INTERDUNAL PONDS AND TAMARACK SWAMPS 179 



and they have black spots near the tips of both wings; the fully 

 matured males have the spots on the front wings only. Other 

 forms to be listed below are also found here in the Myriophyllum 

 ponds, though not as abundantly as a rule as in the later ponds. 



The newer ponds of the dunes may then be described in 

 order, naming them both from the characteristic animals and 

 plants: (i)theLamp- 

 silis luteolus ponds or 

 bare-bottomed ponds; 

 (2) bloodworm ponds 

 or Char a ponds; (3) 

 Ischnura verticalis 

 ponds or bladderwort- 

 milfoil ponds. 



The older ponds 

 are usually them- 

 selves distinctly zon- 

 ated and must be 

 described in terms of 

 zonally arranged 

 plant and animal soci- 

 eties rather than as a 

 single society. Yel- 

 low and white water 

 lilies appear shore- 

 ward from the sub- 

 merged plants, then 



FIG. 198. The sensitive fern, Onoclea sensibilis, 

 underground stem and all. 



come rushes, cat-tails, sedges, and so the filling chara ponds 

 give rise to marshy or swampy areas that seem to evolve into 

 three different types of regions, the differences depending 

 primarily on drainage, namely, (i) the wet forest, (2) the prairie, 

 and (3) the tamarack swamp. 



In the first type (Fig. 175) grasses and sedges grow along 

 the margins, and with them are such plants as the buttonbush, 

 the sensitive fern, marsh marigold, white violet, and the swamp 



