26 BULLETIX 327, U. S. DEPARTMENT OF AGRICULTURE. 
crowding and upright position of the leaves on the upper sides of the 
branches is very characteristic. Leaves of the " leader " or topmost 
central stem (PL XII, a) are sharply pointed and scattered. 
Mature cones of the alpine fir are from 2 J to about 4 inches in 
length by about 1J to 1-J inches in diameter (PL XI) ; after the cone 
scales become loosened by drying out, the cones are considerably 
larger in diameter. Ripe cones are deep purple at first, gradually 
becoming lighter by the time the scales fall. The cone scales bear 
bracts (PL XI, a), which are abruptly rounded or contracted at the 
free end to a slender central point. The ivory-brown seeds (PL 
XI, h) have large, shiny, purplish, or violet-tinged wings. The seed- 
leaves, one-third to one-half an inch long, are usually 4 in number. 
Alpine fir wood is lighter in weight than that of any other Rocky 
Mountain fir. a cubic foot of dry wood weighing about 21.66 pounds. 
It is narrow-ringed, soft, and from pale straw-color to light yellowish 
brown. As a rule, the wood is fairly straight-grained and splits and 
works easily, but it rots rapidly in contact with earth. However, 
the fire-killed, deeply season-checked shafts of this tree, so frequent 
where forest fires have swept the ground, may remain sound above 
ground for many years. Dead timber is locally much used for fuel, 
house logs, and corral poles. Occasionally green timber is sawed into 
rough lumber for local use. Little clear lumber is. however, obtain- 
able even from large trees, because during the greater part of life the 
lower trunk branches are retained down to the ground. 
OCCVBBEXCE AND HABITS. 
Alpine fir always grows in cool, moist, and, in part, subalpine 
situations. It occurs commonly on all slopes at timber line, and, at 
the lower limits of vertical range, in protected valleys, at the heads 
of streams, and about mountain lakes and moist meadows (Map 
Xo. 6). At the Xorth its lowest vertical range is about 3,500 feet, 
though at the South it may reach an elevation of 10.500 feet. Alpine 
fir has a narrow range in altitude at the Xorth. where the timber line 
is relatively low, and at and near which the moisture conditions neces- 
sary for its growth are present. Likewise at the South, the vertical 
range of this fir is narrow, because here the timber line, with the 
accompanying moisture conditions, occurs only at higher elevations. 
The best growth occurs on north slopes in fairly deep, loose, moist 
soil, while much smaller trees are found in the poorest and driest thin 
soils. It grows also in wet situations, but it does not thrive on heavy, 
clayey soils. Its main occurrence is limited by requirement of soil 
moisture to elevations where snowfall is heavy. In general, how- 
