THE SHOOT 



49 



that while the scales persist the young shoot seems sur- 

 rounded by a number of small leaves at its base (Fig. 

 1 8 C). When the bud-scales fall off, they leave the base 

 of the shoot surrounded by scars, which mark the places 

 of their original attachment. At the close of growth on the 

 onset of winter, the 

 shoot, now become 

 what is technically 

 called a twig (Fig. 

 19), shows these 

 scars closely placed 

 together round its 

 base. In the winter 

 it is easy to recog- 

 nise the amount of 

 growth of a twig 

 during the preced- 

 ing year, by noting 

 the distance be- 

 tween this collec- 

 tion of scars and 

 the apex. In an 

 older twig or young 

 branch several 

 such collections of 

 scars can be de- 

 tected, and so the 

 limits of each year's growth can be easily ascertained. 

 With the opening of the bud and the expansion of its 

 leaves as its stem elongates we can trace the sensitive- 

 ness of the shoot to the various influences that sur- 

 round it. We have pointed out the response its axis 

 makes to the influence of gravity and lateral light. We 

 have also incidently mentioned the change of the cur- 

 vature of the leaves which sets in as soon as the bud 

 opens. The change is a response to the access of light 



D 



FIG. 19. Twig of 3 years' growth, bs, scars 

 of bud-scales of each year. The twig shows 

 racemose branching. (After Ward.) 



