograms . . 1642.
(Sargent)

Dry ridges and canons between 2500 and 4000 feet elevation ; the coast
ranges of California ; San Bernardino Mountains to the Cuyamaca
Mountains (Sargent).

276 ANATOMY OF THE GYMNOSPERMS

3. * * P. miocena, Penh.

Transverse. Growth rings broad and prominent ; the tracheids of the spring
wood large and thin-walled, the structure passing gradually into the
thin but rather prominent summer wood composed of about 3-10 rows
of thick-walled tracheids. Resin cells not obvious. Resin passages
small, not very numerous, chiefly in the summer wood, often double, as
in P. Douglasii ; the epithelium cells small and thick-walled. Medul-
lary rays slightly resinous. The entire structure of the transverse
section bears a strong resemblance to the fine-grained wood of P.
Douglasii.

Radial. Bordered pits in i row. Cells of the medullary rays straight, the
thin upper and lower walls devoid of pits. Pits on the lateral walls of
the ray cells about 4 per tracheid.

Tangential. Ordinary rays i-seriate or 2-seriate in part, the cells oval or
round, thick-walled, about 24.5 p. broad. Fusiform rays narrow, the
cells thick-walled, the resin canal narrow.

Material silicified or preserved in the natural state.

Eocene of the Great Valley and Porcupine Creek groups, Saskatche-
wan ; Miocene of Cariboo, British Columbia.

15. * LARIX, TOURN. PLATES 48 AND 49

Transverse. Summer wood prominent, usually dense, the transition from
the spring wood more or less abrupt. Resin passages without thy-
loses but with thick-walled epithelium. Resin cells somewhat frequent,
but scattering on the outer face of the summer wood.

Radial. Ray tracheids prominent, sometimes interspersed ; the terminal
walls of the parenchyma ray cells thick and strongly pitted. Bor-
dered pits in i or 2 rows. Tracheids wholly without spirals.

Tangential. Fusiform rays prominent, usually high and narrow, the cells
small and thick-walled, the resin passage usually small. Cells of the
ordinary rays oval to oblong.

A well-defined genus, at once distinguished by the narrow and usually high
fusiform rays, the resin cells scattering on the outer face of the summer
wood, and the absence of spiral tracheids.

SYNOPSIS OF SPECIES

Bordered pits in 1-2 rows.

Pits on the tangential walls of the summer wood not confined to the
outermost tracheids.

Pits on the lateral walls of the ray cells 2-6 or 8 per tracheid.
Ray cells (tangential) rather unequal, sometimes in pairs,
somewhat variable, oval or oblong,
i. L. occidentalis.

LARIX

277

Pits on the tangential walls of the summer wood confined to the
outermost tracheid.

Pits on the lateral walls of the ray cells 2-6 per tracheid.

Ray cells (tangential) equal, uniform, and oblong, more
rarely oval.

2. * L. americana.
Bordered pits in I row, sometimes in pairs.

Pits on the tangential walls of the summer wood confined to the
outermost tracheid.

Pits on the lateral walls of the ray cells 3-6 ; those on the tan-
gential walls of the summer wood numerous and small.

Ray cells (tangential) equal and very uniform, narrowly
oblong.

3. L. Lyallii.

Pits on the lateral walls of the ray cells 2-6 per tracheid ; those
on the tangential walls of the summer wood few, small, con-
fined to the outermost wall.

Ray cells (tangential) oblong, more rarely oval, and much broader.

4. L. leptolepis.

1. L. occidentalis, Nutt.
Tamarack

Transverse. Growth rings usually broad, the dense and prominent sum-
mer wood about one half the spring wood, from which the transition
is abrupt. Tracheids of the summer wood large, squarish, in regular
rows. Tracheids of the spring wood very large and thin-walled,
squarish-hexagonal, in very regular rows, rather uniform. Medullary
rays prominent, rather resinous and broad, i cell wide, distant 2-6
rows of tracheids. Resin passages few, large, without thyloses, the
epithelium narrow, rather thin-walled, the nutritive layer thick-walled,
resinous. Resin cells widely scattering on the outer face of the
summer wood, but readily recognized by their abundant resinous
contents.

Radial. Rays conspicuously resinous throughout ; the tracheids narrow
and marginal, rarely interspersed. Ray cells chiefly straight through-
out and equal to 3-9 spring tracheids ; the upper and lower walls
chiefly thick and unequal, sparingly pitted throughout, more strongly
so in the summer wood ; the terminal walls coarsely pitted throughout ;
the lateral walls with elliptical and distinctly bordered pits, with a
narrow, chiefly oblong or lenticular orifice, numerous, at first 6-8 per
tracheid, soon greatly reduced in size, and in the summer wood
abruptly i per tracheid. Bordered pits conspicuously in 1-2 rows,
more rarely in i row only, elliptical, the orifice very large. Pits on
the tangential walls of the summer wood rather numerous but small
and often obscure. Resin cells about 12.5 p. wide and 60-150 p.
long.

278 ANATOMY OF THE GYMNOSPERMS

Tangential. Rays rather numerous, low to very high. Fusiform rays with
a large resin canal without thyloses, the epithelium cells thick-walled.
Ordinary rays often very high, chiefly very uniform, and not con-
tracted at the position of the rarely interspersed tracheids ; the paren-
chyma cells rather unequal, sometimes in pairs, oval or oblong,
somewhat variable.

This species appears to be more or less variable according to local con-
ditions of growth. From low elevations specimens appear to exhibit
little variation, but from high elevations (Mt. Higgins, Montana, altitude
8700 feet) they present very well-defined structural deviations. These
appear chiefly in the much narrower and unequal growth rings.

A tree 30-45 m. high, with a trunk upward of 1.50 m. in diameter.

Wood heavy, exceedingly hard and strong, rather coarse grained, com-
pact, satiny, susceptible of a fine polish, very durable in contact with
the soil, and of great economic value.

Relative specific gravity 0.7407

Percentage of ash residue 0.09

Approximate relative fuel value 74-

Coefficient of elasticity in kilograms on millimeters . . 1658.

Ultimate transverse strength in kilograms 524.

Ultimate resistance to longitudinal crushing in kilograms 11,023.

Resistance to indentation to 1.27 mm. in kilograms . . 2395.
(Sargent)

Abundant in the Kootenai-Columbia valley of British Columbia (Macoun);
through the mountain ranges of northern Washington to the western
slopes of the Rocky Mountains of Montana; the Blue Mountains of
Washington and Oregon ; moist mountain slopes and benches between
2500 and 5000 feet elevation ; scattered among other trees, never form-
ing separate forests (Sargent).

2. L. americana, Michx.

Larch. Black Larch. Tamarack. Hackmatack

Transverse. Growth rings rather broad and uniform, sometimes double.
Summer wood rather dense, about one fourth to one half the spring
wood, from which the transition is either gradual or abrupt, the
tracheids small, conspicuously unequal and not in very regular rows,
distinctly rounded. Spring tracheids large, hexagonal, radially elon-
gated, thin. Medullary rays prominent, broad, i cell wide, distant
2-8, rarely more, tracheids. Resin passages large, equal to 2-3
tracheids, devoid of thyloses ; the epithelium cells flat, rather thin-
walled ; the nutritive parenchyma scanty, thick-walled ; not very
numerous, chiefly in the summer wood. Resin cells few, widely scat-
tering on the outer face of the summer wood, nonresinous, distin-
guished by (i) their thinner walls and advanced position, and (2) by
the sieve-plate structure of the terminal walls.

LARIX 279

Radial. Rays somewhat resinous throughout ; the tracheids prominent,
numerous, and marginal. Parenchyma ray cells straight or barely
contracted in the summer wood ; the upper and lower walls thick,
unequal, and usually sparingly pitted ; the terminal walls coarsely
pitted throughout ; the lateral walls with distinctly bordered pits, the
narrow orifice chiefly oblong, 2-6 per tracheid, becoming distinctly
smaller toward the summer wood, where they are abruptly reduced to
2, and finally I, per tracheid. Bordered pits in I or 2 rows, large,
elliptical, becoming smaller and round toward the summer wood.
Pits often showing an equatorial band. Pits on the tangential walls
of the summer wood numerous, small, approximate, on the outer-
most tracheids only. The outer summer tracheids often show a
marked tendency to the formation of spirals. Resin cells 15 //.wide,
about 1 25 p. long.

Tangential. Rays numerous, medium to high, sparingly resinous. The
fusiform rays with a broad central tract and a large resin canal
without thyloses. The ordinary rays rather broad, sometimes 2-seriate
in part ; the cells thick-walled, chiefly rather equal, uniform, oblong,
more rarely oval. Rays somewhat contracted at the position of the
narrow and interspersed tracheids.

A tree 24-30 m. high, with a trunk upwards of .90 m. in diameter. Wood
heavy, hard, very strong, rather coarse grained, compact, durable in
contact with the soil.

Relative specific gravity 0.6236

Percentage of ash residue 0.33

Approximate relative fuel value 62.16

Coefficient of elasticity in kilograms on millimeters . . 1261.

Ultimate transverse strength in kilograms 384.

Ultimate resistance to longitudinal crushing in kilograms 8763.

Resistance to indentation to 1.27 mm. in kilograms . . 1675.
(Sargent)

Cold, wet swamps, often covering extensive areas, or northward on moist
uplands and intervale lands. This tree, together with the black spruce,
dominates nearly all the swampy land from Newfoundland, Labrador, and
the eastern provinces of Canada to the Rocky Mountains ; northward
to latitude 65°, where it is reduced to a height of 6-8 feet (Macoun);
southward through the northern United States to northern Pennsylvania,
northern Indiana, Illinois, and central Minnesota (Sargent).

A well-defined, widely distributed, and common tree in the Pleistocene
and more recent deposits, where the remains are preserved in a natural
state, and often most perfectly.

Leda clays, Montreal; Scarborough Heights, Ontario; Moose River,
Ontario ; Lower Till of Fort Madison, Iowa ; Ithaca, New York ; Don
Valley, Toronto ; the black clays of the Columbian Formation (equiva-
lent to Pleistocene of northern localities) at Dahlonega, Georgia ; peat
bogs of New Brunswick.

280 ANATOMY OF THE GYMNOSPERMS

3. L. Lyallii, Parl.

Tamarack. Mountain Larch

Transverse. Growth rings narrow, variable. The summer wood prominent
and dense or sometimes open, equal to about one half to one third
the spring wood; the tracheids in regular rows, very unequal, small,
radially narrow and rounded. Spring tracheids rather large, squarish-
hexagonal, thin-walled, very uniform in regular rows. Medullary rays
prominent, not very broad, i cell wide, distant 2-8 rows of tracheids.
Resin canals not very numerous, small and widely scattering, devoid
of thyloses, the epithelium not very narrow, thick-walled, the nutrient
parenchyma obscure or wanting. Resin cells somewhat numerous,
slightly resinous and easily distinguished.

Radial. Rays sparingly resinous throughout, the tracheids rather numerous,
marginal, sometimes interspersed. Ray cells very straight through-
out, equal to 3-7 spring tracheids ; the upper and lower walls thick,
somewhat conspicuously pitted ; the terminal walls coarsely pitted
throughout ; the lateral walls with numerous small, oval, distinctly
bordered pits with an oblong, narrow orifice, 3-6 per tracheid, in the
summer wood abruptly reduced to i. Bordered pits in i row, often
in pair's, elliptical, large. Pits on the tangential walls of the summer
wood rather numerous but small, and confined to the outermost
tracheid wall. Resin cells few, 15 /i, wide, 110-155 /x, chiefly about
125 fji, long.

Tangential. Rays rather numerous, low to high, somewhat resinous. Fusi-
form rays very narrow and variable in height ; the narrow' and linear
terminals often very unequal ; the cells all thick-walled ; the resin
canal small, usually narrow and oblong, often much reduced and
nearly obliterated. Ordinary rays more or less 2-seriate in part,
narrow, the cells very equal and uniform, narrowly oblong.

A low, straggling, Alpine tree, rarely exceeding 15 m. in height, with a
trunk upwards of 1.50 m. in diameter.

In the Rocky Mountains of Washington and Montana (Sargent); summit
of South Kootenai Pass ; from Cascade Mountain, Bow River Valley,
westward ; forming the last belt of timber on all the peaks of the Rocky
Mountains, and ranging from 6000 to 7000 feet elevation ; growing with
Pinus albicaulis (Macoun).

4. L. leptolepis, Gordon

Jap. = Fiijimatsit

Transverse. Growth rings rather broad. The very prominent and dense
summer wood composed of very angular and unequal tracheids in
irregular rows ; nearly equal to the spring wood, from which the tran-
sition is abrupt. Spring tracheids large, thin-walled, very uniform in
regular rows. Medullary rays prominent, i cell wide, distant 2-10 rows
of tracheids. Resin passages not numerous, somewhat widely scat-
tering, chiefly in the summer wood, the epithelium rather thin-walled,

PICEA 281

the nutritive parenchyma thick-walled ; equal to 1-2 tracheids, devoid
of thyloses. Resin cells on the outer face of the summer wood few,
distant ; recognized by their thin walls and more advanced position,
and the sieve-plate structure of the terminal walls.

Radial. Rays somewhat resinous throughout, with prominent, chiefly nar-
row, but often numerous, marginal tracheids, rarely interspersed.
Ray cells conspicuously straight throughout ; the upper and lower
walls rather thick, at first rather sparingly, but in the summer wood
very strongly, pitted ; the terminal walls coarsely pitted throughout ;
the lateral walls with rather small, oval, bordered pits, with a len-
ticular orifice, 2-6, abruptly reduced to i, per tracheid in the summer
wood. Bordered pits very large, with a large oval orifice, elliptical,
numerous, and often compact, two thirds the width of the tracheid,
in i row. Pits on the tangential walls of the summer wood few,
small, confined to the outermost tracheid wall. Resin cells 15 /A wide,
1 10-265 P- i°ng> chiefly about 125^.

Tangential. Rays rather numerous and resinous. The fusiform rays
narrow, the canal small without thyloses, the epithelium rather thick-
walled. Ordinary rays medium to high, contracted at the position of
the interspersed tracheids ; the parenchyma cells chiefly equal and
uniform, oblong, more rarely oval and broader.

16. * PICEA, LINK. PLATES 50 AND 51

Transverse. Growth rings variable, the transition to the usually prominent
summer wood gradual. Resin passages with or without thyloses, but
with thick-walled epithelium cells. Resin cells wholly wanting.

Radial. Ray tracheids conspicuous, chiefly narrow, marginal, or some-
times interspersed. Terminal walls of the ray cells usually strongly
pitted. Tracheids wholly without spirals.

Tangential. Fusiform rays chiefly narrow, with linear and often very
unequal and much-prolonged terminals ; the cells small and thick-
walled ; the central tract of I small resin passage without thyloses
but with thick-walled epithelium. Cells of the ordinary rays oblong,
more rarely oval.

This genus is readily distinguished from Larix and Pseudotsuga by the
absence of resin cells and of spiral tracheids.

SYNOPSIS OF SPECIES

Ray cells (tangential) variable, round, oval, or oblong.

Pits on the tangential walls of the summer wood chiefly or wholly
confined to the outermost wall.

Pits on the lateral walls of the ray cells 1-3 per tracheid.
Ray cells (tangential) equal.

Spring tracheids rounded-hexagonal, the structure not
very open.

10. P. sitchensis.

282 ANATOMY OF THE GYMNOSPERMS

Pits on the tangential walls of the summer wood few, often widely
scattering and extending for some distance into the summer wood.
Pits on the lateral walls of the ray cells 2-6, chiefly 4, per tra-
cheid.

Ray cells (tangential) conspicuously unequal.

Spring tracheids large, thin-walled, uniform in regular
rows, squarish-hexagonal.

6. P. polita.

Ray cells (tangential) usually very equal and uniform, oblong or oval.

Pits on the tangential walls of the summer wood chiefly or wholly
confined to the outermost tracheid wall.

Pits on the lateral walls of the ray cells 2-4 per tracheid.

7. P. bicolor.

Pits on the lateral walls of the ray cells 2-6 per tracheid.

3. * P. alba.

Pits on the tangential walls of the summer wood not confined to the
outermost wall, but chiefly small and inconspicuous.
Rays (radial) nonresinous.

Pits on the lateral walls of the ray cells at first narrowly bor-
dered, 2-5 per tracheid, in the summer wood reduced to i.
Ray cells (tangential) rather thick-walled.

Spring tracheids rounded-hexagonal ; the summer
wood rather open but prominent, upwards of one
half the spring wood.

4. P. Engelmanni.

Pits on the lateral walls of the ray cells with an oblong
orifice, 2-6 per tracheid, toward the summer wood reduced
to 2, and finally to i.

Ray cells (tangential) thin-walled.

Spring tracheids hexagonal, very thin-walled ; the
summer wood very thin and open, often barely
distinguishable.

8. P. pungens.

Rays (radial) locally resinous, the resin chiefly confined to the
thicker-walled and more strongly pitted cells, more rarely dif-
fused throughout the central cells.

Pits on the lateral walls of the ray cells with a lenticular
orifice, at first 2-6 per tracheid, more rarely 2 throughout,
in the summer wood reduced to 2, and finally to i.

Spring tracheids squarish-hexagonal, not very uniform,
the walls rather thin.

9. * P. nigra.

PICEA 283

Pits on the lateral walls of the ray cells with an oblong,
narrow orifice, 3-5 per tracheid, in the summer wood
reduced to 2, and finally to I.

Spring tracheids large, squarish-hexagonal, very unequal
in regular rows, the walls thin.

5. P. jesoensis.

Pits on the lateral walls of the ray cells with a narrow,
oblong orifice, at first sometimes upwards of 7 per tra-
cheid, soon 2-4, and in the summer wood 1-2.

Spring tracheids large, squarish, very uniform in regular
rows, the walls rather thin.

2. P. rubra.

Pits on the lateral walls of the ray cells with a narrow,
oblong orifice, becoming much extended in the summer
wood ; 2-3, more rarely 4, per tracheid, becoming i in the
summer wood.

Spring tracheids distinctly hexagonal, conspicuously
unequal in regular rows, the walls not very thin.
i. P. Breweriana.

1. P. Breweriana, Wats.

Weeping Spruce

Transverse. Growth rings rather thin and uniform. Summer wood rather
thin, of about 10-16 tracheids, prominent, not very dense, the tran-
sition from the spring wood gradual ; the tracheids unequal, in
rather regular rows, usually much compressed. Spring tracheids dis-
tinctly hexagonal, conspicuously unequal, in regular rows, the walls
not very thin. Resin passages rather numerous, scattering, often in
small groups, and more or less imperfectly formed ; the epithelium
in 1-2 rows of very variable but thick-walled, often resinous, cells.
Medullary rays prominent, resinous, distant 2-8, more rarely 12, rows
of tracheids.

Radial. Rays sparingly resinous ; the ray tracheids marginal. Ray cells
straight or becoming fusiform in the summer wood, equal to 6-7
spring tracheids ; the terminal walls coarsely pitted ; the upper and
lower walls rather thick, unequal, more or less obscurely pitted except
in the summer wood ; the lateral walls with conspicuously bordered,
round, or oval pits, with an oblong orifice which becomes much ex-
tended in the summer wood, 2-3, more rarely 4, per tracheid, becoming
i in the summer wood. Bordered pits numerous, often much crowded,
in i row, elliptical. Pits on the tangential walls of the summer wood
rather numerous, not confined to the outermost tracheid wall.

Tangential. Rays numerous, somewhat resinous, medium to high, not
very broad ; the cells chiefly equal and uniform, oblong, or more
rarely oval. Fusiform rays rather few, narrow ; the terminals often
much prolonged.

284 ANATOMY OF THE GYMNOSPERMS

A tree upwards of 30 m., or more rarely 36 m. in height, with a trunk

.6o-.9o m. in diameter.
Wood soft, close grained, compact, with a satiny surface.

Relative specific gravity 0.5141

(Sargent)

This tree occurs in small, scattered groves in the elevated mountain
regions of California and Oregon, between 4000 and 7500 feet altitude
(Sargent).

2, P. rubra, Dietr.
Red Spruce

Transverse. Growth rings narrow, rather variable. Summer wood narrow,
not very prominent, upwards of 10 tracheids, rather open; the tran-
sition from the spring wood gradual. Spring tracheids rather large,
not very thin-walled, in very regular rows and very uniform, squarish.
Resin passages widely scattering, not numerous, medium and equal
to about 2 tracheids ; the epithelium composed of rather small, thick-
walled cells ; wholly devoid of thyloses. Resin cells wholly wanting.
Medullary rays I cell wide, not numerous or prominent, distant 3-14
rows of tracheids.

Radial. Rays sparingly resinous, the resin usually localized and more or
less confined to the thicker-walled and more strongly pitted cells ; the
ray tracheids prominent, marginal, rarely interspersed. Ray cells
straight throughout, or barely fusiform in the summer wood, equal to
about 5-7 spring tracheids; the terminal walls strongly pitted; the
upper and lower walls rather thin, distantly and obscurely pitted,
or in the summer wood more or less strongly pitted ; the lateral walls
with small, elliptical, bordered pits with an oblong orifice, at first
sometimes upwards of 7 per tracheid, soon 2-4, and in the summer
wood 1-2. Bordered pits broadly elliptical or round, in i row, not
crowded, but variable in size. Pits on the tangential walls of the
summer wood very small and much compressed.

Tangential. Rays somewhat numerous, medium, sparingly resinous. Fusi-
form rays narrow, the resin canal small with thick-walled epithelium.
Ordinary rays not broad, medium, the cells very equal and uniform,
oblong, or sometimes oval throughout.

A tree usually 21-24 ni., and occasionally 30-33 m. in height, with a
trunk .6o-.9o m. in diameter.

Valley of the St. Lawrence and the northern shores of Prince Edward
Island, southward through Quebec, the Maritime Provinces, and along
the Atlantic coast to southern Maine and Cape Cod ; through the hilly
interior and the mountainous parts of New England and New York,
thence along the Allegheny Mountains to the high peaks of western
North Carolina (Sargent).

PICEA 285

3. * P. alba, Ait.

White Spruce

Transverse. Growth rings thick. Summer wood thin, rather prominent,
upwards of one fourth the spring wood from which the transiton
is gradual, rarely abrupt ; the structure rather dense ; the tracheids
conspicuously squarish. Spring wood open, the tracheids squarish-
hexagonal, uniform in very regular rows, the walls thin. Resin pas-
sages scattering, rather large, round, commonly without thyloses,
equal to 2-3 tracheids ; the epithelium of very unequal, chiefly narrow,
and rather thin-walled cells. Medullary rays not very numerous,
rather prominent, narrow, i cell wide, distant 2-14 rows of tracheids.

Radial. Rays very sparingly resinous; the ray tracheids prominent, mar-
ginal, sometimes interspersed in the higher rays. Ray cells straight
throughout, equal to 5-13 spring tracheids ; the terminal walls coarsely
pitted ; the upper and lower walls rather thin, unequal, sparingly pitted
in the spring wood, strongly pitted in the summer wood; the lateral
walls with numerous small, oval pits with a lenticular orifice, 2-6 per
tracheid, in the summer wood abruptly reduced to 2, and finally to i.
Borderedpitsin i row, numerous, round, or elliptical, the orifice large; in
the summer wood becoming remote and finally obscure, the orifice usu-
ally a prolonged slit. Pits on the tangential walls of the summer wood
very flat and obscure, chiefly confined to the outermost tracheid wall.

Tangential. Rays rather numerous, nonresinous, low to high. Fusiform
rays narrow, the cells thin-walled, the resin canal small, the epithelium
composed of thick-walled cells. Ordinary rays narrow, not conspic-
uously contracted by the occasionally interspersed tracheids ; the cells
very equal and uniform, oblong, narrow.

A tree 15-50 m. high, with a trunk upwards of .90 m. in diameter.
Wood light, soft, not strong, close and straight grained, compact, satiny.

Relative specific gravity 0.4051

Percentage of ash residue 0.32

Approximate relative fuel value 4°-38

Coefficient of elasticity in kilograms on millimeters . . 1023.

Ultimate transverse strength in kilograms 319.

Ultimate resistance to longitudinal crushing in kilograms 5489.

Resistance to indentation to 1.27 mm. in kilograms . . 1117.
(Sargent)

According to Bovey the following data have been obtained :

Coefficient of strength in pounds for :

Bending '. 5°°°

Torsion 9°°°

Compression 3200

Shear 360

Weight of i cubic foot 3°

Newfoundland, Anticosti, Nova Scotia, and New Brunswick, westward
through Quebec and Ontario to the forest limit of Manitoba ; in the

286 ANATOMY OF THE GYMNOSPERMS

prairie region being found in the sand hills bordering the first prairie
steppe. Occasionally in the valley of the Saskatchewan and on the
Bow River from Calgary, where it is mixed with P. Engelmanni ; on the
Athabasca to latitude 54° 7' 34" (Macoun). Coast of Maine through
northeastern Vermont and westward through northern Michigan and
Minnesota to the Black Hills of Dakota ; along the Rocky Mountains of
Montana, where it reaches its greatest development along streams and
lakes in the Flathead region, at elevations of 2500-3500 feet (Sargent).

Pleistocene of the Scarborough period of which it is characteristic, at
Scarborough Heights, Ontario.

Material preserved in the natural state, but showing the effects of exten-
sive decay.

4. P. Engelmanni, Engelm.

IVhite Spruce. Engelmanri 's Spruce

Transverse. Growth rings broad. Summer wood very prominent and
rather open, about one half to one third the spring wood, from which
the transition is gradual ; the tracheids often much compressed radially.
Spring tracheids rounded-hexagonal, unequal in regular rows, the
walls thin. Resin passages without thyloses, not very numerous ; the
epithelium cells very unequal, rather thin-walled. Medullary rays not
very prominent, narrow, I cell wide, distant 2-7 rows of tracheids.

Radial. Rays nonresinous; the ray tracheids prominent, marginal. The
ray cells generally straight and equal to 7 spring tracheids ; the ter-
minal walls strongly pitted ; the upper and lower walls medium and
sparingly pitted, except in the summer wood ; the lateral walls with
small, oval, and at first narrowly bordered pits, 2-5 per tracheid, in
the summer wood gradually reduced to i. Bordered pits in i row,
large, not very numerous, round or elliptical, the orifice finally becom-
ing a prolonged slit upwards of 34 p.. Pits on the tangential walls of
the summer wood small and not prominent, chiefly confined to the
outermost wall.

Tangential. Rays rather numerous, medium to high, nonresinous. The
fusiform rays rather broad, the resin canal large and round, with
thick-walled epithelium. The ordinary rays rather narrow, the cells
very equal and uniform, narrowly oblong, rarely broader.

A large tree 24-26 m. high, with a trunk upwards of 1.20 m. in diameter.
Wood very light, soft, not strong, very close and straight grained, com-
pact, satiny.

Relative specific gravity 0.3449

Percentage of ash residue 0.32

Approximate relative fuel value 33-38

Coefficient of elasticity in kilograms on millimeters . . 808.

Ultimate transverse strength in kilograms 245.

Ultimate resistance to longitudinal crushing in kilograms 4271.

Resistance to indentation to 1.27 mm, in kilograms . . 1217.
(Sargent)

PICKA 287

This tree characterizes the interior plateau of British Columbia, with the
exception of the dry southern portions, forming dense groves in the
mountains. It ranges northward to latitude 54° 7' 34" at an altitude of
2600 feet (Macoun). Dry gravelly ridges and slopes between 5000 and
11,500 feet elevation, constituting the most valuable timber tree of the
central Rocky Mountains, where it forms extensive forests, generally
above 8500 feet elevation. Rare and of small size in the mountains of
Washington, Oregon, and Montana (Sargent).

5. P. jesoensis, Carr.

Jap. =. To hi

Transverse. Growth rings narrow, uniform. The very thin summer wood
open and composed of 5-10 tracheids, about one fourth the spring
wood, from which the transition is rather gradual. Spring tracheids
large, squarish-hexagonal, thin-walled, very unequal but in regular
rows. Resin passages not very numerous, chiefly large, with thyloses,
the epithelium of very unequal, rather thick-walled cells. Medullary
rays not numerous, rather resinous and prominent, i cell wide, dis-
tant 2-8 rows of tracheids.

Radial. Rays sparingly and locally resinous ; the ray tracheids prominent
and often interspersed. Ray cells somewhat contracted at the ends,
equal to 3-7 spring tracheids ; the terminal walls coarsely pitted ; the
upper and lower walls not very thick, conspicuously pitted, especially
in the summer wood ; the lateral walls with small, oval, bordered pits
with a narrow orifice, 3-5 per tracheid, in the summer wood reduced
to 2, and finally to i. Bordered pits large, strongly elliptical, in i row,
rather numerous, often in compact rows towards the ends of tracheids.
Pits on the tangential walls of the summer wood rather few, small,
and inconspicuous.

Tangential. Rays not very numerous, low to medium, sparingly resinous.
Fusiform rays rather broad, the rather large resin canal with thick-
walled epithelium, chiefly without thyloses. Ordinary rays not very
broad, contracted at the position of the sparingly interspersed tra-
cheids ; the cells rather thick-walled, very equal and uniform, narrowly
oblong, rarely oval.

6. P. polita, Carr.

Jap. = Iramomi

Transverse. Growth rings thin, very variable. Summer wood prominent,
rather dense but variable, from 3 tracheids thick upwards, equal to
one half to one third the spring wood from which the transition is
rather gradual; the tracheids variable. Spring tracheids rather large
and thin-walled, uniform in regular rows. Resin passages rather
numerous, large but variable, equal to 1-4 tracheids, with thyloses;
the epithelium of very unequal, rather thin-walled cells. Medullary
rays rather numerous and broad, i cell wide, resinous, distant 2-8 or
lo rows of tracheids.

288 ANATOMY OF THE GYMNOSPERMS

Radial. Rays locally very resinous throughout ; the ray tracheids low,
unequal, marginal, sometimes interspersed. Ray cells more or less
contracted at the ends, especially in the summer wood, equal to 7-8
spring tracheids; the terminal walls thin, often locally thickened or
sparingly pitted, sometimes entire ; the upper and lower walls thicker
and strongly pitted in the resinous cells, thinner and sparingly pitted
in the nonresinous cells ; the lateral walls with small, oval, bordered
pits, the orifice narrow, oblong, 2-6, chiefly 4, per tracheid, in the
summer wood rather abruptly reduced to i. Bordered pits numerous,
elliptical, in i row, sometimes in pairs. Pits on the tangential walls
of the summer wood rather few and not very prominent, flat, often
widely scattering, and extending for some distance into the summer
wood.

