SPRUCE AND BALSAM FIR TREES. 21 
varietal technical names, 6 of which are now reduced to synonymy, 
and 11 of which (varietal names) distinguish garden or cultivated 
forms of the tree. These varietal forms are distinguished mainly by 
differences in the habit of growth, form and size of the crown, and 
by the color and length of the leaves. One of the best marked of 
these varieties is a very much dwarfed plant, Abies balsamea hudsonia 
(Knight) Veitch, originally found growing at high elevations. 
Abies balsamea var. macrocarpa is a form with longer leaves and 
larger cones than are borne by the ordinary type of this fir, and was 
raised from seed of trees found in the region of Wolf Eiver, Wis. 
DISTINGUISHING CHAKACTERISTICS. 
Abies balsamea attains a height of from 25 to 75 feet (under the 
best conditions for growth), and a diameter of from 10 to 28 inches; 
exceptional trees are somewhat taller and of slightly larger diameter. 
Smaller trees, including almost stemless prostrate forms, occur in 
exposed high places and in other unfavorable situations. 
The crown form of young trees growing in the open is broadly 
conical and ends in a long, sharp point. The branches are slender, 
regularly arranged in distinct circles or whorls about the trunk, and 
extend down to the ground. In older trees the lower branches hang 
down slightly, while those of the upper crown trend upward. When 
balsam fir grows in a dense stand, the long lower-crown branches are 
soon shaded out, leaving the gradually tapered trunk clear for one- 
half to two-thirds of its length and surmounted by a short, rather 
narrowly conical, sharp-pointed crown. The bark on the lower 
trunks of mature and middle-aged trees is about one-half inch thick, 
dull red-brown, and superficially divided into small, rather easily 
detached, thinnish scales. The bark of young trees, and also of the 
upper stems of old ones, is smooth and ash-colored and thickly set 
with resin " blisters," 1 which, as the bark becomes thicker and older, 
are gradually dried up and finally obliterated. Young twigs are cov- 
ered with very fine, short hairs, which adhere until the branchlets 
are about 3 years old. The mature spherical buds, one-eighth to 
three-eighths of an inch in diameter, are slightly resinous. 
The mature leaves are deep blue-green, shiny on the upper side, and 
conspicuously whitish (with rows of stomata) on the under side, the 
latter becoming less bright after the leaves are 2 or 3 years old. 
Leaves of the lower-crown branches (PL VII) differ, as a rule, very 
greatly in their form and arrangement 2 on the twigs from both those 
1 The so-called " Canada balsam " of apothecary shops is the crude oleoresin obtained 
from these pockets or blister-like cavities by puncturing the thin overlying bark and 
squeezing the contents into a small-mouthed receptacle. Gathering this resin constitutes 
an industry of considerable importance, especially in eastern Canada. 
2 Occasional trees are found, especially in the western range of this tree, on which the 
leaves are more or less crowded on the upper sides of the lower-crown branches, some- 
what as in Plate VIII. 6. 
