454 



GENERAL MORPHOLOGY OF PLANTS 



in arctic lands, the forested areas along river bottoms in prairie or 

 plains regions, etc. 



639. Aquatic plant societies. In general we might dis- 

 tinguish three kinds. First. Fresh-water plant societies, with 

 floating algae like spirogyra, cedogonium, etc., the floating duck- 

 meats, riccias; the plants of the lily type with roots and stems 

 attached to the bottom and leaves floating on the surface, like 

 the water-lily and certain pondweeds, and finally the completely 



Fig. 413- 



Macrophytes in the upper zone of the photic region. Ascophyllum and Fucus at low 

 tide, Hunter's Island, New York City. (Photograph by M. A. Howe.) 



submerged ones like certain pondweeds, the bassweed (Char a), 

 etc. Second. Marine plant societies, which are made up mostly 

 of the red and brown algae or " seaweeds," though some green 

 algae and flowering plants also occur. Third. The salt marshes 

 where the water is brackish and there is usually a luxuriant 

 growth of marsh-grasses. (See Chapter LV of the author's 

 College Text-book of Botany.) 



