CH. VII] 



STIPULES. 



99 



In order to expose a large surface with a small expen- 

 diture of material the leaf must obviously be thin, just as 

 gold-leaf, which is required to expose a large area and is of 

 valuable material, is thin. Moreover if a leaf were not 

 thin, some of the cells would be so much shaded by the 

 others that they would be unable to assimilate. 



The flat broad part of the leaf is the blade or lamina 

 (fig. 45), the stalk (which is often absent) is technically 

 known as the petiole. At the base of the petiole in 

 many leaves are a pair of outgrowths known as the 

 stipules (fig. 45), these are clearly seen in the leaf of the 

 rose, in the cherry, and in the pansy. 



\ 



FIG. 45. 



STIPULATE, i.e. STIPULE-BEARING, LEAVES. 



On the left a pansy-leaf, on the right that of the cherry. The numbers 

 refer to the venation ; (1) mid-rib ; (2) and (3) secondary and 

 tertiary veins. 



From Le Maout and Decaisne. 



72 