Tangential. Rays numerous, low to high, rather broad, resinous. The
fusiform rays rather narrow, with a small resin canal and thick-walled
epithelium. Ordinary rays contracted at the position of the occa-
sionally interspersed and very narrow tracheids ; the parenchyma
cells conspicuously unequal and variable, from round or oval to
oblong, often narrow and high.

7. P. tricolor, Mayr.
Jap. - 6-Tdhi

Transverse. Growth rings narrow, uniform. The narrow summer wood of
6-10 tracheids, about equal to one third to one half the spring wood
from which the transition is rather gradual ; not very dense, the tra-
cheids much flattened and rounded. Spring tracheids conspicuously
squarish, thin-walled, uniform in very regular rows. Resin passages
rather large, often with thyloses ; the epithelium composed of very
unequal, thick-walled cells. Medullary rays rather prominent, some-
what resinous, i cell wide, distant 2-10 rows of tracheids.

Radial. Rays somewhat resinous, the resin localized; the ray tracheids
numerous, prominent, and marginal, often interspersed. Parenchyma
cells straight, equal to about 8 tracheids; the terminal walls thin, at
first sparingly, soon strongly, pitted throughout ; the upper and lower
walls medium, very sparingly pitted, or again thicker and strongly
pitted, especially in the summer wood ; the lateral walls with small,
elliptical, bordered pits, with an oblong orifice, 2-4 per tracheid,
abruptly reduced to I in the summer wood. Bordered pits large,
elliptical, or round, in i row. Pits on the tangential walls of the
summer wood not very numerous, small, chiefly confined to the outer-
most wall.

Tangential. Rays rather numerous but low to medium, somewhat resinous.
The fusiform rays chiefly low, narrow, the usually small resin canal
with thick-walled epithelium. Ordinary rays conspicuously contracted
at the position of the very narrow, interspersed tracheids; the paren-
chyma cells thick-walled, equal and chiefly uniform, oblong, often
narrow, rarely oval.

PICEA 289

8. P. pungens, Engelm.
Blue Spruce. Colorado Spruce

Transverse. Growth rings broad. The very thin and often barely distin-
guishable summer wood gradually passing into the spring wood ; the
tracheids very unequal and often much compressed radially. Spring
tracheids hexagonal, very thin-wailed, uniform in regular rows. The
structure is very open throughout. Resin passages rather few, small,
and scattering, with small and very unequal, thick-walled epithelium
cells ; thyloses few or wanting. Medullary rays rather numerous and
broad, i cell wide, distant 2-9 rows of tracheids.

Radial. Rays nonresinous ; the ray tracheids numerous and marginal,
rarely interspersed. Parenchyma cells chiefly straight, equal to about
7 spring tracheids ; the terminal walls coarsely pitted ; the upper and
lower walls medium and entire or conspicuously pitted throughout ;
the lateral walls with small, oval, bordered pits with an oblong orifice,
2-6 per tracheid, toward the summer wood reduced to 2, and finally
to i. Bordered pits numerous, in i row, elliptical or round; the round
orifice becoming lenticular in the summer wood. Pits on the tangen-
tial walls of the summer wood small, not numerous or prominent,
chiefly confined to the outermost walls.

Tangential. Rays numerous, nonresinous, medium to high. The fusiform
rays narrow, the resin canal rather small, with thick-walled epithelium.
The ordinary rays contracted at the position of the occasionally inter-
spersed tracheids ; the parenchyma cells rather thin-walled, very equal
and uniform, oblong, rather narrow.

A tree 30-46 m. high, with a trunk upwards of .90 m. in diameter.
Wood very light, soft, weak, close grained, compact, satiny.

Relative specific gravity 0.3740

Percentage of ash residue 0.38

Approximate relative fuel value 37.26

Coefficient of elasticity in kilograms on millimeters . . 553.

Ultimate transverse strength in kilograms 194.

Ultimate resistance to longitudinal crushing in kilograms 4128.

Resistance to indentation to 1.27 mm. in kilograms . . 1267.
(Sargent)

Along borders of streams in damp or wet soil, generally between 6000 and
9000 feet elevation, and never forming forests. Rare and local. Valley of
the Wind River and south through the mountains of Wyoming, Colorado,
and Utah (Sargent).

9. * P. nigra, Ait.

Black Spruce

Transverse. Growth rings rather broad, variable. The summer wood
usually much less than but upwards of one half the spring wood, from
which the transition is gradual ; the structure open. Spring tracheids
squarish-hexagonal, not very uniform, in regular rows, the walls
rather thin. Resin passages chiefly in the summer wood, equal to 2-4

290 ANATOMY OF THE GYMNOSPERMS

tracheids with thyloses ; the epithelium cells very much flattened,
rather thin-walled. Medullary rays rather prominent, i cell wide,
rather numerous, distant 2-8 rows of tracheids.

Radial. Rays very sparingly resinous ; the ray tracheids prominent, mar-
ginal, sometimes interspersed. Parenchyma cells straight or rarely
narrower at the ends, long ; the terminal walls coarsely pitted ; the
upper and lower walls medium, sinuately unequal, distantly and often
obscurely pitted except in the summer wood ; the lateral walls with
small, oval, bordered pits with a lenticular orifice, 2-6 per tracheid,
more rarely 2 throughout, in the summer wood reduced to 2, and
finally to i. Bordered pits numerous, crowded, round, or elliptical, the
orifice large, round, becoming narrow in the summer wood and par-
allel with the tracheid axis. Pits on the tangential walls of the sum-
mer wood very narrow and small, but generally numerous.

Tangential. Fusiform rays very narrow and high ; the cells small and thick-
walled ; the terminals very long and linear, often unequal ; the resin
canal rather small and narrow, oblong. Ordinary rays very narrow,
the cells very equal and uniform, oblong and narrow at least in the
higher rays, more rarely rather broad and oval.

A tree 15-21 m. high, with a trunk upwards of .90 m. in diameter.
Wood light, soft, not strong, close and straight grained, compact, satiny.

Relative specific gravity 0.4594

Percentage of ash residue 0.27

Approximate relative fuel value 45-71

Coefficient of elasticity in kilograms on millimeters . . iioo.

Ultimate transverse strength in kilograms 318.

Ultimate resistance to longitudinal crushing in kilograms 6520.

Resistance to indentation to 1.27 mm. in kilograms . . 1240.
(Sargent)

Abundant in Newfoundland and in every part of Canada except southern
Ontario and the prairie region, ranging northward to latitude 65°, where
it terminates in association with Betula papyrifera (Macoun). Through
the northern United States to Pennsylvania, central Michigan, Wiscon-
sin, and Minnesota, and along the Allegheny Mountains to the high
peaks of North Carolina (Sargent).

Pleistocene deposits at Hamilton (Erie clays), Ontario ; the Moose River,
Ontario ; Don Valley and the Leda Clays, Montreal. This plant occurs
in considerable abundance and is essentially typical of the Don period,
where it is associated with another undescribed species, possibly the same.

Material preserved in a natural state, though usually much altered by
decay.

10. P. sitchensis, Can-.
Tideland Spruce. Sitka Spruce

Transverse. Growth rings thickish. Summer wood very prominent, equal to
or exceeding the spring wood from which the transition is gradual, not
very dense. Spring tracheids commonly strongly rounded-hexagonal,

PINUS 291

the walls rather thin, but the structure as a whole not very open. Resin
passages few, not very large, with thyloses ; the epithelium of small,
thick-walled cells, resinous. Medullary rays not very numerous, prom-
inent or broad, i cell wide, distant 2-9 rows of tracheids, more
rarely 1 1 .

Radial. Rays somewhat resinous locally ; the ray tracheids prominent,
marginal, rarely interspersed. Parenchyma cells somewhat contracted
at the ends, equal to 6-10 spring tracheids ; the terminal walls coarsely
pitted ; the upper and lower walls medium or thin and entire, or in
the resinous cells and summer wood becoming thicker and pitted ; the
lateral walls with rather few and small, narrowly bordered pits with a
lenticular orifice, 1-3, more rarely 4, per tracheid, in the summer wood
reduced to 2, and finally to i. Bordered pits in i row, elliptical, large;
the orifice large and round or lenticular, in the summer wood becoming
narrow and parallel with the tracheid axis. Pits on the tangential walls
of the summer wood few, small, and chiefly or wholly confined to the
outermost tracheid wall.

Tangential. Rays medium to high, somewhat resinous. The fusiform rays
narrow, the resin canal small, with small and thick-walled epithelium
cells. Ordinary rays rather broad, conspicuously contracted at the
position of the narrow and occasionally interspersed tracheids ; the
parenchyma cells equal but variable from round to oval or oblong.

A large tree of great economic value, 46-61 m. high, with a trunk 2.40—

5.19 m. in diameter.
Wood light, soft, not strong, close and straight grained, compact, satiny.

Relative specific gravity 0.4287

Percentage of ash residue 0.17

Approximate relative fuel value 42.80

Coefficient of elasticity in kilograms on millimeters . . 99°.

Ultimate transverse strength in kilograms 277.

Ultimate resistance to longitudinal crushing in kilograms 5653.

Resistance to longitudinal crushing to 1.27 mm. in kilograms 1 160.
(Sargent)

Chiefly confined to the coast of British Columbia, where it attains large
size (Macoun) ; Alaska, south to Mendocino County, California, not
extending more than 50 miles inland from the coast (Sargent).

17. * PINUS, TOURN.

Transverse. Growth rings usually broad. The more or less prominent
summer wood variable. Resin passages prominent, chiefly large, with
prominent thyloses and thin-walled, variable, several-layered epithe-
lium. Resin cells wholly wanting.

Radial. Ray tracheids prominent and always limiting the ray, often inter-
spersed, sometimes predominant, and in rays only a few elements
high, commonly constituting the entire structure ; the upper and lower
walls often dentate (Sec. II), the teeth sometimes united across the
tracheid so as to form more or less prominent reticulations. Ray cells

292 ANATOMY OF THE GYMNOSPERMS

of one or two kinds. Bordered pits on the tangential walls of the sum-
mer wood either numerous (Sec. I) or usually wanting (Sec. II).
Tracheids wholly without spirals. Resinous tracheids sometimes pres-
ent, the resin forming radial plates opposite the rays and simulating
Sanio's bands.

Tangential. Fusiform rays chiefly large and broad ; the cells of the inflated
portion chiefly large and thin-walled ; the central tract occupied by
i large resin passage with thyloses and thin-walled epithelium. Ordi-
nary rays chiefly i -seriate, more or less conspicuously contracted by
the interspersed tracheids.

SYNOPSIS OF SPECIES

A. PINUS PROPER

Existing Species

Sec. I. Pits on the tangential -walls of the summer wood prom-
inent. Medullary tracheids prominent, sparingly interspersed,
their upper and lower walls not dentate.

A. The lateral walls of the ray cells (radial) with small, numer-
ous, and more or less conspicuously bordered pits ; the upper
and lower walls thick and coarsely pitted ; the terminal walls
coarsely pitted ; the thick side walls (tangential) not inflated
or incurved. The rays sometimes show thin-walled cells with-
out pits, which are conterminous and interspersed.
Ray cells (radial) of I kind only, all thick-walled and strongly pitted.

Rays nonresinous (radial), the tracheids numerous, marginal, often
interspersed.

Pits on the lateral walls of the ray cells 1-4, chiefly 4, throughout,
but finally 2, per tracheid in the outer summer wood.

Ray cells (tangential) conspicuously unequal and variable,
from round to oval or oblong, those of the low rays often
three times higher than wide.

3. P. monophylla.

Rays more or less resinous (radial), the tracheids marginal, sparingly
or rarely interspersed.

Pits on the lateral walls of the ray cells 2-4 per tracheid throughout.
Ordinary rays (tangential) sparingly resinous, somewhat con-
tracted by occasionally interspersed, narrowly oval, or
oblong tracheids ; the cells equal and chiefly uniform, oval
to oblong, rarely narrow.

i. P. Parryana.

Ordinary rays (tangential) somewhat resinous, rather broad,
not perceptibly contracted by the occasionally interspersed

PINUS 293

and equal tracheids ; the cells very equal, chiefly very
uniform, narrowly oval or oblong, rarely broader.

2. P. cembroides.

Pits on the lateral walls of the ray cells 1-5 throughout, or finally
1—2, per tracheid in the summer wood.

Ordinary rays rather broad and nonresinous (tangential),
somewhat contracted by the narrower and smaller, occasion-
ally interspersed tracheids ; the cells very equal and uniform,
narrowly oval to oblong.

4. P. Balfouriana.

Ray cells (radial) of 2 kinds: (i) thick-walled and strongly pitted;
(2) thin-walled, devoid of pits, conterminous, and interspersed.

Pits on the lateral walls of the ray cells 3-6, soon 4, or in the outer
summer wood 2, per tracheid.

Ordinary rays (tangential) nonresinous, numerous, the cells equal,
uniform, oval, or oblong.

Fusiform rays (tangential) few, narrow.

5. P. aristata.

Pits on the lateral walls of the ray cells 1-4 throughout, or in the
marginal cells upwards of 5 or 6, per tracheid.

Ordinary rays (tangential) numerous, broad, the cells chiefly equal,
uniform, oval, and narrow.

Fusiform rays (tangential) rather numerous, small, and narrow.

6. P. edulis.

B. Lateral walls of the ray cells (radial) with large, open, and
simple, oval, or lenticular pits, 1-2 per tracheid; the upper
and lower walls thin and distantly or even obscurely pitted;
the terminal walls thin and entire or locally thickened ; the
thin side walls (tangential) either inflated or incurved.
Ray cells (transverse or tangential) with their very thin side walls strongly
inflated and projecting into the cavities of the adjacent tracheids.

Pits on the lateral walls of the ray cells oval or squarish, or finally
lenticular, 1-2, chiefly i, per tracheid throughout.

Resin passages numerous and large, chiefly in or near the summer
wood ; when in the former situation, central to a large tract of

thin-walled tracheids.

10. P. reflexa.

Ray cells (transverse or tangential) with their thin side walls not strongly
inflated, but commonly incurved or sometimes convex.

Pits on the lateral walls of the ray cells chiefly 1-2 per tracheid.
Resinous tracheids (radial) not present.

Rays (tangential) strongly resinous, the cells oval, unequal,
variable.

294 ANATOMY OF THE GYMNOSPERMS

Pits on the lateral walls of the ray cells 1-2, in the sum-
mer wood reduced to i, per tracheid.

8. P. monticola.
Rays (tangential) nonresinous.

Ray cells (tangential) oval, equal, and uniform.

Pits on the lateral walls of the ray cells 1-2, or in
the marginal cells 3-4, per tracheid.

9. P. flexilis.

Ray cells (tangential), oblong, narrow, equal, and uniform.
Pits on the lateral walls of the ray cells 1-2 through-
out, rarely 3, per tracheid.

11. * P. strobus.

Ray cells (tangential) chiefly equal, but more or less vari-
able, from broadly to narrowly oval or oblong.

Pits on the lateral walls of the ray cells 2 per tra-
cheid throughout, rarely I or 3.

7. P. Lambertiana.

Ray cells (tangential) oblong and narrow, more rarely
oval and broader, not very variable.

Pits on the lateral walls of the ray cells i per tra-
cheid throughout, or in the early spring wood 2
per tracheid.

12. P. parviflora.

Resinous tracheids (radial or tangential) present, the resin in
plates opposite the rays and simulating Sanio's bands.
Rays (tangential) nonresinous.

Ray cells (tangential) oval or oblong, not very variable.
Pits on the lateral walls of the ray cells i per tra-
cheid throughout, more rarely 2.

13. P. albicaulis.

Ray cells (tangential) oblong and narrow, more rarely
oval and broader, not very variable.

Pits on the lateral walls of the ray cells i per
tracheid throughout, or in the early spring wood
2 per tracheid.

12. P. parviflora.

Sec. II. Pits on the tangential walls of the summer wood usu-
ally wanting. Medullary tracheids prominent, more or less,
often strongly, interspersed, their upper and lower walls den-
tate or the teeth so prolonged and united across the cavity as
to form a more or less dejinite and sometimes very strongly
defined reticulum.

PINUS 295

A. Pits on the lateral walls of the ray cells large and open,
chiefly i, and not exceeding 2, per tracheid.

Ray cells of i kind only.

Pits on the lateral walls of the ray cells simple throughout.
Epithelium of the resin passages resinous.

Bordered pits in i row, sometimes in pairs.

Ray tracheids simply dentate, rarely interspersed.

Pits on the lateral walls of the ray cells 1-2, chiefly
i, per tracheid.

21. P. resinosa.

Ray tracheids simply dentate, but numerous and inter-
spersed and often predominant.

Pits on the lateral walls of the ray cells large, oval,
oblong, or lenticular, 1-2, chiefly i, per tracheid.

22. P. tropicalis.

Pits on the lateral walls of the ray cells large and conspicuously bor-
dered in the summer wood.

Epithelium of the resin passages nonresinous.

Resin passages (transverse) large, numerous, scattering.
Bordered pits in i row.

Ray tracheids (radial or tangential) simply dentate,
not interspersed.

Pits on the lateral walls of the ray cells i,
rarely 2, per tracheid.

23. P. Thunbergii.

Ray tracheids (radial or tangential) somewhat inter-
spersed, sparingly reticulated in the summer wood.
Pits on the lateral walls of the ray cells strictly
i per tracheid.

24. P. densiflora.

B. Pits on the lateral walls of the ray cells generally rather
small and upwards of 6 per tracheid, at least 2 or more per
tracheid.

Ray cells (radial) of I kind only and thin-walled.

Fusiform rays (tangential) with the cells of the inflated portion all or
chiefly rather thick-walled.

Epithelium of the resin passages (transverse) chiefly in 1-2 rows,
resinous.

Summer wood dense.

Bordered pits in i row, or sometimes in pairs.

Pits on the lateral walls of the ray cells 1-6 per tra-
cheid.

296 ANATOMY OF THE GYMNOSPERMS

Ray tracheids strongly predominant and
strongly reticulated throughout.

i 7. P. Banksiana.

Fusiform rays (tangential) with the cells of the inflated portion all or
chiefly thin-walled, all broken out.

Epithelium of the resin passages (transverse) chiefly or wholly in
i row, nonresinous (rarely resinous in P. taeda and P. rigida).
Summer wood open.

Bordered pits in i row, sometimes in pairs.

Pits on the lateral walls of the ray cells 1-5, chiefly
2, per tracheid, becoming bordered in the summer
wood.

Ray tracheids sparingly interspersed, strongly
reticulated throughout.

15. P. rigida.

Pits on the lateral walls of the ray cells 1-4, rarely 5,
per tracheid.

Ray tracheids more or less reticulated in the
summer wood, often interspersed.

25. P. Murrayana.
Bordered pits in 1-2 rows.

Pits on the lateral walls of the ray cells i -6, chiefly
2-4, per tracheid.

Ray tracheids sparingly (very rarely strongly)
reticulated throughout.
39. P. taeda, Linn.

Pits on the lateral walls of the ray cells i -5 per tracheid.
Ray tracheids when interspersed very low,
strongly reticulated throughout.

14. P. clausa.
Summer wood dense.

Bordered pits in 1-2 rows.

Pits on the lateral walls of the ray cells 1-6, chiefly
2-4, per tracheid.

Ray tracheids sparingly (rarely strongly) retic-
ulated throughout.

39. P. taeda.

Ray tracheids high, very strongly reticulated
throughout.

The ray cells apparently all of i kind, but
differentiating slightly.
41. P. cubensis.

PINUS 297

Pits on the lateral walls of the ray cells 1-5 per tra-
cheid.

Ray tracheids strongly reticulated throughout,
often predominant, and, when interspersed,
very low.

14. P. clausa.

Pits on the lateral walls of the ray cells 1-4 per tra-
cheid.

Ray tracheids chiefly high, conspicuously pre-
dominant, and strongly reticulated throughout.

20. P. echinata.
Bordered pits in I row, sometimes in pairs.

Pits on the lateral walls of the ray cells 1-4 per
tracheid.

Ray tracheids chiefly high, conspicuously pre-
dominant, and strongly reticulated throughout.

20. P. echinata.

Epithelium of the resin passages (transverse) distinctly in i or
more rows, nonresinous.

Summer wood dense, rarely somewhat open.
Bordered pits in 1-2 rows.

Pits on the lateral walls of the ray cells 1-6, chiefly
2-4, per tracheid.

Ray tracheids sparingly (rarely strongly) retic-
ulated throughout.

39. P. tasda.

Ray tracheids high, very strongly reticulated
throughout.

Ray cells apparently all of i kind, but

differentiating slightly.
41. P. cubensis.

Pits on the lateral walls of the ray cells 2-5, chiefly
4, per tracheid.

Ray tracheids commonly predominant and inter-
spersed, very strongly reticulated throughout.

40. P. palustris.

Epithelium of the resin passages (transverse) distinctly in i or
more rows, resinous.
Summer wood open.

Bordered pits in i row or sometimes in pairs.

Pits on the lateral walls of the ray cells 1-4, rarely 5,
per tracheid.

298

ANATOMY OF THE GYMNOSPERMS

Ray tracheids sparingly interspersed, strongly
reticulated throughout.

16. P. serotina.

Pits on the lateral walls of the ray cells 1-5, chiefly
2, per tracheid, becoming bordered in the summer
wood.

Ray tracheids sparingly interspersed, strongly
reticulated throughout.

15. P. rigida.
Bordered pits in i row.

Pits on the lateral walls of the ray cells 1-6, chiefly
2 or 3, per tracheid, but very variable.

Ray tracheids often predominant, interspersed,
sparingly reticulated.

19. P. glabra.

Summer wood dense (sometimes open in P. tasda and P.
cubensis).

Bordered pits in 1-2 rows.

Pits on the lateral walls of the ray cells 1-6, chiefly
2-4, per tracheid.

Ray tracheids sparingly (very rarely strongly)
reticulated throughout.

39. P. Ucda.

Ray tracheids high, very strongly reticulated
throughout.

Ray cells apparently all of one kind, but
differentiating slightly.
41. P. cubensis.

Pits on the lateral walls of the ray cells 2-5, chiefly
4, per tracheid.

Ray tracheids commonly predominant and inter-
spersed, very strongly reticulated throughout.

40. P. palustris.
Bordered pits in i row.

Pits on the lateral walls of the ray cells 1-6, chiefly
2 or 3, per tracheid, but very variable.

Ray tracheids interspersed, often predominant,
sparingly reticulated.

19. P. glabra.
Bordered pits in i row, or sometimes in pairs.

Pits on the lateral walls of the ray cells 1-6, chiefly
2-4, per tracheid.

PINUS $99

Ray tracheids high, very strongly reticulated
throughout.

Ray cells apparently all of one kind, but

differentiating slightly.
41. P. cubensis.

Pits on the lateral walls of the ray cells 1-6 per
tracheid.

Ray tracheids strongly predominant and strongly
reticulated throughout.

17. P. Banksiana.

Pits on the lateral walls of the ray cells 1-4, rarely 5,
per tracheid.

Ray tracheids sparingly interspersed, strongly
reticulated throughout.

16. P. serotina.

Pits on the lateral walls of the ray cells 1-5, chiefly
2, per tracheid, becoming bordered in the summer
wood.

Ray tracheids sparingly interspersed, strongly
reticulated throughout.

15. P. rigida.

Pits on the lateral walls of the ray cells 1-4, chiefly
2, per tracheid.

Ray tracheids sparingly interspersed, distinctly
reticulated throughout.

1 8. P. contorta.

Ray cells (radial) of 2 kinds: (i) thick-walled ; and (2) thin-walled.

Fusiform rays (tangential) with the cells of the inflated portion all or
chiefly thick-walled.

Epithelium of the resin passages (transverse) in 1-2 or more rows,
nonresinous.

Summer wood dense.

Bordered pits in i row or sometimes in pairs.

Pits on the lateral walls of the ray cells (i) 1-3,
bordered in the summer wood; and (2) 1-4, chiefly
2-3, per tracheid.

Ray tracheids more or less interspersed, retic-
ulated throughout.

34. P. pungens.

Epithelium of the resin passages (transverse) in 1-2 or more rows,
resinous.

Summer wood open.

3oo ANATOMY OF THE GYMNOSPERMS

Bordered pits in i row or sometimes in pairs.

Pits on the lateral walls of the ray cells 1-5, chiefly 2,
per tracheid, becoming bordered in the summer
wood.

Ray tracheids sparingly interspersed, strongly
reticulated throughout.

15. P. rigida.

Pits on the lateral walls of the ray cells (i) 1-4; and
(2) 1-3, chiefly 2, per tracheid, the two forms of
cells clearly defined.

Ray tracheids reticulated in the summer wood,
predominant in the low rays of which they
often compose the entire structure.

36. P. muricata.

Pits on the lateral walls of the ray cells 2-4 through-
out, the two forms of cells merging and not always
clearly defined.

Ray tracheids strongly dentate and becoming
sparingly reticulated in the summer wood,
interspersed, often predominant.

30. P. chihuahuana.
Summer wood dense.

Bordered pits in i row or sometimes in pairs.

Pits on the lateral walls of the ray cells 2-4 through-
out, the two forms of cells merging and not always
clearly differentiated.

Ray tracheids strongly dentate and becoming
sparingly reticulated in the summer wood,
interspersed, often predominant.

30. P. chihuahuana.

Fusiform rays (tangential) with the cells of the inflated portion all
thin-walled and usually broken out.

Epithelium of the resin passages (transverse) in 1-2 or more rows,
nonresinous.

Summer wood open.

Bordered pits in I row.

Pits on the lateral walls of the ray cells,i-6, chiefly
2 or 3, per tracheid, but very variable.

Ray tracheids interspersed, often predominant,
sparingly reticulated.

19. P. glabra.

Pits on the lateral walls of the ray cells (i) 1-4 ; and
(2) 2-4, chiefly 4, per tracheid.

PINUS 301

Ray tracheids predominant, sparingly retic-
ulated.

33. P. scopulorum.
Bordered pits in i row, sometimes in pairs.

Pits on the lateral walls of the ray cells 1-4, rarely 5,
per tracheid.

Ray tracheids more or less reticulated in the
summer wood, often interspersed.

25. P. Murrayana.

Pits on the lateral walls of the ray cells 2-5, chiefly
3-4, per tracheid.

Ray tracheids strongly predominant, strongly
dentate, and more or less reticulated through-
out.

31. P. Jeffrey!.

Pits on the lateral walls of the ray cells (i) 1-4;
and (2) 1-3, chiefly 2, per tracheid.

Ray tracheids often predominant, reticulated
throughout.

27. P. Coulteri.
Bordered pits in 1-2 rows.

Pits on the lateral walls of the ray cells 1-6, chiefly
2-4, per tracheid.

Ray tracheids sparingly (rarely strongly) retic-
ulated throughout.

39. P. tseda.

Ray tracheids high, very strongly reticulated
throughout.

41. P. cubensis.

Summer wood dense, more rarely somewhat open.
Bordered pits in i row.

Pits on the lateral walls of the ray cells (i) 1-4;
and (2) 2-4, chiefly 4, per tracheid.
Ray tracheids predomi nant, sparingly reticulated.

33. P. scopulorum.
Bordered pits in I row, sometimes in pairs.

Pits on the lateral walls of the ray cells (1)1-4 ; ar>d
(2) 1-3, chiefly 2, per tracheid, the two forms of
cells clearly defined.

Ray tracheids reticulated in the summer wood,
predominant in the low rays of which they
often compose the entire structure.
36. P. muricata.

302 ANATOMY OF THE GYMNOSPERMS

Pits on the lateral walls of the ray cells (i) 1-3,
bordered in the summer wood; and (2) 1-4,
chiefly 2-3, per tracheid.

Ray tracheids more or less interspersed, retic-
ulated throughout.
34. P. pungens.
Bordered pits in 1-2 rows.

Pits on the lateral walls of the ray cells 2-5, chiefly
4, per tracheid.

Ray tracheids commonly predominant and inter-
spersed, very strongly reticulated throughout.

40. P. palustris.

Pits on the lateral walls of the ray cells 1-6, chiefly
2-4, per tracheid.

Ray tracheids high, very strongly reticulated
throughout.

41. P. cubensis.

Epithelium of the resin passages (transverse) in 1-2 or more
rows, resinous.

Summer wood dense.

Bordered pits in I row.

Pits on the lateral walls of the ray cells 1-6, chiefly
2 or 3, per tracheid, but very variable.

Ray tracheids interspersed, often predominant,
sparingly reticulated.

19. P. glabra.

Pits on the lateral walls of the ray cells 2-4 per
tracheid, rarely 5.

Ray tracheids strongly reticulated, often pre-
dominant.

32. P. ponderosa.
Bordered pits in i row, sometimes in pairs.

Pits on the lateral walls of the ray cells 1-6, chiefly
2-4, per tracheid.

Ray tracheids sparingly (rarely strongly) retic-
ulated throughout.

39. P. taeda.

Pits on the lateral walls of the ray cells (i) 2-6,
chiefly 4 ; and (2) 1-4, chiefly 4, per tracheid.
Ray tracheids predominant, very strongly retic-
ulated throughout.
35. P. inops.

PINUS 303

Bordered pits in 1-2 rows.

Pits on the lateral walls of the ray cells 1-6, chiefly
2-4, per tracheid.

Ray tracheids high, very strongly reticulated
throughout.

41. P. cubensis,

Pits on the lateral walls of the ray cells 2-5, chiefly
4, per tracheid.

Ray tracheids sparingly interspersed, predomi-
nant, strongly dentate, and somewhat retic-
ulated in the summer wood.

38. P. Sabiniana.

Ray tracheids commonly predominant, often
interspersed and very strongly reticulated
throughout.

40. P. palustris.

Pits on the lateral walls of the ray cells 1-6, chiefly
4, per tracheid.

Ray tracheids sparingly (rarely strongly) retic-
ulated throughout.

39. P. taeda.
Summer wood open.

Bordered pits in i row or sometimes in pairs, the latter
sometimes numerous (P. arizonica).

Pits on the lateral walls of the ray cells (i) 1-2,
rarely 6, chiefly 2 ; and (2) 1-3 per tracheid.
Tracheids sparingly predominant and sparingly
reticulated.

37. P. insignis.

Pits on the lateral walls of the ray cells (i) 2-4;
and (2) 2-3 per tracheid.

