﻿206 Nichols: The vegetation of Connecticut 



lain by marl, and since Sphagnum is reputedly calciphobous, it 

 was at first thought that here, at least, its absence could be easily 

 accounted for. But in a nearby swamp which likewise overlies a 

 calcareous subsoil Sphagnum is abundant. Similar observations 

 by Davis* in Michigan, together with the experimental evidence 

 advanced by Transeau and Weberf would make it appear highly 

 improbable that the presence or absence of Sphagnum can be cor- 

 related with the presence or absence of lime. As a rule, in the 

 floating mat succession, Sphagnum seldom precedes the shrubs 

 and sedges, except to an inconsequential degree. There are a 

 few ponds in southeastern Connecticut where Sphagnum macro- 

 phyllum, a remarkable southern coastal-plain species with leaves 

 fully half an inch long, constitutes an important part of the free- 

 floating vegetation. But this condition is exceptional. In a bog 

 the Sphagnum usually appears first as a superficial layer growing 

 on the surface of the shrub or sedge mat; but once established it 

 often develops so rapidly and luxuriantly as to exert a profound 

 influence on the character of the bog vegetation. | Growing 

 upward in dense masses around and among the stems of various 

 shrubs, etc., this plant commonly forms cushions which sometimes 

 rise as much as two feet above the original water level. Ante- 

 cedent plants which are unable to accommodate themselves to this 

 change in environmental conditions are gradually eliminated. 



Broadly speaking, the ability of a plant to exist in a bed of 

 rapidly growing Sphagnum may be said to depend on its ability to 

 keep pace with the upward growth of the moss. The necessity of 

 keeping the foliage above the surface of the substratum is too 

 obvious to require more than passing mention. But it seems very 

 likely that it is equally important that the roots of the plant be 

 kept above the zone of permanent saturation. For as the 

 Sphagnum plants grow upward, dying away below, the lower part 

 of the cushions becomes more and more compact and, due largely 

 to the well-known capacity of Sphagnum stems and leaves for 

 sucking in water, acting like a sponge, it becomes completely 

 saturated. As the Sphagnum cushions increase in height, then, 



* 1907. loc. ciL, p. 276. 

 t See Transeau, 1906, loc. cil., p. 32. 



t In this connection see also W. S. Cooper's discussion of the behavior of Sphag- 

 num in Isle Royale bogs. Bot. Gaz. 55: 200-206. 1912. 



