4i8 George E. Nichols, 



drained ponds. Of species with submerged or floating leaves 

 the most commonly represented are Nymphaea variegata and 

 Castalia odorata, Eriocaulon septangulare, Ranunculus Flammula 

 reptans and Utricularia intermedia. In addition to these, various 

 sedges may grow in the shallow water around the margin or 

 elsewhere, such species as Eleocharis palustris vigens, Carex 

 oligosperma and Scheuchseria palustris, together with the buck-_ 

 bean, Menyanthes trifoliolata. Of particular importance, how-_ 

 ever, because of their frequently prolific growth, are the aquatic 

 sphagnums, notably Sphagnum Pylaisei and S. cuspidatum 

 (including the var. Torreyi), and certain filamentous algae. But 

 there is the greatest variation in the vegetation even of closely 

 adjacent and seemingly quite similar ponds. One may be quite 

 choked up with aquatic sphagmmis, while in the next there 

 is scarcely any vegetation save a dense growth of algae on the 

 bottom. One may contain a rank growth of Eleocharis, its 

 neighbor a similar growth of Menyanthes, or neither of these 

 species may be present ; and so on. Practically all undrained 

 ponds are mucky at the bottom and along the shores. The 

 dynamics of the vegetation in lakes and ponds are discussed in 

 later paragraphs. 



2. The Formation-types of Lake-, Spring-, and Precipitation- 

 swamps 



a. THE ASSOCIATION-COMPLEXES OF WELL-DRAINED SWAMPS 



As elsewhere suggested, throughout the region of coniferous 

 forests, wherever the ground is sufficiently wet, there is a 

 tendency for the substratum, through the influence of vegetation 

 in obstructing the drainage, to become boggy. In view of this 

 fact, it would not have been at all surprising to find that swamps 

 similar to the undrained type of the lowlands were entirely lack- 

 ing here. But this is not the case. While the majority of the 

 swamps belong to the undrained or poorly drained types, swamps 

 are frequently encountered which unmistakably are of the 

 well-drained type. The following list of plants, from an open 

 swamp situated on a fairly steep, springy hillside in the forested 

 region, scarcely a mile from the edge of the barrens, is quite 

 characteristic of well-drained swamps in this region : it has been 

 practically duplicated in other similar areas. 



