636 



BOTANY OF THE LIVING PLANT 



posterior petal is the large vexillum or standard ; the two lateral are the 

 alae or wings, which invest the anterior carina, or keel. The latter is formed 

 from two obliquely anterior petals, inserted by separate stalks, but fused 

 distally, so as to enclose the stamens and carpel. 



Androecium, stamens 10, perigynous : nine are united by their stalks into 

 a tube ; the tenth, which is posterior, is separate to its base. The anthers are 

 completely enclosed in the carina. 



Gynoecium, carpel i, apocarpous, superior. It is a pod, containing numerous 

 ovules, with placentation on the posterior margins. The style is longer than 



Fig. 489. 



Flower of Lotus corniculatus, L. I. flower compleie. II. with vexillum removed. 

 III. with alae and part of carina removed. IV. carina slit longitudinally. V. one of 

 the alae. VI. stamens of different length. VII. carpel in section. VIII. floral 

 diagram. s= sepals; v = vexillum ; A = alae; e = carina; s = stamens; st= stigma. 



the stamens, and bears a capitate stigma. The pod is almost surrounded by 

 the united filaments, but access to the honey-secretion, which is on the enlarged 

 receptacle round its base, is gained through the slits right and left of the 

 separate stamen. The fruit when ripe is a dry pod, splitting longitudinally 

 into halves. 



Pollination. The mechanism of the flower is elaborate, and secures cross- 

 pollination notwithstanding the close relation of anthers and stigma, which 

 are both enclosed in the funnel-like carina. For the stigma is not receptive 

 until it has been rubbed, and remains infertile till the insect-visitors, which 

 are bees, arrive. Searching for nectar, and guided by the converging red 

 lines on the standard, the bee alights on the projecting wings ; its weight is 

 transmitted by their interlocking surfaces to the keel, which is thus depressed, 

 and yields. The stiff stamens and carpel do not yield, and so first the stigma, 

 and then the anthers with their pollen project through a pore which is left 

 open at the tip of the keel. When the weight of the bee is removed the keel 

 rises, and the stamens and stigma are again enveloped, and are ready for a 



