i88 STEMS 



curs, each axis giving rise to a pair of branches which have 

 developed from the last pair of axillary buds. 



In the axils of the leaves of some plants more than one 

 bud appears. In such cases there is usually one principal 

 or central one. The others are called accessory buds. 

 Thus in the axils of maple trees three buds are borne, 

 though usually only one develops. The advantage of 

 having accessory buds becomes evident when injury, like 

 freezing, befalls the first branches which are put out. 

 Usually it is only under such circumstances that accessory 

 buds develop into branches. 



Adventitious buds are those which occur elsewhere than 

 at the tips or in the axils. They appear on the internodes 

 or even on roots and leaves. Often they arise near where 

 an injury has occurred. Young sprouts or suckers are often 

 seen arising from near the base of the trunks of trees. 

 These come from adventitious buds. Willow stems which 

 are used in making baskets are obtained in abundance by in- 

 juring the trunks of willows in such a way as to stimulate 

 growth from adventitious buds. Elms very often show 

 short, leaf -bearing branches which arise from the main stem 

 below the crown ; such branches are adventitious in 

 origin. 



As to their protective covering, buds are either scaly or 

 naked. Nearly all buds in our climate are protected by 

 firm, dry, brown scales. Naked buds lack scales. Though 

 sometimes occurring in temperate regions, naked buds are 

 principally found in the tropics. Scaly buds are often 

 further protected by an excretion which resembles varnish. 

 This may be seen on buds of the horse-chestnut tree or of 

 the balsam-poplar. Perhaps you have noticed the rich, 

 spicy odor of the balsam-poplar when its buds open. This 



