BUDS AND BRANCHES 



101 



d- 



1907 



1906 



1905 



-1904 

 -1903 



90. The record borne by the twig. In most cases the twig 

 bears upon its surface and in its rings of wood a fairly com- 

 plete record of the most important events of its life. Some of 

 the principal markings on the surface of a 



twig which enable us to make out its history- 

 are : (a) bud-scale scars (from leaf buds) ; 

 (5) fruit scars ; (c) leaf scars. Other mark- 

 ings are found which tell less of the life 

 history of the twig than those just enumer- 

 ated, but which should also be considered, 

 namely, (cT) lenticels. 



The bud-scale scars, as the name implies, 

 are the markings (Figs. 82 and 85, l.sc) 

 left by the falling of the scales when the 

 bud opened. Plants like geraniums, with 

 naked buds, do not show such scars. As the 

 twig or branch in most cases is prolonged 

 by the growth, spring after spring, of its 

 terminal bud, each ring of scars marks the 

 beginning of a new season's growth. In 

 many trees it is easy to determine the age 

 of twigs or branches by counting the number 

 of such rings (Fig. 86). The distance be- 

 tween the rings of scars depends upon the 

 rapidity of growth of the shoot in length, 

 varying all the way from a fraction of an 

 inch to ten or more feet per year. 



If a twig were cut across smoothly, just 

 above and just below a ring of bud-scale 

 scars, would the number of rings of wood 

 in the two sections be the same ? Why, or 

 why not ? 



91. The record; fruit scars. Fruit scars of the same species 

 are often quite unequal in size, the smaller ones marking the 

 positions of unsuccessful fruits, and the larger ones of fruits 

 which grew to maturity. Sometimes in mixed buds the young 



FIG. 86. A slowly 

 grown twig of horse- 

 chestnut in winter 

 condition 



d, dormant buds ; fs, 

 flower-cluster scar. 

 The internodes are 

 numbered in succes- 

 sion (beginning at 

 the bottom) with the 

 respective years dur- 

 ing which they were 

 formed. One third 

 natural size 



