192 NATURAL HISTORY OF PLANTS. 



obovate emarginate, and tapers below into a large claw with involute 

 edges. The two lateral petals, called alee or " wings" (Fr., ailes), 

 symmetrical with respect to each other and far shorter and narrower 

 than the standard, have an irregularly and obliquely oblong limb, 

 with a lateral projection below and a long slender curved claw 

 (fig. 141). The two anterior petals differ from both wings and 

 standard in size and form, but resemble each other. The limb is 

 irregular, and like the wing with the base of the inferior edge of its 

 posterior border produced into an unsymmetrical auricle ; it is un- 

 equally wrinkled and bears on its outer surface, not far from the top 

 of this auricle, a depression by which it clings to a corresponding 

 projection on the inner face of the wing. The claw is here also 

 slender and curved, and coheres for a certain distance along its 

 inferior border with that of the petal symmetrical. This close 

 adhesion is prolonged all the way up the limb ; so that the two 

 anterior petals together form a single piece (fig. 142), which is 

 termed the "keel" or carina (Fr., carlne). In the bud the keel is over- 

 lapped by the wings, themselves again overlapped by the standard — 

 an imbrication known as the vexillary prajloration. The androceum 

 consists of ten stamens, subperigynous like the perianth ; five super- 

 posed to the calyx-lobes, and five, shorter, to the petals. The 

 filaments are diadelphous, the nine anterior being united below into 

 a tube split along its superior edge, while the tenth, superposed to 

 the standard, and hence termed the vexillary stamen, remains free 

 on the superior side of the flower. The free summit of each filament 

 bears an introrse two-celled anther of longitudinal dehiscence. 1 The 

 gynaeceum, formed by a single carpel superposed to the anterior 

 sepal, consists of a subsessile one-celled ovary surmounted by an 

 inflexed style whose apex is dilated into a little stigmatiferous head, 

 below which the dorsal edge of the style bears a thick tuft of hairs. - 

 Above the wall of the ovary next the standard is a longitudinal 

 placenta on whose two lips are inserted a variable number 3 of de- 



1 The pollen is generally ovoidal or ellipsoidal vermis, Lathyrus odoratus and pratensis, and 



in the group. Each group bears three longi- Pisum sativum. 



tudinal folds, which in the spherical moistened 2 In the section Cracca (Riv.,t. 52, nee L.) the 

 grain are represented by either smooth or pa- style is slightly compressed from side to side, and 

 pillose bands. H. Mohl. (in Ann. Sc. Nat., ser. 2, the fruit bears an oblique dilatation at the apex, 

 iii. 341) has found the latter condition in the 3 I'nly two, or rarely three, as we have men- 

 pollen of Vicia Cracca and sylvatica, Orobus tioned in certain of the species of Ervum, which 



are now united with the genus Vicia. 



