PREFACE 



phasized. The assumption has been that a beginning student should 

 acquire a working knowledge and appreciation of the field before 

 he is introduced to matters that might confuse him. 



A reasonable background of botanical and scientific experience 

 is assumed so that, in general, college juniors and seniors might be 

 expected to have the greatest appreciation of a course of this kind. 

 A reasonable knowledge of plant physiology is expected, at least 

 enough for comprehension of ordinary physiological processes. 

 Although a student without some taxonomic training could hardly 

 fully appreciate or enjoy an ecology course dealing with com- 

 munities, he could use this book if he had some knowledge of 

 plants. Both common and scientific names have been given reg- 

 ularly or at least the first time a species is mentioned. The plants 

 which are named are almost without exception rather generally 

 known species of long standing. It is not considered necessary, 

 therefore, to include authorities with scientific names since they 

 may invariably be found in standard manuals. 



Suggestions for collateral reading may be found in the selected 

 general references at the ends of chapters. Cited references are in- 

 dicated in the text by number only and are listed in the bibliog- 

 raphy at the end of the book. Citations are made where it seemed 

 desirable to indicate the authority for or give credit for state- 

 ments used in the text. Again, for those who may wish to go to 

 original sources, references to survey and review papers are in- 

 cluded. The bibliographies of these references are usually so ex- 

 tensive that the advanced student who uses them may quickly 

 accumulate all the source material he needs. 



Those who contributed directly or indirectly to the develop- 

 ment of this book are too numerous to mention specifically, but I 

 am deeply aware of my debt to former instructors, my colleagues, 

 and my students. Many have given invaluable aid in the actual 

 preparation of the book. A very special acknowledgment of as- 

 sistance is due Miss Ruby Williams who, through a careful reading 

 of the manuscript, did much to improve the mechanics of organ- 

 ization and to clarify and simplify the presentation. 



The use of the book in mimeographed form provided a test of 

 its value under a variety of conditions in different sections of the 

 country. It was used in classes by Dr. W D. Billings at the Uni- 



