1905] TRANSEAUBOGS OF THE HURON RIVER VALLEY 431 



for the most part, of Salix Bebbiana, S. discolor, S. sericea, Cornus 

 candidissima, Acer rubrum, and Ulmus americana. Beside the 

 many plants of the sedge-grass society which remain as relicts, the 

 accessory species include Rosa Carolina, Impatiens biflora, Sambucus 

 pubens, Spiraea salicifolia, Prunus serotina, Quercus alba, Q. 

 velutina, and Opulaster opulifolius. These trees grade into the 

 forests of the upland and establish a natural order of succession. 



An interesting comparison is afforded when we note the species 

 dominant along the western or bog margin. Here the outer zone of 

 aquatics is made up of the same species, but this substratum is a 

 floating raft constructed by the plants themselves. Without again 

 enumerating the species, we pass to the society which closely follows 

 their development. 



Bog-sedge and shrub society. This society forms a very complex 

 growth, averaging 50 feet (15 m ) in width. On the lakeward side are 

 the aquatics ; on the other, the growth of tamaracks. The sedges and 

 shrubs are not separable, as in many other localities. Carex fili- 

 formis is by far the most important plant in the society. Its vigorous 

 production of rhizomes and roots especially fit it for the position which 

 it occupies. Certain other plants are locally abundant and of great 

 consequence. These include Dryopteris thelypteris, Menyanthes 

 trifoliata, Eleocharis palustris, Comarum palustre, Sagittaria latifolia, 

 Eriophorum polystachyon, Carex teretiuscula, Typha latifolia, Salix 

 myrtilloides, S. Candida, Betula glandulosa, 6 Oxycoccus macrocar- 

 pus, and Andromeda polifolia. As accessory species may be men- 

 tioned Salix discolor, S. Bebbiana, Cicuta bulbifera, Cardamine 

 pratensis, Chamaedaphne calyculata, Campanula aparinoides, Rumex 

 Britannica, Epilobium adenocaulon, Asclepias incarnata, Pogonia 

 ophioglossoides, Blephariglottis blephariglottis, Limodorum tuber- 

 osum, Marchantia polymorpha, Aulacomnium palustre, Sarracenia 

 purpurea, Drosera rotundifolia, Boehmeria cylindrica, Carex comosa, 

 C. hystricina, Cornus stolonifera, Parnassia caroliniana, Viola blanda, 

 and Penthorum sedoides. Here and there occur young tamaracks 

 which by their growth inaugurate the next society. 



Tamarack society. As development proceeds, the shrubs and 



6 The form found here and at Delhi corresponds more closely to this species than 

 to B. pumila, but its characters are intermediate. 