Ray tracheids strongly predominant and
strongly reticulated.

29. P. Torreyana.

Pits on the lateral walls of the ray cells 2-4 per
tracheid.

Ray tracheids dentate and somewhat reticulated
throughout, sometimes interspersed and pre-
dominant.

28. P. tuberculata.

Pits on the lateral walls of the ray cells 2-4, chiefly
4, per tracheid.

304 ANATOMY OF THE GYMNOSPERMS

Ray tracheids strongly predominant, strongly
dentate, and somewhat reticulated in the
summer wood.

26. P. arizonica.

Pits on the lateral walls of the ray cells (i) 1-6,
chiefly 4 ; and (2) 1-4, chiefly 4, per tracheid.
Ray tracheids predominant, very strongly retic-
ulated throughout.

35. P. inops.
Bordered pits in I row.

Pits on the lateral walls of the ray cells 1-6, chiefly
2 or 3, per tracheid, but very variable.

Ray tracheids often predominant, interspersed,
sparingly reticulated.
19. P. glabra.

B. **PITYOXYLON (Pinoxylon)

Extinct Species
Ray tracheids present.

Upper and lower walls of the ray tracheids dentate.
Bordered pits in 2 rows.

Resin passages numerous, large, scattering.

Pits on the lateral walls of the ray cells 1-2 per tracheid.

42. ** P. (Pinoxylon) dacotense.
Upper and lower walls of the ray tracheids not dentate.

Bordered pits in i row.

Transition from the spring to the summer wood gradual.
Ordinary rays (tangential) 1-2 seriate in part.
Resin passages (transverse) very large.

Medullary rays (transverse) distant 3-8, more
rarely 8, rows of tracheids.

43. ** P. Aldersoni.
Ordinary rays (tangential) strictly i-seriate.

Resin passages (transverse) very large.

Medullary rays (transverse) distant upwards of
25 rows of tracheids.

44. * * P. amethystinum.

Resin passages (transverse) rather large, the epi-
thelial cells resinous.

Medullary rays (transverse) distant upwards of
9, or rarely 15, rows of tracheids.

45. ** P. (Pinus) columbiana.

PINUS 305

Resin passages obliterated.

Bordered pits on the lateral walls of the ray
cells 2-3 per tracheid.

46. ** P. Peali.

Bordered pits in 1-3, chiefly 2, rows, round or hexagonal.
Ordinary rays (tangential) 2-seriate in part.
Resin passages not represented.

47. * * P. chasense.
Ray tracheids wholly wanting.

Bordered pits in i row.

Resin passages numerous, large, chiefly in the summer wood,
filled with prominent and resinous thyloses, the epithelium
1-2 cells thick, not extended into parenchymatous tracts.

48. * * P. statenense.

Resin passages numerous, small, chiefly in the summer wood, devoid
of thyloses, the epithelium composed of a single layer which ex-
tends into a prominent and often broad tract of wood parenchyma.

49. ** P. scituatense.

A. PINUS PROPER

Existing Species

Section I. Soft Pines
1. P. Parryana, Engelm.

Pinon. Nut Pine

Transverse. Growth rings chiefly narrow but very variable. Summer wood
very open and chiefly very thin, but in the broader rings upwards
of one half the spring wood, from which the transition is very gradual ;
the tracheids in regular rows, conspicuously unequal and rounded.
Spring tracheids squarish-hexagonal, unequal in regular rows, the walls
rather thin. Medullary rays numerous, broad, i cell wide, distant 2-6
rows of tracheids. Resin passages numerous, medium, and variable,
very scattering throughout the entire growth ring ; the several-layered
epithelium composed of very large, rather thick-walled cells, more or
less resinous.

Radial. Rays sparingly resinous ; the tracheids numerous, marginal, high,
rarely interspersed. Parenchyma ray cells chiefly straight and rather
narrow, but in the narrower growth rings and in the summer wood
becoming shorter and distinctly fusiform ; the upper and lower walls
thick and conspicuously though often distantly pitted, becoming more
strongly pitted in the fusiform cells ; the terminal walls locally thick-
ened or coarsely pitted ; the lateral walls with small, round pits with
a more or less definite though variable border and a lenticular orifice,
2-4 per tracheid. Bordered pits in i row, rather numerous, broadly

306 ANATOMY OF THE GYMNOSPERMS

elliptical. Pits on the tangential walls of the summer wood rather
numerous, small and chiefly confined to the two outermost walls. Resin-
ous tracheids wanting.

Tangential. Fusiform rays numerous, very narrow ; the cells of the inflated
portion all thin-walled and usually much broken out ; the somewhat
thicker-walled structure of the central tract generally present and
embracing a small resin canal. Ordinary rays sparingly resinous,
medium, numerous, broad, somewhat contracted by occasionally inter-
spersed, narrowly oval or oblong tracheids ; the thick-walled cells
usually equal and somewhat uniform, oval to oblong, rarely narrow.
Resinous tracheids wanting.

A small tree 6-9 m. high, with a trunk upwards of .45 m. in diameter.
Wood light, soft, close grained, and compact.

Relative specific gravity 0.5675

Percentage of ash residue 0.54

Approximate relative fuel value 56.44

Coefficient of elasticity in kilograms on millimeters . . 378.

Ultimate transverse strength in kilograms 182.

Ultimate resistance to crushing in kilograms .... 5420.

Resistance to indentation to 1.27 mm. in kilograms . . 3126.
(Sargent)

Larkin's Station, San Diego County, California, and southward into Lower
California, where it forms extensive forests on high mesas and slopes
(Sargent).

2. P. cembroides, Zucc.

Pi noii. A'at Pine

Transverse. Growth rings not broad, variable, more or less conspicuously
double, the structure as a whole rather dense. Summer wood rather
open, either very thin or upwards of equal to the spring wood, from
which the transition is very gradual and from which it cannot be
readily distinguished ; the tracheids distinctly rounded, unequal, but in
rather regular rows. Spring tracheids hexagonal, not large, very un-
equal and variable, but in regular rows. Medullary rays prominent
and numerous, broad, I cell wide, distant 1-6, rarely 10, rows of tra-
cheids. Resin passages numerous, not large, chiefly in the middle or
inner portion of the growth ring, the several-layered epithelium com-
posed of large, thick- and thin-walled, nonresinous cells.

Radial. Rays somewhat resinous, the resin localized, granular, rarely mas-
sive ; the tracheids not very numerous, marginal, rarely interspersed ;
the lateral walls with very small pits about 2 per tracheid. Paren-
chyma ray cells conspicuously contracted at the ends throughout,
short, equal to 8-10 tracheids; the upper and lower walls thick, uni-
form, conspicuously pitted throughout : the terminal walls thin but
locally thickened or more often coarsely pitted ; the lateral walls with
small, round pits, with a more or less obvious though very unequal
border and a lenticular orifice, at first 2-4, but in the summer wood

PINUS 307

reduced to 2, and finally to I, per tracheid, when they take the form of
very narrow and much prolonged slits. Bordered pits in i row,
numerous. Pits on the tangential walls of the summer wood small
and numerous, extending far into the summer wood. Resinous tra-
cheids wanting.

Tangential. Fusiform rays numerous, very narrow, usually high, the cells
'of the inflated portion very thin-walled and chiefly wanting, except
the persistent, thicker-walled central tract, which includes a small
resin canal. Ordinary rays numerous, medium, somewhat resinous,
rather broad, not perceptibly contracted by the occasionally inter-
spersed, equal, but higher and oblong tracheids ; the cells thick-walled,
very equal, chiefly very uniform, and narrowly oval or oblong, rarely
broader. Resinous tracheids wanting.

A small tree 6-7 m. high, with a trunk rarely exceeding .30 m. in diameter.
Wood light, soft, very close grained, and compact.

Specific gravity 0.6512

Percentage of ash residue 0.90

(Sargent)

Dry ridges and slopes at 3300 feet elevation. Santa Catalina Mountains of
Arizona and through northern Mexico (Sargent).

3. P. monophylla, Torr.

Pinon. Nut Pine

Transverse. Growth rings thin, unequal, often double. Summer wood thin,
of 3-5 tracheids and open, the tracheids in more or less irregular rows,
unequal. Spring tracheids squarish-hexagonal, rather variable, not
large, the walls rather thin and commonly showing the secondary wall
infolded. Medullary rays not very prominent, numerous, broad, i cell
wide, distant 1-6, or more rarely 10, rows of tracheids. Resin passages
very large and numerous, the several-layered epithelium composed of
large and variable cells, both thick- and thin-walled.

Aadial. Rays nonresinous ; the tracheids numerous, marginal, often inter-
spersed. Parenchyma ray cells short, strongly contracted at the ends ;
the terminal walls commonly thick and coarsely pitted ; the upper and
lower walls thick and strongly pitted ; the lateral walls with more or
less obviously-bordered pits, with a prolonged, slit-like orifice which
becomes lenticular in the earlier spring wood, 1-4, chiefly 4, per tra-
cheid, finally reduced to 2 in the outer summer wood. Bordered pits
numerous, in i row, elliptical. Pits on the tangential walls of the sum-
mer wood numerous, medium to large, conspicuously lenticular. Res-
inous tracheids wanting.

Tangential. Fusiform rays rather numerous and narrow, the cells of the
'inflated portion large and very thin-walled, often much broken out, the
persistent central tract containing a resin canal of medium size. Ordi-
nary rays numerous, broad, very sparingly resinous, not contracted by
interspersed tracheids ; the cells conspicuously unequal and variable,

308 ANATOMY OF THE GYMNOSPERMS

from round to oval or oblong, those of the low rays often three times
higher than wide, those of the higher rays sometimes twice the width
of others.

A small, bushy tree 4-6 m. high, with a trunk upwards of I m. in diameter.
Wood light, soft, weak, brittle, close grained, and compact.

Specific gravity 0.5658

Percentage of ash residue 0.68

Approximate relative fuel value 56.20

Coefficient of elasticity in kilograms on millimeters . . 435.

Ultimate transverse strength in kilograms 123.

Ultimate resistance to longitudinal crushing in kilograms 4389.

Resistance to indentation to 1.27 mm. in kilograms . . 2713.
(Sargent)

Dry gravelly slopes and mesas between 3000 and 6000 feet elevation. Near
Lake Utah, to the eastern foothills of the California Sierras, and south
along the mountain ranges of the Great Basin to the San Francisco
Mountains of eastern Arizona (Sargent).

4. P. Balfouriana, A. Murr.

Foxtail Pine

Transverse. Growth rings narrow, uniform, the structure very open through-
out. Summer wood thin, of 2-6 tracheids and open, the tracheids
large in regular rows, uniform, the transition from the spring wood
gradual. Spring tracheids rather large, very thin-walled, hexagonal,
chiefly in regular rows, but conspicuously unequal. Medullary rays
rather prominent and numerous, broad, i cell wide, distant 2-8 rows of
tracheids. Resin passages medium, rather numerous, widely scatter-
ing, the somewhat extensive epithelium composed of large, thin-walled,
more or less resinous cells.

Radial. Rays sparingly resinous ; the tracheids rather numerous, marginal,
rarely interspersed. Parenchyma ray cells short and straight ; the upper
and lower walls thick and very strongly pitted ; the lateral walls with
numerous, small, round, or oval pits, at first with a prominent border
and narrowly lenticular, prolonged orifice, the border becoming obscure
and variable toward the summer wood, and the orifice broader, 1-5 per
tracheid, finally reduced to 1-2 in the summer wood. Bordered pits
numerous and round, in i row, nearly as broad as the tracheid. Pits on
the tangential walls of the summer wood very numerous and contig-
uous on the outermost wall, becoming scattering in the older tracheids,
small but rather broadly lenticular. Resinous tracheids wanting.

Tangential. Fusiform rays narrow, the cells of the inflated portion large,
thin-walled, resinous, the resin passage not large. Ordinary rays
medium to high, rather broad, nonresinous, and somewhat contracted
by the rather narrower, smaller, and occasionally interspersed tra-
cheids; the thick-walled cells very equal and uniform, narrowly oval to
oblong.

PINUS 309

A small tree 15-19 m. high, with a trunk upwards of .90 m. in diameter.
Wood light, soft, weak, brittle, very close grained, compact, satiny, and
susceptible of a good polish.

Specific gravity Q-5434

Percentage of ash residue .... 0.41

Approximate relative fuel value 54-17

Coefficient of elasticity in kilograms on millimeters . . 594.

Ultimate transverse strength in kilograms 181.

Ultimate resistance to longitudinal crushing in kilograms 5398.

Resistance to indentation to 1.27 mm. in kilograms . . 2350.
(Sargent)

Dry, open ridges, forming upon Scott's Mountain a broad belt of open
forest between 5000 and 8000 feet elevation. Mt. Whitney, California,
and about the head waters of the King and Kern rivers (Sargent).

5. P. aristata, Engelm.

Foxtail Pine. Hickory Pine

Transverse. Summer wood thin, upwards of 8 tracheids, barely distinguish-
able, very open, the tracheids often variable in more or less conspic-
uously irregular rows. Spring tracheids rather large, conspicuously
squarish-hexagonal, very uniform in regular rows, the walls thin, the
transition to the summer wood very gradual. Medullary rays rather
prominent and broad, i cell wide, distant 2-6, more rarely 10, rows of
tracheids. Resin passages numerous, rather large, the rather exten-
sive and many-layered epithelium composed of large, very thin-walled,
nonresinous cells.

Radial. Rays sparingly resinous throughout ; the tracheids numerous, mar-
ginal, sparingly interspersed. Parenchyma ray cells of 2 kinds : (i) the
cells more or less strongly contracted at the ends ; the upper and lower
walls thick, strongly pitted ; the terminal walls coarsely pitted ; the
lateral walls with round or oval but rather small pits, with a lenticular
orifice and an obvious border which becomes variable and obscure
toward the summer wood, at first 3-6, soon uniformly about 4, or in
the outermost summer wood 2, per tracheid ; and (2) cells occasionally
interspersed and often conterminous with the cells of the first kind ;
the terminal walls thin and not pitted, but often locally thickened ;
the upper and lower walls thin and not pitted ; the lateral walls devoid
of pits. Bordered pits numerous, in i row, elliptical, as broad as the
tracheid. Pits on the tangential walls of the summer wood chiefly
confined to the outermost wall, where they are numerous, apparently
not extending beyond the second wall, small, distinctly lenticular.
Resinous tracheids wanting.

Tangential. Fusiform rays rather few, narrow, the cells of the short termi-
nals thick-walled, those of the inflated portion very thin-walled and
much broken down or wanting, the more persistent central tract with
a rather small resin passage with delicate epithelium. Ordinary rays

310 ANATOMY OF THE GYMNOSPERMS

numerous, nonresinous, low to medium, slightly contracted by the
occasionally interspersed tracheids. Parenchyma ray cells not very
thick-walled, equal, rather uniform and oval, more rarely becoming
either round, oval, or oblong; sometimes with interspersed thin-walled
cells of similar form and size.

A tree 15-30 m. high, with a trunk upwards of 2.40 m. in diameter.
Wood light, soft, not strong, very close grained, and compact.

Specific gravity 0.5572

Percentage of ash residue 0.30

Approximate relative fuel value 55-56

Coefficient of elasticity in kilograms on millimeters . . 715.

Ultimate transverse strength in kilograms 279.

Ultimate resistance to longitudinal crushing in kilograms 5209.

Resistance to indentation to 1.27 mm. in kilograms . . 2140.
(Sargent)

Dry, gravelly ridges ; mountains of southeastern California, Nevada, north-
ern Arizona, and southern Utah to Colorado above 7500 feet, in Colorado
reaching 12,000 feet (Sargent).

6. P. edulis, Engelm.
Pinon. Nut Pine

Transverse. Growth rings narrow, unequal. Summer wood thin, of 3-4
tracheids, and not prominent, but very open throughout ; the tracheids
strongly unequal in conspicuously irregular rows, the walls thin, the
transition to the spring wood gradual. Spring tracheids open, squarish,
unequal, and in more or less irregular rows, the walls thin. Medullary
rays not very prominent, numerous, rather broad, i cell wide, dis-
tant 2-7 rows of tracheids. Resin passages numerous, large, the
many-layered epithelium often forming extensive tracts composed
of large and very variable, often thick-walled, somewhat resinous
cells.

Radial. Rays very sparingly resinous ; the tracheids marginal, rarely inter-
spersed. Parenchyma ray cells conspicuously narrower at the ends,
short, of 2 kinds: (i) the upper and lower walls thick and entire or
distantly pitted, becoming more strongly pitted locally or in the sum-
mer wood ; the terminal walls generally thick and coarsely pitted or
rarely thin and devoid of pits ; the lateral walls with small and round
pits with a variable, often obscure border and a lenticular orifice, 1-4,
more rarely 5 or 6, in the marginal cells, in the summer wood becoming
2, per tracheid ; and (2) thin-walled cells sparingly interspersed and
conterminous with those of the first kind ; the terminal walls thin and
locally thickened ; the upper and lower as well as the lateral walls
devoid of pits. Bordered pits numerous, small, elliptical, in i row.
Pits on the tangential walls of the summer tracheids numerous on the
outermost wall, becoming fewer in the older tracheids, rather small
and broadly lenticular. Resinous tracheids wanting.

PINUS 3 1 1

Tangential. Fusiform rays rather numerous, chiefly small and narrow ; the
inflated portion with rather large and very thin-walled cells ; the resin
passage small. Ordinary rays low to medium, numerous, rather broad,
not restricted by the equal and occasionally interspersed tracheids ;
the cells chiefly equal, rather uniform, oval, chiefly narrow and thick-
walled, but sometimes with interspersed thin-walled cells often of
greater height.

A small tree 6-9 m. high, with a trunk upwards of .90 m. in diameter.
Wood light, soft, not strong, brittle, close grained, compact, and durable in
contact with the soil.

Specific gravity 0.6388

Percentage of ash residue 0.62

Approximate relative fuel value 63.49

Coefficient of elasticity in kilograms on millimeters . . . 421.

Ultimate transverse strength in kilograms 191.

Ultimate resistance to longitudinal crushing in kilograms 5578.

Resistance to indentation to 1.27 mm. in kilograms . . . 3388.
(Sargent)

Eastern base of Pikes Peak, Colorado ; south through New Mexico to the
mountains of western Texas. Dry mesas and slopes, generally on lime or
sandstone, reaching elevations of 9000 feet in Colorado (Sargent).

7. P. Lambertiana, Douglas
Sugar Pine

Transverse. Growth rings narrow, uniform. Summer wood about one
fourth to one third the spring wood, from which the transition is
gradual, the structure rather open. Spring tracheids large, squarish-
hexagonal, in regular rows, very uniform, the walls thin. Medullary
rays not very prominent or numerous, rather broad, i cell wide, distant
2- 1 8 rows of tracheids. Resin passages very large, rather numerous,
the epithelium prominent, of several layers composed of very thin-
walled cells, very resinous.

Radial. Rays barely if at all resinous ; the tracheids short, rather broad,
marginal and sparingly interspersed and then very narrow. Parenchyma
ray cells chiefly straight ; the upper and lower walls thin and obscurely
pitted ; the terminal walls thin and not pitted but sometimes locally
thickened ; the lateral walls with very large, oval pits, chiefly 2 per
tracheid throughout, rarely I or 3. Bordered pits distinctly in 1-2 rows,
elliptical, numerous. Pits on the tangential walls of the summer wood
numerous, but rather small and narrowly lenticular, not confined to the
outermost walls. Resinous tracheids wanting.

Tangential. Fusiform rays numerous, large, and very broad, the inflated
portion composed of rather thin-walled, often strongly resinous, cells, the
very large resin passage with thin-walled epithelium. Ordinary rays
rather numerous, nonresinous, low to medium, strongly constricted at

312 ANATOMY OF THE GYMNOSPERMS

the position of the very narrow and small, interspersed tracheids ; the
parenchyma cells rather equal but variable from broadly to nar-
rowly oval, the thin side walls sometimes strongly inflated, rarely
incurved.

A large tree 46-92 m. high, with a trunk upwards of 7 m. in diameter.
Wood very light, soft, coarse, but straight grained, compact, satiny, and
easily worked.

Specific gravity 0.3684

Percentage of ash residue 0.22

Approximate relative fuel value 36.76

Coefficient of elasticity in kilograms on millimeters . . . 794.

Ultimate transverse strength in kilograms .... . 255.

Ultimate resistance to longitudinal crushing in kilograms 5382.

Resistance to indentation to 1.27 mm. in kilograms . . 1244.
(Sargent)

Cascade and Coast Ranges of Oregon, where it descends to 1000 feet above
sea level, from the head of the Mackenzie River and the valley of the
Rogue, southward along the western flanks of the California Sierras,
where it reaches an elevation of 4000-8000 feet ; through the coast
ranges to the Santa Lucia Mountains, and in the San Bernardino and
Cuyamaca mountains (Sargent).

8. P. monticola, D. Don
White Pine

Transverse. Growth rings variable. Summer wood open and very thin and
imperceptibly passing into the spring wood, the tracheids in regular
rows, variable, squarish. Spring wood very open, the tracheids large
and squarish, rather thin-walled. Medullary rays prominent and resin-
ous, not numerous, rather broad, i cell wide, distant 2-17 rows of tra-
cheids. Resin passages very large, rather numerous, the epithelium
rather extensive and resinous.

Radial. Rays conspicuously resinous throughout, the ray tracheids narrow,
marginal, often interspersed. Parenchyma ray cells straight ; the upper
and lower walls thin and entire or again with locally numerous, broad
pits, unequal ; the terminal walls thin and entire or again locally thick-
ened ; the lateral walls with very large, oval or oblong or lenticular
pits, chiefly 1-2 per tracheid throughout, in the summer wood reduced
to i with a lenticular orifice. Bordered pits round or elliptical, in i row
or sometimes in pairs. Pits on the tangential walls of the summer
wood small and narrowly lenticular, chiefly on the outermost wall.
Resinous tracheids wanting.

Tangential. Fusiform rays not numerous, broad and high, the cells of the
inflated portion large and thin-walled, often much broken down. Ordi-
nary rays low to medium, strongly resinous, when of a few elements

PINUS 313

only, wholly composed of tracheids ; much contracted at the position
of the often interspersed and very narrow tracheids ; the parenchyma
cells unequal, oval, and somewhat variable ; the thin lateral walls
strongly incurved or convex, sometimes much inflated.

A large tree 30-46 m. in height, with a trunk upwards of 1.50 m. in

diameter.
Wood very light, soft, not strong, close and straight grained, and compact.

Specific gravity 0.3908

Percentage of ash residue 0.23

Approximate relative fuel value 38.99

Coefficient of elasticity in kilograms on millimeters . . 950.

Ultimate transverse strength in kilograms 260.

Ultimate resistance to longitudinal crushing in kilograms 5349.

Resistance to indentation to 1.27 mm. in kilograms . . 1071.
(Sargent)

A somewhat uncommon but valuable timber tree, usually below 3000 feet
elevation in British Columbia, but rising to 7000-10,000 feet in Cali-
fornia. Cceur D'Alene and Bitter Root Mountains of Idaho, to the valley
of the Flathead River, northern Montana: south along the Cascade Moun-
tains of Washington and Oregon, and the California Sierras to Calaveras
County (Sargent) ; Vancouver Island ; the Gold and Coast ranges of
British Columbia, disappearing at an elevation of 2235 feet (Macoun).

9. P. flexilis, James
White Pine

Transverse. Growth rings narrow, rather uniform. Summer wood very thin,
of 3-4 tracheids and open, the tracheids large, squarish, uniform.
Spring wood very open, the tracheids squarish, rather variable, the
walls thin. Medullary rays not prominent or numerous, i cell wide,
distant 2-8 rows of tracheids. Resin passages large, numerous, the
epithelium very thin-walled.

Radial. Rays nonresinous ; the low, marginal, and sparingly interspersed
tracheids rather numerous. Parenchyma ray cells straight ; the upper
and lower walls with frequent, broad pits ; the terminal walls thin and
not pitted ; the lateral walls with large, oval, or oblong-lenticular pits,
1-2, or in the marginal cells more rarely 3-4, per tracheid, in the
summer wood reduced to I and lenticular. Bordered pits elliptical,
large, in i row, rather numerous. Pits on the tangential walls of the
summer wood numerous and prominent, broadly lenticular, especially
numerous on the outermost wall, becoming scattering within. Resin-
ous tracheids wanting.

Tangential. Fusiform rays few, rather high and broad, the cells of the
inflated portion very thin-walled and often completely broken out.
Ordinary rays numerous, medium, nonresinous, not conspicuously

314 ANATOMY OF THE GYMNOSPERMS

contracted by the sparingly interspersed tracheids ; the cells equal,
oval, and uniform, thin-walled ; the lateral walls not concave or
convex.

A tree 15-18 m. high, with a trunk upwards of 1.20 m. in diameter.
Wood light, soft, close grained, and compact.

Specific gravity Q-4358

Percentage of ash residue 0.28

Approximate relative fuel value 43-42

Coefficient of elasticity in kilograms on millimeters . . 676.

Ultimate transverse strength in kilograms 266.

Ultimate resistance to longitudinal crushing in kilograms 5591.

Resistance to indentation to 1.27 mm. in kilograms . . 1727.
(Sargent)

Rocky Mountains of British Columbia (Macoun) ; southward through the
Rocky Mountains to Utah, Nevada, New Mexico, and Texas; Inyo
Mountains and Mount Silliman, California (Sargent).

10. P. reflexa, Engelm.
White Pine

Transverse. Growth rings variable, often double. Summer wood conspic-
uous but thin or upwards of one half the spring wood, from which the
transition is gradual, the structure open. Spring tracheids large, squar-
ish-hexagonal, the walls rather thickish, conspicuously unequal, and
often in irregular rows. Medullary rays not very broad, i cell wide,
distant 2-10 rows of tracheids, somewhat prominent ; the side walls of
the cells conspicuously inflated and projecting into the adjacent tra-
cheid cavities. Resin passages numerous and large, chiefly in or near
the summer wood ; the epithelium composed of large and thin-walled,
very resinous cells ; when in the summer wood the resin passage is
central to a large tract of thin-walled tracheids.

Radial. Rays nonresinous ; the tracheids numerous, low, marginal, and
sparingly interspersed. Parenchyma ray cells straight; the upper and
lower walls rather thickish and entire or again somewhat strongly
pitted, especially in the summer wood ; the terminal walls thin and
entire or locally thickened ; the lateral walls with large, oval, or squar-
ish pits which finally become lenticular, 1-2, chiefly i, per tracheid
throughout. Bordered pits numerous, elliptical, in i row, distinctly
smaller and round toward the summer wood where the orifice becomes
a more or less extended slit merging into double striations. Pits on the
tangential walls of the summer wood rather small and flat, narrowly
lenticular, chiefly confined to the outermost wall where they are rather
numerous. Resinous tracheids wanting.

Tangential. Fusiform rays broad, rather numerous, the cells of the inflated
portion very large, thin-walled. Ordinary rays medium to low, not very
numerous, nonresinous, rarely contracted by smaller, interspersed tra-
cheids ; the parenchyma cells equal, oval, or oblong, the thin side walls
strongly inflated, more rarely incurved.

PINUS 315

A tree 24-30 m. high, with a trunk sometimes exceeding .60 m. in diameter.
Wood light, hard, not strong, close grained, and compact.

Specific gravity 0.4877

Percentage of ash residue 0.26

(Sargent)

Rocky ridges and slopes of almost inaccessible canons at elevations between
6000 and 8000 feet. High mountains of southeastern New Mexico, to the
Santa Rita Mountains and the Santa Catalina Mountains of Arizona
(Sargent).

11. * P. strobus, Linn.

White Pine. Weymouth Pine

Transverse. Growth rings usually thick. Summer wood usually thin, of
about 8 tracheids, rather conspicuous, variable and rather open, some-
times double ; the tracheids squarish, unequal in regular rows, the tran-
sition from the spring wood gradual. Spring wood open, the rather
large but very unequal tracheids distinctly hexagonal and thin-walled.
Medullary rays not very prominent or broad, i cell wide, few, distant
2-16, or more rarely 20, rows of tracheids. Resin passages numerous,
medium, the epithelium sparingly resinous.

Radial. Rays nonresinous, the tracheids long and low, numerous, marginal
and sparingly interspersed when they are very low. Parenchyma ray
cells straight, equal to 6-1 5 spring tracheids ; the upper and lower walls
rather thickish and entire or distantly pitted ; the terminal walls thin
and entire or somewhat locally thickened ; the lateral walls with very
large, oval, or lenticular pits 1-2 per tracheid throughout, more rarely
3 per tracheid. Bordered pits rather numerous in i row, large, strongly
elliptical, much reduced, and finally obscure in the summer wood where
the orifice becomes a prolonged, diagonal slit. Pits on the tangential
walls of the summer wood numerous but small, chiefly narrowly lenticu-
lar. Resinous tracheids wanting.

Tangential. Fusiform rays few, not very broad, nonresinous ; the cells of
the inflated portion large and thin-walled, often much broken out, or in
small branches often wholly wanting. Ordinary rays low to medium, not
very numerous, narrow, nonresinous ; the cells equal, rather uniform,
oblong, narrow, the side walls rarely convex, more generally concave.

A large tree of the greatest economic value, 24-52 m. high, with a trunk

upwards of 3.50 m. in diameter.
Wood light, soft, not strong, very close and straight grained, compact,

easily worked, and susceptible of a beautiful polish.

Specific gravity 0.3854

Percentage of ash residue 0.19

Approximate relative fuel value 38.47

Coefficient of elasticity in kilograms on millimeters . . 851.

Ultimate transverse strength in kilograms 267.

Ultimate resistance to longitudinal crushing in kilograms 6219.

Resistance to indentation to 1.27 mm. in kilograms . . 1194.
(Sargent)

316 ANATOMY OF THE GYMNOSPERMS

The following determinations are after Bovey :
Coefficient of strength in pounds for :

Bending 4,800

Torsion 1 0,000

Compression 3>5°°

Shear 34°

Weight per cubic foot 26

One of the most valuable and widely spread trees of Canada, extending from
Newfoundland, Anticosti, Nova Scotia, and New Brunswick throughout
Quebec and Ontario, and westward nearly to Lake Winnipeg (Macoun) ;
southward through the northern United States to Pennsylvania, the south-
ern shores of Lake Michigan ; La Salle, Illinois ; Davenport, Iowa ; along
the Allegheny Mountains to northern Georgia (Sargent).

