BUDS 



25 



38. Adventitious buds. — A wound may cause the formation 

 of buds at any point upon a stem, and sometimes they appear 

 where apparently there has been no injury. They are irregular 

 in that thej^ do not come from the axils of leaves ; such buds are 

 said to be adventitious. On the power of most plants to produce 

 adventitious buds depends the process of propagation by cut- 

 tings. A cutting is a part detached from the parent which 

 becomes an independent plant by the for- 

 mation of new roots. All wounds begin 

 to heal by the formation of loose thin- 

 walled colorless tissue, the callus (Fig. 

 14). Usually before cuttings strike root 

 a callus is formed on the lower end, but 

 the adventitious buds from which the 

 roots come do not spring from the callus, 

 contrary to common opinion, but from in- 

 ternal tissue. Nearly all hardy fruits can 

 be propagated from cuttings, but the com- 

 mon apples, pears, peaches, plums, and 

 cherries, while they form the protective 

 callus readily, do not easily produce ad- 

 ventitious roots. The shoots which break 



so plentifully from stumps of trunks and branches of hardy 

 fruits come from adventitious buds. Some branches spring 

 from adventitious buds and hence bear no relation to the leaves, 

 that is in particular, do not follow the geometric law which 

 governs the position of branches which arise from the axils of 

 leaves. 



39. Buds classified as to arrangement on the stem. — The 

 shape, aspect, and manageableness of woody fruit-plants are 

 largely determined by the arrangement of their branches, which, 

 of course, is dependent on bud arrangement, and buds, in turn, 

 on leaf arrangement. Buds, leaves, and branches of all hardy 

 fruits are either opposite or alternate. They are oppos^ite when 

 there are two at the same node, the two in every case being on 

 opposite sides of the stem. They are alternate when there is 

 only one from each node. When alternate no one is on the same 

 side of the stem as the one next above or below it. The arrange- 

 ment of buds on shoots of plants is of prime importance in 



Fig. 14. Callus on 

 grape-cuttings. 



