554 Part IV. Chapter 3. 
nowhere abundant, while in the Teton Mountains this tree occurs about 
timber line on the northern slopes and follows streams down to lower elev- 5 
ations. Pinus flexilis occurs on exposed peaks. In Colorado Adres subalpina 
reaches up to the average timber line also extending well down the mountain : 
sides on cold northern slopes. Here it is rare and locally distributed among 
Picea Engelmanni and occasionally with Pinus Murrayana, but never mingles 
with Abies concolor. 
The subalpine belt presents four chief features. The first and most typic consists of 
a forest of medium density with little underbrush, the ground being covered with low shrubby 
Vaceiniums, En er is or rushes while Xerophyllum tenax forms dense’swards. Litter is scanty 
Forests of this character are found about 5,500 feet elevation 
The third aspect is that of densely brush- 
rush consists of Alnus viridis, Sorbus sambucifolia, Ledum 
covered areas with thin forest. 
e amount of 
glandulosum, Menziesia u M. glabella, Rhododendron albiflorum with a 
itter and no u edges of this belt are occupied by Vaccinium occidentale and Betula 
glandulosa. Above this ker for example in the Coeur d’Alene Mountains exists one where moun- 
tain hemlock, Tsuga Pattoniana and Pinus albicaulis are dominant. There is not much under- 
growth, but Sorbus sambucifolia and S. occidentalis occur. 
e subalpine coniferae in southwestern Colorado on southwestern slopes are mainly Picea 
Engelmanni and Abies grandis. These two species either Se or in forests of one alone 
cover the western mountain slopes down to forests of Pinus ponderosa Beige Be Pioen2 
Engelmanni is the only tree at timber line, but Abie yoa7 reaches very # 
Pseudotsuga Douglasii (= P.taxifolia = P. RER is not very common in ee Cote a 
(9,000— 7,000 feet) descending into the region of Pinus edulis and Juniperus occidentalis. Abis 
concolor is not seen on the western slope?). ” 
4. Still another type of forest is formed by the almost pure stands of 
Pinus Murrayana (Pinus Murrayana Facies). In northwestern Montana 
about Flathead Lake, this pine usurps the low morainic ridges leading from 
mountain spurs while Pseudotsuga Douglasii occupies sunny rocky slopes. 
The forests of the Yellowstone Park consist principally of Pinus Murrayana, 
the lodge pole pine, intermingled with groves of Populus tremuloides. 
pine reaches its best development on the drier plateaus between 7,000 an 
8,000 feet, here forming go per cent. of the forest’). 
e bulk of the forests in the Teton range consists of Pinus Murrayana with Populus 
tremuloides, Picea Engelmanni along streams between 7,000 and 10,000 feet. Pseudotsug 
Douglasii (not abundant), Populus angustifolia (along streams in the valleys), P. trichocarpa ( 
common), Juniperus communis (very uncommon), J. virginiana (little found), Pinus flexilis (in Erz 
places, and on dry ridges from 7,500 feet upward). : 
The prevailing tree in northern Wyoming in nn Hin Lone Mountains is the lodge pole pine 
with Pinus flexilis scattered among it and in ain localities Picea Engelmanni makes 
considerable growth, while Pseudotsuga Douglasii gr P. taxifolia) is rare. Pinus Murrayana E . 
1) BRANDEGEE, T. S.: The Flora of southwestern Colorado. Bulletin Geoisgha: 
Geographical Survey of the Territories. Vol. II No. 3. Washington, June 6, 1876; see 
Ramarey, Francis: Wild Flowers and Trees of Colorado 1909, pages ı—78, profusely il 
2) Tower, G. E.: The reproductive Characteristies of ee pole Pine. Proc. Soc. ‘Amer. 
Foresters IV 11909): 84—106. The Plant World XII: 24 
