MODIFICATION OF THE ORGANS OF PLANTS 7l 



The basilar leaves (fig. 38, A to E), which are 

 usually withered in an adult branch, have more or 

 less completely lost their assimilative function, and 

 merely serve as a protection to 

 the bud. The hypopod plays an 

 important part in this modifica- 

 tion, but there are evidences of a 

 partial degeneration, the epipod 

 being reduced in size in propor- 

 tion as the assimilating function 

 is lost. 1 



The apical leaves also have 

 partially lost their assimilative 

 function, and have assumed, like 

 the basilar leaves, a protective 

 function which they exercise on 

 the floral buds. This modification FlG . 39 _ Le ave 8 from the 

 is effected differently to that of 

 the basilar leaves, but is equally 

 attended with evidences of degener- F ' bract of the involucre ' 

 ation. The hypopod continues to gain, as the epipod 

 loses, in importance, but the leaflets, instead of de- 



1 On examining the foliage leaves of a plant from above down- 

 wards, one finds successively leaves with large stipules and small 

 leaflets (fig 38, E), then leaves with very small leaflets crowded at 

 the end of the hypopod and which have only the basilar part of the 

 petiole (fig. 38, D), and then leaves of which the epipod and the 

 free part of the petiole have disappeared (fig. 38, c). Finally, at 

 the base of the plant there are leaves in which the hypopod is 

 markedly reduced, and which carry nothing but small stipules 

 (fig. 38, A and B). 



