IO4 A Study of the Vegetation of 



The Eleocharis-Carex Ass odes 



This plant community covers areas along the flood plains of 

 smaller streams which are wet during the rainy season but often 

 quite dry during the late summer months. Likewise, about the 

 borders of lakes and springs it occupies situations of lower water 

 content than those characterized by Scirpus or Typha. 



The Eleocharis consocies is dominated by E. palustris. It some- 

 times covers considerable areas with a pure growth (Fig. 31). 

 Its rhizomes form extensive mats which abound at the edge of 

 ponds as well as in the shallow water. Associated with it is E. 

 acicularis. It likewise has well developed and extensive root- 

 stocks, while those of E. acicularis bella are very short so that 

 the mats assume the form of dense round tufts. Because of its 

 lesser height-growth the latter species is easily distinguishable 

 from the former. 



Frequently occurring in mixture with Eleocharis are various 

 sedges and rushes of the following community. 



The Carex-Juncus Mictium. I have never seen in this region 

 any considerable area dominated by one species of Car ex or 

 Juncus. However, a study of the fragmentary areas charac- 

 terized by this community reveals the dominance of Car ex ne- 

 braskensis and Juncus balticus locally. More often the follow- 

 ing species occur in a puzzling mictium : 



Car ex lanuginosa Juncus bufonius 



Car ex monile pad fie a Juncus ensifolius 



Carex nebraskensis Juncus suksdorfii 



Carex pachystachya Juncus tenuis 

 Juncus balticus 



In addition to relicts of the preceding communities, associated 

 with the above species are to be found numerous other plants of 

 which the most important are Beckmannia erucaeformis, Radic- 

 ula curvisiliqua, Alopecurus calif ornicus, Epilobiwn adenocaulon, 

 Carex utriculata, and Mentha canadensis borealis. The last- 

 named plant is very important ecologically. It has well devel- 

 oped and extensive rhizomes. It not only thrives in very wet 



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