Pleistocene deposits of the Don Period, Toronto.

Material preserved in natural state, but showing the effects of extended decay.

12. P. parviflora, Sieb. et Zucc.

Jap. = Himekomatsu

Transverse. Growth rings rather broad, the usually thin summer wood up-
wards of one half the spring wood, from which the transition is gradual.
Summer wood rather open, often double, the tracheids conspicuously
unequal, rounded-hexagonal. Spring tracheids rather large, squarish,
uniform, in regular rows, rather thin-walled, radially elongated. Med-
ullary rays not prominent or numerous, very narrow, i cell wide, distant
2-10 rows of tracheids. Resin passages large, rather numerous, the
epithelium composed of large and thin-walled cells.

Radial. Rays nonresinous ; the tracheids low, marginal, rarely interspersed.
Parenchyma ray cells straight, equal to about 5-7 spring tracheids ; the
upper and lower walls very variable, chiefly rather thin, often distantly
and obscurely pitted ; the terminal walls thin and not pitted ; the lateral
walls with large, oval, or radially elongated simple pits, i, or in the
early spring wood 2, per tracheid, in the summer wood becoming verti-
cally lenticular. Bordered pits very large and narrowly elliptical, rather
numerous, in i row. Pits on the tangential walls of the summer wood
small, rather few and widely scattering, except on the outermost wall.
Resinous tracheids apparently wanting.

Tangential. Fusiform rays broad, the large resin canal with prominent
thyloses and thin epithelium cells, the cells of the inflated portion all
thin-walled. Ordinary rays narrow, conspicuously contracted at the posi-
tion of the much narrower, occasionally interspersed tracheids ; the
parenchyma cells chiefly equal, rather thin-walled, somewhat variable,
chiefly oblong and narrow or sometimes oval and much broader, but
uniform in the same ray, the lateral walls concave, more rarely convex.
Resinous tracheids sparingly present, the resin in plates simulating
Sanio's bands.

PINUS 317

13. P. albicaulis, Engelm.
White Pine

Transverse. Growth rings medium, uniform. Summer wood very thin and
open, the tracheids in regular rows, squarish, the transition from the
spring wood very gradual. Spring tracheids large, squarish-hexagonal,
rather uniform in regular rows, rather thin-walled. Medullary rays
rather broad, I cell wide, somewhat prominent, distant 2-8 rows of
tracheids. Resin passages medium, rather numerous, the prominent
and somewhat resinous epithelium composed of large and thin-walled
cells. Resinous tracheids often present but not prominent, forming
radial series contiguous to the medullary rays.

Radial. Rays nonresinous ; the tracheids long and low, marginal, rarely
interspersed. Parenchyma ray cells straight ; the upper and lower walls
medium, variable, and with variable, often distant but chiefly broad
pits ; the terminal walls thin and not pitted ; the lateral walls with large,
oval, or broadly lenticular pits, 1-2, chiefly i, per tracheid throughout.
Bordered pits numerous, large, round, in i row. Pits on the tangential
walls of the summer wood not very numerous, rather small and flat,
chiefly on the outermost walls. Resinous tracheids somewhat numerous
and prominent, the resin forming plates opposite the medullary rays
and simulating Sanio's bands.

Tangential. Fusiform rays high, rather narrow, the cells of the inflated
portion medium to small and thin-walled. Ordinary rays rather numer-
ous, medium, nonresinous, somewhat contracted at the position of the
occasionally interspersed and rather narrower tracheids ; the cells
rather equal and oval or oblong, the walls thin, often concave, more
rarely convex. Resinous tracheids somewhat prominent, the resin in
plates simulating Sanio's bands.

A small Alpine tree, 6-12 m. high, with a trunk rarely .60 m. in diameter.
Wood light, soft, not strong, brittle, close grained, and compact.

Specific gravity 0.4165

Percentage of ash residue 0.27

Approximate relative fuel value 4' -54

Coefficient of elasticity in kilograms on millimeters . . 512.

Ultimate transverse strength in kilograms 249.

Ultimate resistance to longitudinal crushing in kilograms 5296.

Resistance to indentation to 1.27 mm. in kilograms . . 1716.
(Sargent)

Rocky Mountains of British Columbia between 6000 and 7000 feet eleva-
tion, northward to latitude 53° (Macoun) ; Cascade and Blue mountains
of Washington and Oregon ; Scott's Mountain, Mt. Shasta, and the high
peaks of the Sierra Nevadas to Mt. San Bernardino, California. Dry,
gravelly ridges at the extreme limit of growth, in the San Bernardino
Mountains attaining an elevation of 10,500 feet, and at the highest eleva-
tions becoming a prostrate shrub (Sargent).

3l8 ANATOMY OF THE GYMNOSPERMS

Section II. Hard Pines

14. P. clausa, Sarg.
Sand Pine. Scrub Pine. Spruce Pine

Transverse. Growth rings thick, often double. Summer wood dense, rarely
somewhat open, often exceeding the spring wood, from which the tran-
sition is usually very abrupt, and within the same section showing both
open and dense structure ; the tracheids rounded, unequal, and often in
irregular rows. Spring tracheids hexagonal, not very uniform, the walls
rather thickish. Resin passages large, chiefly in the summer wood ;
the epithelium composed of large, round, and thin-walled cells chiefly
in i row, occasionally in 2 rows and forming more or less eccentric
tracts. Medullary rays not very prominent or broad, i cell wide, distant
2-8 rows of tracheids.

Radial. Rays nonresinous ; the tracheids often predominant and when
interspersed often becoming very low, strongly reticulated throughout.
Ray cells of one kind only, the cells rather broad, long fusiform ; the
terminal walls thin and entire; the upper and lower walls very thin;
the lateral walls with very variable, lenticular, or oval pits, 1-5, chiefly
2-3, per tracheid, in the summer wood reduced to i. Bordered pits
conspicuously in 1-2 rows, elliptical, in the summer wood abruptly
reduced to 14.4 /JL, and finally to 7.2 p.. Pits on the tangential walls of
the summer wood wholly wanting.

Tangential. Fusiform rays medium to high, rather broad ; the terminals
acute, somewhat prolonged, and composed of few tracheids ; the
inflated portion composed of very large, rounded, and usually extremely
thin-walled cells among which there may be an occasional tracheid.
Ordinary rays numerous and presenting three principal aspects: (i) low
rays with large oval, central parenchyma cells and small, terminal tra-
cheids, fusiform ; (2) higher rays composed of large, squarish-celled
and thin-walled parenchyma, with a few narrower, terminal tracheids ;
and (3) the highest rays composed of large, thin-walled, oval, and broad
parenchyma cells with small terminal and smaller interspersed tracheids
causing local contractions.

A tree 21-24 m- high, with a trunk upwards of .75 m. in diameter.
Wood light, soft, not strong, brittle.

Specific gravity 0.5576

Percentage of ash residue 0.31

Approximate relative fuel value 55-°9

Coefficient of elasticity in kilograms on millimeters . . 543.

Ultimate transverse strength in kilograms 214.

Ultimate resistance to longitudinal crushing in kilograms 6028.

Resistance to indentation to 1.27 mm. in kilograms . . 2100.
(Sargent)

Barren, sandy dunes and ridges of Florida ; shores of Pensacola Bay and
southward within 30 miles of the coast to Pease Creek ; on the east
coast occupying a narrow ridge south of St. Augustine (Sargent).

PINUS 3 1 9

15. P. rigida, Mill.

Pitch Pine

Transverse. Growth rings thick. Summer wood dense, sometimes rather
open, very prominent, often double, the transition from the spring wood
gradual or somewhat abrupt ; the tracheids rounded, not uniform, in
rather irregular rows. Spring tracheids large, squarish-hexagonal, very
unequal in regular rows. Resin passages large and numerous, chiefly
in the summer wood; the epithelium in 1-2 rows of large, irregularly
rounded, thin-walled, and often resinous cells which sometimes become
thicker-walled in the outer limits, forming more or less extensive tracts
eccentrically developed about the canal. Medullary rays rather promi-
nent but few, distant 2-16, rarely 27, rows of tracheids. This wood
shows a strong tendency to radial fracture.

Radial. Rays nonresinous ; the tracheids strongly reticulated throughout,
sparingly interspersed, very low, not conspicuously predominant. Ray
cells of one kind, rarely of two kinds, chiefly low and long fusiform ; the
terminal, upper, and lower walls very thin and usually much broken
out; the lateral walls with very variable, lenticular, or oval pits: (l)
upwards of 6 per tracheid ; and (2) 1-3, chiefly 2, per tracheid, usually
becoming more prominent in the low rays, and in the summer wood
often distinctly bordered, or again simple and very variable, often large.
Bordered pits in I row or pairs, elliptical. Pits on the tangential walls
of the summer wood wholly wanting.

Tangential. Fusiform rays not very numerous, rather low and broad ; the
terminals acute and composed of a few small tracheids ; the cells of the
inflated portion very thin-walled and large, but usually much broken out.
Ordinary rays chiefly rather low and presenting two principal aspects:
(i) low rays composed of thin-walled parenchyma much broken out,
and a few small, terminal tracheids ; and (2) higher rays of similar
parenchyma cells with small, terminal, and few interspersed tracheids,
the latter causing local contractions.

A tree 12-24 m- high* with a trunk upwards of .90 m. in diameter.
Wood light, soft, not strong, brittle, coarse grained, and compact.

Specific gravity 0.5151

Percentage of ash residue 0.23

Approximate relative fuel value 5l-39

Coefficient of elasticity in kilograms on millimeters . . . 581.

Ultimate transverse strength in kilograms 316.

Ultimate resistance to longitudinal crushing in kilograms . 5687.

Resistance to indentation to 1.27 mm. in kilograms . . . 2123.
(Sargent)

Valley of the St. John River, New Brunswick, to the northern shores of
Lake Ontario (Macoun) ; south through the Atlantic states to Georgia ;
westward to the western slopes of the Allegheny Mountains of West
Virginia and Kentucky (Sargent).

320 ANATOMY OF THE GYMNOSPERMS

16. P. serotina, Michx.

Pond Pine. Marsh Pine

Trans-verse. Growth rings thick. Summer wood dense or in the narrow
rings rather open, often exceeding the spring wood, from which the
transition is commonly very abrupt ; the tracheids large and not very
uniform, hexagonal, in very regular rows. Spring tracheids large,
squarish, the walls thin. Resin passages numerous and large, chiefly
in the summer wood; the epithelium in i-several rows of very large,
round, and dark resinous cells, forming an extensive tract which is
often strongly eccentric to the canal. Medullary rays prominent, broad,
I cell wide, more or less resinous, distant 2-8 rows of tracheids.

Radial. Rays more or less resinous throughout; the tracheids commonly
predominant, very variable in height, strongly reticulated throughout,
sparingly interspersed. Ray cells of one kind only, chiefly rather high,
more or less fusiform, equal to 4-6 spring tracheids, resinous ; the
terminal, upper, and lower walls thin and usually much broken out;
the lateral walls with very variable, lenticular pits, 1-4, rarely 5, per
tracheid, becoming very narrow and much prolonged slits in the sum-
mer wood. Bordered pits in i row or somewhat frequently in pairs,
and thus more or less 2-rowed, round, or elliptical. Pits on the tan-
gential walls of the summer wood wholly wanting.

Tangential. Fusiform rays rather numerous, resinous, narrow, medium to
high, the terminals acute, more rarely prolonged, and composed of
small tracheids ; the inflated portion composed of large, thin-walled
cells usually much broken out. Ordinary rays medium, numerous,
broad, resinous, and presenting three principal aspects : (i) low rays of
i-several thin-walled, resinous parenchyma cells with small, termi-
nal tracheids ; (2) higher rays chiefly composed of very large, oblong,
and often strongly reticulated tracheids with i or 2 large, resinous
parenchyma cells much broken out ; and (3) the highest rays of several
oblong, resinous parenchyma cells with few terminal tracheids, or
again variously contracted through the presence of small, interspersed
tracheids.

A tree 12-24 rn. high, with a trunk upwards of .90 m. in diameter.
Wood heavy, soft, not strong, brittle, coarse grained, and compact.

Specific gravity 0.7942

Percentage of ash residue 0.17

Approximate relative fuel value 79.29

Coefficient of elasticity in kilograms on millimeters . . 1170.

Ultimate transverse strength in kilograms 497.

Ultimate resistance to longitudinal crushing in kilograms 8079.

Resistance to indentation to 1.27 mm. in kilograms . . 4740.
(Sargent)

An uncommon species in low, peaty soil, ponds, and along the borders of
streams. North Carolina and south near the coast to the head of the
St. John's River, Florida (Sargent).

PINUS 321

17. P. Banksiana, Lamb.

Scrub Pine. Gray Pine. Jack Pine

Transverse. Growth rings narrow, uniform. Summer wood dense, about
one half the spring wood, from which the transition is generally abrupt;
the tracheids in regular rows, rather uniform. Spring tracheids con-
spicuously squarish, uniform in regular rows, the walls thin. Resin
passages rather small, rather numerous, widely scattering ; the epithe-
lium in 1-2 rows of thin-walled cells, those of the first row much
flattened, those of the second row large, irregularly rounded and resin-
ous, with an occasional thick-walled cell, the whole forming an eccentric
tract. Medullary rays not very broad, somewhat prominent, distant
2-10 rows of tracheids.

Radial. Rays sparingly resinous ; the ray tracheids strongly predominant
and for the most part strongly reticulated throughout, interspersed.
Ray cells of I kind only, short fusiform and equal to about 4 spring
tracheids ; the terminal walls thin and not pitted ; the upper and lower
walls variable, sometimes very thin and entire, or again thicker and
unequal ; the lateral walls with very irregularly oval or lenticular and
unequal pits, 1-6 per tracheid, in the summer wood becoming i.
Bordered pits in i row, sometimes in pairs or again distinctly 2-rowed,
elliptical, becoming smaller and more distant toward the summer wood,
where they are quickly reduced and are finally obscure or wanting. Pits
on the tangential walls of the summer wood wholly wanting.

Tangential. Fusiform rays rather low and narrow, rather few ; the terminals
acute or somewhat prolonged and chiefly composed of tracheids ; the
cells of the inflated portion large and rather thin-walled, generally all
present. Ordinary rays low and chiefly narrow, presenting three prin-
cipal aspects: (i) low rays composed of oblong or narrowly oval,
thin-walled parenchyma cells with narrowly oblong, terminal tra-
cheids ; (2) low rays of similar composition, but the parenchyma cells
much thinner-walled ; and (3) the highest rays composed chiefly of
narrow tracheids with a few broader, oblong parenchyma cells inter-
spersed.

A small tree 9-22 m. high, with a trunk rarely exceeding .75 m. in diameter.
Wood light, soft, not strong, rather close grained, and compact.

Specific gravity 0.4761

Percentage of ash residue 0.23

Approximate relative fuel value 47-5°

Coefficient of elasticity in kilograms on millimeters . . 942.

Ultimate transverse strength in kilograms 278.

Ultimate resistance to longitudinal crushing in kilograms 6329.

Resistance to indentation to 1.27 mm. in kilograms . . 1609.
(Sargent)

Halifax, Nova Scotia, northwesterly to the Athabasca River and down the
Mackenzie River to the Arctic Circle ; eastward it hardly becomes a tree,
but westward it increases in size, and westward of Lake Winnipeg it

322 ANATOMY OF THE GYMNOSPERMS

equals the red pine of the east in height and diameter (Macoun) ; south-
ward through northern Maine ; at Ferrisburg, Vermont ; thence westward
along the southern shores of Lake Michigan to central Minnesota.
Barren, sandy soil, more rarely in rich loam (Sargent).

18. P. contorta, Loud.
Scrub Pine

Transverse. Growth rings thick. Summer wood dense, conspicuous, often
exceeding the spring wood ; the tracheids in regular rows, those in the
outer portion generally much compressed, variable, those of the central
portion more uniform and with rounded lumens; transition from the
spring wood gradual. Spring tracheids hexagonal, unequal, in regular
rows, the walls rather thin. Resin passages scattering, numerous,
small; the epithelium in 1-3 rows of angular, thin-walled cells which
merge outwardly into thicker-walled elements, the whole forming an
irregular and somewhat extended tract. Medullary rays rather narrow,
i cell wide, not prominent, rather numerous, distant 2-12 rows of
tracheids.

Radial. Rays nonresinous ; the tracheids numerous, low, sparingly inter-
spersed and sometimes predominant, distinctly reticulated throughout.
Ray cells of one kind only and variously fusiform ; the terminal,
upper, and lower walls very thin and often much broken out or wholly
wanting; the lateral walls with large, oblong, or lenticular pits which
often become round or oval when the ray is only i cell high, and on
the inner face of the spring wood in all rays, 1-4, chiefly 2-3, per
tracheid, in the summer wood greatly reduced in size, shape, and
number. Bordered pits in i row, sometimes in pairs, elliptical,
becoming much reduced and remote in the summer wood. Pits on
the tangential walls of the summer wood wholly wanting.

Tangential. Fusiform rays not numerous, medium ; the terminals acute,
rarely somewhat prolonged, and composed of small tracheids ; the cells
of the inflated portion all very thin-walled and generally broken out.
Ordinary rays medium, rather numerous, the thin-walled parenchyma
cells predominant, commonly broken out so as to leave the ray vacant
for nearly the whole height, the tracheids chiefly terminal but occa-
sionally interspersed as somewhat narrower and rounded elements,
causing local but slight contraction.

A small, stunted tree 6-9 m. high, with a trunk upwards of .50 m. in diameter.
Wood light, hard, strong, brittle, and coarse grained.

Specific gravity 0.5815

Percentage of ash residue 0.19

Approximate relative fuel value 58.04

Coefficient of elasticity in kilograms on millimeters . . 1585.

Ultimate transverse strength in kilograms 423.

Ultimate resistance to longitudinal crushing in kilograms 8868.

Resistance to indentation to 1.27 mm. in kilograms . . 2382.
(Sargent)

PINUS 323

Sandy dunes and exposed rocky points, everywhere on the coast of British
Columbia ; when sheltered growing in groves ; rarely found in the
Queen Charlotte Islands (Macoun) ; Alaska and southward from Britisli
Columbia along the coast to Mendocino County, California, and inland
to the western slopes of the coast ranges (Sargent).

19. P. glabra, Walt.
Cedar Pine. Spruce Pine. White Pine

T'ransverse. Growth rings thick. Summer wood of about one half the
spring wood, from which the transition is usually somewhat abrupt,
double or treble, the central portions dense, the outer portions open,
especially when double or treble ; the tracheids rather variable, in
regular rows. Spring tracheids hexagonal, uniform in regular rows,
the walls thin. Resin passages rather abundant, medium ; the epi-
thelium in 1-2 rows of large, rounded and thin-walled, resinous and
irregular cells usually much broken out, but not forming very extended
tracts. Medullary rays not very broad, prominent, or numerous, distant
2-12 rows of tracheids.

Radial. Rays very sparingly resinous, the tracheids sparingly icticulated,
often predominant and interspersed. Ray cells of two kinds : (i ) rather
rare ; and (2) the terminal, upper, and lower walls very thin and often
apparently wanting ; the lateral walls with lenticular, variable pits, 1-6,
chiefly 2 or 3, per tracheid, in the summer wood finally reduced to i
and becoming a short slit. Bordered pits in i row, elliptical, in the
summer wood soon reduced to 9.6 /JL, the orifice often much prolonged,
sometimes rather large and bordered. Pits on the tangential walls of
the summer wood wholly wanting.

Tangential. Fusiform rays not numerous, medium ; the terminals acute, or
slightly prolonged and composed of small tracheids ; the inflated por-
tion composed of thin-walled cells all broken out. Ordinary rays chiefly
low to medium, somewhat numerous, and presenting two principal
aspects: (i) rays composed of large, thin-walled parenchyma cells
much broken out, and few, small, terminal tracheids ; and (2) rays
composed of large, thin-walled parenchyma cells with terminal and
interspersed, chiefly predominant and narrower, tracheids causing local
contraction.

A tree 24-30 m. high, with a trunk upwards of 1.20 m. in diameter.
Wood light, soft, not strong, brittle, very coarse grained, not durable.

Specific gravity 0.3931

Percentage of ash residue 0.45

Approximate relative fuel value 39. 1 3

Coefficient of elasticity in kilograms on millimeters . . 448.

Ultimate transverse strength in kilograms 212.

Ultimate resistance to longitudinal crushing in kilograms 4604.

Resistance to indentation to 1.27 mm. in kilograms . . 1694.
(Sargent)

324 ANATOMY OF THE GYMNOSPERMS

South Carolina to the Chattahoochee region of Florida, chiefly near the
coast, thence through the Gulf States south to latitude 32° 30' to the
valley of the Pearl River, Louisiana, its greatest development being in
Alabama and Mississippi (Sargent).

20. P. echinata, Mill.
Yellow Pine. Short-Leaved Pine

Transverse. Growth rings thick. Summer wood thick, very prominent,
dense, and often exceeding the spring wood from which the transi-
tion is generally very abrupt ; the tracheids unequal in regular rows,
but varying greatly in different growth rings so that the structure
presents a very variable density. Spring tracheids large, squarish-
hexagonal, the walls thin. Resin passages numerous but large and
scattering; the epithelium composed of i row of thin-walled cells, less
frequently becoming 2-rowed in part, the cells often resinous. Medul-
lary rays prominent, rather broad, numerous, distant 2-8 rows of
tracheids.

Radial. Rays somewhat resinous throughout ; the ray tracheids rather
high, conspicuously predominant and very strongly reticulated through-
out, often composing the entire ray. Ray cells of one kind, rarely of
two kinds, few, interspersed, fusiform ; the terminal, upper, and lower
walls very thin and much broken out; the lateral walls with very
variable, lenticular pits, 1-4 per tracheid, becoming more or less obso-
lete in the summer wood. Bordered pits in i row or pairs, rarely
2-rowed, elliptical, in the summer wood reduced to 7.2 fj., when the
orifice often becomes obscure or eccentric. Pits on the tangential
walls of the summer wood wholly wanting.

Tangential. Fusiform rays rather numerous, high, the terminals prolonged,
linear, and composed of broad parenchyma cells with terminal tra-
cheids ; the cells of the inflated portion very thin-walled and usually
all broken out. Ordinary rays rather numerous, high, presenting two
principal aspects: (i) low rays composed of thin-walled parenchyma
much broken out, and small, terminal tracheids ; and (2) higher rays
composed of oblong tracheids with few, interspersed, broader cells of
thin-walled parenchyma, thus causing local expansions.

A tree 24-30 m. in height, with a trunk upwards of 1.35 m. in diameter.
Wood varying greatly, heavy, hard, strong, generally coarse grained, and
compact.

Specific gravity 0.6104

Percentage of ash residue 0.29

Approximate relative fuel value 60.86

Coefficient of elasticity in kilograms on millimeters . . 1375.

Ultimate transverse strength in kilograms 443.

Ultimate resistance to longitudinal crushing in kilograms 7628.

Resistance to indentation to 1.27 mm. in kilograms . . 2064.
(Sargent)

PINUS 325

Staten Island, New York, thence southward to. western Florida and
through the Gulf States to Tennessee and eastern Texas ; through
Arkansas to Oklahoma ; southeastern Kansas, southern Missouri, and
in Union County, Illinois (Sargent).

21. P. resinosa, Ait.
Red Pine. Norway Pine

Transverse. Growth rings very thick, often double. Summer wood about
one fifth the spring wood, from which the transition is very gradual ;
not very dense, but when double the outer band is generally more open
with the tracheids less compressed, the inner band is more dense with the
tracheids usually thick-walled and more conspicuously compressed ;
the tracheids round-hexagonal, conspicuously unequal in regular rows,
the walls rather thick. Spring tracheids hexagonal, uniform in regular
rows, the walls thickish. Resin passages very scattering, not numer-
ous, large ; the epithelium not extensive, about 2 layers thick, the cells
of the layer next the canal radially flattened, those of the other layers
oval, often resinous. Medullary rays rather prominent and broad,
numerous, distant 2-9 rows of tracheids.

Radial. Rays nonresinous, the ray tracheids low, marginal, rarely inter-
spersed, conspicuously dentate. Ray cells long and low, straight, or
in the summer wood often conspicuously contracted at the ends ; the
terminal walls thin and entire ; the upper and lower walls rather thin,
remotely and imperfectly pitted ; the lateral walls with very large,
oval or oblong, very variable pits, which become lenticular toward the
summer wood, 1-2, chiefly i, per tracheid throughout. Bordered pits
in i row, sometimes in pairs, elliptical. Pits on the tangential walls of
the summer wood wholly wanting.

Tangential. Fusiform rays not numerous, chiefly rather low and broad, the
'cells rather large and thin-walled throughout. Ordinary rays medium,
nonresinous, numerous, rarely contracted by much smaller and nar-
rower, interspersed tracheids ; the cells chiefly equal but not very
uniform, oval or squarish, rather large, and thin-walled, the lateral
walls very thin and chiefly concave.

A tree 24-46 m. high, with a trunk upwards of 1.37 m. in diameter.
Wood light, not strong, hard, rather coarse grained, and compact.

Specific gravity 04854

Percentage of ash residue o-27

Approximate relative fuel value . . . 48. 4 !

Coefficient of elasticity in kilograms on millimeters . . . 1132.

Ultimate transverse strength in kilograms 341.

Ultimate resistance to longitudinal crushing in kilograms . 7274.

Resistance to indentationlo 1.27 mm. in kilograms . . . 1353.
(Sargent)

326 ANATOMY OF THE GYMNOSPERMS

The following determinations are after Bovey :
Coefficient of strength in pounds for :

Bending 5,400

Elasticity 1,430,000

Torsion 11,500

Compression 3,900

Shear 380

Weight per cubic foot 33

Rather a widely distributed but somewhat localized tree flourishing partic-
ularly in the poorest soils ; Nova Scotia, New Brunswick, Quebec, and
westward to Lake of the Woods (Macoun) ; through the New England
States to northern Pennsylvania and westward to Michigan and central
Minnesota (Sargent).

22. P. tropicalis, Morelet

Transverse. Growth rings narrow, unequal. Summer wood chiefly rather
dense but somewhat variable, usually exceeding the spring ; the tra-
cheids hexagonal-oblong, uniform, and in regular rows ; transition from
the spring wood abrupt or more rarely gradual. Spring tracheids
large, conspicuously squarish or hexagonal, the walls rather thin.
Medullary rays prominent, resinous, i cell wide, broad, distant 2-8, or
more rarely 12, rows of tracheids. Resin passages numerous, large,
resinous, and chiefly confined to the summer wood ; the epithelium of
1-2 rows of thin-walled cells which often form tangentially extended
tracts.

Radial. Ray tracheids rather low and rather sparingly dentate, never reticu-
late ; numerous and interspersed, often predominant. Medullary rays
resinous, the cells all of one kind ; the upper, lower, and terminal walls
thin and commonly much broken down; the side walls with large,
oval, oblong, or lenticular pits, 1-2, chiefly i, per tracheid, in the
summer wood often reduced and vertically lenticular. Pits on the
tangential walls of the summer tracheids wholly wanting, but often
appearing on the tangential walls of the first spring tracheid. Bor-
dered pits large, in i row or in pairs, the latter often approximating so
as to form 2 rows ; in the summer wood becoming much reduced and
rather distant in I row.

Tangential. Fusiform rays somewhat numerous, medium ; the terminals
somewhat prolonged but usually acute and composed of few, thick-
walled tracheids ; the cells of the central tract all thin-walled and much
broken out. Ordinary rays numerous, very resinous, medium ; the cells
oval, uniform, and equal but much broken out ; the higher rays some-
what contracted by the interspersed, rather smaller, and thick-walled
tracheids.

Cuba and Isle of Pines, West Indies.

A careful comparison of this wood with that of P. resinosa will show that
while they are very closely related, there are, nevertheless, essential struc-
tural differences which compel us to recognize them as distinct species.

PINUS 327

23. P. Thunbergii, Parl.

Jap. = Ktiromatsu

Transverse. Growth rings rather broad, variable. Summer wood dense,
sometimes equal to the spring wood from which the transition is
abrupt, rarely gradual, often double ; the rounded tracheids rather
equal in regular rows. Spring tracheids large, hexagonal, unequal
in regular rows, the walls rather thin. Resin passages rather nu-
merous, rather large and scattering; the epithelium in 1-2 rows of
very large and very thin-walled cells not extending much beyond the
central canal ; nonresinous ; in the summer wood the layer next the
canal is much compressed and the cells are barely recognizable. Med-
ullary rays few, not very broad or prominent, distant 2-8 rows of
tracheids.

Radial. Rays nonresinous ; the ray tracheids more or less dentate but not
reticulate, generally predominant and marginal, not interspersed. Ray
cells of one kind only, straight ; the terminal walls thin and entire ; the
upper and lower walls thickish and entire or distantly and obscurely
pitted ; the lateral walls with very large, oblong, or lenticular pits,
almost strictly i, rarely 2, per tracheid, in the summer wood becoming
distinctly bordered, when they are broadly oval with a long, slitlike
orifice. Bordered pits large, elliptical, not very numerous, in i row.
Pits on the tangential walls wholly wanting.

Tangential. Fusiform rays rather numerous but low and broad, the chiefly
rather short terminals wholly composed of small, oval tracheids, and
a few parenchyma cells, the inflated portion composed of very thin-
walled cells much broken out. Ordinary rays rather numerous, low to
medium, nonresinous, not very broad but presenting two principal
aspects : (i) narrow rays composed of a few central, oval parenchyma
cells and several variable, terminal tracheids ; and (2) broader rays
composed of oval parenchyma cells and a few terminal and small
tracheids.

24. P. densiflora, Sieb. et Zucc.
Jap. = Akamatsu

Transverse. Growth rings very uniform. Summer wood one half the spring
wood, from which the transition is abrupt, chiefly dense but somewhat
variable, the tracheids rounded, unequal in regular rows. Spring tra-
cheids hexagonal, rather uniform, in regular rows, the walls thickish.
Resin passages numerous, large, scattering; the epithelium in 1-2
rows of thin- and thick-walled cells, easily broken out and generally
wanting, nonresinous. Medullary rays few, not very prominent, very
narrow, rather obscure, distant 2-20 rows of tracheids.

