BUDS 95 
wool or down which they afterwards lose. Those of the 
tulip tree are enclosed for a little time in thin pouches, 
which serve as bud-scales, and are thus entirely shielded 
from direct contact with the outside air. 
112. Dormant Buds. — Generally some of the buds on a 
branch remain undeveloped in the spring, when the other 
buds are beginning to grow, and this inactive condition 
may last for many seasons. Finally the bud may die, or 
some injury to the tree may destroy so many other buds 
as to leave the dormant ones an extra supply of food, and 
this, with other causes, may force them to develop and to 
grow into branches. 
Sometimes. the tree altogether fails to produce buds at 
places where they would regularly occur. In the lilac the 
terminal bud usually fails to appear, and the result is con- 
stant forking of the branches. 
113. Adventitious Buds. — Buds which occur in irregu- 
lar places, that is, not terminal nor in or near the axils of 
leaves, are called adventitious buds; they may spring from 
the roots, as in the silver-leafed poplar, or from the sides 
of the trunk, as in our American elm. In many trees, for 
instance willows and maples, they are sure to appear after 
the trees have been cut back. Willows and poplars are 
thus cut back or pollarded, as shown in Plate ITI, in order 
to cause them to produce a large crop of slender twigs _ 
suitable for basket-making or for withes. 
Leaves rarely produce buds, but a few kinds do so 
when they are injured. Those of the bryophyllum, a 
plant allied to the garden live-for-ever, when they are 
removed from the plant while they are still green and 
fresh, almost always send out buds from the margin. 
These do not appear at random but are borne at the 
