506 ECOLOGICAL CLASSIFICATION OF PLANTS 



plants of swamp societies are the Sagittarias, Bulrushes, Cat-tails, 

 Rushes, Sedges, and Reedgrasses, which form fringes around 

 ponds and lakes [Figs. 456 and 457). Some trees, such as Wil- 

 lows, Poplars, Birches, and Alders, are common in swamp societies. 

 In a swamp of the bog type, Sphagnum Moss, Orchids, and some 

 trees, such as the Tamarack, Pine, and Hemlock, are character- 

 istic plants. 



Aside from Rice, which is a Hydrophyte during a part of its 



Fig. 455. — A pond in which are growing Water Lilies, plants typical of a 

 Pond-weed society. After C. M. King. 



development, the hydrophytic societies are not noted for plants 

 important economically. 



Mesophytic Societies. — The mesophytic societies comprise 

 the common vegetation. They require a medium amount of 

 moisture and a fertile soil. To these societies belong our culti- 

 vated plants, weeds, and deciduous forests. The mesophytic 

 condition is the arable condition and is the normal or optimum 

 condition for plants. If a hydrophytic area is to be cultivated, 

 it must be drained and made mesophytic. 



