An introduction to structural botany

Part II An Introduction

TO

PART II

FLOWERLESS PLANTS

By DUKINFIELD HENRY SCOTT

HONORARY KEEPER OF THE JODRELL LABORATORY, ROYAL BOTANIC GARDENS, KEW AUTHOR OF “ STUDIES IN FOSSIL BOTANY”

WITH 119 ILLUSTRATIONS

FOURTH EDITION

LONDON

ADAM AND CHARLES BLACK 1904

All Rights Reserved.

WELLCOME INSTITUTE

LIBRARY

Coll.

we^VlOmec

Call

No.

NOTE TO THE FOURTH EDITION.

The present edition has been revised and brought up to date where necessary. The most important change is under Type XXI., the Lichens, the description of which has been considerably extended, so as to include an account of the sexual reproduction, the evidence for sexuality in Lichens having been materially strengthened of late years. The author is greatly indebted to Dr. 0. V. Darbishire for various valuable suggestions regarding this group, and especially for the opportunity of making use of the three new Figures (Figs. 102—104), which are taken from Dr. Darbishire’s introduction to Dr. v. Fischer-Benzon’s work on the Lichens of Schleswig- Holstein.

D. H. SCOTT.

September 9, 1903.

Preface To Part It

Owing to the immense variety of organisation among the Cryptogams, it has been necessary to describe a much larger number of types in the present volume than in Part I. While it was possible to give some idea of the main outlines of structure in Flowering Plants by the full description of three representatives, it has seemed desirable to select no less than twenty - three types for the illustration of Cryptogams, and even then many important groups have been left out. The increased number of types has involved a curtness of treatment, in most cases, which only the relative simplicity of many of the forms has rendered possible.

It is hoped, however, that the essential morphological points have been brought out, and that a certain continuity has been maintained throughout the book so that the study of the selected examples may serve to give a connected idea — however elementary — of the great groups of plants. In order to afford a general view of the whole field, the concluding summary has been added.

When theoretical points are touched on, the great aim has been to avoid dogmatism, and, so far as space vn vin

PREFACE permitted, to put the reader in possession of the evidence as a whole. This applies especially to the question of alternation of generations, as to the nature of which such different views are held.

As regards the fundamental homologies between Cryptogams and Phanerogams, an attempt has been made to demonstrate, and not merely to state them. Unless the student be taught to follow the reasoning by which such conclusions are arrived at, morphology loses at once its interest and its educational value.

It may be well to state again explicitly that the use of this book requires to be accompanied from the first commencement onwards — ( 1 ) by the study of living plants in the field, without which all botanical teaching is dull and barren ; and (2) by practical work in the laboratory.

The author is indebted to the Trustees of the British Museum for permission to make use of the cuts, reproduced in Figs. 113-117, from Mr. Arthur Lister’s Monograph of the Mycetozoa. As in Part I., the figures signed 11. S. have been drawn from nature by Mrs. D. H. Scott. Figs. 5 and 44 are the work of Mr. W. C. Worsdell. The source of all figures not original is acknowledged in the descriptions. Special thanks are due to Professor J. Bretland Farmer for his kind help in connection with the Liverworts and the Fucaceax

D. II. SCOTT.

October 12, 1S96.

