iv.] CLOVER, ANTHYLLIS, ONONIS. 91 



the pistil and stamens are thus partly uncovered, as 

 shown in Fig. 73. When the pressure is removed, 

 the flower resumes its former position. 



Trifolium repens (the White Clover) agrees with 

 Lotus in its general structure, but is somewhat 

 simpler. The wings are actually united to the keel at 

 one point. In T. pratense the flowers are longer, and 

 the honey is only accessible to those bees which have 

 a very long proboscis. As in other such cases, however, 

 Bombus terrestris obtains access to it by eating a hole 

 through the side of the flower. According to Darwin 

 this species is only fertilised by humble bees, but 

 Delpino disputes this. Trifolium subterraneum has 

 small cleistogamous flowers (Mohl. Bot. Zeit., 1863) 

 besides the usual ones. 



Anthyllis vulneraria also agrees with Lotus in its 

 general arrangement. The tube of the flower is, how- 

 ever, elongated ; and in consequence, this species is 

 only visited by bees with long tongues. In the young 

 flower, though the pistil is in the keel, and neces- 

 sarily in contact with the pollen, H. Miiller has 

 observed that the stigma is dry, arid that no pollen 

 adheres to it. Subsequently, however, when most, or 

 all, of the pollen has been removed, the stigma 

 becomes sticky, and pollen adheres closely to it. 



In Ononis (the Restharrow) the general arrange- 

 ment is very similar. There are, however, several 

 important differences. Ononis does not secrete honey, 

 and consequently there is no need for the separation 

 of the upper stamen, which in this genus is attached 

 to the rest. Again, in Ononis all the stamens are 

 thickened at the end ; the outer ones, however, much 



