110 FLOWER STRUCTURE 



but perfectly hardy in mild districts near the sea. The 

 blossom is so designed as to benefit from the visits 

 of humming-birds or large hawk-moths; wherefore, 

 although Salvia is entitled as a Labiate to four perfect 

 stamens, two of these have been sacrificed by conversion 

 into plain short rods, obstructing the passage to the 

 nectary. Any creature attempting to get at the honey 

 must press against the rods, which, acting as levers, 

 cause the anthers on the perfect stamens to descend 

 and discharge their pollen on the beak and head of the 

 humming-bird. The anthers then begin to shrivel and 

 wither away. In this species of Salvia the pistil 

 descends with the stamens, but its stigma is not recep- 

 tive until the anthers have become functionless, when 

 it grows longer and becomes ripe for fertilisation. The 

 levers continue operative, causing the stamens to 

 descend every time the flower is visited, bringing the 

 pistil with them, so that the stigma at the free end of 

 the pistil is sure to come in contact with pollen brought 

 by bird or insect from another and later blossom. 

 Effective security against self-fertilisation is secured 

 by the anthers ripening and discharging their pollen 

 before the stigma in the same flower is ready for 

 impregnation. 



This species of sage is obviously planned to profit by 

 the visits of winged creatures larger than any that can 

 be expected in the British Isles ; for although a honey- 

 bee, thrusting its way to the nectary, must set the 

 machinery in motion, the pollen generally misses the 

 insect, falling behind its tail. Humble-bees, being too 

 corpulent to enter the narrow throat of the flower, have 



