VI PREFACE. 



standpoint of the different members of the plant, their special 

 function and their special relations to environment. The stem, 

 root, leaf, flower, etc., are carefully examined and their ecological 

 relations pointed out. This together with the study of physiology 

 and representatives in the groups of plants forms a thorough 

 basis for pure plant ecology, or the special study of vegetation 

 in its relation to environment. 



There is a study of the factors of environment or ecological 

 factors, which in general are grouped under the physical, climatic, 

 and biotic factors. This is followed by an analysis of vegeta- 

 tion forms and structures, plant formations and societies. Then 

 in order are treated briefly forest societies, prairie societies, 

 desert societies, arctic and alpine societies, aquatic societies, and 

 the special societies of sandy, rocky, and marshy places. 



Acknowledgments. The author wishes to express his grate- 

 fulness to all those who have given aid in the preparation of this 

 work, or of the earlier editions of Elementary Botany; to his 

 associates, Dr. E. J. Durand, Dr. K. M. Wiegand, and Professor 

 W. W. Rowlee, of the botanical department, and to Professor 

 B. M. Duggar of the University of Missouri, Professor J, C. 

 Arthur of Purdue University, and Professor W. F. Ganong of 

 Smith College, for reading one or more portions of the text; 

 as well as to all those who have contributed illustrations. 



Illustrations. The large majority of the illustrations are new 

 (or are the same as those used in earlier editions of the author's 

 Elementary Botany) and were made with special reference to 

 the method of treatment followed in the text. Many of the 

 photographs were made by the author. Others were contributed 

 by Professor Rowlee of Cornell University; Mr. John Gifford 

 of New Jersey; Professor B. M. Duggar, University of Missouri; 

 Professor C. E. Bessey, University of Nebraska; Dr. M. B. Howe, 

 New York Botanical Garden; Mr. Gifford Pinchot, Chief of 

 the Bureau of Forestry; Mr. B. T. Galloway, Chief of the 

 Bureau of Plant Industry; Professor Tuomey of Yale University; 

 and Mr. E. H. Harriman, who through DC. C. H. Merriam 

 of the National Museum allowed the use of several of his copy- 



