394 ON SEEDLINGS 



increases in length, requiring support, the tip of the leaf from 

 the fifth or the sixth onwards forms a small, simple tendril. 

 The stem is four- winged owing to the leaves being decurrent 

 at their bases. The stipules on the lower leaves are more or 

 less adnate to the edges of the latter, with subulate, free 

 points, becoming triangular higher up, and ultimately becom- 

 ing wholly adnate or entirely aborted. 



Tribe Phaseolece. As far as the cotyledons are concerned, 

 there are two very distinct types of seedlings in this tribe, with 

 several intermediate forms. All, however, agree in the first 

 two leaves being simple and opposite, with generally very short 

 petioles. The ultimate leaves are pinnately trifoliolate. 



The type with aerial cotyledons is represented by Clitoria 

 Ternatea (fig. 286). They are oblong, falcate or indented on 

 one side, a peculiarity already described. Others agreeing 

 with this are Butea frondosa, Pueraria Thunbergiana (fig. 

 288), and Centrosema Plurnieri. Dolichos falcatus differs in 

 having oval, fleshy cotyledons ; Erythrina monosperma in 

 having oblong, fleshy, and slightly concave cotyledons ; and 

 Phaseolus vulgaris (fig. 290) in having them oblong, falcate, 

 fleshy, and directed to one side of the stem. In all three cases 

 they exhibit a tendency to become subterranean, but are carried 

 above ground by the extraordinary vigour of the plants and 

 the elongation of the hypocotyl. The first pair of leaves in 

 Dolichos falcatus are cordate ; those of Erythrina monosperma 

 are very much larger and rotund-cordate, emarginate, and very 

 deeply auricled, almost sagittate at the base, with the third 

 leaf compound. Phaseolus vulgaris conforms very nearly to 

 the latter. Those of Pueraria Thunbergiana are roundly 

 rhomboid, and those of Centrosema Plumieri oblong-cor- 

 date. A case of more gradual evolution occurs in Clitoria 

 Ternatea, which has the first pair of leaves small and lanceo- 

 late, while the third is obovate, emarginate, and much larger. 

 The fourth is broadly oblong, emarginate, and many times 

 larger than the first two, but in some individuals the fourth 

 leaf is trifoliolate or imperfectly so. The fifth and sixth leaves 

 are pinnately trifoliolate, with small oval or elliptic leaflets. 



The cotyledons are strictly subterranean in Erythrina 

 Vesp_ertilio, Phaseolus multiflorus, Vigna lutea, V. vexillata, 



