10. S. rigid a Muhl, Cordate Willow. Heartleaf Willow. Several-stemmed shrub, 2-4 (-6) m. high; twigs slender to midsized, 1-5 mm. in diameter, yellowish to becoming dark brown, the younger pubescent; buds small, 2-5 mm. long, colored and clothed as the twigs. Common along stream banks and ditches and in mostly low grounds, Delaware to Virginia, Kentucky, Missouri, and Nebraska, north to Nova Scotia and west to James Bay, Saskatchewan, and northern Montana.

11. S. pyrifolia Andersson. Balsam Willow. Shrub 1-5 m. high, with usually clustered stem but occasionally tree-like; bark grayish, smooth; twigs yellowish (young) to reddish-brown or dark olive brown, glabrous, shining; buds 2-6 mm. long, stout, scarcely pointed, colored as twigs. Moist to wet or swampy ground, Nova Scotia and northern New England to Minnesota and Alberta, north to Labrador and northern British Columbia.

12. S. glaucophylloides Fernald. Dune Willow. Usually many-stemmed shrub 2-4 or 5 m. tall, occasionally tree-like; twigs usually rather short and stout, yellowish to chestnut-brown and dark-brown, younger somewhat pubescent (or white-tomentose in var. albovestita); buds midsized, 2-5 (-8)mm. long, stoutish, colored and clothed as the twigs. Sand dunes and sandy shores, calcareous slopes, and sometimes in swamps, Maine to Indiana and Wisconsin, north to Newfoundland and Hudson Bay.

13. S. petiolaris J. E. Smith. Slender Willow. Clumpy shrub to a few-stemmed tree, 2-5 or rarely 6-7 m. high; bark gray; twigs slender, leafy, yellowish or yellowish-green and puberulent to dark brown and glabrous (reddish-brown in dry areas); buds small, 2-5 or rarely 6 mm. long, acute to obtuse, colored as the twigs. Moist meadows, streams, and lake shores, New Jersey to Nebraska, Colorado, and Montana, north to New Brunswick, James Bay, and Alberta.

14. S. sericea Marsh. Silky Willow. Shrub with clustered stems or small tree, 2-6 or 8 m. high; bark gray; twigs slender, light brown to mostly dark brown, younger somewhat pubescent to puberulent, older glabrate-glabrous (plants with older twigs pubescent probably represent S. subsericea (Andersson) Schneider, which occurs from Massachusetts to Nebraska and north to Nova Scotia and Alberta); bud-scales small, 2-5 or rarely 6 mm. long, colored and clothed as the twigs. In moist, rocky to gravelly ground, often near or in running water, Georgia to Arkansas, north to Nova Scotia, New Brunswick, Michigan, and Iowa.

15. S. caprea L. Goat Willow. Florist's Willow. Tall shrub or small tree, sometimes with a single trunk, 2-3 m. high; bark gray; twigs stout, mostly 3-5 (-6) mm. in diameter, yellowish-brown to dark brown, pubescent to glabrescent; buds stout at maturity, midsized to large, 4-9 mm. long, younger acute, older obtuse, colored and clothed as the twigs. Introduced from Europe, where it has many and varied uses. Sparingly cultivated in America, chiefly as a "pussy" willow, and used extensively by florists for early spring decorations, as are the introduced S. cinerea L. and the native S. discolor Muhl. Escaped around old nurseries. S. cinerea is closely related but twigs and buds are more densely pubescent.

16. S. discolor Muhl. Pussy Willow. Glaucous Willow. Few-stemmed shrub or small tree, 2-5 or rarely 7.5 m. high; bark thin, usually smooth, reddish-brown; twigs stout, 3-6 mm. in basal diameter, reddish or reddish-purple to mostly dark brown, glabrous or youngest thinly pubescent (more densely so in var. latifolia Andersson);buds large, 4-9 mm. long, acute to obtuse, colored and clothed as the twigs. Common in swamps and moist lowlands, Delaware to Kentucky, Missouri, South Dakota, and Montana, north to Newfoundland, James Bay, and British Columbia.

17. S.. humilis Marsh. Upland Willow. Prairie Willow. Sprangly shrub with several spreading stems, 1-3 m. high; twigs midsized to stoutish, 2-4 mm. in basal diameter, greenish-yellow or yellowish-brown to orange-red or reddish-brown to dark brown, pubescent to puberulent to glabrate; buds midsized to large, 5-8 mm. long, colored and clothed as the twigs. Scattered but common on upland areas in open woodlands, dry barrens, rocky bluffs, sandy ground, and prairies; occasionally in swampy areas, Florida to eastern Texas, north to Newfoundland, Quebec, North Dakota, and Saskatchewan.

18. S. tristis Ait. Dwarf Upland Willow. Dwarf Prairie Willow. Low, many-stemmed shrub, 0.4-1 m. high; twigs slender, leafy, 1-3 mm. in basal diameter, yellowish-brown to brown, pubescent; buds small, 1-3 mm. long, pubescent. Similar to S. humilis but smaller in every way. Occasional on dry and often sandy uplands, roadsides, thicket-borders, mountain balds, etc.; irregularly distributed from Florida to Oklahoma, north to Quebec and Saskatchewan.

19. S. bebbiana Sarg. Bebb Willow. Beaked Willow. Few-stemmed shrub or small tree (sometimes single trunk), 2-6 or rarely 9 m. high; bark grayish, rough and scaly; twigs slender to midsized, 1-3 mm. in basal diameter, often divaricate, the shorter often crooked, reddish to brown or dark brown, sometimes orange-red or purplish, younger pubescent, older less pubescent to glabrous; buds small, 3-5 mm. long, colored and clothed as the twigs; the projecting petiole-bud scars often conspicuous on basal portion of older twigs. Common on moist to wet or somewhat drier ground from New Jersey to South Dakota, southwest to New Mexico and California, north to Newfoundland and Alaska.

20. S. purpurea L. Purple Osier. Bitter Willow. Many-stemmed shrub 1-2. 5 m. tall or taller; bark smooth, very bitter; twigs slender, flexible, yellow to yellowish-brown or reddish-brown, rarely purplish, glabrous, sometimes shining; buds remarkable for often being opposite or sub-opposite as well as alternate, midsized, 3-8 mm. long, acute to obtuse, yellow-brown to reddish-brown, glabrous. Widely introduced in colonial times and cultivated for basket-making, the staminate for ornament; sparingly escaped in the northeastern United States.