2 28 THE POPULAR SCIENCE MONTHLY 



rushes, sedges and salt-grasses. Frequently even the beach, many feet 

 back from the water's edge, is so thoroughly impregnated with salts that 

 they crystallize and form a white crust over the surface. This results 

 in an absolutely barren zone. Back of that portion of the beach washed 

 by the waves the salt-enduring plants develop very copiously. The salt- 

 grass {Disiichlis spicata) is usually controlling in such places where the 

 low plants develop a very close tenacious sod. Beyond the belt of salt- 

 grasses the taller stems of other grasses, sedges and rushes make up 

 another distinct zone which may completely encircle the pond or lake. 

 These plants are very dark green, so that the belts of vegetation about 

 the saline lakes stand in marked contrast to the duller tones of the sur- 

 rounding hills. Still farther back beyond the zone of tall plants the 

 shore vegetation of the saline lake passes either abruptly or gradually 

 into the typical wet meadow vegetation. 



The appearance of the fresh-water lakes is quite different. First of 

 all there is usually a wealth of submerged or half -submerged plants. 

 Some of these lakes are literally filled with great masses of pondweeds 

 (Potaniogeton, several species), and the water milfoil {Myriophyllum 

 spicatum). The bottom, in the shallower portions of such lakes, is 

 covered with a carpet of stonewort ( Chara fcetida, etc. ) , while the stems 

 of the submerged flowering plants are richly coated with algae of many 

 kinds. In late summer certain of these algae become broken away from 

 their substrata and float about on the surface of the water. During 

 high winds at this time great quantities of these, such as the net sack 

 (ClathrocysUs ceruginosa), are washed on the beach in yellow green 

 splashes. So there are many very interesting animals in the fresh- 

 water lakes, a sponge being one of the common forms. 



The white, encrusted beach is absent from the fresh-water lakes, as 

 also are the belts of salt-enduring plants. The commonest marginal 

 plant here is the great bulrush {Scirpus lacustris). Frequently this is 

 the only plant between the bunch-grass association of the hills and the 

 open water of the lake. Sometimes other species such as cat tail 

 {Typha latifolia), and the giant reed grass {Phragmites phragmites) 

 occur in mixture with the bulrush, or these may now and then form 

 separate belts. Wild rice grass (Zizania aquatica) is a common mar- 

 ginal or shallow-water inhabitant of many of the lakes. This plant is 

 about as tall as the bulrush, but because of its leafy stems it often forms 

 much denser stands in the shallow water. When the seed is ripe every 

 bed of wild rice is a Mecca for thousands of water fowl that live in the 

 vicinity of the lakes. Wild ducks become so thick at times in these rich 

 feeding grounds that the noise they make reminds one of an over-stocked 

 barnyard. 



The lakes range in size from small ponds to bodies of water one and 



