VI.] 



HIBISCUS. 



143 



with veins following the curvature of the edge ; and 

 palmate, or lobed leaves with veins running straight 

 to the edge. The veins contain vascular bundles 

 which conduct the nourishment sucked up by the 

 roots, and it is clearly better that they should hold a 

 straight course, rather than wind round in a curve. 



Fig. 93. — Hibiscus pednncnlatus. Seedling. 



Moreover, as the nourishing fluids pass more rapidly 

 along these vascular bundles, the leaf naturally grows 

 there more rapidly, and thus assumes the lobed form, 

 with a vein running to the point of each lobe. 



On the whole, we see, I think, that many at any 

 rate of the forms presented by leaves have reference 

 to the conditions and requirements of the plant. If 



