TWIGS OF TREES IN WINTER 43 



the twig was terminated by a bud similar to that of Fig. 12, and 

 had also two small lateral buds resembling b. Fig. 13. In 

 the spring of 1897 the buds opened, and the bud-scales fell 

 off and left scars at 4. The terminal bud then grew as in Figs. 

 13 and 14 and produced a considerable length of stem marked 

 1897, with several lateral buds upon it, each of which developed 

 in the axil of a leaf, as at h, Fig. 14. From the small lateral 

 buds just beneath the terminal one short shoots originated in 

 a similar manner. 



12. The amount of growth of twigs during one year or one 

 growing-season is represented by the length between two sets of 

 bud-scale scars (4, Fig. 19, tiS to ffi). 



As the scars are often visible upon the bark for several years 

 they are useful aids in the determination of the age of any length 

 of tree, Stem, or twig. Frequently small buds are present in the 

 axils of bud-scales, and as the internodes between the latter 

 remain short such buds appear crowded together upon the twigs 

 and are often visible after the scars have been obliterated (Fig. 

 57, between A and B). 



The length of stem which a bud produces during a year's 

 growth is very varied, some leaf-buds giving rise to shoots not 

 more than a small fraction of an inch long, while others reach a 

 length of several feet. Much depends upon the kind of plant, 

 its age, treatment, and the position of the bud upon the tree, as 

 well as upon external circumstances, such as climate and soil. 

 In trees which are unmolested the length of the shoots produced 

 each year by the terminal buds goes on increasing from extreme 

 youth onwards until a certain age is reached, after which the 

 yearly length of the shoots begins to diminish. The age at which 

 the growth is at a maximum is different for different trees, some 

 forming their longest shoots when they are 15 to 20 years old, 

 others not until 30 to 40 years have elapsed. In old age the large 

 number of buds to be supplied with water and food-constituents, 

 and their increasing distance from the wnter-supply in the 



