PINACEAE 



The Firs 

 Characteristics of the Genus Abies Mill. 



HABIT. Tall, pyramidal, evergreen trees; dense, spirelike 

 crowns; slender, horizontal, whorled branches; and straight, 

 gradually tapering trunks. 



LEAVES. Spirally arranged, linear, sessile, and single; usu- 

 ally flat and blunt; extending from all sides of twig but mostly 

 appearing 2-ranked by a twist near their base; persistent for 

 7-10 years; usually grooved above and with stomatiferous lines 

 below; 2 resin canals in cross section; when falling, leaving a 

 conspicuous, smooth, circular scar on twig. 



FLOWERS. Monoecious, axillary, single; male, or pollen- 

 bearing, numerous on lower sides of lower crown branches, oval 

 or cylindrical, with yellow to scarlet anthers; female, or cone- 

 and seed-bearing, on upper side of topmost branches, erect, 

 globose to oblong, consisting of numerous, imbricated, 2-ovuled 

 scales much shorter than their bracts. 



FRUIT. Woody, erect cones; maturing in one season; scales 

 thin, fan-shaped, and falling at maturity from the central, 

 spikelike axis which persists many years. Seed: 2 under each 

 scale; large, thin wing; peculiar, conspicuous resin-vesicles. 



TWIGS. Smooth, glabrous, or pubescent. Winter buds: 

 small, mostly subglobose or ovoid, with thin, loosely imbricated 

 scales and usually thickly covered with resin. 



BARK. Young bark thin, smooth, with numerous blister-like 

 resin pockets; old bark smooth or furrowed; Canada balsam 

 obtained from the resin blisters of balsam fir. 



WOOD. Light, soft, and weak; color whitish to light brown, 

 the summer wood frequently with a purplish tinge; resin ducts 

 absent; used for pulp, containers, and general construction. 



SILVICAL CHARACTERS. Tolerant, moisture-loving trees 

 of cool sites; slow to fast growing; moderately long-lived. 



GENERAL. This genus contains about 35 species widely 

 scattered through North and Central America, Europe, Asia 

 and northern Africa. There are 9 species native to North America. 



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