Radial. Rays nonresinous ; the ray tracheids dentate, sparingly reticulate
in the summer wood, usually predominant and marginal, sparingly
interspersed. Ray cells of one kind only and straight ; the terminal
walls thin and entire ; the upper and lower walls thin, somewhat uni-
form, not obviously pitted; the lateral walls with very large and

328 ANATOMY OF THE GYMNOSPERMS

simple, oblong, or oval pits, almost strictly i per tracheid, in the
summer wood distinctly bordered and then large, oval, with a broad,
oblong orifice. Bordered pits large, elliptical, rather numerous, in
i row. Pits on the tangential walls of the summer wood wholly
wanting.

Tangential. Fusiform rays rather numerous, medium, narrow, the slightly
prolonged terminals composed of a few small tracheids ; the gradually
inflated portion composed of very thin-walled cells all broken out.
Ordinary rays medium, rather numerous, not very broad and present-
ing two principal aspects: (i) low to medium rays composed of
i-several oval parenchyma cells with small, terminal tracheids which
often become predominant ; and (2) the highest rays with numerous
tracheids and few, interspersed parenchyma cells.

25. P. Murrayana, A. Murr.

Black Pine. Lodge Pole Pine. Spruce Pine

Transverse. Growth rings usually broad. Summer wood very thin, the
structure very open throughout, the transition from the spring wood
very gradual ; the tracheids compressed, unequal, rather squarish, in
somewhat irregular rows. Spring tracheids somewhat squarish-hex-
agonal, often in very irregular rows, unequal, the walls thin. Resin
passages rather small and scattering; the epithelium in i row of very
large and thin-walled, somewhat radially flattened, nonresinous cells,
immediately inclosed by a layer of large, thin-walled tracheids. Med-
ullary rays prominent, broad, i cell wide, numerous, distant 2-9, more
rarely 1 1 rows, of tracheids.

Radial. Rays uniformly somewhat resinous throughout ; the ray tracheids
sparingly dentate, more or less reticulate in the summer wood, mar-
ginal and interspersed, often predominant. Ray cells apparently of
two kinds, but merging so as to be more or less indistinguishable,
strongly but variously fusiform ; the terminal walls thin and entire or
locally thickened ; the upper and lower walls either entire or locally
and irregularly thickened, thin ; the lateral walls with rather small,
round, oval, or lenticular pits, at first simple, but toward and in the
summer wood with a more or less obvious border and oblong orifice,
1-4, rarely 5, per tracheid, in the summer wood reduced to 1-2. Bor-
dered pits in i row, sometimes in pairs, not much crowded but strongly
elliptical. Pits on the tangential walls of the summer wood wholly
wanting.

Tangential. Fusiform rays low, few and small, rather broad, more or less
unequal, acute or somewhat prolonged, the cells rather small and
thick-walled throughout, the central tract usually much broken out.
Ordinary rays numerous, broad, when a few cells high conspicuously
fusiform ; the high rays commonly contracted at the position of small
and frequently interspersed tracheids ; the parenchyma cells rather
thin-walled, round, or transversely oval, very unequal and variable, the
higher rays commonly showing smaller and thicker-walled cells either
singly or in pairs.

PINUS 329

A tree 18-24 m. high, with a trunk upwards of 1.20 m. in diameter.
Wood light, soft, not strong, close and straight grained, easily worked,
compact, not durable.

Specific gravity 0.4096

Percentage of ash residue 0.32

Approximate relative fuel value 40-83

Coefficient of elasticity in kilograms on millimeters . . 771.

Ultimate transverse strength in kilograms 241.

Ultimate resistance to longitudinal crushing in kilograms 5328.

•Resistance to indentation to 1.27 mm. in kilograms . . 1379.
(Sargent)

An Alpine tree somewhat localized in the Rocky Mountains of British
Columbia at elevations of 3500-4000 feet, and northward to latitude
62° (Macoun) ; mountain ranges of Washington, Oregon, and the Sierra
Nevadas of California to San Jacinto ; southward through the moun-
tains of Idaho, Montana, Wyoming, Colorado, and Utah to New Mexico
and northern Arizona. The tree attains it greatest development in the
California Sierras, in the interior occurring on dry, gravelly soil cover-
ing immense areas. In the Rocky Mountain region it occupies the
borders of moist Alpine meadows between 6000 and 9000 feet elevation
(Sargent).

26. P. arizonica, Engelm.
Yellow Pine

Transverse. Growth rings chiefly thick but variable, often double. Summer
wood thin, of about 4-10 tracheids but very variable, usually very
open ; the tracheids very unequal, now small and round or again large
and much compressed, often in very irregular rows ; transition from
the spring wood somewhat gradual. Spring tracheids large, hexagonal,
uniform, in regular rows, the walls thin. Resin passages very large,
rather abundant; the epithelium in 2 rows, that next the canal com-
posed of large and rather thin-walled cells which are immediately
bounded by a layer of rather thick-walled, large, rounded, and often
resinous cells. Medullary rays broad, i cell wide, rather prominent,
sparingly and locally resinous, distant 2-10 rows of tracheids.

Radial. Rays locally resinous ; the ray tracheids strongly predominant,
strongly dentate, and somewhat reticulated in the summer wood. Ray
cells sparingly fusiform and of two kinds: (i) rather numerous, the
terminal walls thin and entire ; the upper and lower walls rather thick
and very coarsely pitted ; the lateral walls with variously oval, oblong,
or lenticular pits, 2-4, chiefly 4, per tracheid, becoming 2 in the sum-
mer wood ; (2) the cells equal to about 5 spring tracheids, the terminal
walls thin and entire ; the upper and lower walls thin and entire ; the
lateral walls with oval, oblong, or round pits, 2-4, chiefly 4, per tra-
cheid, becoming 2 in the summer wood. Bordered pits in I row,
sometimes in pairs, often numerous, elliptical. Pits on the tangential
walls of the summer wood wholly wanting.

330 ANATOMY OF THE GYMNOSPERMS

Tangential. Fusiform rays rather numerous and narrow, the terminals
somewhat prolonged but rather broad, the cells of the inflated portion
rather thick-walled, those of the terminals large and thin-walled.
Ordinary rays rather numerous, low to medium, much narrowed by
the numerous and very variable, interspersed, and predominant tra-
cheids ; the relatively few parenchyma cells often resinous, very
unequal and variable, oval, both thick- and thin-walled, the latter
often much broken out.

A large tree 61-91 m. high, with a trunk 3.60-4.57 m. in diameter.
Wood variable in quality and value, hard, heavy, strong, brittle, not coarse
grained nor durable, compact.

Specific gravity 0.4715

Percentage of ash residue 0.35

Approximate relative fuel value 50.28

Coefficient of elasticity in kilograms on millimeters . . 824.

Ultimate transverse strength in kilograms 279.

Ultimate resistance to longitudinal crushing in kilograms 6292.

Resistance to indentation to 1.27 mm. in kilograms . . 1740.
(Sargent)

Interior of British Columbia south of latitude 51°, thence southward along
the mountain ranges of the Pacific region to Mexico ; eastward to the
Black Hills of Dakota, Colorado, and western Texas. Dry, rocky ridges
and prairies, or in the northern portion of California, rarely in cold, wet
swamps, reaching its greatest development on the western slopes of the
California Sierras (Sargent).

27. P. Coulteri, D. Don

Pitch Pine

Transverse. Growth rings thick, variable. Summer wood thin, upwards of
10 tracheids and open, the transition gradual ; the tracheids very vari-
able, rounded, and often much compressed, in conspicuously irregular
rows. Spring tracheids large, squarish-hexagonal, the walls rather
thin. Resin passages rather abundant, medium ; the epithelium in
i -several rows of large, rather thick-walled, and chiefly rounded cells,
nonresinous, often forming extensive and irregular tracts about the
canal. Medullary rays broad, i cell wide, rather prominent, distant
2-20 rows of tracheids.

ial. Rays sparingly resinous throughout ; the tracheids low, often pre-
dominant, more or less reticulated throughout, and often composing
the entire structure in low rays. Parenchyma cells fusiform, of two
kinds: (i) high and prominent, especially in the low rays; the ter-
minal walls thin and not pitted ; the upper and lower walls thick and
coarsely pitted ; the lateral walls with round or oval and prominent pits,
1-4, more rarely 6, per tracheid, becoming 1-2 in the summer wood;
and (2) the cells fusiform, the terminal walls thin and not pitted ; the
upper and lower walls very thin, often much broken out, or again

PINUS 331

somewhat thickened, and thus passing into cells of the first order ; 1 1n-
lateral walls with oval or lenticular pits, 1-3, chiefly 2, per tracheicl
throughout, very unequal and variable in form and size. Bordered
pits in i row, sometimes in pairs, elliptical, becoming greatly re-
duced in the summer wood, and finally wanting. Pits on the tangential
walls of the summer wood wholly wanting.

Tangential. Fusiform rays rather numerous, medium, narrow ; the acute or
rarely prolonged terminals almost wholly composed of tracheids ; the
cells of the inflated portion very thin-walled and usually broken out.
Ordinary rays rather numerous, low to high, nonresinous and presenting
three principal aspects: (i) low rays wholly composed of tracheids
and thick-walled parenchyma cells, rarely 2-seriate, at least in part ;
(2) i-seriate rays with the thin-walled parenchyma of the central portion
much broken out, and showing an interspersed thick-walled paren-
chyma cell near the center; and (3) i-seriate rays chiefly composed
of thin-walled parenchyma terminated above and below by thick-walled
cells and tracheids.

A tree 24-26 m. high, with a trunk upwards of 1.80 m. in diameter.
Wood light, soft, not strong, brittle, and coarse grained.

Specific gravity °4I33

Percentage of ash residue O-37

Approximate relative fuel value 41.18

Coefficient of elasticity in kilograms on millimeters . . 1141.

Ultimate transverse strength in kilograms 325.

Ultimate resistance to longitudinal crushing in kilograms 5874.

Resistance to indentation to 1.27 mm. in kilograms . . 1475.
(Sargent)

The Coast Range of California, most abundant and attaining its greatest
development in the San Jacinto Mountains (Sargent).

28. P. tuberculata, Gord.

Knob-Cone Pine

Transverse. Growth rings thick. Summer wood prominent, open, upwards
of equal to the spring wood ; the tracheids very unequal in regular
rows, distinctly rounded, or the outermost more or less compressed
and with much thinner walls; the transition from the spring wood
gradual. Spring tracheids hexagonal, somewhat variable, in regular
rows, the walls thin. Resin passages rather numerous, chiefly in the
summer wood, scattering, large ; the epithelium in 1-3 rows of large
and very thin-walled and resinous cells which form a more or less
extended tract and often merge into thicker-walled parenchyma or thin-
walled tracheids. Medullary rays rather broad, i cell wide, not prom-
inent, sparingly and locally resinous, distant 2-15 rows of tracheids.

Radial. Rays sparingly and locally resinous, the resin massive ; the ray
tracheids about equal to the parenchyma cells, sometimes predominant
and interspersed, the upper and lower walls dentate, more or less
reticulated throughout. Ray cells of two kinds: (i) thick-walled,

332 ANATOMY OF THE GYMNOSPERMS

somewhat fusiform cells chiefly confined to the low rays and some-
what rare; the terminal walls thin and locally thickened ; the upper
and lower walls thick and strongly pitted ; the lateral walls with round
or lenticular and usually simple, rarely bordered pits, 2-4 per tracheid ;
and (2) fusiform cells, with the terminal, upper, and lower walls very
thin and usually much broken out ; the lateral walls with variously
lenticular, round or oval pits, 2-4, chiefly 4, per tracheid, in the sum-
mer wood reduced to 2, and finally to I, and becoming very narrow
and much-prolonged slits. Bordered pits in i row, sometimes in pairs,
elliptical. Pits on the tangential walls of the summer wood wholly
wanting.

Tangential. Fusiform rays not numerous, medium to low, narrow, very
unsymmetrical, the terminals chiefly acute, rarely somewhat prolonged ;
the inflated portion wholly composed of very thin-walled cells which
are commonly broken out. Ordinary rays medium, rather numerous
and very broad, presenting three principal aspects : (i) low rays wholly
composed of terminal tracheids and thin-walled, resinous parenchyma
commonly broken out ; (2) higher rays composed of very thin-walled,
resinous parenchyma much broken out, with terminal, interspersed
and predominant, small tracheids which cause local contraction ; and
(3) low rays composed of tracheids with i central, thick-walled paren-
chyma cell.

A tree 18-22 m. high, with a trunk upwards of .90 m. in diameter.
Wood light, soft, not strong, brittle, coarse grained, and compact.

Specific gravity Q-3499

Percentage of ash residue 0.33

Approximate relative fuel value 34-88

Coefficient of elasticity in kilograms on millimeters . . 429.

Ultimate transverse strength in kilograms 175.

Ultimate resistance to longitudinal crushing in kilograms 4207.

Resistance to indentation to 1.27 mm. in kilograms . . 1372.
(Sargent)

Dry, gravelly ridges and slopes, not common, 2500-5000 feet eleva-
tion. Valley of the Mackenzie River, Oregon, and southward along the
slopes of the Cascade and Sierra Nevada mountains, and in the California
Coast Range from Santa Cruz to the San Jacinto Mountains (Sargent).

29. P. Torreyana, Torr.
Soledad Pine

Transverse. Growth rings variable, the structure showing a marked tend-
ency to radial fracture. Summer wood prominent but rather open,
about one third the spring wood, from which the transition is abrupt
when thin, but when thicker the transition is often gradual both ways ;
the tracheids large, squarish, and often in irregular rows. Spring
tracheids large, squarish, rather uniform in regular rows, the walls
medium. Resin passages scattering, medium ; the epithelium com-
posed of large, thin-walled, irregular and resinous cells in 1-3 rows,

PINUS 333

which form an irregular tract and outwardly pass into occasional
thick-walled cells. Medullary rays broad, i cell wide, not very prom-
inent, distant 2-10 rows of tracheids.

Radial. Rays sparingly resinous, the resin confined to the thin walls ; the
tracheids about equal to, or in the low rays exceeding, the parenchyma
cells ; rarely interspersed, strongly reticulated throughout. Ray cells
of two kinds: (i) cells rather abundant, chiefly straight; the terminal
walls thin and entire ; the upper and lower walls thick, coarsely and
imperfectly pitted ; the lateral walls with very prominent and round,
elliptical or oblong pits which sometimes become distinctly bordered
in the summer wood, 2-4, chiefly 4, per tracheid ; and (2) cells broad,
fusiform, and variable ; the terminal, upper, and lower walls very thin
and much broken down ; the lateral walls with oval or lenticular vari-
able pits which become very narrow and often much elongated in the
summer wood, 2-3 per tracheid. Bordered pits in i row, sometimes
in pairs, elliptical, in the summer wood quickly reduced to 12-14 /A,
and finally to 7.2 p.. Pits on the tangential walls of the summer wood
wholly wanting.

Tangential. Fusiform rays rather numerous, small to medium, the terminals
acute, rarely somewhat prolonged, usually inflated for the whole
height ; the cells of the terminals composed of thick-walled paren-
chyma and small tracheids, those of the inflated portion very thin-
walled and generally broken out. Ordinary rays low to medium,
somewhat numerous, broad, very rarely contracted by the small and
much narrower, interspersed tracheids of the highest rays ; thick-
walled parenchyma cells few ; thin-walled parenchyma cells predom-
inant, resinous, much broken out.

A low, short-lived, gnarled, and crooked tree 6-8 in. high, with a trunk

upwards of .33 m. in diameter.
Wood light, soft, not strong, brittle, rather close grained, and compact.

Specific gravity 04879

Percentage of ash residue . 0.35

Approximate relative fuel value 50.62

Coefficient of elasticity in kilograms on millimeters . . 542.

Ultimate transverse strength in kilograms 323.

Ultimate resistance to longitudinal crushing in kilograms 4548.

Resistance to indentation to 1.27 mm. in kilograms . . 2309.
(Sargent)

A very local tree in San Diego County, California, and possibly Lower
California and the islands off Santa Barbara (Sargent).

30. P. chihuahuana, Engelm.
Yellow Pine

Transverse. Growth rings thin, variable. Summer wood thin, variable,
the thicker zones dense, the thin zones open ; the transition from the
spring wood rather abrupt ; the tracheids in regular rows, variable.
Spring tracheids squarish-hexagonal, very unequal in regular rows,

334 ANATOMY OF THE GYMNOSPERMS

the walls rather thin. Resin passages very round, large, somewhat
numerous ; the epithelium cells at first flattened and rather thin-walled,
quickly passing into large, rounded, thick-walled, and strongly resinous
wood-parenchyma cells which often form extensive and somewhat
irregular tracts. Medullary rays prominent, resinous, broad, i cell
wide, distant 2-10 rows of tracheids.

Radial. Rays locally and strongly resinous, the resin massive ; the ray
tracheids low, marginal, and interspersed, often predominant, strongly
dentate and sparingly reticulated in the summer wood. Ray cells of
two kinds, but merging and not always clearly distinguishable: (i)
thick-walled, fusiform cells ; the terminal walls thin and locally thick-
ened ; the upper and lower walls coarsely pitted ; the lateral walls
with very variable, oval, or lenticular pits, 2-4, chiefly 3, per tracheid,
becoming i in the summer wood ; and (2) thin-walled, fusiform cells ;
the terminal, upper, and lower walls thin and not pitted, the former
often locally thickened ; the lateral walls with lenticular, chiefly narrow
and simple pits, 2-4 per tracheid, becoming 1-2 in the summer wood.
Bordered pits in i row, sometimes in pairs, elliptical, becoming smaller
toward the summer wood, where they are finally obscure. Pits on the
tangential walls of the summer wood wholly wanting.

Tangential. Fusiform rays rather numerous, low, variable, rather broad
and unsymmetrical ; the terminals acute or prolonged ; the cells vari-
able, chiefly thick-walled throughout, often resinous. Ordinary rays
low, numerous, resinous, and strongly contracted by the frequently
interspersed and much narrower tracheids ; the parenchyma cells of
two kinds : (i) thick-walled cells chiefly predominant ; and (2) thin-
walled cells more or less broken out, interspersed.

A small tree 18-24 m. high, with a trunk upwards of .45-. 60 m. in diameter.
Wood light, soft, strong, brittle, close grained, and compact.

Specific gravity °-5457

Percentage of ash residue 0.39

Approximate relative fuel value 54-37

Coefficient of elasticity in kilograms on millimeters . . 726.

Ultimate transverse strength in kilograms 355.

Ultimate resistance to longitudinal crushing in kilograms 5398.

Resistance to indentation to 1.27 mm. in kilograms . . 2470.
(Sargent)

Dry, rocky ridges and slopes between 5000 and 7000 feet elevation.
Arizona, New Mexico, and Chihuahua, Mexico, not common (Sargent).

31. P. Jeffrey!, A. Murr.

Bull Fine. Black Pine

Trans-verse. Growth rings narrow, rather uniform. Summer wood thin
and open, or again very thin and very open ; the tracheids uniform in
regular rows, more rarely unequal in irregular rows ; the transition from
the spring wood rather gradual. Spring tracheids large, hexagonal,

PINUS 335

very unequal in regular rows, the walls rather thin. Resin passages
large, scattering ; the epithelium composed of very large, rounded,
rather thin-walled and variable cells in 1-3 rows, often forming rather
large tracts. Medullary rays broad, i cell wide, not very prominent,
distant 2-16 rows of tracheids.

Radial. Rays nonresinous ; the tracheids strongly dentate and more or less
reticulated throughout, numerous and strongly predominant. Ray
cells of two kinds: (i) thick-walled cells prominent, fusiform, equal
to about 5 spring tracheids ; the terminal walls locally thickened ; the
upper and lower walls strongly thickened and pitted ; the lateral walls
with prominent, round pits, 2-5, chiefly 3-4, per tracheid, conter-
minous with and merging into the cells of the second order; and
(2) fusiform cells equal to about 5 spring tracheids ; the terminal
walls thin and not locally thickened ; the upper and lower walls thin
and entire or more rarely locally thickened ; the lateral walls with
lenticular or oval, very variable pits, 1-4 per tracheid. Bordered pits
in i row, sometimes in pairs, elliptical, becoming quickly reduced in
the summer wood, and finally 7.2 /A. Pits on the tangential walls of
the summer wood wholly wanting.

Tangential. Fusiform rays few, medium, the terminals acute or somewhat
prolonged ; the cells of the inflated portion large and thin-walled,
usually much broken out. Ordinary rays rather numerous, medium to
high, nonresinous, chiefly composed of narrow tracheids with inter-
spersed and much broader parenchyma cells. Parenchyma cells of two
kinds : (i) thick-walled cells which predominate in low rays, becoming
interspersed in high rays ; and (2) the usually broader, more squarish,
and thin-walled cells.

A large tree 30-31 m. high, with a trunk upwards of 4 m. in diameter.
Wood light, strong, hard, rather coarse grained, and compact.

Specific gravity 0.5206

Percentage of ash residue 0.26

Approximate relative fuel value 5°-53

Coefficient of elasticity in kilograms on millimeters . . . 925.

Ultimate transverse strength in kilograms 318.

Ultimate resistance to longitudinal crushing in kilograms 6679.

Resistance to indentation to 1.27 mm. in kilograms . . . 1850.
(Sargent)

Dry, gravelly slopes between 6000 and 8000 feet elevation. Along the
Sierra Nevadas of California from Siskiyou Mountains to the San Ber-
nardino and San Jacinto mountains (Sargent).

32. P. ponderosa, Lawson
Yellow Pine. Bull Pine

Transverse. Growth rings thin, variable. Summer wood variable, dense,
sometimes open, the transition from the spring wood often abrupt ; the
tracheids round-hexagonal, unequal, and in somewhat irregular rows.

336 ANATOMY OF THE GYMNOSPERMS

Spring tracheids squarish-hexagonal, variable, in somewhat regular rows,
rather thick-walled. Resin passages medium, numerous, chiefly in the
summer wood; the epithelium in 1-3 rows of rather large and very
thin-walled cells, succeeded by thick-walled elements, the whole forming
a somewhat extended tract which commonly breaks out in making trans-
verse sections. Medullary rays very broad, i cell wide, nonresinous,
not numerous, distant 2-15, or sometimes 20 rows of tracheids.

Radial. Rays nonresinous ; the tracheids predominant or equal to the paren-
chyma cells, and usually strongly reticulated. Parenchyma cells of two
kinds : ( i ) rather few ; the terminal walls thin and locally thickened ;
the upper and lower walls rather thick but not very strongly pitted ;
the lateral walls with very conspicuous, round or lenticular, very vari-
able pits, 2-4, rarely 5, per tracheid ; and (2) variously contracted cells,
the terminal, upper, and lower walls thin and entire ; the lateral walls
with lenticular or oval pits, 1-4 per tracheid. Bordered pits in I row,
round or more generally elliptical. Pits on the tangential walls of the
summer wood wholly wanting.

Tangential. Fusiform rays somewhat numerous, low to medium ; the termi-
nals acute, composed wholly of tracheids ; the cells of the inflated por-
tion very thin-walled and usually broken out. Ordinary rays low,
numerous, nonresinous; the tracheids chiefly terminal or when inter-
spersed causing a slight contraction ; the thick-walled parenchyma cells
chiefly terminal, few, the thin-walled parenchyma occupying the central
region and forming the greater portion of the ray, generally broken out,
the cells oval, variable.

A large tree 61-91 m. in height, with a trunk upwards of 4.57 m. in

diameter.
Wood varying greatly in quality and value, heavy, hard, strong, brittle, not

coarse grained or durable, compact.

Specific gravity 0.4715

Percentage of ash residue 0.35

Approximate relative fuel value 46.99

Coefficient of elasticity in kilograms on millimeters . . . 887.

Ultimate transverse strength in kilograms 307.

Ultimate resistance to longitudinal crushing in kilograms 6037.

Resistance to indentation to 1.27 mm. in kilograms . . . 1719.
(Sargent)

Interior of British Columbia south of latitude 51°, south and east along the
mountains of the Pacific region to Mexico, the Black Hills of Dakota,
Colorado, and western Texas. Dry, rocky ridges; rarely in cold, wet
swamps, reaching its greatest development on the western slope of the
California Sierras. After Pseudotsuga Douglasii, the most generally dis-
tributed and most valuable timber tree of the Pacific forests (Sargent).
The distribution of this species and the qualities of the wood are not
clearly separable from the next species.

PINUS 337

33. P. scopulorum, Lemmon

Transverse. Summer wood very variable, rather open, commonly double ;
the tracheids in very regular rows and uniform, but generally much com-
pressed ; the transition from the spring wood rather abrupt. Spring
tracheids conspicuously squarish, rather uniform in regular rows, large
and thin-walled. Resin passages rather numerous and scattering, not
large ; the epithelium nonresinous, composed of about 2 rows of very
large and very thin-walled cells, those of the limiting layer flattened,
those of the secondary layers round, merging into a few thick-walled,
round parenchyma cells on the borders of the wood tracheids. Medul-
lary rays rather broad, i cell wide, rather numerous but not prominent,
distant 2-10, more rarely 17, rows of tracheids.

Radial. Rays nonresinous ; the ray tracheids commonly high, marginal, or
becoming interspersed in the higher rays, predominant and sparingly
reticulated. Ray cells of two kinds: (i) the terminal walls thin and
locally thickened ; the upper and lower walls thick and strongly pitted ;
the lateral walls with round, simple pits 1-4 per tracheid, conterminous
and interspersed with those of the second order ; and (2) the terminal,
upper, and lower walls thin and not pitted or locally thickened ; the
lateral walls with small, lenticular pits, 2-4, chiefly 4, per tracheid,
becoming i or 2 in the summer wood. Bordered pits in i row,
numerous, crowded, elliptical. Pits on the tangential walls of the
summer wrood wholly wanting.

Tangential. Fusiform rays not numerous, narrow ; the somewhat prolonged
terminals composed of tracheids ; the inflated portion composed of very
thin-walled cells, usually all broken out. Ordinary rays rather numerous,
low to medium, nonresinous, conspicuously contracted by the somewhat
narrower, sometimes interspersed, and conspicuously predominant tra-
cheids ; the thick-walled parenchyma cells few, not prominent, the thin-
walled parenchyma cells occupying the central tract, oval, variable.

34. P. pungens, Michx. f.

Table Mountain Pine. Hickory Pine

Transverse. Growth rings thick. Summer wood very prominent, dense or
sometimes somewhat open, often double, the transition from the spring
wood gradual, sometimes abrupt ; the tracheids in regular rows, vari-
able, rounded. Spring tracheids strongly hexagonal, very unequal in
regular rows, the walls rather thick. Resin passages rather large,
numerous, chiefly ill the summer wood ; the epithelium in i row of
very thin-walled and nonresinous cells, rarely much exceeding the canal
and forming eccentric tracts of limited extent. Medullary rays rather
broad, somewhat prominent, numerous, distant 2-15 rows of tracheids.

Radial. Rays somewhat resinous throughout ; the tracheids variable, often
predominant, reticulated throughout and more or less interspersed.
Ray cells of two kinds : (i) cells numerous and long fusiform ; the ter-
minal walls entire or locally thickened ; the upper and lower walls
strongly thickened and coarsely pitted ; the lateral walls with very vari-
able, oval, or lenticular pits, 1-3 per tracheid, in the summer wood
distinctly bordered, the orifice a prolonged slit ; and (2) cells variously

338 ANATOMY OF THE GYMNOSPERMS

fusiform, the terminal, upper, and lower walls thin and usually much
broken out; the lateral walls with lenticular or oval, very variable
pits, 1-4, chiefly 2 or 3, per tracheid, in the summer wood becoming
distinctly bordered, the orifice an extended slit, conterminous with
tracheids and cells of the first order. Bordered pits in i row or pairs,
elliptical, and toward the summer wood soon replaced by narrow slits,
which often lead into strong, double striations. Pits on the tangential
walls of the summer wood wholly wanting.

Tangential. Fusiform rays not numerous, low and broad, the chiefly acute
terminals composed of a few tracheids ; the cells of the inflated portion
very thin-walled, chiefly broken out, or again rather thick-walled in part
and persistent. Ordinary rays low to medium and presenting four prin-
cipal aspects : ( i ) low rays of thin-walled parenchyma, much broken out,
and small, terminal tracheids; (2) low rays of thick-walled parenchyma
and small, terminal tracheids ; (3) higher rays of thick-walled paren-
chyma and both terminal and interspersed tracheids with occasional
thin-walled parenchyma ; and (4) the highest rays of thin-walled, resin-
ous, and interspersed thick-walled parenchyma, together with terminal
and interspersed tracheids.

A tree 9-18 m. high, with a trunk upwards of 1.05 m. in diameter.
Wood light, soft, not strong, brittle, coarse grained, and compact.

Specific gravity 0.4935

Percentage of ash residue 0.27

Approximate relative fuel value 49.22

Coefficient of elasticity in kilograms on millimeters . . 803.

Ultimate transverse strength in kilograms 310.

Ultimate resistance to longitudinal crushing in kilograms 5670.

Resistance to indentation to 1.27 mm. in kilograms . . . 1842.
(Sargent)

Allegheny Mountains, Pennsylvania to Tennessee, in the high mountains of
the latter attaining its greatest development (Sargent).

35. P. inops, Ait.

Jersey Pine. Scrub Pine

Transverse. Growth rings thick, often double. Summer wood rather dense,
sometimes more or less open, equal to about one fourth or one third the
spring wood, from which the transition is usually abrupt ; the tracheids
strongly unequal, chiefly in regular rows. Spring tracheids squarish,
large, very uniform in regular rows, the walls thin. Resin passages
rather numerous, medium; the epithelium in 1-2 rows of large, round,
thin-walled or again rather thick-walled, resinous cells, which are often
developed eccentrically about the canal, and become thicker-walled
especially on the outer limits. Medullary rays prominent, rather broad,
i cell wide, not numerous, distant 2-12 rows of tracheids.

Radial. Rays somewhat resinous, the resin massive, localized ; the tracheids
numerous, low, very variable and very strongly reticulated throughout,
predominant, often interspersed. Ray cells of two kinds : (i) the terminal

PIN US 339

walls thin and locally thickened ; the upper and lower walls more or
less thickened and coarsely pitted ; the lateral walls with lenticular
or oval, variable pits, 2-6, chiefly 4, per tracheid, finally becoming slit-
like and reduced to i in the summer wood or eventually obsolete, often
conterminous with tracheids or with thin-walled parenchyma cells ; and
(2) the predominant elements ; the terminal, upper, and lower walls thin ;
the lateral walls with very variable, oval, or lenticular pits, 1-4 or more
rarely 5, chiefly 4, per tracheid, in the summer wood merging into pro-
longed slits or finally into round, bordered pits with an oblong, narrow
orifice; fusiform, chiefly high. Bordered pits in I row or pairs, ellip-
tical, becoming round and conspicuously smaller toward the summer
wood, where they are finally reduced to 7.2 /JL. Pits on the tangential
walls of the summer wood wholly wanting.

