442 RYDBERG: PHYTOGEOGRAPHICAL NOTES 
belong principally to the foothills. The following wooded for- 
mations may be distinguished, though elements of two or more 
are often mixed. 
I. PINE FOREST 
This consists mostly of a mixture of Pinus scopulorum, A pinus 
flexilis and Pseudotsuga mucronata. In some places, however, 
one or another of these species is predominant. This formation 
is limited mostly to the south slopes of the mountains, which are 
drier and hotter and where the soil is rather poor. 
The last one of the three species mentioned seems to be more 
indifferent, however, to soil and moisture than the others, being 
found on the north as well as on the south slopes and associating 
with the pines as well as with the spruces, baisams, and aspens. 
To the three species are added in the northern part of the Southern 
Rockies the lodge-pole pine, Pinus Murrayana. In some places 
this forms pure stands, especially on burnt over areas, since it 
germinates readily and is quick in its growth. 
Of the trees belonging to this formation, none is transcontinen- 
tal or common to the Rockies and the Eastern Canadian Zone, 
three are common to the Rockies and the Pacific Highlands and 
one is endemic. Among the shrubs and herbs all four categories 
are found. As the transcontinentals and the eastern plants act 
much the same they will be treated together as an eastern element. 
Those marked ‘‘¢’’ are found in the Southern Rockies only, not 
in the Northern. The nomenclature throughout follows the 
writer’s ‘Flora of the Rocky Mountains and Adjacent Plains,” 
New York, 1917. 
I. TREES 
a. Western 
Pinus Murrayana Pseudotsuga mucronata 
A pinus flexilis 
b. Endemic 
Pinus scopulorum 
2. SHRUBS 
a. Eastern or transcontinental 
Rubus pubescens Lepargyraea canadensis 
