Transcriber’s Notes: Underscores “_” before and after a word or phrase indicate _italics_ in the original text. Equal signs “=” before and after a word or phrase indicate =bold= in the original text. Small capitals have been converted to SOLID capitals. Illustrations have been moved so they do not break up paragraphs. Footnotes have been moved to the end of the chapter in which they occur. Typographical errors have been silently corrected. [Illustration: CYCAS REVOLUTA (see page 311). (_Frontispiece._)] ELEMENTARY BOTANY BY GEORGE FRANCIS ATKINSON, PH.B. _Professor of Botany in Cornell University_ _THIRD EDITION, REVISED_ [Illustration] NEW YORK HENRY HOLT AND COMPANY 1905 Copyright, 1898, 1905 BY HENRY HOLT AND COMPANY ROBERT DRUMMOND, PRINTER, NEW YORK PREFACE. The present book is the result of a revision and elaboration of the author’s “Elementary Botany,” New York, 1898. The general plan of the parts on physiology and general morphology remains unchanged. A number of the chapters in the physiological part are practically untouched, while others are thoroughly revised and considerable new matter is added, especially on the subjects of nutrition and digestion. The principal chapters on general morphology are unchanged or only slightly modified, the greatest change being in a revision of the subject of the morphology of fertilization in the gymnosperms and angiosperms in order to bring this subject abreast of the discoveries of the past few years. One of the greatest modifications has been in the addition of chapters on the classification of the algæ and fungi with studies of additional examples for the benefit of those schools where the time allowed for the first year’s course makes desirable the examination of a broader range of representative plants. The classification is also carried out with greater definiteness, so that the regular sequence of classes, orders, and families is given at the close of each of the subkingdoms. Thus all the classes, all the orders (except a few in the algæ), and many of the families, are given for the algæ, fungi, mosses, liverworts, pteridophytes, gymnosperms, and angiosperms. But by far the greatest improvement has been in the complete reorganization, rewriting, and elaboration of the part dealing with ecology, which has been made possible by studies of the past few years, so that the subject can be presented in a more logical and coherent form. As a result the subject-matter of the book falls naturally into three parts, which may be passed in review as follows: