98 



INTRODUCTION TO BOTANY 



92. Competition among buds and branches. Seen from a 

 little distance the top of a tree usually appears like a some- 

 what conical or hemispherical mass of leafy branches, but on 



looking along the trunk up into 

 the tree top one sees that the 

 interior of the crown is hollow, 

 nearly destitute of leaves, and 

 with few live twigs on the 

 trunk (except near its upper 

 end) and few on or near the 

 bases of the branches. A very 

 large proportion of all the 

 much-shaded twigs that might 

 be developed into branches 

 during the growth of a tree 

 are actually killed by light- 

 starvation. They cannot do 

 photosynthetic work and are 

 therefore without food. 



Cutting off the top or the 

 main branches of many kinds of 

 trees (pollarding*) causes buds 

 along the trunk and larger 

 branches to develop into slen- 

 der twigs, used for withes and 

 for basket-making (fig. 82). 



93. Fruit spurs. A. fruit spur 

 is a short fruit-bearing twig 

 borne on the side of a branch 

 (figs. 83 and 84). Apple, pear, 

 plum, and cherry trees afford 

 capital examples of the production of fruit spurs. At the tip 

 of the spur a flower bud (or a mixed bud) is borne, and this 

 usually develops into a cluster of flowers, one or more of 

 which, under favorable conditions for growth, may mature 

 into fruit. In the apple and the pear (fig. 84), although the 



FIG. 82. A pollarded willow send- 

 ing out many slender twigs from 

 buds which would not have grown 

 if the main branches had not been 

 cut away 



