SALICACEAE. 309 



raceme-like, peduncled ; capsules ovoid, acute, 2-valved, 8-12 mm. long, shorter 

 than or equalling their pedicels. In swamps, S. Conn, and N. Y. to Ga., west to 

 La., north in the Miss. Valley to Ind. and Ark. April-May. 



3. Populus candicans Ait. Balm of Gilead. A large tree, reaching a height 

 of 30 m. and a trunk diameter of 2 m., with spreading branches; the buds large 

 and very resinous. Leaves broadly cordate, dark green above, pale beneath, 

 acuminate, more coarsely crenate than in the next with gland-tipped teeth, 6-15 

 cm. long, 3-12 cm. wide, pubescent when young, generally glabrous in age, with 

 the exception of the ciliate margins and pubescent veins and petioles; otherwise 

 like the following. N. B. to N. J. west to Minn., but mostly escaped from culti- 

 vation. (P. balsamifera candicans A. Gray.) 



4. Populus balsamifera L. Tacamahac. Balsam Poplar. (I. F. f. 1165.) 

 A large tree, with nearly smooth gray bark, reaching a maximum height of about 

 25 m. and a trunk diameter of 2 m., the branches stout, ascending, the large buds 

 very resinous, the foliage glabrous. Leaves broadly ovate, dark green and shining 

 above, pale beneath, acute or acuminate at the apex, rounded or acute at the base, 

 crenulate, 7-12 cm. long; aments and bracts somewhat pubescent; stamens 18-30; 

 lobes of the stigmas broad; capsule ovoid, 2-valved, short-pedicelled. In moist or 

 dry soil, especially along streams and lakes, Newf. to Hudson Bay and Alaska, 

 south to N. Y., Neb. and Nev. April. 



5. Populus angustifolia James. Narrow-leaved or Black Cottonwood. 

 (I. F. f. 1 166. ) A slender tree, maximum height about 20 m., trunk diameter 6 dm. ; 

 crown narrowly pyramidal, branches ascending; foliage glabrous. Twigs terete, 

 gray; leaves lanceolate, ovate-lanceolate or ovate, spreading, drying brownish, 

 gradually acuminate or acute at the apex or some of them obtuse, narrowed, 

 rounded or rarely subcordate at the base, 5-12 cm. long, 1-3 cm. wide, finely cren- 

 ulate from base to apex; petioles plano-convex, not flattened laterally, 6-12 mm. 

 long; lateral veins 8-15 on each side of the blade; staminate aments oblong-cylin- 

 dric, 2-6 cm. long; lobes of the stigmas broad; capsules ovoid, short-pedicelled. 

 In moist soil, especially along streams, N. W. Terr, to Neb., N. Mex., and Ariz. 

 April-May. 



6. Populus acuminata Rydberg. Rydberg's Cottonwood. (I. F. f. 1167.) 

 A slender tree, with terete twigs, reaching approximately the dimensions of P. 

 angustifolia, the crown broadly pyramidal with spreading branches, the foliage 

 glabrous. Leaves rhomboid-lanceolate, spreading or drooping, drying green, 

 abruptly or gradually long-acuminate at the apex, cuneate, obtuse or rounded at 

 the base, 5-15 cm. long, 2-6 cm. wide, crenulate or the base entire; petioles slen- 

 der, 2-6 cm. long; staminate aments about 3 cm. long; pistillate aments slender, 

 drooping, 7-12 cm. long; capsules ovoid, obtuse, distinctly pedicelled. Black Hills, 

 S. Dak. to Utah, south to N. Mex. April-May. 



7. Populus nigra L. Black Poplar. (I. F. f. 1171.) A large tree, some- 

 times 30 m. tall and the trunk 12 dm. in diameter, usually much smaller. Twigs 

 terete; young foliage somewhat pubescent, the mature leaves firm, nearly or quite 

 glabrous; petioles slender, flattened laterally; leaves broadly deltoid, abruptly 

 acuminate at the apex, broadly cuneate or obtuse at the base, crenate, 5-10 cm. 

 long; staminate aments 3-5 cm. long; stamens about 20; pistillate aments 5-12 

 cm. long in fruit, spreading; capsules oblong, very obtuse, borne on pedicels of 

 much less than their own length. Valleys of the Hudson and Delaware Rivers, 

 naturalized from Europe. April-May. 



The Lombardy Poplar, Populus Italica, commonly planted for ornament, occa- 

 sionally spreads by sending up shoots from its subterranean parts. 



8. Populus deltoides Marsh. Cottonwood. Necklace Poplar. (I. F. f. 

 1 1 72.) A large tree, the greatest of the poplars, attaining a maximum height of 

 45 m. and a trunk diameter of 2.2 m., the bark grayish-green, somewhat rough 

 •when old. Foliage glabrous; leaves broadly deltoid-ovate, abruptly acuminate at 

 the apex, crenulate, truncate at the base, 10-17 cm. long; petiole flattened later- 

 ally, stout, about as long as the blade; bracts glabrous, deeply fimbriate; staminate 

 aments drooping, 7-12 cm. long, 10-12 mm. in diameter; pistillate aments loosely 