Tangential. Fusiform rays medium, rather few, narrow ; the terminals acute
and composed of large and small tracheids ; the inflated portion com-
posed of thin-walled tissue, much broken out and more or less resinous.
Ordinary rays chiefly low and presenting three principal aspects: (i)
low rays distinctly fusiform, with a large tracheid in the center and
small terminal tracheids ; (2) higher rays of i-several large, thin-walled,
and resinous cells, much broken out, with or without interspersed thick-
walled cells, sometimes in pairs, and terminal tracheids of variable
size ; and (3) the highest rays composed of large, thin-walled paren-
chyma cells, often with resin, but usually much broken out, terminal
tracheids and i -several small, interspersed tracheids, causing local
contractions.

A tree 24-36 m. high, with a trunk upwards of .90 m. in diameter.

Wood light, soft, not strong, brittle, very close grained, compact, and durable.

Specific gravity °-53°9

Percentage of ash residue 0.30

Approximate relative fuel value 52-93

Coefficient of elasticity in kilograms on millimeters . . . 543.

Ultimate transverse strength in kilograms 281.

Ultimate resistance to longitudinal crushing in kilograms 5765.

Resistance to indentation to 1.27 mm. in kilograms . . . 2496.
(Sargent)

Sandy, generally barren soil. Long and Staten islands, New York ; south-
ward usually near the coast to South Carolina and westward through
eastern and middle Kentucky to southeastern Indiana (Sargent).

36. P. muricata, D. Don

Prickle -Cone Pine

Transverse. Growth rings thick. Summer wood prominent but rather thin,
about one fifth the spring wood, variable, both dense and open ; the
tracheids variable, in the open zones often much compressed and in
irregular rows, the walls variable ; the transition from the spring wood
rather gradual. Spring tracheids ^hexagonal, unequal, in regular rows.

340 ANATOMY OF THE GYMNOSPERMS

the walls rather thin. Resin passages scattering, rather small, somewhat
numerous, chiefly in the summer wood; the epithelium in 1-2 rows of
large, rounded, thin-walled, often strongly resinous cells, which some-
times become thick-walled at the outer limits. Medullary rays not
numerous or prominent, rather narrow, i cell wide, distant 2-30 rows
of tracheids.

Radial. Rays locally somewhat resinous, the resin massive ; the ray tra-
cheids strongly predominant, often composing the entire structure of the
low rays, in the higher rays marginal, more rarely interspersed, reticulated
in the summer wood. Ray cells of two kinds : * (i) rather frequent but
not predominant except in the low rays, rather high and long fusiform ;
the terminal walls thin, sometimes strongly pitted ; the upper and lower
walls rather thick and coarsely pitted ; the lateral walls with prominent
and very variable, oval, round, or lenticular pits, 1-4 per tracheid ;
and (2) cells resinous, the terminal, upper, and lower walls thin and
much broken out; the lateral walls with lenticular pits 1-3, chiefly 2,
per tracheid. Bordered pits in i row, sometimes in pairs, numerous,
elliptical. Pits on the tangential walls of the summer wood wholly
wanting.

Tangential. Fusifonn rays low, the terminals acute, rarely prolonged ; the
cells of the inflated portion large and rather thin-walled, often wholly
broken out. Ordinary rays low, rather broad, the cells very variable in
shape from oval to squarish, and presenting four principal aspects: (i)
low, fusiform in shape, composed of thick-walled, oval parenchyma cells
with terminal tracheids ; also higher rays of the same aspect ; (2) low
rays of thick- and thin-walled, oval parenchyma — the latter resinous,
but otherwise not very different — and small, terminal tracheids; (3)
higher rays of large, broad, thin-walled, resinous parenchyma, 1-2 thick-
walled parenchyma cells and terminal tracheids ; and (4) the highest
rays of thick-walled parenchyma and interspersed tracheids with local
contractions. Parenchyma cells oval, very narrow.

A tree 24-36 m. high, with a trunk upwards of .90 in. in diameter.
Wood light, very strong and hard, coarse grained, and compact.

Specific gravity 0.4942

Percentage of ash residue 0.26

Approximate relative fuel value 49.29

Coefficient of elasticity in kilograms on millimeters . . . 1194.

Ultimate transverse strength in kilograms 441.

Ultimate resistance to longitudinal crushing in kilograms 8142.

Resistance to indentation to 1.27 mm. in kilograms . . . 1950.
(Sargent)

The coast ranges of California, reaching its greatest development in Men-
docino County. Rare and local, in cold peat bogs or barren, sandy
gravel below 2000 feet elevation (Sargent).

1 The distinction between these two forms of cells is not very clear in this
species and is best expressed by the terms " thicker " and " thinner " as applicable
to elements which are not very different, or which merge by gradual transitions.

PINUS 341

37. P. insignis, Douglas
Monterey Pine

Transverse. Growth rings thick, often double. Summer wood rather open,
the transition from the spring wood very gradual ; the tracheids very
unequal in more or less irregular rows, often strongly compressed radi-
ally. Spring tracheids hexagonal, very unequal in somewhat regular
rows, the walls medium. Resin passages scattering, numerous, rather
large ; the epithelium in 1-3 rows of very large, round, but variable and
rather thin-walled, resinous cells. Medullary rays very prominent, broad,
i cell wide, not very numerous, distant 2-12, more rarely 21, rows of
tracheids.

Radial. Rays resinous, the resin localized, granular, more rarely massive
or in the cell wall ; the ray tracheids sparingly reticulated and sparingly
predominant, when interspersed, very low and unequal. Ray cells of
two kinds: (i) cells usually low and prominent, especially in the low
rays ; the terminal walls often thick and coarsely pitted ; the upper and
lower walls very variable, in the low rays thick and coarsely pitted, in
the higher rays thin and barely pitted so as to approach cells of the
second order ; the lateral walls with variously oval or lenticular pits,
1-2, rarely 6, chiefly 2, per tracheid ; (2) cells straight or variously
fusiform; the terminal, upper, and lower walls very thin, commonly
much broken out ; the lateral walls with broadly oval or variously len-
ticular pits, 1-3 per tracheid, in the summer wood reduced to much-
prolonged slits. Bordered pits in i row, sometimes in pairs, elliptical.
Pits on the tangential walls of the summer wood wholly wanting.

Tangential. Fusiform rays somewhat abundant, medium, rather narrow, the
terminals acute or somewhat prolonged, chiefly composed of small tra-
cheids ; the cells of the inflated portion chiefly thin-walled and usually
much broken out, but dark and resinous. Ordinary rays medium, rather
broad, composed of thicker- and thinner-walled cells and presenting four
principal aspects: (i) low rays composed of thick-walled parenchyma
and tracheids, distinctly fusiform ; (2) i-seriate rays composed of sev-
eral cells of thick-walled parenchyma and tracheids, usually nonresinous ;
(3) i-seriate rays composed of terminal tracheids, thick-walled and
thin-walled parenchyma, usually much broken out through the central
region, more or less resinous ; and (4) the highest rays showing inter-
spersed, narrow tracheids with strong, local contractions.

A tree 24-30 m. high, with a trunk upwards of .90 in diameter.
Wood light, soft, not strong, brittle, close grained, and compact.

Specific gravity Q-4574

Percentage of ash residue °-3°

Approximate relative fuel value 45-6°

Coefficient of elasticity in kilograms on millimeters . . . 979.

Ultimate transverse strength in kilograms 316.

Ultimate resistance to longitudinal crushing in kilograms 6680.

Resistance to indentation to 1.27 mm. in kilograms . . . 1687.
(Sargent)

Rare and local, on sandy soil in proximity to the seacoast, California (Sargent).

342 ANATOMY OF THE GYMNOSPERMS

38. P. Sabiniana, Douglas

Digger Pine. Bull Pine

Transverse. Growth rings thick, variable, often double. Summer wood
variable, upwards of one fourth to one half the spring wood, from which
the transition is somewhat abrupt, dense, or again rather open ; the
tracheids very unequal, chiefly in irregular rows, the larger ones often
much compressed. Spring tracheids rather large, squarish-hexagonal,
uniform in regular rows, the walls thickish. Resin passages medium,
not very numerous, chiefly in the summer wood : the epithelium of 2 or
more rows of large, irregularly flattened and very thin-walled, somewhat
resinous cells, often forming an irregular and somewhat extended tract.
Medullary rays prominent, somewhat resinous, broad, i cell wide, dis-
tant 2-10 rows of tracheids.

Radial. Rays sparingly resinous ; the tracheids low but very variable, mar-
ginal, predominant and sparingly interspersed, often composing the
entire structure of low rays, strongly dentate and somewhat reticulate
in the summer wood. Ray cells of two kinds : (i) cells rather numerous,
chiefly in low rays ; the upper and lower walls thick, strongly but irreg-
ularly pitted ; the lateral walls with prominent, round and bordered, or
simple and lenticular pits, 2-5, chiefly 4, per tracheid ; (2) cells rather
low and variable, not conspicuously fusiform ; the terminal, upper, and
lower walls very thin and entire ; the lateral walls with variously lentic-
ular pits without an obvious border, 2-4, chiefly 2, per tracheid, becoming
reduced to i in the summer wood. Bordered pits conspicuously in 1-2
rows, numerous, elliptical, becoming smaller and round toward the summer
wood. Pits on the tangential walls of the summer wood wholly wanting.

Tangential. Fusiform rays rather numerous, narrow ; the terminals acute
or prolonged linear, chiefly composed of tracheids ; the cells of the
inflated portion large and very thin-walled, often much broken out.
Ordinary rays chiefly low, not very numerous, nonresinous, broad, the
tracheids chiefly terminal and much narrower, rarely interspersed, pre-
senting four principal aspects: (i) thin-walled parenchyma with termi-
nal and interspersed tracheids; (2) i-seriate rays with a few terminal,
thick-walled tracheids, but chiefly composed of large and very thin-walled
parenchyma cells ; (3) thin-walled parenchyma with terminal tracheids
and interspersed, thick-walled parenchyma ; and (4) i-seriate rays com-
posed of tracheids and thick-walled parenchyma.

A large tree 24-30 m. high, with a trunk upwards of 1.20 m. in diameter.
Wood light,soft,notstrong,brittle and very coarse grained, compact,not durable.

Specific gravity 0.4840

Percentage of ash residue 0.40

Approximate relative fuel value 48.18

Coefficient of elasticity in kilograms on millimeters .... 585.

Ultimate transverse strength in kilograms 333.

Ultimate resistance to longitudinal crushing in kilograms 5387.
Resistance to indentation to 1.27 mm. in kilograms . . 2202.
(Sargent)

Very common in the foothills region : Coast Range and western slope of
the Sierra Nevadas below 4000 feet elevation, California (Sargent).

PINUS 343

39. P. taeda, Linn.
Loblolly Pine. Old Field Pine

Transverse. Growth rings broad. Summer wood open or sometimes rather
dense, often double and often equal to the spring wood, from which the
transition is abrupt ; the tracheids large, strongly unequal but in rather
regular rows. Spring tracheids large, squarish, the walls thin. Resin
passages numerous, chiefly in the summer wood, very large ; the epithe-
lium composed of very thin-walled, sometimes resinous cells, chiefly in
i row and strongly compressed upon the face of the tracheid structure,
more rarely becoming 2-rowed in part and forming an eccentric tract
of limited extent. Medullary rays rather prominent, broad, i cell wide,
distant 2-8 rows of tracheids.

Radial. Rays nonresinous ; the tracheids sometimes predominant in the higher
rays, but often interspersed, low and unequal throughout, sparingly,
rarely strongly reticulated. Ray cells of two kinds: (i) cells rare and
occurring only (?) in the low rays, where they are conterminous with the
tracheids ; the terminal walls thin and entire ; the upper and lower walls
thick and strongly but incompletely pitted ; the lateral walls with round
or oval pits, upwards of 6 per tracheid; (2) cells variously fusiform,
often straight ; the terminal, upper, and lower walls very thin and com-
monly much broken out ; the lateral walls with variable, oval, or lentic-
ular pits, 1-6, chiefly 2-4, per tracheid, in the summer wood commonly
reduced to I. Bordered pits in I or 2 rows or often i row or pairs,
elliptical. Pits on the tangential wralls of the summer wood wholly
wanting. The tracheids of the summer wood sometimes exhibit a dis-
tinct tendency toward the formation of spirals.

Tangential. Fusiform rays rather high and narrow', the terminals acute or
prolonged and finally wholly composed of small tracheids ; the cells of
the inflated portion commonly wanting. Ordinary rays medium and
presenting two principal aspects: (i) higher rays composed of thin-
walled parenchyma cells chiefly broken out, with very small, terminal,
and interspersed tracheids, the latter causing local contractions ; and
(2) lower rays of thin-walled parenchyma much broken out, rarely
showing a thick-walled parenchyma cell, and small, terminal tracheids.

A large tree 24-46 m. high, with a trunk upwards of 1.50 m. in diameter.
Wood light, not strong, brittle and very coarse grained, not durable.

Specific gravity O-5441

Percentage of ash residue 0.26

Approximate relative fuel value 54-27

Coefficient of elasticity in kilograms on millimeters . . 1128.

Ultimate transverse strength in kilograms 377.

Ultimate resistance to longitudinal crushing in kilograms 6834.

Resistance to indentation ^o 1.27 mm. in kilograms . . . I7J9-
(Sargent)

Low, wet clay or sandy soil ; southern Delaware to Tampa Bay, Florida,
generally near the coast ; westward through the Gulf States to the valley
of the Colorado River, Texas, and northward through southern Arkansas
to the valley of the Arkansas River (Sargent).

344 ANATOMY OF THE GVMNOSPERMS

40. P. palustris, Miller
Long -Leaved Pine. Southern Pine. Yellow Pine

Transverse. Growth rings thin, very variable. Summer wood dense, often
very thin, the transition from the spring wood very abrupt ; the tracheids
very uniform in regular rows. Spring tracheids squarish, rather uniform,
in regular rows, often radially elongated, the walls rather thick. Resin
passages numerous and large, chiefly in the summer wood; the epithe-
lium composed of large, rounded, often resinous cells in i row, fre-
quently becoming several-rowed in part and forming more or less
extensive and strongly eccentric tracts about the canal. Medullary rays
very prominent, broad, i cell wide, distant 2-10, more rarely 15, rows
of tracheids.

Radial. Rays sparingly resinous throughout ; the ray tracheids often inter-
spersed, commonly predominant, very strongly reticulated throughout.
Ray cells of two kinds : (i) rather few but prominent and conterminous
with tracheids into which they merge ; the terminal walls thin and not
pitted ; the upper and lower walls somewhat strongly but unequally
thickened and pitted ; the lateral walls with broadly and variously len-
ticular or round pits, 2-5 per tracheid ; and (2) very long-fusiform cells ;
the terminal, upper, and lower walls very thin and usually much broken
out ; the lateral walls with very variable, lenticular, or oval, sometimes
very large, pits, 2-6, chiefly about 4, per tracheid, in the summer wood
reduced to i. Bordered pits conspicuously in 1-2 rows, elliptical. Pits
on the tangential walls of the summer wood wholly wanting.

Tangential. Fusiform rays not numerous, often very high, acute, the linear
terminals much prolonged with terminal or interspersed tracheids, but
with the structure very commonly wanting except at the extremities ;
the low, inflated portion usually showing only a remnant of very thin-
walled, delicate tissue. Ordinary rays medium, rather numerous, broad,
presenting three principal aspects: (i) low rays with few, thin-walled
parenchyma cells much broken out, and terminal tracheids of very vari-
able size ; (2) higher rays of several large, thin-walled parenchyma cells
much broken out, and narrow, oval to oblong, terminal tracheids, rarely
with interspersed thick-walled parenchyma ; and (3) the highest rays
composed of a few large, thin-walled parenchyma cells, with small, ter-
minal, and narrow, often high and interspersed tracheids.

A tree of the greatest economic value 18-29 m- l"gh> witn a trunk upwards

of i. 20 m. in diameter.
Wood heavy, exceedingly hard, very strong and tough, coarse grained, com-

pact, and durable.

Specific gravity .............. 0.6999

Percentage of ash residue ........... 0.25

Approximate relative fuel value ......... 69.82

Coefficient of elasticity in kilograms on millimeters . . . 1,488.

Ultimate transverse strength in kilograms ...... 490.

Ultimate resistance to longitudinal crushing in kilograms 10,074.

Resistance to indentation to 1.27 mm. in kilograms . . . 2,508.
(Sargent )

PINUS

345

Dry, sandy loam of the coastal plain, forming extensive forests almost to the
exclusion of other species ; rarely found along the borders of swamps in
low, wet soil. Southeastern Virginia to Tampa Bay, Florida ; westward
through the Gulf States to the Red River in Louisiana, and the Trinity
River in Texas; rarely more than 150 miles from the coast (Sargent).

41. P. cubensis, Griseb.

Slash Pine. Swamp Pine

Transverse. Growth rings variable. Summer wood variable, dense or open,
the transition from the spring wood usually -very abrupt ; the tracheids
conspicuously rectangular, very uniform and regular, with small, round
cavities and very thick walls, or again strongly rounded, very unequal,
often much compressed, the general structure both open and dense.
Spring tracheids squarish or rounded, the walls rather thin. Resin
passages numerous, large, chiefly in the summer wood ; the epithelium
in 1-2, rarely 3, rows of rather thin-walled, usually much flattened,
resinous cells. Medullary rays prominent, very broad, i cell wide,
numerous, distant 2-8, rarely 12, rows of tracheids.

Radial. Rays sparingly resinous ; the ray tracheids rather high, predominant
in the low rays, everywhere very strongly reticulated. Ray cells of two
kinds : ( i ) short-fusiform cells equal to about 4 spring tracheids ; the
terminal walls thin and entire, locally thickened or coarsely pitted ; the
upper and lower walls thin and much broken down, but more commonly
thicker and irregularly pitted, these two forms gradually merging so that
they are not readily separable, sometimes conterminous with and merging
into tracheids ; the lateral walls with variable, chiefly lenticular pits, 1-6,
chiefly about 2-4, per tracheid, in the summer wood reduced to slits or
becoming obsolete. Bordered pits in 1-2 rows, numerous, elliptical, in the
summer wood quickly reduced and finally obscure or wholly wanting.
Pits on the tangential walls of the summer wood wholly wanting.

Tangential. Fusiform rays rather numerous, high, and narrow, the terminals
acute or prolonged and composed of very large, broadly oval paren-
chyma cells and very large, terminal tracheids ; the short, inflated por-
tion composed of thin-walled parenchyma cells much broken out.
Ordinary rays rather numerous, broad, medium, the cells chiefly broadly
oval ; composed of dominant parenchyma cells with chiefly terminal,
sparingly interspersed, often high, and narrow tracheids.

A tree 24-30 m. high, with a trunk upwards of .90 m. in diameter.
Wood heavy, exceedingly hard, very strong, tough, coarse grained, compact,
and durable.

Specific gravity 0.7504

Percentage of ash residue 0.26

Approximate relative fuel value 74-83

Coefficient of elasticity in kilograms on millimeters . . . 1,577.

Ultimate transverse strength in kilograms 500.

Ultimate resistance to longitudinal crushing in kilograms 10,626.

Resistance to indentation to 1.27 mm. in kilograms . . . 2,985.
(Sargent)

346 ANATOMY OF THE GYMNOSPERMS

South Carolina and southward near the coast to the Florida Keys ; westward
along the Gulf coast to the Pearl River, Louisiana, not more than 50 or (10
miles inland ; also in the West Indies (Sargent) ; Bahamas and Isle of
Pines (Shaw).

B. PITYOXYLON (Pinoxylon)

Fossil Species Only

42. P. dacotense, Knowlton

" Transverse. Annual rings broad and very distinct, even to the naked
eye, being 2-4.5 mm. in width. Distinction between the spring and
autumn wood very plain, the former appearing as broad, white bands,
and the latter as dense black bands of varying width. Under the micro-
scope the line of demarcation between fall and spring wood is observed
to be very sharp indeed. The fall wood consists of thick-walled cells
of an elliptical or oblong outline, rather loosely placed. The succeeding
spring wood is composed of very large cells with relatively thin walls.
The medullary rays are long and quite thick-walled. There are no resin
cells in the wood. The resin passages are present and quite numerous.
They do not seem to be confined to any particular portion of the ring,
but are scattered, being perhaps most numerous in the fall wood. They
are of relatively large size and lined with thin-walled epithelium.

" Radial. The walls of the spring and summer wood have 2 rather irreg-
ular rows of large, bordered pits. In rare cases these pits are in a single
row. The average size of the outer circle is .025 mm., that of the inner
circle about .015 mm. The cells of the rays are rather long, covering
the width usually of some 4 or more cells of the spring wood. They
are rather thick-walled, the walls being strongly dentate or somewhat
irregularly thickened. The ray cells are provided with a few scattered,
bordered pits, usually only i to the width of a spring cell of the wood,
although not rarely there are 2 in a similar width. They are always in i
row on the ray cell.

" Tangential. Medullary rays in a single, superimposed series, from i to
rarely 30 cells, the average being from 5 to 12 cells high. None of the
rays in the sections examined are of the fusiform type or contain resin
passages. The wood cells are, as far as can be made out, without pits
or markings of any kind" (Knowlton).

Trunks of medium size ; material silicified.

Upper (?) Jurassic near Sturgis, South Dakota (Knowlton).

43. P. Aldersoni, Knowlton

" Transverse. The annual rings are very distinct, being plainly discernible
to the naked eye. Some of the broadest rings are fully 9 mm. wide and
none less than 6 mm. The demarcation between fall and spring wood
is very pronounced, the cells of the fall wood being small, compressed,
and thick-walled, while those of the early spring wood are very large,
and, of course, thin-walled. The cells of the spring and summer wood
continue for a width of 5 mm., but little, if any, diminished in size.

PITYOXYLON 347

Then they become slightly smaller and thicker-walled and pass gradually
into the fall wood. The resin ducts are very large. They are not found
in the summer wood, but occur irregularly in the early fall and late fall
wood. The medullary rays as observed in this section arc straight and
separated by 3-8 or to rows of wood cells. The individual cells are
apparently long.

'•'•Radial. Notwithstanding the fact that the wood seems to be perfectly pre-
served, it does not reveal the structure well in this section. The wood

* cells are seen to be sharp-pointed where they join. They are, of course,
broad in the spring and summer wood and very narrow in the fall wood.
It is very difficult to make out the pits, but in exceptionally well-pre-
served portions a few may be faintly seen. They are scattered, but in
a single series. They are so obscure that no satisfactory measurements
can be made. The medullary rays in this section are long, thick-walled,
and without markings, so far as can be made out.

" Tangential. This section is very plain. The medullary rays are numerous
and in a single series, although occasionally a ray may be observed in
which there are 2 series of cells for a short distance. In such cases
the cells are always smaller than the ordinary ray cells. The number
of cells making up each ray ranges from 2 to 30 or more, but the average
number is about 8-15. The rays in which there is a resin duct are
rather rare. The duct is large, taking up all the width of the ray. The
remainder of the ray is 3 rows of cells high in the middle, and is reduced
to i at the extremities. The wood cells show plainly in this section.
They are not provided with pits or other markings" (Knowlton).

Trunks of large size, 3-5 feet in diameter. Material silicified.
Tertiary of the Yellowstone National Park, at Specimen Ridge, near head
of Crystal Creek, and Yancy Fossil Forest (Knowlton).

44. P. amethystinum, Knowlton

" Transverse. Much like P. Aldersoni except that the rings are narrower,
the cells of the spring and summer wood are smaller, and the late fall
cells have thinner walls. The resin ducts are also much the same, being
in general only a little smaller. A few are found in the summer wood,
but most of them are in the fall wood. The rays are not nearly so
numerous as in the last species. They are often separated by as many
as 25 rows of wood cells.

"Radial. The radial section of nearly all woods from the Yellowstone
National Park is more or less obscure. The one under consideration
is no exception to this rule, and it is only after considerable search that
the pits can be determined. They are in a single row and are rather
small. They are so obscure that it is impossible to make trustworthy
measurements. The medullary rays, as seen in this section, are com-
posed of long, thin-walled cells, and, so far as can be determined, they
are without pits or other markings.

" Tangential. This section shows the structure very plainly. The medullary
rays are abundant and always in a single series, except the large, com-
pound ones. The number of cells in each ray varies from 2 to 10 or 12,
the average number being about 6. The compound rays inclosing the

348 ANATOMY OF THE GYMNOSPERMS

n-sin ducts are rather small, with 3 rows of cells in the middle portion.
No markings can be made out on the wood cells in this section"
(Knowlton).

This species is very closely allied to the preceding, and should perhaps be
referred to it. The main points of difference are the following: smaller
resin ducts that are occasionally found in the summer wood ; smaller
wood cells throughout ; smaller and shorter compound medullary rays ;
ordinary rays always in a single series of 2-12 cells (average 6) instead
of 2-30 or more (average 12) (Knowlton).

This species cannot be separated from the preceding on the basis of the
characters given, and it is undoubtedly the same, though recognized here
provisionally (D.P.P.).

Trunks of small and medium size. Material silicified.

Tertiary of the Yellowstone National Park at Specimen Ridge, near the head
of Crystal Creek (Knowlton).

45. P. columbiana, Penh.

Transverse. Growth rings variable though generally very broad in large
stems. Spring wood usually predominant, the transition to the summer
wood gradual but in the narrower rings more or less abrupt and some-
times conspicuously so ; the tracheids large, thick-walled and often con-
spicuously so, definitely rounded, often radially oval, chiefly uniform,
more or less equal, in regular radial rows. Summer wood conspicuous,
dense, and often rather thin. The structure as a whole is that of a rather
dense wood of medium hardness. Medullary rays prominent, not very
numerous, resinous, and distant upwards of 9 or more rarely 1 5 rows of
tracheids. Resin passages conspicuous, rather large, and scattering
throughout the growth ring, the parenchyma cells large, thin-walled,
and in 2 rows, or forming large and irregular tracts upwards of 6-9
tracheids wide, resinous; thyloses not obvious.

Radial. Medullary rays resinous ; the tracheids rather numerous, marginal
and interspersed, not obviously predominant, very variable and often
as high as or higher than, long, sparingly dentate ; the parenchyma cells
all of one kind and rather thin-walled, straight, and equal to about 4
wood tracheids; the upper and lower walls strongly (?) pitted; the terminal
walls straight or diagonal and apparently not pitted; the lateral walls
with simple, round or lenticular pits of medium size, 2-4, chiefly 2, per
tracheid. Bordered pits on the tangential walls of the summer tracheids
small and not numerous ; those of the radial walls rather large, round,
or oval in i compact row, and generally numerous.

Tangential. Fusiform rays rather numerous, short, the broad central tract
'with thin-walled parenchyma chiefly broken out, the unequal terminals
composed of broad, oval cells chiefly 'in i row. Ordinary rays low to
medium, i-seriate, not materially contracted by the interspersed tra-
cheids; the parenchyma cells somewhat unequal and variable from
oblong to oval or broad and round.

Calcified fragments of stems and branches, and also cones in the Tertiary
of Kettle River, near Midway, British Columbia.

PITYOXYLON 349

46. P. Peali, Knowlton

" Transverse. This section shows the late fall and early spring wood. The
contrast in the thickness of the cells makes a very clearly marked ring.
This ring of growth was very broad, being in some cases fully 10 mm.
The medullary rays show in this section also as long, slender cells.

"Radial. The specimens are in a fine state of preservation. The cells of
the spring and summer wood are very broad and marked with a single
series of large, scattered, bordered pits. The medullary rays are prom-
inent. They are composed of very long cells, each of which is marked
usually by 2 or 3 small, oblong, or nearly circular bordered pits the
width of each wood cell.

" Tangential. The medullary rays are arranged in a single series of from 2
to occasionally 20 superimposed cells. The resin tubes occurring in
the midst of a medullary ray are quite numerous. There are no recog-
nizable pits or markings on the tangential walls of the wood cells"
(Knowlton).

Material silicified.

Miocene of the upper Gallatin Basin, Montana (Knowlton).

47. P. chasense, Penh.

Transverse. Tracheids chiefly in regular radial rows, very variable in size,
squarish, about 44 x 44 //, broad; the walls 12.5 /j. thick. Medullary
rays numerous, chiefly i cell wide, occasionally 2-3 seriate. Growth
rings wholly wanting. Resin cells and resin canals not represented.

Radial. Ray cells all of one kind ; straight, equal to 2-4 tracheids ; the
upper and lower walls thin and not pitted ; the terminal walls thin, not
pitted, straight or curved ; the structure of the lateral walls not deter-
minable, but the pits are probably round. Bordered pits in 1-3 rows,
chiefly 2 rows, round or hexagonal, 12.5 /j. broad, the orifice probably
round.

Tangential. Rays of two kinds: (i) i-seriate rays, the cells oblong, 25 p.
broad, often 2-seriate in part ; and (2) fusiform rays, the terminals linear
and of the structure of the i -seriate rays ; the central tract very broad,
nearly round ; the cells large, thin-walled, irregular, and inclosing a
small, central resin passage with large epithelium cells.

Material silicified. Specimens represented by small fragments of stem.
From the Chase Formation (Permian) at Coon Creek, Chase County,
Kansas (Prosser).

48. * * P. statenense, Jeff, and Chrys.

Transverse. Growth rings variable, chiefly narrow but usually well defined ;
summer wood very variable, of the narrower rings 1-5, but of the
broader rings many tracheids thick and constituting upwards of two
thirds the total thickness ; transition from the spring wood somewhat
abrupt; the broader growth rings sometimes showing 2 zones of
summer wood. Tracheids round-hexagonal or rectangular, rather

35°

ANATOMY OF THE GYMNOSPERMS

uniform but conspicuously unequal, disposed in unequal and some-
what irregular rows ; those of the spring wood thin-walled, about
32 x 39 /A, those of the summer wood rather thin-walled, about 1 9 x 29 p..
Medullary rays very resinous, broad, i cell wide, and distant about 2-8
rows of tracheids. Specialized resin cells wholly wanting. Resin
passages numerous, large, chiefly in the spring wood and filled with
prominent, resinous thyloses, the epithelium 1-2 cells thick, and not
extended into parenchymatous tracts.

