86 Principles of Plant Culture. 



We can usually decide if detached dormant shoots of 

 trees and shrubs, as cions and cuttings, are of the 

 preceding year's growth or older, since, as a rule, only 

 wood formed the preceding year has visible undeveloped 

 buds.* 



131. Adventitious (ad-ven-ti'-tious) Buds. Although 

 buds are normally formed only at the nodes of the stem, 

 they may under the stimulus of unusual root pressure 

 (102) be formed without regard to nodes. The trunk of 

 a vigorous elm, willow or horse-chestnut tree, cut off 

 early in the season, often develops a multitude of buds 

 from the thickened cambium (69) at the top of the 

 stump, and a circle of shoots often spring up about the 

 base of a tree of which the top has been injured by over- 

 pruning or severe cold. Such buds are called adventitious. 

 It is, however, often difficult or impossible to distinguish 

 between adventitious buds and those that have been 

 previously overgrown (130). 



The roots of many plants, as the plum, choke cherry, 

 raspberry etc., develop adventitious buds freely, especi- 

 ally when injured, a fact often utilized in propagation 

 by root cuttings (376). 



132. Leaf-Buds and Flower-Buds. Buds may contain 

 only rudimentary leaves, or they may contain rudimen- 

 tary flowers, with or without leaves. The former are 

 called leaf- or wood-buds, the latter flower- or fruit-buds. 

 Flower-buds are modified leaf-buds. Both originate in 

 the cambium layer (69) and are normally located at the 

 apex of the stem or in the axil of a leaf (128-129). 



* Exceptions to this rule are not uncommon in unthrifty trees and 

 shrubs. 



