PRUNING 221 
grown in the light. Thus many forest trees which have short, 
thick, and much branched trunks, when growing in pastures, grow 
tall slender stems with branches only at their tops when grown 
in forests where they are much shaded. It is for this reason that 
most forest trees grow trunks more valuable for lumber when 
grown in thick stands. (Figs. 199 and 200.) This principle is 
observed in growing Sorghum and Corn chiefly for fodder, in which 
case the plants are grown in thick stands, so that their stems will 
be finer and, therefore, better for feed. Such a response to shade 
is often an advantage to plants, for it is through the elongation 
of their stems that plants compete for light by endeavoring to 
raise their leaves above the shade of neighboring plants. 
Also the development of stem tissues is more or less influenced 
by light. Stems grown in diminished light do not have their 
mechanical tissues so well developed. For example, when grain 
plants receive insufficient light on account of being much crowded, 
they have commonly weak stems and are likely to lodge. The 
bast fibers of flax are finer when the plants are thick on the 
ground, and when flax is grown for fibers it is commonly grown 
in thick stands. 
Pruning 
Pruning consists in cutting away portions of the plant and is 
done for reasons too numerous for more than a few to be men- 
tioned here. 
First, trees that tend to grow tall and slender may be induced 
to acquire a low thick top by subjecting them to the process called 
“heading-in,”’ which consists in pruning the main branches so that 
growth in height is checked and a good development of lateral 
branches is induced. This method is often used in controlling 
the shape of shade and fruit trees. It is by this means that hedges 
are made to grow low and dense and thus capable of turning stock 
when used for fences. 
Second, often, as in case of fruit trees, pruning has for its pur- 
pose the checking of growth which has been so thoroughly ex- 
hausting the food supply as to result in a shortage of fruit buds. 
In this case growth is checked by removing the terminal buds 
from the leaders and the food supply thereby conserved. 
Third, plants are sometimes pruned to delay maturity. For 
example, in growing Sweet Peas the young pods are pinched off 
