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 IIT 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 
