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 
Fic. 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. 
