THE WORK OF A LEAF 
275 
distinguish one kind of plant from another and to describe 
and classify them. We need to know the meaning of certain 
terms used in describing leaves in order to read or to talk 
about them intelligently, so we must be familiar with those 
most commonly known. These can soon be learned by 
referring to the figures and explanations. 
In many ways, flowering plants are more intricate organ¬ 
isms than animals. Without the ability to change their 
environment, they must depend upon the soil as they find 
it, rich or poor, wet or dry, soft or hard, to furnish them 
water and such food materials as come to them in liquid form. 
Without being able to seek shelter, they must take sun or 
shade, heat or cold, rainy weather or dry, pure or impure 
air just as each comes. Lacking organs of offense or defense 
against other plants they must contend with them for mois¬ 
ture, air, and light, besides being subject to the attacks of 
organisms which injure them. In addition to making of 
themselves the best plants possible under the conditions, 
they must produce numerous offspring, furnish each new 
plant with a supply of food, and send them all out into the 
world to meet and to make use of such conditions as they 
may find. An examination of the plants in any garden or 
yard will show that varying degrees of success have been 
attained. In every case, however, it represents the best 
that could be done under the circumstances. When we 
consider that plants have not intelligence such as animals 
possess, it appears all the more remarkable that they can 
accomplish so much, often under very adverse conditions. 
The biologist’s great interest in plants is in the ways they 
adapt themselves to carry on their life processes under all 
sorts of conditions, as well as in the processes themselves. 
Those who raise plants can expect success only as they are 
able to supply the conditions under which each plant thrives 
best, and to control conditions and organisms which may be 
unfavorable. 
