196 A ^ATURALIST IN THE GREAT LAKES REGION 



In the center of such a sphagnum bog is frequently found 

 a small lake that is filling, and this may be occupied in part by 

 chara (Fig. 186). Quite commonly the lake, 

 if it is sufficiently deep, will have, shoreward 

 from the chara zone, a zone of water lilies, 

 first the white, then the yellow. 

 The water shield is commonly 

 found growing with the white 

 water lilies. Next comes a zone 

 of floating sedges, the rhizomes 

 of which mat together so densely 

 as to form quite substantial foot- 



FIG. 237. Ragged orchis, Habenaria lacera, details 

 of blossom in small figures. Drawing by L. N. Johnson. 



ing. This zone of floating sedges pushes 

 farther and farther out into the lake as ice 

 might form at the margin of a pond. The 

 chief mat-forming sedge is Carex filiformis 

 (Fig. 227). The shore sedge, Carex riparia 



