4 A TEXT-BOOK OF BOTANY 
tions; and a plant with several organs has so many delicate 
adjustments to care for that it is impossible, as yet, for us 
to explain why all of its parts are placed just as they are. 
7. Some conspicuous organs.—The prominent plants, 
which are spoken of as herbs, shrubs, and trees, have three 
conspicuous organs, root, stem, and leaf, which are con- 
cerned with nutrition; and most of these plants have at 
some time also another structure, the flower, which is con- 
cerned with reproduction. Our first attention will be given 
to these three great nutritive organs. A tree, for example, 
has its roots extending more or less widely through the soil; 
from the roots a stem rises into the air and branches more or 
less extensively; and upon this stem or its branches leaves 
are borne. Such is the general plan of the more complex 
plants; and our first purpose will be to discover what these 
organs are doing, and why they are so related to one another 
and to their surroundings. 
