POLLINATION AND FERTILIZATION 445 
pollination (fig. 64). Bignonia, the Golden Shower, has 
a sensitive stigma which closes when touched—thus an 
insect entering the flower pollinates it, then reaches the 
stamens and gets fresh pollen. By the time it leaves 
the flower the stigma is closed, so self-pollination is 
prevented. 
Salvia has an ingenious arrangement. ‘The corolla is 
bilabiate, and the lower lip forms a convenient resting 
place for insects. There are only two stamens and 
these have short filaments, and long connectives. The 
upper half of each connective bears a half anther, the 
lower halves, which are much shorter, are united 
together. The whole arrangement forms a lever, so 
that when an insect enters the flower and presses 
against the lower halves of the connectives, the upper 
lobes bend down and its back gets dusted with pollen. 
The flower is protandrous and later on the stigma bends 
down so that it is just touched by an insect entering 
the flower. “The mechanism can most easily be seen in 
the blue Salvia. If a pencil is inserted in the opening of 
this flower the stamens will be seen to bend down and 
deposit pollen on the top of it (figs. 65 and 66). 
Most of the Compositae are specially adapted for 
cross-pollination. The perfect fiorets have honey at the 
base of the style. The syngenesious anthers are introrse 
and the pollen is shed into the anther tube. The 
flower is protandrous and at this stage the stigmas are 
closed. The style, which is often hairy, then grows 
out of the stamen tube, carrying the pollen with it to 
the top of the flower, where it can be taken by visiting 
insects. The stigmas ae separate, the inner surface 
