72 



DESCRIPTIVE BOTANY. 



PART I. 



In \hcLathyrus aphaca (fig. 6*9.) 

 all the leaves become tendrils, 

 except the first pair in the 

 young plants, which are com- 

 pound, and have two or three 

 pairs of leaflets. Occasion- 

 ally an odd leaflet (6) is de- 

 veloped on the tendrils, in a 

 later stage of growth, which 

 further indicates the origin of 

 the organ on which it is seated. 

 A provision is made for sup- 

 plying the want of leaves in this 

 plant, by an unusual development of the stipules (a), 

 which are so large that they might readily be mis- 

 70 



taken for real leaves. All tendrils, however, do not 

 originate in the modification of the leaf; but some 

 are derived from an altered condition of the stipules, as 

 in the cucumber ; others, from a transformation of the 

 branches or peduncles, as in the vine (fig. 70.). In 

 fact, they may result from any of the caulinar append- 

 ages, which become lengthened out at their extremi- 



