SUBJECTS TREATED IN THIS BOOK 3 
prepares the way for others. On exposed rocks only very small 
plants are able to grow at first, but due to their presence soil 
accumulates and larger plants are able to follow. Such problems 
as the above are studied in Ecology. Ecology studies plants in 
relation to the effects of soil, climate, and friendly, or hostile 
animals and plants. It also studies the effect of the different 
conditions upon the form and structure of plants. 
Piant GkroGRAPHY is much like Ecology and treats of the dis- 
tribution of the different kinds of plants over the earth’s surface. 
Taxonomy, or Systematic Botany, treats of the classification 
of plants. As a result of this kind of study, plants have been 
arranged in groups, such as Alge, Bacteria, Fungi, Mosses, 
Ferns, and Seed Plants. These large groups are further sub- 
divided into smaller groups. Keys have been arranged by which 
plants unknown to the student may be identified. Through the 
study of Systematic Botany one can learn the names and some 
of the characteristics of the different kinds of Grasses, weeds, 
shrubs, and trees that grow on the farm or in any other region. 
Economic Botany treats of the uses of plants to man. 
PALEOBOTANY is concerned with the history of plants as shown 
by their preserved forms, known as fossils, which occur in the 
different layers of rock composing the earth’s crust. Paleobotany 
is studied in connection with Geology. In the study of this 
subject much has been learned about the plants which lived 
millions of years ago, and this knowledge is very useful in under- 
standing the evolution of the plants which now exist. 
Subjects treated in this Book.— To become a master in any 
one of the above subjects would require years of one’s time. A 
study of any of the special subjects of Botany requires a general 
knowledge of the anatomy and the functions of plant struc- 
tures This means that one must have a general course in 
Botany before making a special study of Morphology, Plant 
Physiology, or any of the special botanical subjects. One 
purpose of this book is to give a general knowledge of cultivated 
plants, of plants not cultivated but like the Rusts and Smuts 
related to Agriculture, and of those plants which one must 
know in order to understand the evolution of plants. Another 
purpose is to give such a general knowledge of plant anatomy 
and the functions of plant structures, that one will have the 
necessary knowledge for the study of such agricultural subjects 
