Leaves. 



FIG. 31. 



Mosaic of Virginia Creeper leaves. The 

 plant is climbing a wall and the blades 

 of the leaves stand vertically. 



as little as possible in reaching them, and that in some way 



the light assists them in manufacturing the starch which is 



an important food of the 



plant Having reached this 



conclusion, we find it all the 



more interesting to note 



how the leaves strive to 



intercept the light which 



comes their way, and how 



the form and size of the 



plant and the disposition 



and direction of growth 



of its branches are also 



adapted to this purpose. 



The same end is attained 

 in various ways by differ- 

 ent plants. When plants are prostrate on the ground or 

 have grown up over a wall, the leaves spread out more 

 or less horizontally in the 

 first instance, but vertically 

 in the last, and intercept 

 nearly all of the light which 

 falls within the radius of 

 the branches (see Fig. 31). 

 When plants are upright, 

 the tiers of branches and 

 leaves are so separated that 

 the light can strike between 

 them; when the leaves are 

 crowded together in ro- 

 settes, the lower leaves 

 grow out beyond the upper ones and produce broad sur- 

 faces only in the exposed area (see Fig. 32); or, when the 



FIG. 32. 



Dandelion plant viewed from above. 

 Leaves in rosettes. 



