1934 



A TEXTBOOK OF THEORETICAL BOTANY 



position they block access to the nectar. The whole arrangement forms a 

 bent or bell-crank lever, pivoting on the tips of the stamen filaments. 



Fig. 1 86 1. — Salvia sclarea. Clary. Inflores- 

 cence with old flowers showing the long 

 exserted styles and bifid stigmas. 



When an insect thrusts its head into the flower the sterile anther plates 

 are pushed upwards and backwards so that the fertile anther lobes covered 



I 



Fig. 1862. — Salvia prateusis. Flowers in longitudinal section, to illus- 

 trate pollination. A, Younger, and B, older stages, showing the 

 hinged stamens and the later extrusion of the stigmas. See in text. 



with pollen are brought forwards and downwards. By the same action 

 entrance is gained to the nectar and pollen is liberally dusted on to the back 



