BOTANY OF LARIMER COUNTY 127 
to be found here. Since, however, there are no exposed rocks present 
the shrubs of the foothills do not obtain a foothold. In the lateral valleys 
next to the granites where one side of the valley is flanked by granite 
and the other by sandstone it is interesting to note that such plants as 
Selaginella do not occur at all. But Selaginella is very abundant on 
the exposed rocks and coarse talus of the granite hills a hundred feet 
away. (The valley grassland is shown in Figs. 1 and 5.) 
PARTIAL List OF PLANTS OF THE VALLEY GRASSLAND FORMATION 
Bouteloua oligostachya Leucocrinum montanum 
Bouteloua curtipendula Eriogonum flavum 
Koeleria cristata Artemisia frigida 
Poa spp. Artemisia rhizomata 
Bromus porteri Artemisia gnaphaloides 
Bromus pumpellianus Tetraneuris acaulis 
Agropyron occidentale Pentstemon 
Agropyron vaseyt Lomatium nudicaule 
Hordeum pusillum Antennaria sp. 
Muhlenbergia sp. Grindelia squarrosa 
Canyon Forest Formation.—This formation extends along the stream 
banks wherever there is a narrow canyon and is seen also in the steep 
gulches which carry only storm water. It is difficult to name any one 
or even a few species as characteristic of this formation.‘ However, 
if it were necessary to give a name compounded of the names of character- 
istic species it might be called the Pseudotsuga-Salix Formation. Along 
canyon walls with north exposure the Douglas spruce (Pseudotsuga) 
extends down almost to the bank of the stream. Here it is replaced 
by willows. But many deciduous trees are mixed in with the species 
mentioned. Canyon walls exposed to the south have very few Douglas 
spruces but often rock pines, cedars and junipers. These xerophytic 
plants occur chiefly at the upper part of the wall. Here also may be 
found such plants as currants, skunk bush (Rhus trilobaia), Indian currant 
(Symphoricarpos). In places where the stream current is slow and an 
accumulation of humus is found it becomes possible to distinguish a 
Stream Bank Marsh Society dominated by sedges but containing such 
other plants as buttercups, flags, cow-parsnips, shooting stars and 
1 This corresponds roughly to the Populus angustifolia — Salix nuttallii Formation 
recognized in Boulder County, Colo., by Younc, Bot. Gaz. 44: 344. 1907. 
g My y 3 9°7 
