1624 



A TEXTBOOK OF THEORETICAL BOTANY 



Fig. 1479. — HeUeborus niger. Christmas Rose. 

 Flower. 



In H. viridis the pollination mechanism is similar but the flowers open 

 more widely and the insects visiting the young flower, before the filaments 

 have elongated, must hang on to the styles in order to suck the nectar. 



Fig. 1480. — Helleboiiis J'oetidus. Flower in vertical section showing the proto- 

 gynous protrusion of the stigmas and the subsequent elongation of the 



stamens. 



In Aquilegia vulgaris (Fig. 1481) the nectar is secreted at the base of the 

 petal spurs. These spurs are funnel-shaped and readily accommodate the 

 head of a humble bee. Since the flowers are pendulous, rain does not reach 

 the nectar and the insect is forced to hang on to the spur with its fore-legs 

 and to the stamens and carpels with its two hind pairs. In so doing, in 

 young flowers, the lower surface of the abdomen comes into contact with 



