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 River, Wis. 



DISTINGUISHING CHARACTERISTICS. 



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. 



