FOLIAGE LEAVES: THE LIGHT- RELATION. 



21 



plant is conical, a form very common in herbs with entire 

 or nearly entire leaves. In plants whose leaf blades are 

 broken up into leaflets (compound or branched leaves), 

 however, no such diminution in size toward the top of the 

 stem is necessary (see Fig. 17), though it may frequently 



PIG. 15. A plant showing much-branched leaves, which^ 

 out cutting off the light from 01 



cur in great profusion with- 

 ther. 



occur. When a broad blade is broken up into leaflets 

 the danger of shading is very much less, as the light can 

 strike through between the upper leaflets and reach the 

 leaflets below. On the lower leaves there will be splotches 

 of light and shadow, but they will shift throughout the 

 day, so that probably a large part of the leaf will receive 

 light at some time during the day (see Fig. 14). The 



