PREFACE 
It is the purpose of this flora to describe in a systematic way, for the 
use of the beginner, the more important economic plants of California 
in connection with the more important or well-known native plants. 
Every agricultural student should have some training ‘in systematic bot¬ 
any, combined with practise in the use of a flora. Material of the well- 
known native plants, which can usually be had in abundance, furnishes 
an excellent means for studying the distinctive structural features and 
special biology of the more important families. If the cultivated crop 
plants and other economic plants be studied at the same time, the familiar 
plants of both garden and field are thrown into an orderly sequence in 
the student’s mind, because shown in relation to their nearest relatives. 
No course in agricultural botany should be considered satisfactory that 
does not include a study of the relationships of the principal natural 
families of seed plants, their geographic distribution and the place of the 
economic plants amongst them. 
No attempt is made, in this bock, to describe all cultivated plants, any 
more than all native plants. The description of all the cultivated plants 
in California would require perhaps thirty volumes of the present size. 
This book, however, includes a number more than sufficient to exercise 
the student in the characters of the important natural families, and to 
develop for him the fascination of plant relationships. 
For assistance in putting the manuscript through the press the author 
is indebted to Joyce M. Saunders, botanical artist, and A. C. Carlson, 
Associate in Botany, University of California, and to his students and 
research assistants, Elsie M. Zeile and Herbert L. Mason. Other 
acknowledgements are indicated at appropriate places in the text. 
Willis Linn Jepson. 
Berkeley, California, 
Dec. 12, 1923. 
THE DEVELOPMENT OF IDEAS IN CLASSIFICATION 
While the Chaldeans and Egyptians cultivated science, and gave some 
attention to plants, the more important of ancient written records re¬ 
garding botany begin with the Greeks. The earliest study of plants was 
of course economic; plants were looked to for their uses. Practically all 
the essentials of Grecian knowledge is summarized in the Enquiry into 
Plants by Theophrastus, who was the pupil of Plato and fellow-pupil of 
Aristotle. Theophrastus described not only the plants of Greece, but 
from trained scientific observers who accompanied the military expedi¬ 
tions of Alexander the Great to the Orient, he obtained accounts of such 
plants as the Banyan, Myrrh, Cotton Plant and Frankincense. 
Plants were classified by the Greeks into Herbs, Shrubs and Trees, a 
crude arrangement but one which was to last a long time. Theophrastus 
discussed at length and in a highly interesting manner the flowers of 