CONTENTS OF PART II

PACK

Preface , , . . . . , . vii

CHAPTER I Type IV

Selaginella Kratjssiana ..... 1

I. External Characters —

A. Vegetative Organs ..... 2

R. Reproductive Organs ..... 6

II. Internal Characters of the Vegetative Organs , . 7 b. The Leaves . . . . .12

c. The Rhizophores and Roots . . .13

d. Growing-Points and Mode of Branching —

/3. Rhizophores and Roots . . .14

III. Reproduction and Life-History —

a. The Sporangia and Spores . , .16

b. Germination of the Microsporcs . . .20

c. Germination of the Megasporcs . . .24

d. Fertilisation and Embryology . . . 2S

Comparison between Selaginella and the Gymnosperms . 31

ix

X

Type V

FACE

The Male Fern ( Aspiclium Filix-Mas) . . . .37

I. External Characters —

A. Vegetative Organs . ... 38

B. Reproductive Organs . . . , .42

II. Internal Structure of the Sporophyte—

A. The Vegetative Organs —

1. The Stem —

a. The Vascular System . , ,44

/ 3 . Other Tissues of the Stem . . .48

2. The Leaf . . . . 4S

4. The Growing-Points — p. The Root ..... 53

y. The Leaf ..... 55

B. Reproductive Organs of the Sporophyte . . 55

III. The Oopliyte or Sexual Generation —

A. Development and Structure of the Prothallus . 61

B. Development and Structure of the Sexual Organs —

1. The Antlieridia ..... 65

2. The Archegonia ..... 67

C. Fertilisation ...... 69

D. Embryology . . . . . .71

E. Comparison between the Life-History of Ferns and

that of the Higher Plants . . .73

Type VI

The Field Horsetail ( Equisctum arvcnse ) . . .78

I. External Characters of the Sporophyte —

A. Vegetative Organs ..... SO

B. Reproductive Organs ..... S2 xi

II. Internal Structure and Development of the Sporopliyte —

1. Vegetative Organs — b. The Leaves . . . . .90

c. The Roots . . . . .90

d. Growing Points and Branching . . .92

2. Reproductive Organs of the Sporopliyte . . 96

III. Development and Structure of the Sexual Generation

(Oophyte) —

1. The Prothallus . . . . .100 a. The Antheridia . . . . .101

b. The Archegonia . . . . .102

Chapter II Tiie Bryopiiyta . . .109

A. THE LIVERWORTS

Type VII

Pellia epiphylla — a. The Antheridia . . . . .114

b. The Archegonia . . . . .116

c. Fertilisation . . . . .119

3. The Sporogonium or Fruit —

a. External Characters . . . .120

b. Development . . . . .121

Xll

B. THE MOSSES

Type VIII

Pxr.R

Funaeia hygrometrica ...... 126

1. The Leafy Stem —

a. Structure . . . . . .128

b. Apical Development . . . .132

3. The Sporogonium or Fruit . . . .137

4. Germination of the Spores . . . .142

CHAPTER III THE ALGJE A. THE CHLOROPH Y CEA2 Type IX

(Edogonium — a. Asexual . . .

Type X

Ulothrix zonata— -

Type XI

SriROGYRA —

. 146

. 150

. 152

. 159

. 160

. 163

. 170 xm

Type XII

Vaucheria ....

TACK

. 174

. 175

Type XIII

Pleurococcus vulgaris .

B. THE PH^EOPHYCEJE

Type XIV

Ectocarpus siliculosus —

Type XV

Pelvetia canaliculata .

C. THE FLORIDE.E

Type XVI

Callithamnion corymbosum — a. Asexual . . .

1. Sexual

D. THE CYANOPHYCEiE

N OSTOC

Type XVII

XIV

Chapter IV Page

, . 216

Type XVIII

t

Pythium Baryanum . . . . ,

, . 213

, . 221

b. Sexual . . . . .

, . 224

Type XIX

PlLOBOLUS CRYSTALLINES .

, 223

. 229

, . 230

, . 233

Type XX

SpHjEROTHECA Castagnei —

Type XXI

Physcia parietina ...... 240

1. Structure and Mode of Life .... 241

Type XXII

PlJCCINIA GRAM IN IS ...... 253

Type XXIII

The Mushroom ( Agaricus cavipestris ) .... 266

CONTENTS xv

CHATTER V

PA OK

Type XXIV

Bacillus subtilis . . . , , , 273

Type XXV

Cladothrix diceotoma . 273

CHAPTER VI Type XXVI

BADHAMIA UTR1CULARIS —

1. The Plasmodium . . , , <281

2. The Sporangia and Spores . 285-

Chapter VII Conclusion , , , 290'

STRUCTURAL BOTANT part II

FLOWERLESS PLANTS