364 BOTANICAL GAZETTE [NOVEMBER . 
Arenaria Fendleri Chrysopsis villosa (ch) 
ora Jamesii (ch) Chrysopsis spp. (ch) 
Berberis olium Townsendia exscapa 
Thlaspi shake Townsendia grandiflora 
Physaria floribunda (/) Machaeranthera aspera 
Lesquerella montana Helianthus pumilus 
Sedum stenopetalum (ch) Hymenoxys floribunda (south) 
Potentilla pennsylvanica strigosa __ Gaillardia aristata 
Potentilla Hippiana Artemisia frigida (ch) 
Astragalus Purshii Artemisia gnaphalodes var. (ch) 
Geranium Parryi (ch) Senecio Nelsonii (ch) 
Mentzelia spp. 
The more important representations of the association in special habitats: 
(1) The mixed consocies of mixed detrital slopes. This term may 
applied to the very sparse plant community of slopes on which the fragments of 
rock-débris are of all sizes, and in which as a result conditions for plant life 
vary extremely locally. The vegetation may be regarded as a mosaic of dif- 
ferent variants of primitive grassland, with the addition of certain components 
from other vegetation types, as the lichen, shrub, and pine associations (see 
figs. 4, 8). 
(2) The Geranium-Chrysopsis consocies of unstable granite-gravel slopes, 
in which the loose bunches of these two plants are the most frequent or the only 
plants in the loose decomposed granite soil. 
(3) The Artemisia frigida-Koeleria consocies of stony detrital slopes (rock 
talus, frequently). The habitat is quite common though seldom very exten- 
sive; the sage may be very abundant without the grass Koeleria; it is an im- 
portant species in the northern Great Plains and in the mountains up to 
10,000 ft. 
(4) The compacted granite-gravel consocies. Dwarfed plants of Erigeron 
compositus, Senecio Nelsonii, and a few other species are characteristic in level 
or gently rolling top surfaces, on which the thin coarse soil has become com- 
pacted into a hard floor (fig. 3). In its most extreme condition seen, the 
Erigeron was the only plant, occupying less than 4 per cent of surface. Rather 
infrequently, Potentilla Hippiana occupies these situations, forming a pure 
growth which spreads vegetatively. 
(5) The mat consocies of gravel slides. These habitats are more frequent 
in the Pike’s Peak highland than in the Front Range proper, where they are 
This plant has narrow pinnately 5-divided leaves, and appears to be quite 
sess different from the entire or apically 3-divided form with dense white 
canescence. With this structural difference is an apparently constant habitat differ- 
ence; the di lly in very coarse soil, the other i in clay, abundant only 
at the mountain-front. Itish tk on determine 
e forms 
Ges eis Ne eek a eas 
