SOME PLANT MARRIAGES 



429 



pollen. "When the insect has sipped its fill of nectar, it flies off to another 

 and perhaps older flower, the stigma of which is mature and pretty sure 

 to receive some of the pollen from the last flower. Thus cross-pollination 

 is effected. 



What is known as percussive mechanism is admirably illustrated in the 

 Salvias, that genus of labiate flowers to which belongs the Common Sage 

 (Salvia ojficinalis) of our gardens. The remarkable feature in this form 

 of mechanism is the rocking part of the stamens, which, as we saw when 

 speaking of the male organs of plants, is a specialized form of the 

 connective. The connective is, in fact, a curved bar attached to the filament 

 of the stamen by a movable joint, 

 and running transversely to it. The 

 upper part of this curved bar is the 

 longer and bears the anther (fig. 

 501) ; while the stubby lower part has 

 no anther and is finished off with a 

 knob. The flowers are diandrous and 

 the stamens are so close together 

 that the knobs, which stand just in 

 the open jaws of the corolla, almost 

 touch. Tucked away in the upper 

 hooded portion of the corolla is the 

 style ; but its forked stigma is closed 

 during the first stage of the flower, 

 its services not being required till 

 later. The nectaries are situated deep 

 down in the tube of the corolla, near 

 the ovary, so that when a bee alights 

 on the landing-stage it must push its 

 head right into the jaws of the flower 

 before it can get at the nectar. Here 

 the knobs of the two connectives 

 block the way, and both of these 

 knobs get struck by the bee's head. 

 This is the act of percussion which 

 puts the machinery in motion. In- 

 stantly the connectives swing round 

 on their hinges, and the pollen-bear- 

 ing anther-lobes are brought down 

 upon the bee's back, besprinkling it 

 with the yellow dust. Should the 

 next flower visited be in the female 

 stage, the pistil will present a differ- 

 ent appearance from that described 



