BRANCHING STEMS 



177 



Stem as it would be if all the buds developed into branches, 

 and compare it with your diagrams of excurrent and deli- 

 quescent growth. 



247. Definite and Indefinite Annual Growth. — The pres- 

 ence or absence of terminal buds gives rise to another im- 

 portant distinction in plant development — that of definite 

 and indefinite annual growth. Compare with any of , the 

 twigs just examined, a branch of rose, honey locust, sumac, 

 mulberry, etc., and note the difference in their modes of 

 termination. The first kind, where the bough completes 

 its season's increase in a definite time and then devotes 

 its energies to developing a strong terminal bud to begin 

 the next year's work with, are said to make a definite or 

 determinate annual growth. Those plants, on the other 

 hand, which make no provision for the future but go 

 straight on flourishing and rejoicing, like the grasshopper 

 in the fable, till the cold comes and literally nips them in 

 the bud, are indefinite, or indeterminate annual growers. 

 Notice the effect of this habit upon their mode of branch- 

 ing. The buds toward the end of each shoot, being the 

 youngest and tenderest, are most readily killed off by 

 frost or other accident, and hence the 

 new branches spring mostly from the 

 older and stronger buds near the base 

 of the stem. It is this mode of branch- 

 ing that gives to plants of this class 

 their peculiar bushy aspect. Such 

 shrubs generally make good hedges on 

 account of their thick undergrowth. 

 The same effect can be produced arti- 

 ficially by pruning. 



248. Differences in the Branching of 

 Trees. — We are now prepared to un- 

 derstand something about the causes 

 of that endless variety in the spread of 

 bough and sweep of woody spray that 

 makes the winter woods so beautiful. 



327. — Winter spray of 

 ash, an opposite-leaved 

 tree. 



ANDREWS'S I50T. — 12 



