STUDIES IN LAKE AND STREAMSIDE VEGETATION 1 53 



amphibium and other hydrophytes so abundant in lakes of lower alti- 

 tude. Species of Utricularia sometimes occur in lakes of high altitude 

 elsewhere but none have been seen by the writers in the sub- alpine and 

 alpine districts of northern Colorado. In the foothill lakes Utricularias 

 are abundant. 



Half-submersed plants are generally absent from the lake except 

 Carex utriculata which, in places, forms a prominent zone about one 

 meter wide along shore. There are no species of Scirpus or other com- 

 mon half- submersed plants of lower altitudes. 



Sedge Zone 



The zone of sedges really begins in shallow water. Carex utriculata, 

 as just noted, sometimes extends into the water (see Fig. 9). About 10 

 meters (32 ft.) may be taken as the average width of the sedge zone but on 

 the north shore for a distance it is almost absent (see Fig. 1) and the 

 willows and birches come nearly to the edge of the lake. The sedges col- 

 lected are six in number, five species of Carex and one of Eleocharis. 

 The gentians, which are characteristic of the autumn aspect, occur chiefly 

 in this zone with the sedges. 



The soil is very wet at all times and hence may be called "physiologi- 

 cally cold" even though it warms up in late summer with the heating 

 of the lake water. Here then it is natural that many alpine plants 

 should be found; 1 in fact one-third of the species belong to the alpine 

 and sub-alpine districts. In the shrub zone only one-sixth and in the 

 forest only one-fourteenth of the species belong essentially to higher 

 altitudes. A comparison of the vegetation with that of the " wet mead- 

 ows" at high altitudes can be made by reference to a recent paper by 

 Mr. W. S. Cooper, 2 who names the following species which are also 

 represented at Redrock Lake: Carex spp., Caltha leptosepala, Sedum 

 rhodanthum, Sieversia turbinata, Elephantella groenlandica, Dasyste- 

 phana ronianzovii (Gentiana frigida). 



Straggling shrubs from the next zone are found as invaders among 

 the sedges in some places. This invasion occurs in places where the 



1 See the table in account of floristics. 



» Cooper, W. S., "Alpine Vegetation in the Vicinity of Long's Peak, Colorado," Bot. Gaz., Vol. XLV, 

 PP- 310-37, 1908. 



