42 



BOTANY 



brookside flowers is the jewel weed. It well deserves its name, a pendent 

 flaming jewel of orange. 



The flower is very irregular in shape. Are the flowers single or in clusters ? 

 The sepals as well as the petals are colored. The former are three in num- 

 ber, one of which is saclike in shape and contracted at one end into a spur. 

 The petals are also three in number. Open the flower. Notice how short 

 the filaments of the five stamens are. Make a note of their position with 

 relation to the pistil. Would self-pollination be possible in this flower? 



If it is possible to study jewel weed out of doors in its native habitat, it 

 will be found that humming birds are the visitors which seem best adapted 

 to cross-pollinate the flower. A careful series of observations by some girl 

 or boy upon the cross-pollination of this flower might add much to our 

 knowledge regarding it. 



Jewel weed has the habit of producing (usually in the fall) inconspicuous 

 flowers which never open but which produce seeds capable of germination 

 and growth. Such flowers are said to be deistogamous. In England, where 

 the plant has been introduced, it is found to produce more deistogamous 

 flowers than showy ones, and the showy ones do not produce seed. There 

 are no humming birds in England, and without this means of pollination 

 the deistogamous form prevails. Make a front view drawing of the flower 

 of jewel weed twice natural size. 



Many other examples of adaptations to secure cross-pollination 

 by means of the visits of insects might be given. The moun- 

 tain laurel; which makes our hillsides so beautiful 

 in late spring, shows a remarkable adaptation in 

 having the stamens caught in little pockets of the 

 corolla. The weight of the visiting insect on the 

 corolla releases the anther of the stamen from 

 the pocket in which it rests, and the body of the 

 visitor is dusted with pollen.^ 



The milkweed or butterfly weed (Asdepias cor- 

 niiti) is another example of a flower adapted to 

 insect pollination.^ 

 fl:| Still another example of cross-pollination is found 



in the yucca, a plant somewhat like the Spanish 

 bayonet. In this flower the stigmatic surface is 

 above the anther, and the pollen is sticky and 

 could not be transferred except by insect aid. This is accom- 

 plished in a remarkable manner. A little moth called the Pronuba 



* See Hunter and Valentine, Manual, page 57. 



2 For an excellent account of cross-pollination of this flower, the reader is referred 

 to W. C. Stevens, Introduction to Botany. Orchids are well known to botanists as 

 showing some very wonderful adaptations. For simple reference reading, see 

 Coulter, Plant Relations. A classic easily read by children is Darwin, On the Per- 

 tilization of Orchids. 



Pronuba pollinat- 

 ing pistil of 

 yucca. 



