wow PLANTS 13A^. 



45 



roundish leaf like that of the so-called nastur- 

 tium. But if the ribs project a little at the edge 

 — in other words, if the cellular tissue docs not 

 quite mi out the whole space between them — 

 we get a slightly indented leaf, like that of the 

 scarlet geranium or the conunon mallow. If tbe 

 unfilled spaces between the cuds of the ribs are 

 much greater, then the ribs project into marked 

 points or lobes, and we get a leaf like that of ivy. 



FIG. 3. — FEATHER-VEINED LEAVES. The foiU' leaVGS liaVG 



similar veins, but are dil^erently filled in. 



Carry the starving of the cellular tissue a little 

 further still, and w^e have a deeply-indented leaf 

 like that of the castor-oil plant. Finally, let the 

 spaces unfilled go right down to the common 

 centre from which the ribs radiate, and we get a 

 divided or compound leaf, like that of the horse- 

 chestnut, with three, five, or seven separate 

 leaflets. (See Fig. 5, No. 1.) 



Similarly with the feather-veined typo (Fig. 3) ; 

 the spaces between the ribs may ])e more or less 

 filled wath cellular tissue in any degree you 



