LEGUMINOS^ 



167 



hairy on the outer side or all round ; while in the Peas 

 the style is flattened, and hairy on the inner side only. 

 The termination of the staminal tube, moreover, is more 

 or less oblique (Fig. Ill), while in the Pea (Fig. 110) 

 it is more abrupt. Several species of the genus have 

 " extra-floral '' nectaries. They are situated on the under 

 side of the stipules, and are generally deeply coloured, 

 often black. The object is probably to attract ants, 



Fig. 110.— Staminal tube of Lathyrus. 



Fio. 111. — Staminal tube of Vioia. 



which then repay the plant by carrying off any small 

 caterpillars, etc. 



V. Oracca. — In this beautiful species the connection 

 of the wing and the keel is carried farther than in the 

 preceding genera. In fact, they are doubly interlocked, 

 so that it is difficult to separate without tearing them. 

 The anthers are ripe, and the pollen shed before the 

 flowers open, but according to Knuth the stigma is not 

 capable of impregnation until the delicate papillse have 

 been scratched and torn by the bee. Though the parts 

 of the flower fit closely to one another, still from the 

 smallness of its size the honey is accessible to most 

 bees, and owing to the conspicuousness of its bunches of 

 bright blue flowers it is much visited by them. From 

 their arrangement and elasticity, the various parts of 

 the flower resume their original position after each 

 visit. The plant is sometimes covered with numerous 

 white silky hairs, sometimes has only a few appressed 

 hairs. 



V. sepium (Bush Vetch). — The arrangement of the 

 flowers resembles that in V. Cracca, but the pistil, 

 instead of a single brush, bears two separate groups of 

 hairs, one on the inner and the other on the outer 

 side, each about 1 m. in length. That on the inner side 