Radial. Bordered pits very numerous in i row, rarely contiguous ; round,
more rarely oval, and about 17.5 /A, the round orifice about 7 /x; in
the summer wood somewhat reduced. Pits on the tangential walls of
the summer wood prominent, large, somewhat numerous. Medullary
rays very resinous ; ray tracheids wholly wanting ; parenchyma cells
all of one kind, more or less contracted at the ends, very variable
but generally equal to about 3-5 spring tracheids ; the upper and
lower walls strongly and rather frequently pitted ; the terminal walls
coarsely pitted or locally thickened ; the lateral walls with rather small,
oval pits, chiefly i per tracheid throughout, or in the marginal cells
and low rays 2 per tracheid.

Tangential. Fusiform rays numerous, medium ; the cells thick-walled ; the
central tract broad and occupied by i large resin canal filled with
thyloses; the terminals chiefly short or rarely prolonged with 1-2
seriate cells. Ordinary rays very variable but chiefly low to medium,
sometimes more or less 2-seriate in part ; very numerous ; the cells
broad but variable and round, oval or squarish, chiefly equal ; in the
low rays commonly becoming oblong.

The middle Cretaceous at Kreischerville, Staten Island. Material in the
form of lignite (Jeffrey).

49. * * P. scituatense, Jeff, and Chrys.

Transverse. Growth rings rather broad but thin, the limits obscured by
displacement of structure ; summer wood chiefly broad, the transition
from the spring wood apparently gradual. Tracheids all rather thin-
walled, those of the spring wood about 26.7 x 44.5 it. Medullary rays
numerous, prominent, resinous, broad, i cell wide and distant about
2-5 rows of tracheids. Resin canals rather numerous, chiefly in the
summer wood and central to broad tracts of parenchyma ; devoid of
thyloses, rather small, regularly oval or round, the epithelium composed
of a single layer of rather small, rounded, and somewhat thick-walled
cells. Wood parenchyma resinous, the cells large, thin-walled ; forming
extensive and prominent tracts about the resin canals often 427 x 570 /x
broad.

Radial. Bordered pits in i row, somewhat distant and not numerous ;
round, about 24.6 p. broad, the lenticular orifice showing a cross ; not
much reduced in the summer wood. Pits on the tangential walls of
the summer tracheids not determinate, apparently wanting. Medul-
lary rays resinous ; ray tracheids apparently wanting ; the parenchyma
cells all of one kind, not contracted at the ends, equal to about 5-8
wood tracheids ; the upper and lower walls rather thick, distantly and

PITYOXYLEN

351

coarsely pitted ; the terminal walls rather thin and locally thickened ;
the lateral walls with round, bordered pits about i 1.5 /A broad, chiefly
i, or sometimes 2, per tracheid, the orifice lenticular, diagonal. Wood
parenchyma resinous ; the cells cylindrical, 2-several times longer
than broad, the radial walls with rather small pits.

Tangential. Ordinary rays resinous, numerous, variable, low to high, 1-2
seriate, or sometimes 3-seriate, and approximating to the fusiform
type through various gradations, but always devoid of resin canals ;
the usually large cells very unequal and very variable, ranging from
oblong to oval, round or transversely oval, the strong inequality and
variability giving a marked irregularity of form to the ray as a whole.
Fusiform rays rather numerous, low to high, the central tract occupied
by i rather small resin canal devoid of thyloses, but with small and
thick-walled epithelium cells ; the terminals short or sometimes un-
equally prolonged to considerable length. Wood parenchyma resinous,
the short-cylindrical cells with thin walls and bearing pits on all their
walls. Rudimentary spirals may be seen in the tertiary layer of many
of the tracheid walls.

Cretaceous (?) of Third Cliff, Scituate, Massachusetts. Material in the
form of lignite (Bowman).

APPENDIX A

DATA FOR TABLE OF ANATOMICAL CHARACTERS, IN

IDENTICAL SERIES

1. Spiral tracheids.

2. Bordered pits in 1-3 rows.

3. Bordered pits in 1-2 rows.

4. Bordered pits in i row.

5. Pits on the tangential walls of the summer wood.

6. Lateral walls of the ray cells with bordered pits.

7. i -seriate rays.

8. Terminal walls of the ray cells thin and entire.

9. Resin cells.

10. Terminal walls of the ray cells locally thickened.

11. Terminal walls of the ray cells strongly pitted.

12. Ray tracheids.

13. Resin passages.

14. Fusiform rays.

15. Thyloses in the resin passages.

1 6. Lateral walls of the ray cells with simple pits.

17. Ray cells of two kinds.

1. Resin cells scattering.

2. Resin cells zonate.

3. Resin cells grouped.

4. Resin cells on the outer face of the summer wood.

5. Ray tracheids marginal.

6. Ray tracheids interspersed.

7. Ray tracheids dentate.

A. Number of species.

B. Percentage value of genus.

353

354

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LITERATURE

ANDERSON, A. P. (1) Ueber abnorme Bildung von Harzbehaltern. MUnchen,

1896.
(2) Comparative Anatomy of the Normal and Diseased Organs of Abies

balsamea affected with ^icidium elatinum. Bot. Gaz., XXIV, 309-344,

1897 (Plates XIV- XV).
BOULGER, G. S. (79) Wood : a Manual of the Natural History and Industrial

Applications of the Timbers of Commerce. London, 1902.
BOVEY, H. T. (3) Theory of Structures and Strength of Materials, pp. 213,

215.

- (4) Presidential Address. Trans. R. S. (Canada), II, iii, 3-24, 1896.

- (5) Results of Experiments on the Strength of White Pine, Red Pine,

Hemlock, and Spruce. Trans. Can. Soc. C. E., XII, 207, 1897.
(6) Results of Tests of White Pine of Large Scantlings. Trans. Can. Soc.

C. E., VII, 135, 1893.
(7) The Strength of Canadian Douglas Fir, Red Pine, White Pine, and

Spruce. Trans. Can. Soc. C. E., IX, 69, 1895.
BRITTON, N. L., and BROWN, A. (8) Illustrated Flora of the Northern United

States and Canada. New York, 1896.
CAMPBELL, D. H. (9) Text-Book of Botany, p. 335.
CONSTABLE, HOWARD. (10) Wood Preservation. U. S. Dept. of Agriculture,

Forestry Div., Bull. I, 1887.
COULTER, J. M. (11) The Gymnosperms and the Seed Habit. Bot. Gaz., XXVI,

153-168, 1898.
COULTER, J. M., and CHAMBERLAIN, C. J. (12) Morphology of the Spermato-

phytes. New York, 1901.
DEBARY, A. (13) Comparative Anatomy of the Phanerogams and Ferns. Oxford,

1887.
(83) Comparative Morphology and Biology of the Fungi, Mycetozoa, and

Bacteria. Oxford, 1887.
DUDLEY, P. H. (14) Structure of Certain Timber Ties; Behavior and Causes of

their Decay in the Roadbed. U. S. Dept. of Agriculture, Forestry Div.,

Bull, i, 1887.

EICHLER, A. E. (15) Naturlichen Pflanzenfamilien, II, 6 et seq.
ENGLER, A. (16) Naturlichen Pflanzenfamilien, II, 24 et seq.
ENGLER, A., and PRANTL, K. (17) Naturlichen Pflanzenfamilien, II, 7-127.
ESSNER, B. (18) Diagnosticher Werth der Anzahl und Hohe der Markstrahlen

bei den Coniferen. Bot. Centralbl., XII, 407, 1882.
FISCHER, II. (19) Ein Beitrag zur vergleichenden Anatomic des Markstrahl-

gewebes und der Jahrkichen Zuwachszonen im Holzkorper von Stamm,

Wurzel und Aesten bei Pinus abies, L. Flora, LXVIII, 1885.

362

LITERATURE 363

IM.AD, HKNKY. (20) Wood Preservation. U. S. Dept. of Agriculture, Forestry

Div., Hull, i, pp. 92-98, 1887.

GOPPKRT, H. K. (82) Fossilen Coniferen. Leiden, 1850.
HAKTIG, GEORG LUDWIG. (21) Lehrbuch fiir Forster. Stuttgart, 1877.
HARTIG, R. (22) Das Holz der deutschen Nadelwaldbaume. Berlin, 1885.
HARTIG, THEO. (23) Anatomic und Physiologie der Holzpflanzen. Berlin, 1878.
HULLICK, A., and JEFFREY, E. C. (87) Affinities of Certain Cretaceous Plant

Remains commonly referred to the Genera Dammara and Brachyphyllum.

Amer. Nat., XL, No. 471, pp. 189-215, 1906 (Plates I-V).
JEFFREY, E. C. (24) The Comparative Anatomy and Phylogeny of the Conif-

erales. Part I, The Genus Sequoia. Mem. Boston Soc. Nat. Hist., 1903.

- (25) A Fossil Sequoia from the Sierra Nevada. Bot. Gaz., XXXVIII,

321-332, 1904.
JEFFREY, E. C., and CHRYSLER, M. A. (86) On Cretaceous Pityoxyla. Bot. Gaz.,

XLII, No. i, pp. 1-14, 1906 (Plates I-II).
KNOWLTON, F. H. (26) New Species of Fossil Wood (Araucarioxylon arizonicum)

from Arizona and New Mexico. Proc. U. S. Nat. Mus., XI, 1888.

- (27) Description of Two New Species of Fossil Coniferous Woods from

Iowa and Montana. Proc. U. S. Nat. Mus., XI, 5-8, 1888.

- (28) A Revision of the Genus Araucarioxylon of Kraus, with Compiled

Descriptions and Partial Synonomy of the Species. Proc. U. S. Nat. Mus.,

XII, 601-617, 1890.

- (29) Notes on Triassic Plants from New Mexico. Proc. U. S. Nat. Mus.,

XIII, 281-285, 1890.

- (30) Fossil Wood and Lignite of the Potomac Formation. U. S. Geol.

Surv., Bull. 56, 1889.

- (31) Description of a Supposed New Species of Fossil Wood from Montana.

Bull. Torr. Bot. Club, XXIII, 250-251, 1896.

- (32) Description of Fossil Wood and Lignites from Arkansas. Ann. Rept.

Geol. Surv. of Arkansas, II, 249-266, 1889.

- (33) Description of Known Fossil Plants from the Laramie of the Yellow-

stone National Park. U. S. Geol. Surv., Monogr. XXXII, Part II, 651-791,
1899.

- (34) A Catalogue of the Cretaceous and Tertiary Plants of North America.

U. S. Geol. Surv., Bull. 152, 1898.

MACOUN, JOHN. (35) Catalogue of Canadian Plants. Exogens. Geol. Surv. Can.,
1883.

- (36) Rept. Geol. Surv. Can., p. 211, 1875-1876.

MASTERS, MAXWELL T. (37) Notes on the Genera of Taxaceae and Coniferae.
Jn'l Linn. Soc., XXX, i.

- (38) The Cypresses of Monterey. Garden and Forest, VII, 298.

- (39) A General View of the Genus Finns. Jn'l Linn. Soc., XXXV, 560-659.
MAYR, HEINRICH. (85) Die Waldungen von Nordamerika. Munchen, 1890. 448

pages (Plates I-XII).
MULLER, N. J. C. (40) Atlas der Hblzstructur. Halle, 1888.

- (41) Botanische Untersuchungen. Heidelburg, 1872.
MURRAY, A. (42) Edinburgh New Phil. Jn'l, N. s., I.

364 ANATOMY OF THE GYMNOSPERMS

NORDI.INGER, IT. (43) Die Technischen Eigenschaften der Hblzer. Stuttgart,

iS6o.
PENHAI.I.OW, I). I'. (44) Taxacerc and Coniferae. Trans. R. S. (Canada), II, iv,

33-56, 1896.

- (45) North American Species of Dadoxylon. Trans. R. S. (Canada), VI, iv,

51-79, 1900.

- (46) Notes on Tertiary Plants. Trans. R. S. (Canada), IX, iv, 33-95, 1903.

- (47) Contributions to the Pleistocene Flora of Canada. Trans. R. S.

(Canada), II, iv, 59-77, 1896.
(48) Canadian Pleistocene Fauna and Flora. B. A. A. S., pp. 525-529,

Bristol, 1898; pp. 7-12, Bradford, 1900.
(49) The Pleistocene Flora of Canada. Bull. Geol. Soc. Amer., I, 311-334.

1890.
(50) Notes on the Cretaceous and Tertiary Plants of Canada. Trans. R. S.

(Canada), VIII, iv, 31-91, 1902.
(51) Notes on Tertiary Plants from Canada and the United States. Trans.

R. S. (Canada), X, iv, 57-76, 1904.

- (52) Observations upon Some Structural Variations in Certain Canadian

Coniferae. Trans. R. S. (Canada), XII, iii, 19-41, 1894.
(53) The Relation of Annual Rings to Age. Can. Rec. Sc., I, 162.

- (54) Some Peculiarities of Plant Growth. Science, III, 354.

- (55) An Ancient Blaze. Can. Rec. Sc., Ill, 500.

- (56) Osmundites skidegatensis. Trans. R. S. (Canada), VIII, iv, 3-29, 1902.

- (57) Notes on Nematophyton crassum. Proc. U. S. Nat. Mus., XVI, 1893.

- (58) Notes on Devonian Plants. Trans. R. S. (Canada), VII, iv, 19-30, 1901.
(59) The Anatomy of the North American Coniferales. Amer. Nat.,

XXXVIII, 243-273; 331-359; 523-5S4; 691-723,1904.

(80) Variation of Water in Trees and Shrubs. Amer. Nat., April, 1886;

Can. Rec. Sc., II, 105.

- (88) A Blazing Beach. Science, XXII, 794-796, 1905.

PIERCE, J. G. (60) Studies on the Coast Redwood. Cal. Acad. Sc., II, 83-106,

1901.

POTONIE, H. (61) Lehrbuch der Pflanzenpalaeontologie. Berlin, 1899.
PRANTL, K. (62) Naturlichen Pflanzenfamilien, II, 33-40.
ROTH, FILIBERT. (63) Timber Pines of the Southern United States. U. S. Dept.

of Agriculture, Forestry Div., Bull. 13, pp. 133-143.
Russow, E. (64) Zur Kenntniss des Holzes, Insonderheit des Coniferenholzes.

Bot. Centralbl., XIII, 29-40; 6o-6S ; 95-109; 134-144; 166-173, 1883.
SACHS,). (84) Physiology of Plants. Oxford, 1887.
SARGENT, C. S. (65) Forest Trees of North America. Tenth Census of the

United States, IX (the whole volume), 1880.

- (66) The Silva of North America, Vols. X, XI, XII. Boston, 1897.
SCHROEDER, J. (67) IIolz der Coniferen. Dresden, 1872.

SCHRENK, H. VON. (68) The Hardy Catalpa. U. S. Dept. of Agriculture, Bureau
of Forestry, Bull. 37, pp. 1-56, 1902.

- (69) Diseases of the Red Cedar. U. S. Dept. of Agriculture, Div. of Pathol-

ogy and Physiology, Bull. 21, pp. 1-21, 1900 (Plates I-VII).

LITERATURE 365

SCOTT, D. IT. (70) The Anatomical Characters presented by the Peduncle of

Cycadaceae. Ann. Bot, XI, 399-419, 1887.
- (81) Studies in Fossil Botany. London, 1900.
SEWARD, A. C. (71) The Maiden Hair Tree (Gingko biloba, L.). Ann. Bot.,

XIV, 109-154.

TUBEUF, K. F. VON, and SMITH, W. G. (72) Diseases of Plants. London, 1897.
WARD, LESTER F. (73) Status of the Mesozoic Floras of the United States.

aoth Ann. Rept. U. S. Geol. Surv., Part II, 418-421, 1898-1899.
WARD, MARSHALL. (74) Timber and Some of its Diseases. London, 1889.
WEISS, G. A. (75) Anatomic der Pflanzen. Wien, 1878.
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the Coal Measures. M. Mic. Jn'l, II, 66-72.
WITTSTEIN, G. C. (77) Organic Constituents of Plants. Translated by Baron F.

von Mueller, Melbourne, Australia, 1878.
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INDEX

Abies, 10, 14, 51, 58, 76, 82, 83, 88, 89,
94, 104, 107, 112-128, 138-152, 156,
157, 187, 196, 197, 253 ; amabilis, 113,
1 15, 121, 255, 260, 359 ; balsamea, 88,
102, 112, 118, 140, 141, 254,258, 359;
bracteata, 102, 121, 138, 139, 145, 254,
262, 359; concolor, 102, 106, 121,
128, 129, 138, 139, 145, 254, 263,359;
excelsa, 88, 359; firma, 121, 138, 139,
145, 254, 264, 359; Fraseri, 58, 112,
118, 254, 255, 359; grandis, 58, 102,
105, 121, 255, 261, 359; lasiocarpa,
112, 118, 255, 256, 359; magnifica,
102, 105, 121, 255, 259, 359; nobilis,
102, 121, 128, 138, 139, 145, 254,
262, 359; Veitchii, 112, 118, 255, 257,

359
Abietmeae, 14, 71, 115, 138, 141, 143,

144, 154. I56

Acer campestre, 26 ; platanoides, 1 59 ;
rubrum, 25

Acetic acid, 21

Acid, acetic, 21 ; hydrochloric, 49; sul-
phuric, 49, 190

/Ecidium elatinum, 140

Aeration, 180

Aerobes, 180

Agaricus, 178; melleus, 140

Age of trees, relation to growth rings, 25

Air pump, 22

Air, removal from sections, 22

Akamatsu, 327

Alcohol, 22, 40, 55, 56

Algae, 192

Alkali, 1 66

American A'aturalist, 15

American yew, 213

Ammonia, 49, 55

Ammoniacal, 182

Anaerobes, 180

Anderson, A. P., 139-141, 148

Angiosperms, 37, 39, 57

Aniline chloride, 49

Anthracite, 172

Anthrax bacillus, 181

Araragi, 214

Araucaria, 14, 28,29, 50-54, 57-61, 65-
67. 70-77. 94. "8, 120, 122, 151,

156,197, 203, 204; argilliacola, 61 ;
arizonicum, 61, 204, 207 ; Bidwillii, 29,

61, 197, 204, 205, 358; brasiliana,
29; Cunninghamii, 29, 61, 73, 204,
205, 358; Doeringii, 61 ; excelsa, 28,
29, 53, 61, 204, 205, 358; Heerii, 61 ;
hugelianum, 61 ; Robertianum, 61,

62, 73 ; Schmidianum, 61 ; subtile, 61 ;
virginianum, 61 ; wurtembergianum,
61

Araucariae, 14

Araucariinese, 14

Araucarioxylon, 61, 62, 65, 70, 72, 151,
156, 204; Edvardianum, 29, 61, 204,
208 ; Hoppertonas, 204, 208 ; obscu-
rum, 204 ; Prosseri, 204, 207 ; virginia-
num, 204, 206 ; Woodworthi, 204, 206

Arbor vita?, 221

Arizona, 192

Ash, 26

Auriferous gravels, 164

Australasia, 4

Australia, 8

Bacilli, 182

Bacillus, 177 ; anthracis, 181 ; anthrax,
181 ; cholera, 181 ; hay, 181 ; sub-
tilis, 181 ; thermophilus, 181 ; tuber-
cle, 181 ; of tuberculosis, 181

Bacteria, 165, 175, 177, 180, 181

Bald cypress, 217

Balm-of-Gilead fir, 258

Balsam, 255; Canada, 21; mountain,
256; she, 255; xylol, 23

Balsam fir, 256, 258, 263; Canada, 258

Bastard cedar, 219

Big tree, 225

Bismarck brown, 23

Black larch, 278

Black pine, 328, 334

Black spruce, 289

Blue spruce, 289

Bordered pits, 19, 21, 33, 39, 46, 59-
77, 103-105, 113, 114, 129, 133, 152,
155, 156, 184, 188, 353

Bozeman, 166

Britton, N. L., 8

Brown coal, 172

367

368

ANATOMY OF THE GYMNOSPERMS

Brown rot, 190

Bull pine, 334, 335, 342

Bunya-Bunya, 205

Calamopitys, 154; saturni, 155

Calcification, 171, 173

Calcified, 191

Calcite, 173, 174

Calcium carbonate, 174

Calcium oxalate, 109

California, 165

California juniper, 166

California nutmeg, 211

Campbell, D. H., 25

Canada, 25, 167

Canada balsam, 21

Canada balsam fir, 258

Canadian Pacific Railway, 164

Canoe cedar, 221

Carbon, 172, 191, 192

Carbon dioxide, 177

Carbonization, 171, 173

Carbureted hydrogen, 172

Catalpa, 26, 153, 179; hardy, 179

Catalpa speciosa, 178, 190

Cedar, 249; bastard, 219; canoe, 221 ;
ground, 250; incense, 219; Oregon,
232 ; Port Orford, 232 ; post, 219 ; red,
164, 178, 184, 190, 221, 246; rock,
249; shrubby red, 251 ; stinking, 21 1 ;
western white, 221 ; white, 219, 221,

~ 232

Cedar pine, 323

Cedar ties, 170

Cell wall, 184, 191

Cells, parenchyma, 60, 79, 85, 88, 89,
93, 100, 105, 115, 116, 128, 131, 135,
151 ; ray, 184, 353; resin, 17, 19, 58,
89, 111-122, 124-129, 134, 138-142,

151-353
Cellulose, 47, 48, 163, 166, 172, 179,

181, 189, 190, 191
Celluloxylon prima;vum, 192
Census, tenth United States, 4, 7, 8,

162

Chamaecyparis, 229
Chamberlain, C. J., 154
Checkered-barked juniper, 251
Chlorophyll, 177
Cholera bacillus, 181
Classification, 193, 195
Closing membrane, 59
Cloves, oil of, 23
Coal, brown, 172; soft, 172
Coleman, A. P., 164
Colonial pine, 205
Colorado spruce, 289
Combustion, spontaneous, 173

Common juniper, 247

Conflagration, 172

Coniferae, 14, 35, 39, 40, 43, 49, 58, 60,
62, 65, 77, 88-90, 102, 105-107, 112,
129, 137, 148, 155

Coniferales, 6, 7, n, 14, 24, 28, 29, 31,
36, 38, 44, 57, 58, 62, 65, 66, 70, 71,
74, 75> 77, 79. 83, 89, 102, 105, 108,
109, in, 118, 143, 148, 151, 154-156,

^ 159, 195, 210

Coniferous wood, 184

Constable, Howard, 6

Coonam, 205

Coorong, 205

Cordaitaceae, 14, 38

Cordaitae, 14

Cordaitales, 14, 28, 29, 31, 36, 57,
58, 83, 105, 106, 109, 154-160, 195,
198

Cordaitean, 156

Cordaites, 60, 67, 71-73, 199, 202; aca-
dianum, 60, 67, 71-73, 199, 202; an-
nulatum, 73, 199, 201 ; Brandlingii,
38> 39, 73; Clarkei, 61, 73, 198, 200;
Hallii, 199, 202; hamiltonense, 60,
71, 73, 199, 200; illinoisense, 73, 199,
201; materiarium, 71, 73, 199, 202;
materioide, 73, 199, 201 ; Newberryi,
60, 61, 71, 73, 198, 200 ; ohioense, 73,
199, 202; ouangondianum, 73, 199,
201; pennsylvanicum, 198, 199; re-
centium, 72, 73, 199, 200

Cork, 172, 191

Coulter, J. M., 154, 155, 160

Cowdie pine, 203

Cretaceous, 68, 174, 192

Cryptomeria, 14, 51, 76, 82, 117, 144,
146, 197, 216; japonica, 50, 216,

353

Crystals, no, in, 192

Crystallization, 192

Cumburtu, 205

Cupressineae, 14, 19, 57, 112, 117, 119-

^ 122, 144, 156, 187

Cupressinoxylon, 13, 230

Cupressoxylon, 13, 62, 192, 230, 238 ;
arkansanum, 231, 240; Calli, 231,
244; cheyennense, 230, 238; colum-
bianum, 231, 241 ; comanchense, 230,
239; Dawsoni, 68, 71, 76, 231, 240;
elongatum, 231, 242; glasgowi, 231,
242 ; macrocarpoides, 230, 238 ;
McGeei, 231, 243 ; pulchellum, 231,
239; Wardi, 231, 241

Cupressus, 10, 13, 14, 32, 51, 76, 82, 83,
87-90, 94, 99, 100, 105, 107, 115, 143,
144, 146, 157, 197, 228, 229, 235;
arizonica, 99, 100, 230, 236, 359;

INDEX

369

Goveniana, 99, 100, 230, 237, 359;
Lawsoniana, 229, 232, 359; Macna-
biana, 83, 230, 236, 359 ; macrocarpa,
76, 230, 235, 359 ; nootkatensis, 69,
88, 229, 233, 359; obtusa, 229, 234,
359; pisifera, 76, 86, 100, 229, 233,
359! pygma^3-) 8; thyoides, 99, 100,

i?o, 359

Cupric acetate, 55

Cutin, 191

Cycadaceas, 38, 151, 155, 160

Cycadales, 14, 155

Cycadean, 155

Cycadofilices, 45, 149, 151, 154-156,
1 60

Cycads, 95, 150, 151

Cypress, 236, 237; bald, 217; decidu-
ous, 217; Lawson's, 232; Monterey,
235 ; Sitka, 233 ; yellow, 233

Cysts, 117, 124, 128-131, 134, 136-146,

^ 150, 152

Czapek, Fr., 190

Dahlonega, 168

Dammar, gum, 56

Dammara, 14, 29, 51, 54, 57, 58, 62, 66,

67, 70, 72-76, 82, 119-122, 151, 156,

158, 197, 203; australis, 54-56, 62,

65, 66, 203, 358
Dawson, Sir J. W., 208, 214
De Bary, A., 25, 28, 33, 35, 37, 39, 44,

64, 66-69, 88, 104, 129, 130, 141, 142,

148, 178

De Vries, H., 152
Decay, 163, 175-192
Deciduous cypress, 217
Desiccation, 181
Devonian, 11, 171, 173
Digger pine, 342
Don River, 214
Don valley, 164-169
Douglas fir, 31, 32, 52, 166, 183, 272-

274

Drought, 25, 26
Dry rot, 178, 182, 185
Dudley, P. H., 170, 171, 178, 183
Durability, 162-174

Eichler, A. E., 44, 109, 112, 115, 116,

156

Elder, 26
Endophytic, 177

Engineering Building, MacDonald, 183
Englemann's spruce, 286
Engler, A., 7
English maple, 26
Enzymes, 163, iSS, 189
Eocene, 151

Ephedra, 69

Epiphytic, 177

Epithelium, 98, 115-117, 124-136, 140,

Ether, 55

Eusporangiate ferns, 149, 151

Facultative parasite, 178

Facultative saprophyte, 178

Fagus sylvatica, 48

Ferguson, Margaret C., 154

Fernow, B. E., 8, 10, n

Ferns, eusporangiate, 149, 151

Fir, Balm-of-Gilead, 258; balsam, 256,
258, 263; Douglas, 31, 32, 52, 166,
183, 272-274; red, 259, 262; silver,
262; white, 260, 261, 263; yellow,
272

Fires, forest, 25, 172

Fission fungi, 175

Flad, Henry, 6

Florida, 25

Food, 186-188

Forests, petrified, 192

Fossil wood, 172

Fossils, 162-174, 191

Foxtail pine, 308, 309

Frost, 25, 26

Fujimatsu, 280

Fundamental tissue, 148, 149, 152

Fungi, 165, 166, 176, 177, 179, 181-184,
189, 191 ; fission, 175

Fungus, 177, 185, 187, iSS

Fusiform rays, 44, 96, 108, 130, 353

Gases, 172

Georgia, 168

Germination, 182

Ginger pine, 232

Gingko, 14, 28, 51, 52, 65, 74, 76,

82, 99, 105, 109, 119, 130, 156, 196,

209; biloba, no, 209, 358; pusilla,

209

Gingkoaceae, 14
Gingkoales, 14, 28, 36, 58, 62, 66,

70, 74, 83, 106, 109, 154-160, 195,

209

Gingkoinea?, 14
Gland, resin, 140
Glucose, 190
Gray pine, 321
Ground cedar, 250
Ground hemlock, 213
Growth, cessation of, 30 ; eccentricity

of, 28; secondary, 35, 70, 104; ter-

tiary, 35, 38
Growth rings, 24, 32, 40, 117, 127,

138-140; eccentricity of, ?S

370

ANATOMY OF THE GYMNOSPERMS

Gum dammar, 56

Gymnosperms, 13, 33, 36, 38, 57, 58,

60, 150, 153, 154-156
Gymnosporangium clavariasforme, 141

Hackmatack, 278

Hadromal, 190

Hematoxylin, Delafield's, 22

Hard pine, 30, 71, 82, 85, 87, 89, 100,

103, 106, 108, 134, 318
Hartig, Georg Ludwig, 6
Hartig, H., 6, 26
Hartig, Theodor, 6, 182
Haustoria, 177, 186
Heartwood, 179
Hemlock, 178, 266, 268, 275; ground,

213; mountain, 269; western, 270
Hemlock ties, 170
Heterangium, 154; Grievii, 72
Hiba, 215

Hickory pine, 309, 337
Himekomatsu, 316
Hinoki, 234
Hoop pine, 205
Horse-chestnut, 26

Idioblasts, crystallogenous, 109-111

Incense cedar, 219

Infiltration, 192

Injuries, 25, 26

Insects, 25, 26

Intercellular spaces, 46, 127

Intercellular substance, 46, 189

Interglacial, 1 1, 165

Iodine, 49

Iramomi, 287

Iron, sulphide of, 174

Jack, J. G., 8, 10

Jack pine, 321

Japan, 4, 8

Jeffrey, E. C., 8, 13, 20, 96, 102, 108,
122, 139-152, 154, 164

Jersey pine, 338

Jesup, M. K., 8

Juniper, 248-253; California, 166;
checkered-barked, 251 ; common, 247

Juniperus, 12, 14, 28, 32, 51, 52,82-84,
87, 88, 94, 99, 100, 105-107, 118, 119,
141, 144, 146, 196, 244; barbadensis,
8; californica, 165, 245, 248, 359;
communis, 12, 140, 245, 250, 359;
conJHgats, 52 (see J. sabinoides) ;
monosperma, 245, 252, 359; nana,
12, SS, 245, 251, 359; occidentalis,
245- 25T- 359: "gida, 12, 245, 247,
359; sabma, 52, 245, 251, 359; sabi-
noides, 245, 249, 359; scopulorum,

