THE LOWER DICOTYLEDONS. 



317 



the stamens (the flower is protogynous) , but before all the 

 anthers have opened the styles (unless already pollinated) 

 bend down and thus bring about self-pollination. 



Eranthis and Paeony show closing movements to protect 

 the pollen and honey (cf . Little Celandine), and Trollius has 

 the flowers nearly closed all the time ; similar protection is 

 given by the inclined or drooping position of the flower in 

 Helleborus and in Aquilegia (Columbine the hooked end of 

 the petal- spurs prevents the honey from dropping out), by 

 the arched hood in Monks- 



POST S.EPAL 



POST PETALS. 



LATERAL 

 SEPAL 



PETALS-: 



hood, and the horizontal 

 position of the flower in 

 Larkspur. The nectaries 

 of Columbine, Larkspur, 

 and Monkshood can only 

 be reached by long-tongued 

 bees ; the flowers open in 

 summer, when bees are 

 plentiful, are visited chiefly 

 by humble-bees, and usu- 

 ally have the rich blue 

 colour characteristic of so 

 many " bee-flowers." 



The flowers of Larkspur 

 (Fig. 123) and Monkshood 

 (Fig. 124) are the most 

 highly specialised in the 

 family, and the visiting 

 insects can only enter in 

 one particular way to reach 

 the well-concealed necta- 

 ries; the stamens move upwards or inwards in turn, as 

 they ripen, so as to block the way to the nectaries, each 

 stamen moving away again when its pollen is shed. In 

 Larkspur the entrance to the spur is further narrowed by 

 the two side-petals, present in most species, which also act 

 as " honey- guides." 



The humble-bee often bites through the petal- spurs 

 of Columbine and the hood-sepal of Monkshood, but the 

 thick double-walled spur of Larkspur seems to prevent 

 this. These three flowers are fine examples of adaptation to 



STEM 



BRACT 



Fig. 124. Longitudinal Section of Flower of 

 Monkshood. 



