r6lE of sedges in COLORADO PLANT COMMUNITIES 
123 
large broken rocks with no soil. Another reason is that these lakes are 
frozen over from November to June, or as late as July. Even during 
August, the water temperature as shown by Dodds (2) is low, about 10 
degrees Centigrade. Wherever the vegetation comes close to the edge of 
the water it 's a dense growth of mosses and sedges, i. e., a. moss moor. This 
Fig. I. A high montane lake (Teller Lake) showing Half-submersed Carex Association 
of Carex rostrata and Carex canescens. This is followed by a narrow zone of Sedge Moor 
dominated by Carex aquatilis. Outside of this is a strip of Meadow in which Carex festi- 
vella is important; farther out is a mixed Dry Grassland with a large amount of Carex siccata. 
is usually elevated as a distinct ''rim" one or two decimeters higher than 
the sedge moor, just as pointed out for montane lakes by Robbins (9). 
Carex scopulorum is probably the commonest sedge of the "rim." 
Sedge Moor Association Type 
This type of plant community exists under conditions similar to that 
described in the preceding section, but the soil is not covered by water. 
Ponds and lakes occur abundantly in the montane, subalpine, and alpine 
zones, and they always have some bordering sedge moor. The lakes at 
higher elevations are either morainic or of the rock-basin type. In the 
montane parks meandering streams give rise to ox-bows. The foothill 
area with its older topography and better drainage has very few lakes. A 
considerable number of natural lakes exist on the plains. Some of these 
are of ox-bow origin, some occupy old channels closed by alluvial damming, 
and some basins have arisen through wind action upon weathered sand-- 
