INTERDUNAL PONDS AND TAMARACK SWAMPS 



195 



Chicago area. It is, furthermore, a widely distributed associa- 

 tion found at its best in northern North America and Eurasia 

 covering very wide areas. The sphagnum bogs found as far 



232 



>».,\ 



233 



234 



235 



236 



Figs. 231-236: Fig. 231. — The sundew, Droscra rotundifoUa; Fig. 232. — 

 Tickseed, Coreopsis grandijlora; Fig. 233. — Cottony grass, Eriophormn gracile; 

 Fig. 234. — Swamp horsetail, Equisetum fluviatile, and section of stalk; Fig. 235. — 

 Swamp fern, Aspidium Thclypterls, and under side of one pinnule; Fig. 236. — 

 Sphagnum moss. 



south as the Chicago area are isolated areas — islands in the midst 

 of the more typical associations. As will be seen in a later chapter 

 they are probably remnants of the vegetation that was quite wide- 

 spread in this region immediately following the glacial period. 



