382 THE STORY OF PLANT LIFE 



may spring with male and female flowers. In the 

 male flower are one or two stamens. The female 

 flower contains four free, single carpels, with a small, 

 entire, cup-shaped perianth or spathe. The ovaries 

 are stalkless within the bracteoles with a short style 

 and broad disc-shaped stigma, half as long as the 

 nut. The anther-stalks are slender. The anthers 

 are two- or four-celled. When ripe the carpels or 

 achenes are stalked or stalkless, narrow, curved, 

 flattened, with a smooth tubercled keel, with a beak, 

 the remains of the style. 



In length the Horned Pondweed is 12 to 18 in. 

 It flowers from May to August, and is a herbaceous 

 annual. 



The plant being monoecious pollination must be 

 effected by outside agency, and the flowers are pol- 

 linated as in Zostera, but the pollen is spherical, not 

 long and thread-like. The male flowers are long- 

 stalked. 



The fruits or achenes are dispersed by the agency 

 of water. 



No other name for this plant is known except the 

 one cited. 



Zannichellia palustris. — Note in Fig. 106 the 

 long, linear leaves, with a whorl-like arrangement, also 

 the beaked aclunes, in fours. 



