1905] TRANSEAUBOGS OF THE HURON RIVER VALLEY 435 



Poplar-willow-maple society. Where the original conditions have 

 been disturbed and a second growth allowed to come in, Populus 

 tremuloides, Salix sericea, Salix discolor, and Acer rubrum have 

 obtained dominance. Where groups of the more mature poplars 

 occur there is scarcely any undergrowth. Elsewhere the following 

 plants occur: Ilicioides mucronata, Salix Bebbiana, Sambucus 

 pubens, Amelanchier oligocarpa, Aronia nigra, Rubus nigrobaccus, 

 Cornus stolonifera, and Rubus strigosus. These form a dense mixed 

 association, with but slight reference to substratum conditions. The 

 smaller species present are Adicea pumila, Osmunda cinnamomea, 

 Rosa Carolina, Onoclea sensibilis, Epilobium adenocaulon, Spiraea 

 salicifolia, Dryopteris thelypteris, Verbena hastata, Solanum dul- 

 camara, Polygonum sagittatum, Spiraea tomentosa, Geum rivale, 

 Polygonum hydropiperoides, Ribes floridum, Ribes oxyacanthoides, 

 Rumex Britannica, Impatiens biflora, Viola blanda, Osmunda 

 regalis. 



On the southeast side of the lake and on the north, conditions 

 have been still more interfered with, and there is now a mixed growth 

 of bog and low-ground plants, which represent stages in the decline 

 of the bog flora and the advent of swamp plants. The tallest forms 

 are willows and clumps of mountain holly. For convenience only, 

 the plants may be enumerated together under the following title : 



Mixed low- ground society. The dominant plants are Salix 

 sericea, S. discolor, Spiraea salicifolia, Poa flava, Solidago serotina, 

 Chamaedaphne calyculata, Oxycoccus macrocarpus, Aster Novae- 

 Angliae, and Rosa Carolina, Epilobium adenocaulon, Aronia .nigra, 

 Andromeda polifolia, Rubus strigosus, Dryopteris thelypteris, 

 Scutellaria galericulata, Juncus effusus, Koellia virginiana, Sambucus 

 canadensis, Geum rivale, Osmunda regalis, Scirpus cyperinus, 

 Galium aparine, Homalocenchrus oryzoides, Juncus tenuis, Asclepias 

 incarnata, Salix Bebbiana, Eupatorium perfoliatum, Gentiana 

 Andre wsii, Lycopus virginicus, Osmunda cinnamomea, Cornus 

 stolonifera, Carex riparia, Viola blanda, Sarracenia purpurea, 

 Dryopteris cristata, D. spinulosa intermedia, and Triadenum vir- 

 ginicum also occur. 



The last two societies are found upon a black peat substratum 

 which is more thoroughly decayed than in other parts of the bog. 



