EACH LEAF LOOKS FOR LIGHT 



45 



the tip of a branch. 

 Leaves which grow 

 in full sunlight 

 tend to persist later 

 in the fall than 

 those which grow 

 in poor light (Fig. 

 77). This fact is 

 s o m e t i in e s ob- 

 scured because the "'"' ^ ne '"' ;uu ' la ' s ' Klvt ' grown towards the light. 



outermost leaves arc most exposed to autumn winds. 



106. Plants which start in cellars, from seeds, bulbs, 

 or tubers, grow until the stored food is exhausted and 

 then die: the leaves do not develop to full size in 

 darkness. Figs. 78 and 7!) show this. Fig. 78 is rhu- 

 barb forced in a cellar for the winter market; Fig. 7!) 

 is u plant grown out -of-doors. Compare Fig. 4'J. 



107. The position or direction of leaves is determined 



largely by exposun to sun- 

 light. In temperate cli- 

 mates, they usually hang 

 in such a way that they 

 re ce ive the g re ate si 

 amount of light. Ob- 

 serve the arrangement 

 of leaves in Fig. 80. 



One leaf shades 1 he nt hel- 

 lo the leas! possible de- 

 gree. II' the plant were 

 placed in a new position 

 with reference to light, 

 the leaves would make 

 an effort to turn their 

 ... , . , blades. Obs e rv < I he 



' mantle of clematis, The leave*, and later 



the n. iw.ts. spread themselves to the light. shingle - like arranevnieiil 



