434 RYDBERG: PHYTOGEOGRAPHICAL NOTES 
caer neseates scopulorum Adoxa moschatellina 
coloradense Valeriana ovata 
Androsace pinetorum Senecio amplectans 
Castilleja confusa 
Restricted to the Northern Rockies 
Shrubs 
Ribes laxtflorum Chiogenes hispudula 
t “ hudsonianum Vaccinium occidentale 
“*  petiolare si globulare 
Azaliastrum albiflorum Linnaea longiflora 
Gaultheria ovatifolia 
Herbs 
tAlsine borealis tOzomelis trifida 
Aqutlegia columbiana - Atelophragma Forwoodit 
A formosa Aragallus foliolosus 
Dentaria rupicola tOsmorrhiza Leibergit 
Parnassia palustris Ligusticum filicinum 
Kotzebuei Moneses reticulata 
Heuchera glabra Pyrola uliginosa 
{Pectianthia Breweri Aster meritus 
2. PINE SLOPES 
The characteristic tree of this formation in the Southern 
Rockies is the bristle-cone pine, Pinus aristata, which occupies dry _ 
slopes and ridges especially on the southern side of the mountains. 
It seldom forms a dense forest. Occasionally Picea Engelmanntt 
or Populus tremuloides has encroached on the pine slopes and then — 
the woods are more dense. In the lower part of the zone the 
bristle-cone pine is often mixed with the limber pine, Pinus flexilis. 
As Pinus aristata seldom makes a close stand but grows scattered 
on the slopes, the undergrowth is mostly made up of the grass 
formations, either that of the mountain slopes or that of the hog-. 
backs. Wherever the trees stand close the undergrowth contains 
more aud more of the element found in the more open woods. 
Some of the more common species are: Arenaria Fendleri, Arnica 
cordifolia, A. pumila, A. Parryi, Polemonium delicatum, Draba 
streptocarpa, D. aureiformis, Pseudocymopterus montanus, Solidago 
