TRANSEAUBOGS OF THE HURON RIVER VALLEY 443 



the appearance of an elongated brown rosette about the^stem^bases. 

 Clitocybe laccata and Boletinus porosus are also abundant in the 

 autumn. The partially decayed stumps bear Peltigera canina. 

 Other species occur in this area, but reach their dominance in the 

 next society. 



Poplar-maple society. Here are brought together the remnant 

 of the bog species, and those more characteristic of swamps and 

 clearings. The trees are mainly Populus tremuloides, with a scat- 

 tering of Acer rubrum. Elm seedlings occur. The shrubby plants, 

 however, make up the bulk of the vegetation. Ilicioides mucronata, 

 Ilex verticillata, Aronia nigra, and Vaccinium corymbosum have 

 almost complete possession, and are struggling with one another for 

 space. All these forms send up stems from the underground parts, 

 so that among them the struggle is largely a mechanical one. How- 

 ever, where the red maple overtops them, the factor of shade enters, 

 and the black choke-cherry and high-bush blueberry are the most 

 tolerant. The mountain holly and black alder prevail elsewhere. 

 The next most important plants are the willows, Salix sericea and 

 S. discolor. Mixed with these are Cornus candidissima, Rubus 

 nigrobaccus, Rosa Carolina, Cornus stolonifera, Spiraea salicifolia, 

 and Rubus strigosus. 



Willow-sedge society. The area dominated by these plants is 

 covered with water in the spring and during moist weather. Although 

 this society is fast being crowded out by the next preceding, it is 

 probable that only a small part of that area was ever occupied by these 

 plants. These plants require a more moist substratum. The domi- 

 nant species are Salix sericea, Carex riparia, C. stipata, Cornus 

 stolonifera, and Osmunda cinnamomea. In the case of the cinna- 

 mon fern found in this bog there is a remarkable development of 

 aerial roots. They are about an inch long and extend outward from 

 the thick rootstock in all directions, forming a dense covering. The 

 roots are thickly covered with root-hairs which have been persistent 

 at least through one winter. The root-hairs are large and brown 

 in color. The appearance of these rootstocks, as a whole, is very 

 suggestive of certain tropical tree ferns. The other species present 

 are Ranunculus abortivus, Polygonum sagittatum, Cicuta bulbifera, 

 Prunella vulgaris, Rubus americanus, Rhus Vernix, Solanum dulca- 



