152 BRITISH FLOWERING PLANTS ohai-. 



of the keel proceeds towards the point, against which the 

 stigma is closely pressed, the pistil being in a state of con- 

 siderable tension. As soon as the stigma is set free the 

 llower explodes, the pistil bends itself as in Fig. 93 and 

 rubs itself against the bee's back, followed almost imme- 

 diately by the longer stamens and a shower of pollen. 

 The explosion is facilitated by the narrow- 

 ness of the claw of the keel, which is re- 

 duced to a mere thread. After explosion 

 the keel hangs down, and the flower gapes 

 widely. Humble bees, hive bees, and 

 Eucera (one of the solitary bees) are alone 

 capable of exploding the flower, but when 

 this is once effected many insects come 

 Fig. 94.— Shoot of to partake of the pollen. Humble bees 

 Broom in vertical ^^^ ]j^-^g hees, Qu the contiary, never con- 



s6ctioii s 110 wins 



bud s protected desccnd to visit exploded flowers. 



by pedestal of j^ ^^Q^er the bud, as in many allied 



last years laufp. ; . j_ , i i , i • . . 



species, IS protected by the persistent con- 

 cave pedestal of the last year's leaf (Fig. 94). 



Spartium junceum (Spanish Broom), so often grown 

 in our shrubberies, agrees in most important particulars 

 with the Common Broom. 



Lotus 



L. corniculatus (Bird's-foot Trefoil) (Fig. 95), so called 

 from the resemblance of the head of pods to the foot of a 

 bird. As in many other leguminous plants, the leaflets 

 have the power of movement, to which we have already 

 referred ; rising and approaching one another at night. 

 The anthers burst and emit their pollen before the 

 flower opens, and indeed before the petals have 

 attained their full size. At this time the ten stamens 

 form two groups, five of them being longer than 

 the others ; but by the time the flower opens they 

 are all of the same length, though the five outer 

 ones are somewhat swollen at the end ; a difference 

 which subsequently becomes still more marked. The 

 pointed end of the keel is now filled by a mass of pollen 



