iv PREFACE 



Plants and relate them to such agricultural subjects as Farm 

 Crops, Forestry, and Horticulture, and to the more advanced 

 courses in Botany; (2) to present the kinds of plants with emphasis 

 upon their evolutionary relationships and their economic im- 

 portance; and (3) to present Evolution, Heredity, and Plant 

 Breeding as related to the improvement of plants. 



The topics are arranged in the book in the order in which I 

 usually present them. The presentation of the reproductive 

 structures and processes of Flowering Plants, followed by 

 that of the vegetative organs, has fitted in at Iowa State 

 College with the time of year at which the agricultural students 

 begin the study of Botany and also with the courses in 

 Agriculture. In other schools where conditions are different, 

 other arrangements of the topics are more suitable. In recogni- 

 tion of this fact, most of the chapters have been written so as to 

 be separately understandable, the aim being to make the book 

 adaptable to any arrangement of topics that the teacher may 

 prefer. 



In the discussion of a subject the presentation of the general 

 features precedes that of the particular features, and the latter 

 are presented in most cases by the study of type plants chosen on 

 account of their familiarity and economic importance. 



The book is intended for an entire year's work in Botany and 

 to be accompanied by laboratory work. Where less time is de- 

 voted to the subject, the organization of the chapters so as to be 

 separately understandable permits a selection of topics according 

 to the requirements of the course. 



The reproductive structures and processes in Flowering Plants 

 (Chapters III and IV) are dwelt upon more than is necessary 

 for students who have had a good course in Botany in a high 

 school. A large percentage of the students in my elementary 

 classes have had no Botany and have difficulty in understanding 

 sexual reproduction in Flowering Plants. In an effort to thor- 

 oughly acquaint the student with this subject, I have dwelt at 

 considerable length upon those phases of the subject that are in 

 my experience difficult for the student to understand. In case 

 students are familiar with this subject, parts of Chapters III and 

 IV can be omitted or read hastily in review. 



Usually there are some students in the class that are especially 

 interested in certain topics and desire a more complete discussion 