8 ; utahensis, 245, 249, 359 ; virgini-
ana, 5, 50, 164, 165, 178, 184, 190,
245, 246, 359

Kansas, 192
Kaurie, 203
Knob-cone pine, 331
Kuromatsu, 327

Laboratory, hydraulic, 183

Larch, 262, 278 ; black, 278 ; mountain,
280 ; Tyrolean, 26

Larix, 10, 14, 44, 47, 51, 71, 76-78, 83,
89, 90, 93,94, 96-98, 107, 114, 1 19-122,
130-134, 138, 142, 146, 156, 168, 187,
195, 276; americana, 34, 40, 41, 43,
63, 66, 68, 71, 75, 77, 86, 132, 168,
277, 278, 360; leptolepis, 66, 277,
280; 360; Lyallii, 50, 277, 280, 360;
occidentalis, 77, 132, 142, 276, 277,
360

Lawson's cypress, 232

Leaf buds, 26

Lentinus lepideus, 170

Lepidodendron selaginoides, 90

Libocedrus, 14, 19, 49, 51, 76, 86, 87,

94. 95> I05> H7-I20> I44> 146, 196,
219; decurrens, 50, 219, 358

Lignification, 48

Lignified, 163

Lignified wall, 190

Lignin, 48, 172

Lignite Tertiary, 76, 108

Lignites, 173

Live oak, 273

Loblolly pine, 343

Lodge-pole pine, 328

Long-leaved pine, 344

Lyginodendron, 1 54

MacDonald Engineering Building, 183

McGill College, 169

McGill University, 183

Maceration, 5, 69; Schulze's, 49

Macoun, John, 214

Maidenhair tree, 209

Maisonneuve, 170

Maki, 216

Mangin's reaction, 49, 190

Manitoba, 214

Maple, English, 26; Norway, 159, 160

Marsh pine, 320

Maxwell, E. J., 8

Medullary rays, 18, 20, 33, 39, 53, 56,

78-108, 130, 135, 141, 143, 151, 152,

1 86, 187

Membrane, closing or pit, 59
Meristematic, 140

INDEX

*> '

J,

Merulius lachrymans, 178, 182
Microtome, 22
Mineralization, 173
Miocene, 141, 164, 191
Missionaries, Franciscan, 25
Momi, 264
Montana, 166, 214
Monterey cypress, 235
Monterey pine, 341
Montreal, 25, 26, 169, 170
Moreton Bay pine, 205
Mountain hemlock, 269
Mountain larch, 280
Mounting sections, 22
Mucilage canals, 149, 151
Mueller, Baron F. von, 8
Muller, N. J. C., 6
Muro, 247

Mycelia, 164-169, 176, 184-189
Mystic Lake, 166

Natural History Society of Montreal,

170

Natitrlichen Pflanzenfamilien, 7
Nedzuko, 222
Nematophycus, 173; crassus, 192;

Logani, 192
Nordlinger, H., 6
Norfolk Island pine, 205
North America, 4 ; silva of, 7, 8
Norway maple, 159, 160
Norway pine, 325
Nut pine, 305-307, 310
Nutmeg, California, 211

Oak, live, 273; red, 273; white, 273

Obligate parasite, 178

Obligate saprophyte, 178

Oil of cloves, 23

Oils, fixed, 55

Old field pine, 343

Oregon, 191

Oregon cedar, 232

Osmundites skidegatensis, 173

6-T6hi, 288

Oxidation, 163, 177

Oxygen, 172, 179, 180, 191

Paleobotany, 151

Panama Railway, 170

Parasites, 140, 141, 177; facultative,

178
Parenchyma cells, 60, 79, 85, 88, 89,

93, 100, 105, 115, 116, 128, 131, 135,

IS'

Parenchyma tissue, 192

Parenchyma tracheids, 17, 33, 35, 115^
117, 120, 124-136, 140

Parenchyma, wood, 17, 53, 55, 58, 109,
112, 122

Parenchymatous, 33, 78

Pathological, 148

Patton spruce, 269

Peat, 172

Pectic acid, 49

Pectin, 47

Penhallow, D. P., 25, 102, 122, 144, 192

Penicillium glaucum, 182

Peridermium pini, 140

Permian, 192

Petrified forests, 192

Phosphureted hydrogen, 172

Photography, 23

Phylogeny, 58, 118, 138-153, 154-161

Phylum, 148, 155

Picea, 10, 12, 14, 51, 76, 78, 82, 83, 87,
89, 90, 93, 94, 96-98, 100, 1 06, 107,
112, 118-121, 128, 130, 133, 134, 138-
146, 156, 167, 187, 195, 281; alba,

133, 134, 167, 282, 285, 360; bicolor,
66, 282, 288, 360 ; Breweriana, 283,
360 ; Engelmanni, 282, 286, 360 ;
jesoensis, 283, 287, 360; nigra, 133,

134, 167, 169, 282, 289, 360; polita,
1 06, 282, 287, 360 ; pungens, 134, 282,
289,360; rubra, 283, 284,360; sit-
chensis, 134, 281, 290, 360

Pierce, J. G., 148

Pine, black, 328, 334; bull, 334, 335,
342 ; cedar, 323 ; colonial, 205 ; cowdie,
203; digger, 342; foxtail, 308, 309;
ginger, 232 ; gray, 321 ; hard, 30, 71,
82, 85, 87, 89, 100, 103, 106, 108, 134,
318; hickory, 309, 337; hoop, 205;
Jack, 321; Jersey, 338; knob-cone,
331 ; loblolly, 343; long-leaved, 344;
lodge-pole, 328; marsh, 320; Monte-
rey, 341 ; Moreton Bay, 205 ; Nor-
folk Island, 205; Norway, 325; nut,
305-307. 310; old field, 343; pitch,
318, 330; pond, 320; prickle-cone,
339; red, 170, 325; sand, 318;
scrub, 318, 321, 322, 338 ; short-
leaved, 324; slash, 345; soft, 71,
103, 106, 134, 305; soledad, 332;
southern, 162, 344; spruce, 318, 323,
328; sugar, 311; swamp, 345; table
mountain, 337; Weymouth, 315;
white, 162, 312-315, 317,323; yellow,

170, 324. 329. 333. 335' 345
Pinoideae, 14
Pinon, 305-307, 310
Pinoxylon, 13, 304; dacotense, 304,

34°

Pinus, 10-14, 19, 44, 47, 51, 62, 66, 68,
71, 75-83. 85, 88-89, 99, 103-108,

372

ANATOMY OF THK ( 1\ -M NOSI'KRMS

112, II6-I2I, 129, 133-136, 138-146,
156, 158, 1 60, 195, 291, 292, 305;

albicaulis, 96, 294, 316, 361 ; aristata,
93, 108, 293, 309, 360 ; arizonica, 108,
304, 329, 361 ; Balfouriana, 86, 293,
308, 360; Banksiana, 296, 299, 321,
361; cembroides, 293, 306, 360; chi-
huahuana, 300, 333, 361; clausa, 71,
77. 89. 93. 98. 99. 103, 104, 296, 297,
318, 361 ; columbiana, 304, 348 ; con-
torta, 13, 299, 322, 361 ; Coulteri, Si,
108, 301, 330, 361 ; cubensis, 26, 63,
68-71, 79, Si, 84, 89, 92, 93, 100,
108, 134, 135, 296-299,301-303, 344,
361; densiflora, 93, 295, 321, 361;
echinata, 11, 26, 297, 324, 361;
edulis, 108, 293, 310, 360; flexilis,
294. 3U. 361 ! glabra, 11, 93, 100,
108, 298, 300, 302, 304, 323, 361 ;
inops, Si, 89, 104, 108, 302, 304,
338, 361 ; insignis, 69, 81, 108, 303,
341, 361 ; Jeffrey!, 13, So, 92, 108,
301, 334, 361 ; koraiensis, 84, 92, 104 ;
Lambertiana, 71, 77, 103, 135, 136,
294, 311, 360; monophylla, 86, 93,
292, 307, 360; monticola, 93, 294,
312, 360; muricata, 300, 301, 339,
361 ; Murrayana, 12, Si, 92, 99, 100,

103, 108, 296, 301, 328, 361; palus-
tris, 26, 31, 51, 71, 77, So, 89, 92, 93,
96, 97, 100, 105, 106, 162, 170, 277,
298, 302, 303, 344, 361 ; Parryana,
106, 292, 305, 360; parviflora, 294,
316, 361 ; ponderosa, 13, 96, 97, 108,
302> 334, 361 : pungens, 68, 81, 89,

104, 108, 134, 135, 299, 302, 337, 361 ;
reflexa, 78, 79, 84, 95, 135, 293, 314,
361 ; resinosa, 31, 84, 92, 105, 170,
188, 295, 325, 361 ; rigida, 103, 104,
296, 298, 299, 300, 318, 361 ; Sabin-
iana, 71, 77, 108, 303, 342, 361 ; scopu-
lorum, 301, 337, 361 ; serotina, 85, 99,
298, 299, 320, 361 ; strobus, 63, 64,
68, 69, 162, 299, 315, 361 ; sylvestris,
69; taeda, n, 34, 40, 41, 43, 69, 71,
77, So, 84, 89, 91-93, 105-108, 134,
296-298, 301-303, 343, 361; Thun-
bergii, 92, 105, 295, 327, 361 ; Tor-
reyana, 31, 89, 303, 332, 361 ; tropi-
calis, 295, 326, 361 ; tuberculata, 303,
331, 361; virgiiiiaiia. See Pinus
inops.

Pit membrane, 59

Pitch pine, 318, 330

Pits, 187; bordered, 19, 21, 113, 114,

129, 133, 152, 155, 156; multiseriate,

67
Pitted tracheids, 17, 33, 34, 45-53

Pityoxylon, 13, 108, 192, 304, 346;
Aldersoni, 304, 346 ; amethystinum,
304, 347; chasense, 20, 305, 349;
Peali, 305, 349 ; scituatense, 305, 350 ;
statenense, 305, 349

Pleistocene, 5, 21, 164, 167, 168

Podocarpacea?, 14, 82

Podocarpus, 14, 51, 74, 76, 112, 115-
119, 122, 144, 146, 197, 216; macro-
phylla, 216, 358

Polypori, 178, 185

Polyporus, catalpa?, 179; juniperinus,
185, 190; Schweinitzii, 191; sulphu-
reus, 191 ; vaporarius, 191 ; versi-
color, 163, 179, 190

Pond pine, 320

Poroxylon, 155, 156, 160

Port Orford cedar, 232

Post cedar, 219

Potassium hydrate, 47, 55, 56

Prantl, K., 7, 138, 149

Preservation, 162-174

Prickle-cone pine, 339

Primary wall, 46, 49, 59

Process plates, 23

Prosenchymatous, 33

Protodammara, 203

Protoplasm, 181

Protoxylem, 38, 40, 59, 155

Pseudotsuga, 9-14, 27-51, 76, 77, 82,
88, 90, 93-98, 107, 114-122, 130-134,
138, 142-146, 156, 195, 271 ; Doug-
lasii, 12, 26, 27, 31, 41, 43, 96, 131,
166, 271, 272, 360; macrocarpa, 12,
41, 43, 52, 1 06, 131, 166, 271, 275,
360; miocena, 43, 191, 272, 276

Pteridophytes, 35

Pyritization, 171, 174

Queen Charlotte Islands, 174
Quercus alba, 273 ; rubra, 273 ; virens,

273

Radial sections, 18, 79; wall, 60, 136

Ray cells, 184; fusiform, 44, 96, 108,
13°. 353; medullary, 18, 20, 33, 39,
53, 56, 78-108, 130, 135, 141, 143,
151, 152, 186, 187; tracheids, 33, 35,
85, 88-93, I02> 105-108, 115, 353

Red cedar, 164, 178, 184, 190, 221, 246

Red fir, 259, 262

Red oak, 273

Red pine, 170, 325

Red spruce, 284

Redpath Museum, 169

Redwood, 224

Reservoirs, secretory, 58, 123, 128, 130,

I36, MS

INDEX

•5 »7 i
6/3

Resin canals. See Resin passages
Resin cells, 17, 19, 58,89, 111-122, 124-

129, 134, 138-142, 151, 353
Resin cysts, 17, 19, 58, 121-124, '38-

146, 150, 152
Resin flux, 140
Resin gland, 140
Resin passages, 17, 18, 19, 20, 44, 58,

78, 79, 89, 98, 108, 111-155, .187, 353
Resinous tracheids, 34, 53-58, 120, 122
Rhizopus nigricans, 182
Rhus typhina, 26
Rock cedar, 249
Rocky Mountains, 214
Rot, brown, 190; dry, 178, 182, 185;

soft, 190; white, 190
Ruthenium, red, 47, 49

Salicacea2, 153

Salisburia, 209

Sambucus racemosa, 26

Sand pine, 318

Sanio's bands, 53, 55

Saprophyte, 177; facultative, 178;

obligate, 178

Sargent, C. S., 4, 7, 8, 13, 162
Savin, 211, 246
Sawara, 233
Scalariform, 38
Scarborough period, 167
Schizogenously, 46, 116
Schizomycetes, 175
Schrenk, H. von, 163, 178, 179, 190
Schulze's maceration, 49
Scott, D. H., 155, 160
Scrub pine, 318, 321, 322, 338
Secondary growth, 70, 104, 189
Secondary wood, 34, 155
Secretory reservoirs, 58, 123, 128, 130,

Sections, mounting, 22 ; preparation of,
21 ; radial, 18; removal of air from,
22; tangential, 18, no, in; trans-
verse, 17

Sequoia, 10, 13, 14, 19, 25, 51, 52, 62,
68, 75-77, 82-87, 94, 99, 100, 107,
112-123, 127-129, 141, i43-J52> J57.
196, 223; Burgessii, 20, 96, 108, 126,
142, 151, 224, 226; gigantea, 52, 65-
67, 84, 86, 139-144, I52> J57< 223,
225, 358 ; Langsdorfii, 142, 144, 224,
226; magnifica, 223, 226; Penhal-
lowii, 96, 1 02, 1 08, 126, 140-144, 148,
164, 224, 228; sempervirens, 52, 86,
94, 113, 114, 117, 121-127, 141-144,
148, 157, 195, 223, 224, 358

She balsam, 255

Shirabe, 257

Short-leaved pine, 324

Shrubby red cedar, 251

Sierra Nevada Mountains, 164

Sigillaria, 75

Silica, 192

Silicification, 5, 167, 171, 173, 174

Silicified, 166, 172, 191

Silurian, 171

Silva of North America, 7, 8

Silver fir, 262

Sitka cypress, 233

Sitka spruce, 290

Slash pine, 345

Sodium carbonate, 21

Soft coal, 172

Soft rot, 190

Soledad pine, 332

Southern pine, 344

Spiral tracheids, 17, 21, 33-45, 152, 353

Spirillum choleras-asiaticas, 181

Spontaneous combustion, 172

Spores, 176, 181, 182, 184

Spring tracheids, 52, 86, 87

Spring wood, 17, 21, 30, 32, 49, 50, 58,
66,69, 104, no, 117, 127, 128, 131-
134, I39-M2, 166, 184, 273

Spruce, black, 289 ; blue, 289 ; Colo-
rado, 289 ; Engelmann's, 286 ; Pat-
ton, 269 ; pine, 318, 323, 328; red,
284 ; Sitka, 290 ; tideland, 290 ; weep-
ing, 283 ; white, 285, 286

Staining, 22

Starch, 179

Stigmaria, 95

Stinking cedar, 211

Stratification, 47

Striation, 47, 69, 191

Sugar, 179

Sugar pine, 311

Sugi, 216

Sulphide of iron, 174

Sulphuric acid, 49, 190

Sumac, 26

Summer tracheids, 43, 52, 86
Summer wood, 17, 21, 31, 32, 39, 49,
50, 58, 68, 69, 92, 104, no, 117, 118,
121, 128, 131, 132, 134, 138-145. l66>
184, 273, 353
Swamp pine, 345
Systematic, 193, 195

Table mountain pine, 337
Tamarack, 277, 278, 280
Tangential sections, 18, 70, no, in
Tangential walls, 65, 66, 75, 129, 136
Taxaceas, 14, 40, 66, 74, 77, 105, 106,

I 12

Taxodiineae, 14, 19, 156

374

ANATOMY OF THE GYMNOSPERMS

Taxodium, 10, 14, 19, 51, 76, 82, 84,87,
1 12-122, 144, 196, 217; distidium,
31,81, 87, 217; laramianum, 217, 218

Taxus,9, 14, 28, 32, 34, 37,40,41, 44, 47,
69, 76, 99, 1 1 2, 1 1 9, 1 44, 1 48, 1 5 1 , 1 84,
196, 212; brevifolia, 42,94, 213, 214,
358; canadensis, 42, 50, 51, 212, 213,
358; cuspidata, 42, 99,213, 214,358;
floridana, 42, 74, 213, 358

Temperature, 181, 182 ; maximum,
182; minimum, 181 ; optimum, 181

Tenth census of the United States, 4,
7,8

Tertiary, 76, 164; lignite, 76, 108

Tertiary wall, 36, 40, 47, 190

Thiselton-Dyer, Sir W. T., 8

Thujopsis, 14, 51, 76, 82, 117-119, 144,
146, 197, 215; dolabrata, 215, 358

Thuya, 10, 14, 32, 51, 76, 82, 89, 99,
107, 117, 119, 122, 144, 146,157, 197,
220; gigantea, 82, 88, 99, 220, 221,
358; japonica, 88, 220, 222, 358;
occidentalis, 220, 221, 358

Thyloses, 79, 126, 129, 131-137, 143,

353

Tideland spruce, 290

Ties, cedar, 170; hemlock, 170

Tissue, fundamental, 148, 149, 152;
wood, 172, 1 86

Tissues, lignified, 163, 189

T6hi, 287

Toronto, 164, 167, 214

Torreya, 9, 14, 32, 34, 37, 40-47, 51,
52, 69, 75, 99, 112, 119, 144, 151, 184,
196, 210; calif ornica, 41, 43, 74, 210,
211, 358; nucifera, 41, 66, 74, 99,
210, 212, 358; taxifolia, 41, 49, 66,
69, 7i, 74, 77, 210, 211, 358

Tracheae, 39

Tracheids, 17, 21, 30, 33-58, 140, 141,
152, 169, 184, 186, 188; parenchyma,
J7, 33, 35- 11S~117, 120, 124-136,
140; pitted, 17, 33, 34, 45-53; ray,
33, 35> 85, 88-93, l°^ 105-108, 115;
resin, 34, 53-58, 120, 122; spiral, 17,
21, 33-45, i52> 353; spring, 52, 86,
87; summer, 43, 52, 86; wood, 30,
34, 88, 1 05, 1 1 o, 1 1 5, 1 27, 1 28, 132, 1 36

Trametes pini, 190

Transition, 31 ; zone, 19, 152

Transverse sections, 17

Traumatic, 141, 148

Trees, age of, 25

Tsuga, 10, 14, 51, 76, 83, 88, 90, 93,
107, 114, 116, 118-123, I28, 129, 139-
148, 156, 197, 265, 267; canadensis,
63, 7i, 77, 170, 178, 265, 266, 359;
caroliniana, 127, 129, 138, 145, 266,

359; Mertensiana, 128, 129, 132, 138,
142, 145, 195, 265, 270, 360; Pat
toniana, 266, 269, 359; Sieboldii, 50,
266, 267, 359

Tubercle bacillus, 181

Tubeuf, K. F. von, 6, 140, 190

Tumor, 148

Tyrolean larch, 26

Vallisneria spiralis, 165
Vascular plants, 192

Walchia, 156

Wall, cell, 184; lignified, 190; primary,
46,49, 59, 189, 190; radial, 60, 136;
secondary, 36, 40, 47, 49, 60, 69, 169;
tertiary, 36, 40, 47, 190; tangential,
65, 66, 75, 129, 136

Warming, E., 181

Weeping spruce, 283

\Veiss, G. A., 48

Western hemlock, 270

Western white cedar, 221

Western yew, 214

W'eymouth pine, 315

W7hite cedar, 219, 221, 232

White fir, 260, 261, 263

White oak, 273

White pine, 162, 312-315, 317, 323

White rot, 190

White spruce, 285, 286

Wittstein, G. C., 55

Wood, coniferous, 184; durability of,
162-174 ; fossil, 172 ; preservation of,
162, 174; secondary, 34, 155; spring,
17, 21, 30, 32, 49, 50, 58, 66, 69, 104,
1 10, 117, 127,128, 131, 134, 139-142,
166, 184, 273 ; summer, 17, 21, 31, 32,
39, 49, 50, 58, 68, 69, 92, 104, no, 117,
118, 121, 128, 131, 132, 134, 138-145,
166, 184, 273, 353

Wood parenchyma, 17, 53, 55, 58, 109,

112, 122

Wood parenchyma tracheids, 35
Wood tissue, 172, 186
\Vood tracheids, 30, 34, 88, 105, no,
115, 127, 128, 132, 136

Xylem, 149
Xylol balsam, 23

Yellow cypress, 233

Yellow fir, 272

Yellow pine, 170, 324, 329, 333, 335,

r345
Yew, 214; American, 213; western, 214

Zea, 35

PLATES

PLATE i. PSEUDOTSUGA DOUGLASII. Transverse section showing the structure

of the fine-grained wood, x 41.2

PLATE 2. TORREYA TAXIFOLIA. Transverse section showing the coalescence
of growth rings in an eccentric development. X 51

PLATE 3- CORDAITES J>RAM>I.IN'GII. Radial section of the transition zone next

the pith, showing the protoxylem to be wholly composed of spiral tracheids.
X 153-4

IM.ATK .). CORDAITES BRANDLINGII. Radial section of the transition zone imme-
diately external to the preceding, and showing the spirals of the tracheids
passing into scahu iforni structure. X 153.4

PLATE 5. CORDAITES BRANDLINGII. Radial section immediately external to
fig. 4, showing the complete formation of scalariform structure, x 153.4

PLATE 6. CORDAITES BRANDLINGII. Radial section immediately external to
fig. 5, showing the reduction of the scalariform structure into imperfectly
formed, multiseriate, bordered pits, x 153.4

PLATE 7. CORDAITES ACADIANTM. Radial section showing the completed bor-
dered pits with a primitive arrangement. < 180

I'I.VIK S. COKDAITI-S N'FWBF.RRYi. Radial section showing the peculiar group-
ing of the bordered pits. X

PLATE 9. CUPRESSUS NOOTKATENSIS. Radial section showing the longitudinal
distribution of fungus mycelui in the tracheids of the wood. X 150

•

PLATE 10. CUPRESSUS NOOTKATENSIS. Radial section .showing the transverse
distribution of fungus mycelia in the tracheids of the wood, and their ivLui<>ns
to the tracheid walls, x 150

PLATK. u. PSEUDOTSUGA MIOCENA. Radial section showing the effects of decay
in breaking up the substance of the cell wall along the lines of striation.
X 127.8

PI.ATK [2. CORDAITES MATERIARIUM. Transverse section showing the absence
of growth rings, the character of the trachricls, and the distribution of resinous
tracheids near the medullary rays, x 40.9

PLATE 13. CORDAITES MATERIARIUM. Tangential section showing the character
of the ordinary medullary rays which are sometimes two-seriate, c 40.9

PLATE 14. DAMMARA AUSTRALIS. Transverse section showing the clearly denned
growth ring and its summer wood, and the distribution of resin cells near the
medullary rays. X 46.8

PLATE 15. DAMMARA AUSTRALIS. Tangential section showing the character of
the medullary rays and the occurrence and location of plates of resin. X 52

PLATE 16. ARAUCARIA GLAUCA. Transverse section showing the general char-
acter of the structure, the absence of growth rings, and the distribution of
resinous tracheids. X 46.8

PLATE 17. ARAUCARIA GLAUCA. Tangential section .showing the character of

the medullary rays, x 46.8

PLATE 18. GINGKO BILOBA. Transverse section showing the development of a
strong growth ring, and the occurrence of crystals as indicated by dark spots
in line with the tracheids. X 46.8

PLATE 19. GINGKO BILOBA. Tangential section showing the character of the

very low medullary rays. X 52

PLATE 20. TORREYA TAXIFOLIA. Transverse section showing the very thin and

open summer wood. X 46.8

PLATE 21. TORREYA TAXIFOUA. Tangential section showing the character of

the medullary rays. X 52

PLATE 22. TAXUS CUSPIDATA. Transverse section showing the rather dense
structure of the thin summer wood. X 46.8

; :

: (

! i ! • ;

• I

i I

i •;

] !

,

PLATK 23. TAXUS CTSPIDATA. Tangential section showing the character of the
very narrow and rather high medullary rays, x 52

PI.ATK 24. THUJOPSIS IHM.AHRATA. Transverse section showing the narrow

L:,]' iwth rings, the thin summer wood, and the distribution of resin celN i:i
the spring wood, x 4(1. S

1

I ;

1 i

1

1

I i

1

1

|

1

f

1

If!

P.

III

i
1

i

* *

I

j

»

1

.

\

.

.

*

' i '
i • ' ,

1

1

1

.

, ' 'l i

PLATE 25. THUJOPSIS DOLABRATA. Tangential section showing the character
of the low rays in the spring wood. X 52

•

>-

•

• - t

~ k

•

'

. .

PLATE 26. CRYPTOMERIA JAPONICA. Transverse section showing the very dense
summer wood and the distribution of resin cells, x 46.8

PLATE 27. CRYPTOMERIA JAPONICA. Tangential section showing the character
of the low rays in the spring wood. X 52

PLATE 28. PODOCARPUS MACROPHYLLA. Transverse section showing the general
structure and the distribution of the numerous resin cells, x 46.8

PLATE 29. PODOCARPUS MACROPHYLLA. Tangential section showing the struc-
ture and very resinous character of the medullary rays, in the region between
the spring and summer woods, x 46.8

PLATE 30. TAXODIUM DISTICHUM. Transverse section showing a double zone of
summer wood and the distribution of resin cells in tangential rows. < 4<>.S

<;

PLATE 31. TAXODIUM DISTICHUM. Tangential section showing the character

of the medullary rays, x 46.8

PLATE 32. LIKOCEDRUS I>E< i RRENS. Transverse section showing the dense
wood and the distribution of the resin cells. X 46.8

PLATE 33. LIBOCEDRUS DECURRENS. Tangential section showing the character
of the rather broad medullary rays and the occurrence of resin, x 64

PLATE 34. THUYA OCCIDENTALIS. Transverse section showing the narrow
growth rings, the very thin summer wood, and the distribution of the resin
cells. X 46.8

PLATE 35- THUYA OCCIDENTALTS. Tangential section showing the very narrow
medullary rays with narrowly oblong cells, taken from the spring wood.
X 64

PLATE 36. SEQVOIA SEMI-ERVIRENS. Transverse section showing the very large
tracheids of the spring wood with thin walls, the rather dense summer wood
with a somewhat abrupt transition from the spring wood, the scattering dis-
tribution of the resin cells, and the occurrence of resin sacs in the initial layer
of the spring wood. X 46.8

PLATE 37- SEQUOIA SEMPERVIRENS. Tangential section from the spring wood
showing the very broad medullary rays, the cells of which are equal and
uniform. X 64

PLATE

38. CUPRESSUS GOVENIANA. Transverse section showing the very thin
summer wood and the distribution of the resin cells, x 46.8

if ':? HI *

.' \. j » fc

t, V §

& I

PLATE 39. CUPRESSUS GOVENIANA. Tangential section showing the very broad

and low medullary rays, x 52

PLATE 40. JUNMPERUS CALIFORNICA. Transverse section showing the char-
acter of the growth rings and the distribution of the resin cells. X 46.8

:e a

PLATE 41. JTNIPERUS CALIFORNICA. Tangential section through the spring
wood showing the character of the low medullary rays. X 64.8

PLATE 42. ABIES NOBILIS. Transverse section showing the occurrence of resin
canals and the distribution of scattering resin cells on the outer face of the
summer wood. X 39.2

PLATE 43. ABIES NOBILIS. Tangential section showing the character of the

medullary rays, x 46.8

I'I.ATK 44. TSI'GA I'ATTOMAXA. Transverse section showing the character of
the summer wood and the distribution of the resin cells on the outer face
of the growth ring. X 46.8

PLATE 45. TSUGA PATTONIANA. Tangential section through the spring wood
showing the character of the medullary rays, x 46.8

PLATE 46. PSEUDOTSUGA DOUGLASII. Transverse section showing the broad
and dense summer wood in a coarse-grained form, and the distribution of
the resin canals. X 46.8

I'I.ATF. 47. PSEUDOTSUGA DoUGLASii. Tangential section showing the low and
broad ordinary rays, together with the often very unequal and narrow fusi-
form rays. X 46.8

I'I.ATF. 48. LARIX AMERICANA. Transverse section showing the dense and broad
summer wood and the distribution of resin canals, x 46.8

PLATE 49. LARIX AMERICANA. Tangential section from the spring wood show-
ing the narrow ordinary rays and the rather broad fusiform rays. X 46.8

PLATE 50. PICEA NIGRA. Transverse section showing the character of the
general structure and the distribution of the resin canals, x 46.8

,

PLATE 51. PICEA NIGRA. Tangential section through the spring wood showing
the structure of the two forms of medullary rays. X 46.8

PLATE 52. PINTS MONTICOLA. (Type of soft pines, Sec. I.) Transverse section
showing the large and thin-walled tracheids of the spring wood, the very thin
and open summer wood, the large resin canals with the associated paren-
chyma broken out. X 46.8

PLATE 53. PINUS MONTICOLA. Tangential section showing the structure of the
two forms of medullary rays. X 46.8

PLATE 54. PINUS GLABRA. (Type of haul pint-s. Sec. 11. 1 Transverse si
tion showing the very broad and very dense summer wood, and the structure
of a resin canal with very large epithelial cells. >< 46.8

PLATE 55. PINUS GLABRA. Tangential section through the spring wood showing
the ordinary rays with terminal tracheids and with the thin-walled paren-
chyma all broken out; the interspersal of the tracheids and their general
predominance; the structure of the low and rather broad fusiform ray, the
thin-walled parenchyma cells of which have been broken out, leaving only a
portion of the rt-Mn canal in the central tract together with the terminal
tracheids. x 46.8