28 The Colorado Experiment Station. 
than one hundred feet tall and two or three feet through. The bark remains 
comparatively thin and smooth for a number of years, but on old trunks be¬ 
comes thick and deeply cracked and furrowed into gray, coarsely broken 
ridiges. The wood is light red or yeliowish in color and variable in density 
and quality. It is largely manufactured intO' lumber lin its northwestern 
range, and is extensively employed in construction work, railway ties, piles, 
and for fuel. Two varieties of this tree, the red and the yellow fir, are dis¬ 
tinguished by lumbermen. The former of these is coarse grained and dark 
colored and is not considered so valuable as the latter. The bark is occasion¬ 
ally used in tanning. 
The Douglaiss spruce is planted quite extenisively as an ornamental tree 
in the eastern United States, and numerous forms or varieties are in culti¬ 
vation. It is a tree of rapid growth, especially when planted in a moist soil. 
It has not made as healthy a growth on the Agricultural College grounds at 
this station as the blue spruce. It is readily grown from seeds, which are 
of fair size. This evergreen may be recommended for planting in the wind¬ 
break and for specimen trees on the lawn. 
GENUS Abies —the eirs, bausams. 
The firs are tall growing, conical trees quite similar in appear¬ 
ance to the spruces. They are fond of the higher altitudes where 
the cold air and the moisture of frequent storms bring them to 
their greatest perfection. The leaves, like those of the spruces, 
are simple and grow from all sides of the branchlets. Those on 
the lower sides of the twigs, however, turn upward in such a way 
as to form flattened masses of foliage. The branches arise in 
whorls from the sides of the main trunk so that when viewed from 
the side such trees appear in the form of circular terraces of foliage 
disposed with beautiful regularity. 
The needles are flattened, usually grooved above and slightly 
notched at the tip. The cones occur only in the topmost parts of 
the trees and stand erect on the upper side of the branches. They 
are mostly purplish or blackish in color, with thin, closely crowded 
scales. When mature the cones break up by the falling away of 
the scales, so that complete cones of the flrs are never found 
beneath the tree. 
The bark on young trees is smooth, but becomes roughened 
and broken on old trunks. The wood is mostly soft and brittle and 
is not prized by the lumbermen. 
The name Balsam, which is often applied to the trees of 
this genus, is suggested by the presence of balsam or resin vesicles 
in the bark. 
The balsam fir of the northeastern states and Canada (Abies 
balsamea) possesses balsam-containing blisters in the bark from 
which the substance known in commerce as “Canada Balsam” 
is obtained. 
KEY TO THE COLORADO SPECIES OE AbieS. 
A. Leaves of vigorous 'lower branches 2.5-4.5 c. m. (1-1% in.) long; the 
two resin tubes, as seen in cross section under hand lens, deeply im¬ 
bedded within the leaf tissue. Cones purple or nearly black. 
1. Abies lasiocarpa. 
