SELF-POLLINATION 



93 



of the visits of insects. 

 The mountain laurel 

 shows a remarkable 

 adaptation in having the 

 anthers of the stamens 

 caught in little pockets of 

 the corolla. The weight 

 of the visiting insect on 

 the corolla releases the 

 anther from the pocket in 

 which it rests so that it 

 springs up, dusting the 

 body of the visitor with 

 pollen. 



In some plants, self- 

 pollination is prevented 

 by certain devices, as in 

 the primroses, in which 

 the stamens and pistils 

 are of different lengths in 

 different flowers. Short 

 styles and long filaments 

 with high-placed anthers 

 are found in some flowers, 

 and long styles and short 

 filaments with low-placed 

 anthers in others. Polli- 

 nation is most likely to be 

 effected by some of the 

 pollen from a low-placed 

 anther reaching the stigma 

 of a short-styled flower, or 

 by the pollen from a high 

 anther being placed upon 

 a long-styled pistil. There 

 are, as in the case of the 

 spiked loose-strife, flowers 



EST •••*• 



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Wright Pierce 



A species of yucca found in the Southwest. It is 

 almost stemless, and has a stout flower stalk 12 to 15 

 feet high carrying a cluster of fragrant, creamy white, 

 bell-shaped flowers. 



