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1902] SURVEY OF THE HURON RIVER VALLEY 131 



((f) A zone of Carex and Sphagnum, whose surface is prac- 

 tically at water level, extends landward from the water's edge 

 from six to twenty-five feet. This is an exceedingly well defined 

 zone {^fig, -?), and lying so close to the water level it is neces- 

 sarily saturated with water, and the tough mat of sedges is in 

 many places little better than a floating morass. The soil under- 

 lying it is composed entirely of black muck and decaying vege- 

 table matter. The most abundant plants are Carex filiformis L., 

 Sphagjiiim, and Potcntilla palustris Scop. 



[d^ A zone of Salix and Popidus, varying from ten to forty 

 feet wide, extends entirely around the lake and stands from 

 three to twenty-four inches above the preceding zone. The soil 

 of this zone is almost entirely of vegetable origin; in different 

 parts and at different seasons it contains varying amounts of 

 water. It never becomes mesophytic in character, and is often 

 hydrophytic, A very few vigorous mesophytic species occur 

 with the characteristic plants of this zone, but they usually show 

 changes of habit to correspond to their environment. The 

 characteristic plants of this zone are Salix alba L., var. vitellina 

 Koch, 5. liicida MuhL, S, myrtilloides L,, Poptdus tremuloides 

 Michx., and Ulmns americana L. 



(^) A zone of Gramineae a7id Compositae lies just outside the 

 last zone, and is from six to thirty inches above it. In this zone 

 ere are adaptations to past, rather than to present conditions. It 

 IS the transition zone in which mesophytic species begin to mix 

 with hydrophytes, its landward border merges gradually into the 

 vegetation of the surrounding country. The greatest admixture 

 of terrestrial plants occurs on the north and southeast shores, 

 where the struggle between plants has been most severe for some 

 ^ time. While it is difficult to designate distinctly characteristic 



plants for this zone, the following are among the most constantly 

 recurring species: Spiraea salicifolia L., Monarda fistidosa L., 

 Riimex obtusif alius L., Enpatorinm perfoliatnm L., Salix discolor 

 MuhL, Jtincus canadensis J. Gray, Epilobium colorahim Muhl., 

 Hypenciim canadense L., Nepeta cataria L., Sambuciis ca7iadensis L., 

 Acer rubnim L., Gentiana Andrewsii Griseb., Bidens bipinnata L. 



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