SALIC ACE AE (WILLOW FAMILY) 131 



Leaves linear, acuminate; pistillate aments 1-2 cm. wide. 



Leaves canescent, entire or remotely denticulate; capsules mostly 5 



mm. long; pedicels 0.5-0.7 mm. long . . . . . . 6. S. exigua. 



Leaves brignt green, denticulate; capsules mostly 6-7 mm. long; 



pedicels 0.5-1.5 mm. long 7. S. fluviatilis. 



Leaves elliptical-oblanceolate, rather closely denticulate; pistillate 



aments 7-8 mm. wide 8. S. melanopsis. 



6. Salix exigua Nutt. Sylva 1: 75. 1842. Color effect grayish: leaves 

 linear, acute at both ends or acuminate at the apex, 5-12 cm. long, 2-10 mm. 

 wide, entire or remotely denticulate, opaque, more or less canescent on both 

 surfaces or silky with a fine silvery tomentum beneath, or on both surfaces 

 on young shoots (then frequently mistaken for S. argophylla) ; petioles 2-7 mm. 

 long: peduncles sometimes 7 cm. long; staminate aments 2-4 cm. long, about 

 7 mm. wide; the pistillate 3-6 cm. long, 1-1.3 cm. wide; scales lanceolate in 

 the pistillate aments, broader in the staminate, mostly acute, nearly glabrous 

 or white pilose on the margins, occasionally on the back also: capsules nar- 

 rowly lanceolate, 4-6 (mostly 5) cm. long, sessile or on pedicels 0.5-0.7 mm. 

 long, especially at the base of the ament, glabrous or thinly villous; gland 

 about 0.5 mm. long; stigmas divided. (S. stenophylla Rydb. Bull. Torr. Bot. 

 Club 28: 271. 1901, an inconstant form; S. luteosericea Rydb. Brit. Man. 

 316. 1901 .) Very common along mountain streams and in wet places through- 

 out our range and westward; variable in foliage characters and sometimes very 

 difficult to distinguish from the next. 



7. Salix fluviatilis Nutt. 1. c. 73. Color effect bright green or slightly 

 grayish: leaves linear or linear-lanceolate, acute or acuminate at the apex, 

 acute at the base, 5-12 cm. long, 2-15 mm. wide, remotely denticulate to 

 spinulose-denticulate; pure green and veiny on both sides, glabrous when 

 mature, often thinly villous with long white hairs when young; petioles 2-9 

 mm. long: aments and scales as in the preceding but the pistillate 1.2-3 cm. 

 wide (sometimes 10 cm. long in low humid regions); scales more nearly 

 glabrous: capsules 5-8 (mostly 7) mm. long, longer east of our limits, glabrous, 

 or silky with long white hairs, especially when young, pedicellate; pedicels 

 0.5-1.5 mm. long; gland often 1 mm. long. S. longifolia. SANDBAR WILLOW. 

 (S. interior Rowlee, Bull. Torr. Bot. Club 27: 253. 1900; S. linearifolia Rydb. 

 1. c.) Most common in eastern Colorado and Wyoming, and in Montana and 

 Idaho, but not abundant anywhere in our limits; exceedingly abundant east- 

 ward across the continent. 



8. Salix melanopsis Nutt. 1. c. 78. A tall, dark green shrub or small tree, 

 3-5 m. high, more divaricately branched than the related species; twigs 

 brown or blackish, often lustrous: leaves oblanceolate or elliptical, acute at 

 both ends, 4-7 or 8 cm. long, 6-15 mm. wide, rather closely denticulate, often 

 spinulose-denticulate, especially near the apex, or subentire, the margin 

 somewhat revolute in drying, dark green and glabrous above, paler, strongly 

 veined, and usually thinly silky-villous beneath; stipules lanceolate to semi- 

 cordate, dentate: aments slender, 3-4 cm. long, the staminate 5-6 mm. wide, 

 the pistillate 7-8 mm. wide; scales oblong to obovate, sometimes erose at the 

 apex, thinly pilose, the pistillate often plainly striate with 3-5 nerves: cap- 

 sules ovate-lanceolate, glabrous, sessile or subsessile, 4-5 mm. long. DUSKY 

 WILLOW. Type locality, old Fort Hall near Pocatello, Idaho. Common in 

 northeastern Oregon, eastern Washington, and British Columbia as far east as 

 the Selkirks. 



IV. RETUSAE. Low, depressed, or creeping species, less than 1 dm. high: leaves 

 minute, entire, glabrous: aments 2-4-flowered: capsules glabrous; stigmas 

 sessile. A single species within our limits. 



9. Salix Dodgeana Rydb Bull. N. Y. Bot. Card. 1: 277. 1899. Delicate, 

 suffruticose, 2 cm. high or less, from short, slender, subterranean stems; twigs 

 yellowish-green, very leafy: leaves oblong or oval, 4-5 mm. long, acutish or 

 obtuse, light green, strongly veined: staminate ament generally 3-4-flowered; 

 stamens 2; filaments glabrous; pistillate aments generally 2-flowered; scales 

 oblong, truncate, sparingly villous-ciliate: capsule oblong-ovoid, glabrous; stig- 



