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ILLINOIS ACADEMY OF SCIENCE 



finally increase the amount of vegetation and make the en- 

 trance of new species an easier matter. 



The succeeding community may be called the Carex-Arte- 

 misia association from the comparative abundance of Carex 

 stenophylla, C. filifolia, Artemisia frigida and A. canadensis. 

 Grasses also begin to be rather conspicuous, being represented 

 by species of Festuca, Muhlenbergia and Koeleria. The mat- 

 forming habits of several of these grasses is of the greatest 

 importance because only within such mats does the formation 

 of humus occur, and with it the advance of the association. 

 Even in this association not more than one-half the surface is 

 actually covered by the vegetation. About this time the in- 

 vasion of other species in small communities giving a patchy 

 character to the vegetation becomes conspicuous. Such ag- 

 gregations are found of all species, but among the more con- 

 spicuous may be mentioned those of Antennaria parvifolia, 

 Campanula rotundifolia, Potentilla spp., Aragallus LambertU, 

 A. Richardsonii, and Achillea millifolium. 



The succeeding stage is well developed and is perhaps the 

 most usual vegetation of the montane parks. It is character- 

 ized by the greater development of grasses in comparison with 

 other herbaceous species and has been designated by Ramaley, 

 who has studied it most extensively, the "dry grassland." From 

 a study of the composition of a large number of permanent 

 quadrats Ramaley 6 finds that there is still much bare ground, 

 amounting to about 25 per cent of the whole area during the 

 month of July. The same investigator reporting upon the 

 composition of the vegetation finds 30 per cent of it com- 

 posed of various species of grasses, species of Muhlenbergia, 

 making up 8.18 per cent, and of Festuca 7.78 per cent. Carex 

 spp. amount to 11.25 per cent and Aragallus spp. to 9.68 per 

 cent, while Selaginella densa still covers more than 5 per cent 

 of the whole area. Among the more common species are 

 Agropyron violacea, Festuca octoflora, F. pseudovina, Koel- 

 eria cristata, Poa spp., Muhlenbergia gracilis, M. Richardsonis , 

 Stipa comata, Carex filifolia, Potentilla Hippiana, P. gracilis, 

 Aragallus Lambertii, A. Richardsonii, Artemisia spp. and Pent- 

 stemon procerus. Other species are rather numerous and 

 some become locally abundant while it is to be noted that all 

 the species of the pioneer associations persist. There can be 

 no doubt that this dry grassland association in its various 

 modifications is a comparatively permanent vegetation and it is 

 even possible that it is the climax for the more exposed situa- 

 tions, altho a rather careful examination leads to the conclusion 

 that it is gradually advancing in mesophytism largely through 



