80 Principles of Plant Culture. 
the loss from a limited amount of shade and crowding will 
be more than made up by the increased number of plants. 
In this case, the amount of crowding that will give the 
maximum yield will depend much upon the fertility and 
moisture of the soil, and must generally be determined by 
experiment. 
124. Stem and Root Development Depend on the 
Number of Leaves. Since the vascular bundles, through 
the formation of which the stem and root increase in diame- 
ter, originate in the leaves (68), the size and firmness of the 
stem and root depend somewhat upon the number of leaves 
the plant bears. The more leaves it has, the more solar 
energy it can transform into plant tissue. The stem is larger 
beneath a vigorous leafy branch, and if cut off some distance 
above a branch, the part thus deprived of its foliage ceases 
to grow, unless it develops new leaves. Trees growing in 
the dense forest, where their lower branches continually 
perish through lack of light, have tall, but very slender 
trunks, and their wood is soft because it contains compara- 
tively little fibrous tissue, while other trees of the same 
species, in the full light of the open field, through the 
large amount of solar energy absorbed by an immense num- 
ber of leaves, develop massive trunks, of which the wood, 
being packed with fibrous tissue, is much stronger than 
that of the forest tree. 
125. The Comparative Size of Leaves on a given 
plant depends much on the water supply during their for- 
mation. The leaves of sap-sprouts (224), that take an undue 
proportion of water, are usually very large, and in upright- 
growing plants, the leaves on the more nearly vertical 
shoots are usually larger than those on the horizontal ones. 
