16 PINACEAE 



9. HESPEROPEUCE Lemmon. BLACK HEMLOCK, MOUNTAIN HEMLOCK. 



Monoecious evergreen trees with spreading branches. Leaves rather plump, 

 keeled beneath, spreading in all directions, articulated to persistent bases (sterig- 

 mata), with stomata on both sides. Staminate aments axillary to leaves of pre- 

 ceding year; anther-sacs opening transversely. Pistillate aments terminal, at 

 first erect; scales in rather many series. Cones maturing the first year; scales 

 persistent. Seeds samara-like. 



1. H. Mertensiana (Bong.) Rydb. A tree usually 10-20 m. high, but some- 

 times up to 35 m. high, with a trunk 2.5-10 dm. in diameter; leaves bluish green, 

 rather thick, blunt-pointed, 1-2.5 cm. long; staminate flowers purple; pistillate 

 flowers erect, dark-purple or yellowish green; cones cylindric, 3-7 cm. long; 

 scales persistent, obovate, striate. Tsuga Pattoniana Sen. T. Mertensiana 

 (Bong.) Sargent. H. Pattoniana Lemmon. Exposed ridges and slopes: Alaska 

 w Mont. Ida. Calif. Subalp. 



10. PICEA Link. SPRUCES. 



Evergreen monoecious trees. Leaves needle-shaped, in ours quadrangular or 

 nearly terete, leaving persistent bases (sterigmata) when falling, scattered, 

 pointing hi all directions. Staminate aments from the axils of the leaves of the 

 preceding year, or rarely terminal; anther-sacs opening longitudinally. Pistil- 

 late aments terminal. Cones maturing the first season, drooping; scales closely 

 imbricate, leathery, thin, without dorsal thickening, persistent. Seeds samara- 

 like, with hyaline wings, remaining attached to the seeds. 



Cone-scales rounded at the apex. 



Branchlets pubescent; cones 1.5-3 cm. long, persistent for several years; scales rigid, 



erose or dentate. 1. P. Mariana. 



Branchlets glabrous; cones 3-5 cm. long, deciduous in the first winter; scales rather 



thin. 

 Cone-scales entire or minutely denticulate on the margins; cones cylindric- 



oblong, 3.5-5 cm. long. 2. P. canadensis. 



Cone-scales erose on the margins; cones ellipsoid, 3-3. 5 cm. long. 3. P. albertiana. 

 Cone-scales more or less rhomboid in outline. 



Branchlets pubescent ; cones 3-5 cm. long. 4. P. Engelmanni. 



Branchlets glabrous; cones 5-9 cm. long. 5. P. pungens. 



1. P. Mariana (Mill.) B.S.P. A tree usually 6-10 m. high, occasionally 25 

 m. high, with a trunk 1-3 dm. in diameter; bark grayish brown, scaly; twigs 

 russet-brown, short-pilose; leaves pale blue-green and glaucous, 1-2 cm. long, 

 callous-tipped at the apex; staminate flowers dark red; pistillate ones purple; 

 cones short, ovoid, 1-3 cm. long, ashy brown, persistent; scales rounded, erose- 

 dentate. P. nigra Link. BLACK SPRUCE. Swamps: Lab. Newf. N.C. 

 Wise. Sask. Alta. -Mack. Boreal -Subartic. 



2. P. canadensis (Mill.) B.S.P. A tree 10-20 m., rarely 30 m. high, with 

 a trunk 3-9 dm. in diameter; bark ashy brown, scaly; branches and sterigmata 

 glabrous; leaves incurved, acute or acuminate, blue-green; staminate flowers 

 pale red, becoming yellow from shedding the pollen; pistillate flowers pale red 

 or yellowish green; cones cylindric or oblong, 3-6 cm. long; scales orbicular, 

 slightly emarginate. P. alba Link. WHITE SPRUCE. River banks and hill- 

 sides: Lab. Newf. Me. n N.Y. Wise. S.D. (Black Hills) Alta. Alaska. 

 Boreal Subarctic. 



3. P. albertiana S. Brown. A slender tree 10-20 m. high; twigs and sterig- 

 mata smooth and shining, yellowish brown, becoming darker in age; leaves 

 pale blue-green, 1.5-2.5 cm. long, incurved, acute or acuminate; pistillate flowers 

 bright crimson; cones ovate, 2.5-3.5 cm. long; scales stiff, rounded, cinnamon- 

 brown. ALBERTA SPRUCE. Mountains: Alta. -n Wyo. 'B.C. Mont. 



4. P. Engelmanni (Parry) Engelm. A tree 25-30 m., rarely 45 m. high, 

 with a trunk 4.5-10 dm. thick; bark light cinnamon-red, loosely scaly; leaves 

 soft, with acute tips, 2.5-3 cm. long, bluish green; staminate flowers dark purple; 

 pistillate ones scarlet, turning chestnut-brown; cones oblong-ellipsoid, subsessile, 

 3-6 cm. long; scales thin, erose-dentate. ENGELMANN'S SPRUCE. Cold moun- 

 tains and ravines, especially on the north sides: Alta. N.M. Ariz. B.C. 

 Yukon. Subalp. -Mont. 



