238 LEAVES 
light, therefore, is a delicate one, and many leaves do not have 
the proper amount of light. 
The more or less horizontal position which the leaves of many 
plants assume enables them to receive the direct and most in- 
tense rays on their upper surface. Leaves in this position receive 
more light rays than those having the oblique or vertical position. 
Fia. 220. — Leaves divided into leaflets. A, leaf of Alfalfa with three 
leaflets. B, Walnut leaf having many leaflets. J, leaflets; p, petiole; s, 
stipules; b, bud. 
The separation of leaves through the elongation of the internodes 
is another means of securing better exposure. For example, dur- 
ing the early growth of the Corn plant, the leaves are closely 
packed around the growing point of the stem and only the outer 
ends of the blades are well exposed. But through the elongation 
of the internodes, all of the leaves are finally separated, so that at 
the time the tassel and ears appear all portions of the leaves 
receive light. 
The way leaves are arranged on the stem is a'so an important 
feature in securing proper exposure. There are three common 
arrangements, alternate, opposite, and whorled. In the alternate 
arrangement, there is but one leaf at a node and they appear to 
alternate, first on one side of the stem, then on a different side. 
