136 



PRACTICAL COURSE IN BOTANY 



exemplified by the buckeye, horse-chestnut, jimson weed, 

 mistletoe, and dogwood (Fig. 155, A). 



Draw a diagram of the buckeye, or 

 other dichotomous stem, as it would be if 

 all the buds developed into branches, and 

 compare it with your diagrams of excurrent 

 and deliquescent growth. Draw diagrams 

 to illustrate the branching of the elm, 

 beech, lilac, linden, rose, maple, or their 

 equivalents. 



153. Definite and indefinite annual 

 growth. — The presence or absence of ter- 

 grams of two-forked minal buds givcs rise to another important 

 pointed bodies in the distinction in plant development — that 

 forks shows where tor- ^f definite and indefinite annual growth. 



minat flower buds or *^ i> ^ • 



flower clusters have Compare With any of the twigs just 

 of^eJowth.^''^''''^'"'' examined, a branch of rose, honey locust, 

 sumac, mulberry, etc., and note the differ- 

 ence 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 continue to grow till the cold comes 

 and literally nips them in the bud, are indefinite, or in- 

 determinate annual growers. Notice the effect of this habit 

 upon their mode of branching. 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 new 

 branches spring mostly from the older and stronger buds 

 near the base of the stem. It is their mode of branching 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. 



