﻿Nichols: The vegetation of Connecticut 197 



ponds where rapid peat accumulation is taking place the filling 

 in of the deeper waters is brought about in this manner. Very 

 often the growth of certain marginal swamp plants is so vigorous 

 as to give rise to a raft-like zone of vegetation which spreads out 

 from the shore over the surface of the water, and which is com- 

 monly referred to as a Floating Mat (Fig. io). There will be 

 described next, then, the manner in which this mat is developed, 

 together with the succession of plant associations which accom- 

 panies the process. And since in Connecticut the floating mat 

 succession is commonly associated with bogs, a type of swamp not 

 yet treated, the two will be considered together, i. e., the suc- 

 cession is assumed to culminate in the formation of a bog. 



Mat Formation due to Sedges. — ^The lake stages in such a suc- 

 cession are identical with those already described. There may 

 thus appear, in order, submersed aquatics, aquatics with floating 

 leaves, and aquatics with aerial foliage; but, due to the encroach- 

 ment of the mat, these stages may be quite abbreviated, and one 

 or all may be eliminated. It is in the transition from lake to 

 swamp that the floating mat comes into play. According to the 

 conception which has been widely circulated, especially in geolog- 

 ical literature previous to 1907, this mat is formed in the following 

 manner. "Certain mosses, particularly those of the genus Sphag- 

 num, have a habit of growing out on the water surface and forming 

 a mat of intertwined stems connected with the shore. At this 

 stage the lake is an open water body with a border of vegetation 

 floating near the rim. Gradually this rim of moss creeps toward 

 the center of the pond until it is completely closed in and covered 

 over with a layer of vegetation. The lake is now a swamp; and 

 such a swamp, with a floating layer of aquatic plants, is known as 

 a ' quaking bog ' ; it is possible in some cases to walk across an old 

 lake on a mat of vegetation while the water remains below. These 

 mosses have a habit of growing at the top while the old stems are 

 dying below, and the rotted fragments drop to the bottom of the 

 pond and help to fill it up."* 



Except for the stress laid on the r61e of Sphagnum and other 

 mosses, the description above quoted portrays the origin and 

 behavior of the floating mat fairly accurately; and for cold, 

 * Rice, W. N.. and Gregory, H. E., op. cit.. p. 249. 



