DRY GRASSLAND OP A MOUNTAIN PARK 255 



composites so characteristic of the plains and lower foothills/ 

 nor are there grasses that develop autumn coloration of yellow 

 or red as in the meadow and sedge moor of the Park, or even in 

 many dry grasslands elsewhere. 



SOCIETIES 



Corresponding to the various exposures to wind and sun, to 

 differences in soil texture, soil temperature, and moisture, there 

 are to be recognized certain societies, facies or aspects of the 

 dry grassland. These are not rigidly fixed but show variations 

 and intergradations. Yet in examining any particular part of 

 the dry grassland it is usually possible to determine the society 

 to which it belongs. In the following list for the sake of brevity 

 only a few species are named with each society, although here, 

 as elsewhere in the present study, manuscript notes have been 

 made of all important features. Many of the subsidiary species 

 are almost ubiquitous so far as the communities under con- 

 sideration are concerned. 



1. Erigeron multifidus society. Erigeron multifidus, Potentilla 

 concinna, Selaginella densa, Aragallus lambertii, Carex stenophylla. 

 A type of community that appears on soil recently exposed, as 

 through change in the course of the creek or, in earlier times, a 

 recession of the glacier; frequent on the top of creek bluffs in 

 coarse sandy soil which dries out rapidly. Aragallus lamhertii 

 •and Selaginella densa are the commonest plants in this society, 



but the distinctive species are Erigeron multifidus and Potentilla 

 concinna. 



2. Carex stenophylla society. Carex stenophylla, Artemisia 

 frigida, A. forwoodii and A. aromatica, Sedum stenopetalum, 

 Chrysopsis uillosa, Potentilla hippiana, Potentilla pennsylvanica 

 strigosa, Selaginella densa, Aragallus lambertii. A community 



^ Ramaley, Francis, Remarks on the distribution of plants in Colorado east 

 of the Divide. Postelsia. 1: 21-53, 1901. 



Ramaley, Francis, Plants of the Florissant region in Colorado. Univ. Colo. 

 Studies 3: 177-185, 1906. 



Vestal, Arthur G., Prairie vegetation of a mountain-front area in Colorado. 

 Bot. Gaz., 68: .377-40, 1914. 



