14 PINACEAE 



Cones 1-2 cm. long, subglobose; their scales few, longer than the bracts; leaves 3-angled. 



1. L. laricina. 

 Cones 2-4 cm. long, ovoid; their scales numerous, shorter than the bracts. 



Leaves triangular; branches soon becoming glabrate. 2. L. occidcntalis. 



Leaves quadrangular; branchlets tomentosa. 3. L. Lyallii. 



1. L. laricina (Du Roi) Koch. A tree 15-25 m. high, with a trunk 3-6 dm. 

 in diameter; bark of the trunk separating into reddish brown or ashy scales; 

 twigs smooth, at first whitish, turning yellowish brown; leaves in clusters of 12- 

 20, somewhat 3-angled, ridged beneath, 2-3 cm. long, bright green; cones russet- 

 brown, 1.5-2 cm. long; scales about 20, obovate, erose, twice as long as the 

 bracts. L. americana Michx. TAMARACK, AMERICAN LARCH. Swamps: Lab. 

 Maes. Pa. '111. -Sask. -Alaska. Boreal Subarct. 



2. L. occidentalis Nutt. A tree with a narrow crown, usually 30-50 m. 

 high, rarely 60-70 m. high, with a trunk 10-15 dm. thick; bark of the trunk very 

 thick, deeply furrowed, cinnamon-brown; twigs dark or grayish brown; leaves 15-30 

 in each cluster, pale greenish yellow, 3-5 cm. long, triangular, ridged on their 

 inner face; cones 3-4 cm. long, short-peduncled; scales villous below the middle 

 outside, obovate, with reflexed margins, shorter than the bracts; the latter 

 lanceolate, 3-toothed at the apex. WESTERN LARCH. Wet or gravelly soil, on 

 mountain sides and valleys: B.C. nw Mont. Ore. Submont. -Mont. 



3. L. Lyallii Parl. A tree 10-15 m. high, with a trunk 2.5-6 dm. in diam- 

 eter, rarely 20 m. high; bark of the trunk slightly furrowed, purplish or reddish 

 brown; twigs pale gray, shining, smooth, white-villous for about two seasons; 

 leaves 4-angled, pale blue-green, 3-4 cm. long, 30-40 in each cluster; cones ellip- 

 soid, 4-5 cm. long, subsessile or short-stalked, tomentose; scales obovate, erose, 

 reddish purple, rarely green; bracts much longer, 3-lobed. LY ALL'S LARCH. 

 High mountain slopes, near timberline: B.C. Alta. -Mont. n Ore. Subalp. 



6. ABIES (Tourn.) Hill. FIR, BALSAM. 



Monoecious evergreen trees with spreading branches. Leaves flattened, 

 leaving rounded scars on the smooth branches (without sterigmata), with 2 

 longitudinal resin-ducts and solitary fibro-vascular bundles, those of the lateral 

 branches appearing 2-ranked by the twisting of the base, those of the cone-bear- 

 ing branches usually curved upward and shorter. Staminate aments in the 

 axils of the leaves of the preceding year, subtended by imbricate bracts; pollen- 

 sacs opening transversely or nearly so. Pistillate aments lateral, erect; cones 

 maturing the first year, erect; scales and bracts deciduous at maturity. Seeds 

 samara-like; wings remaining attached to the seeds. 



Resin-ducts of the leaves within the soft tissues, remote from the epidermis. 

 Bracts longer than the cone-scales; leaves dark green above, pale beneath. 



1. A. balsamea. 

 Bracts much shorter than the cone-scales; leaves blue-green and glaucous. 



Bark of the trunk hard, not corky; cone-scales longer than broad. 2. A. lasiocarpa. 

 Bark of the trunk elastic, corky; cone-scales broader than long. 3. A. arizonica. 

 Resin-ducts of the leaves close to the epidermis on the lower side. 



Bracts obcordate with a short acumination; leaves (except those of the cone-bearing 



branches) emarginate, dark green above, white beneath. 4. A. grandis. 



Bracts truncate with a short acumination; leaves acute or acuminate, seldom obtuse 

 at the apex, pale blue-green and glaucous 5. A. concolor. 



1. A. balsamea (L.) Mill. A tree 15-20 m., rarely 27 m. high, with 

 broadly conic crown; bark on old trunks scaly, of young trunks and branches 

 smooth, warty with resin-blisters; leaves dark green and shining above, silvery 

 white beneath; those of the sterile branches 2-3 cm. long, obtuse; staminate 

 flowers yellow, tinged with purplish; pistillate deeply purple; cones oblong, 

 puberulent, 5-10 cm. long; scales obovate, longer than broad, usually twice as 

 long as the bracts, serrulate. BALSAM FIR. Low ground: Lab. -Mass. Va. 

 Iowa Man. Alta. Mack. Boreal Subarct. 



2. A. lasiocarpa (Hook.) Nutt. A tree usually 25-30 m., rarely 45 m. 

 high, with a trunk 3-10 dm. in diameter, at the timberline a shrub 1-2 m. high; 

 bark of the trunks smooth with resin-blisters, only in old trees somewhat cracked 

 and scaly; twigs usually puberulent; leaves of the lower branches 2.5-4 cm. 

 long, rounded at the apex; staminate flowers dark blue, turning violet; pistillate 



