264 HOW CROPS GROW. 
time with foliage. In this way, too, the gardener molds a 
straggling, ill-shaped shrub or plant into almost any form 
he chooses; for by removing branches and buds where 
they have grown in undue proportion, he not only checks 
excess, but also calls forth development in the parts before 
suppressed, 
Adventitious or irregular Buds are produced from the 
stems as well as older roots of many plants, when they are 
mechanically injured during the growing season. The 
soft or red maple and the chestnut, when cut down, habitu- 
ally throw out buds and new stems from the stump, and 
the basket-willow is annually polled, or pollarded, to induce 
the growth of slender shoots from an old trunk. 
Elongation of Stems,—While roots extend chiefly at 
their extremities, we find the stem elongates equally, or 
nearly so, in all its contiguous parts, as is manifest from 
what has already been stated in illustration of its devel- 
opment from the bud. 
Besides the upright stem, there are a variety of prostrate 
and in part subterranean stems, which may be briefly no- 
ticed. 
Runners and Layers are stems that are sent out hori- 
zontally just above the soil, and coming in contact with the 
earth, take root, forming new plants, which may thence- 
forward grow independently. The gardener takes advan- 
tage of these stems to propagate certain plants. The 
strawberry furnishes the most familiar exemple of runners, 
while many of the young shoots of the currant fall to the 
ground and become layers. The runner is a somewhat 
peculiar stem. It issues horizontally, and usually bears 
but few or no leaves. The layer does not differ from an 
ordinary stem, except by the circumstance, often accident- 
al, of becoming prostrate. Many plants which usually 
send out no layers, are nevertheless artificially dayered by 
bending their stems or branches to the ground, or by ate 
