Salix humboldtiana |
Salix exigua |
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Humboldt's willow |
coyote willow, narrow-leaf willow, sandbar willow |
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Habit | Shrubs or trees, 0.5–5(–17) m. Stems: branches gray-brown, red-brown, or yellow-brown, villous, or tomentose to glabrescent; branchlets yellowish, yellow-brown, or red-brown, pubescent or puberulent, tomentose, short- or long-silky villous. | |||||
Leaves | stipules absent or rudimentary on early ones, foliaceous or rudimentary on late ones; petiole 1–5(–10) mm, pubescent or puberulent, villous, or short-silky adaxially; largest medial blade (sometimes hypostomatous), linear or lorate, (glands marginal), 30–136–143 × 2–14 mm, 6.5–28(–37.5) times as long as wide, base cuneate, margins slightly revolute, entire or remotely spinulose-serrulate, apex acuminate or acute, abaxial surface glaucous (sometimes obscured by hairs), densely long-silky, villous or pilose to glabrescent, hairs appressed or spreading, straight or wavy, adaxial slightly glossy, sparsely or densely long-silky to glabrescent; proximal blade margins entire; juvenile blade yellowish green, densely long-silky-villous abaxially. |
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Staminate flowers | abaxial and adaxial nectaries present and distinct; filaments hairy on proximal 1/2; anthers (sometimes reddish turning yellow). |
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Pistillate flowers | adaxial nectary oblong, ovate, or flask-shaped, relative adaxial nectary/stipe length variable even within same catkin; stipe 0–0.9 mm; ovary obclavate or pyriform, glabrous, pilose, or villous, or sometimes beak hairy, beak bulged below or abruptly tapering to styles; ovules 12–30 per ovary; styles (sometimes distinct), 0–0.5 mm; stigmas flat, abaxially non-papillate with rounded tip, or 2 plump lobes, 0.1–0.5 mm. |
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Capsules | 4–8 mm. |
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Salix | humboldtiana Willdenow: Humboldt willow is not known to occur in the flora area. |
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It | is characterized by: trees, 4–25 m; branches highly brittle at base, bud-scale margins distinct and overlapping adaxially; stipules on late leaves rudimentary or foliaceous; largest medial leaf blade usually linear, abaxial surface not glaucous, adaxial dull; pistillate bract deciduous after flowering; stamens 3–7; capsules with distinct, often raised, white veins.; it occurs throughout much of Mexico to central Chile. |
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Catkins | staminate 7–54 × 2–10 mm, flowering branchlet 1.5–56 mm; pistillate loosely to densely flowered, slender or stout, 14.5–70 × 3–12 mm, flowering branchlet 2–55 mm; floral bract 1.2–2.6 mm, apex acute, convex, or rounded, entire or erose, hairs wavy, straight, or crinkled, abaxially hairy throughout or proximally, or glabrate. |
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2n | = 38. |
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Salix humboldtiana |
Salix exigua |
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Distribution |
Mexico to central Chile |
AZ; CA; CO; ID; MT; NE; NM; NV; OK; OR; TX; UT; WA; WY; AB; BC
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Discussion | Salix humboldtiana is closely related to S. nigra in its generally narrow leaf blades, which are not glaucous abaxially. The two differ in the following characters: S. humboldtiana has leaf blades linear to sometimes narrowly oblong (10–28.6 times as long as wide), ovaries usually ovoid to ellipsoid, ovary walls often stomatiferous and with raised, white veins, and capsule valves relatively thick, slightly recurved. S. nigra has leaf blades usually narrowly lanceolate (6–13 times as long as wide), ovaries pyriform to obclavate, ovary walls neither stomatiferous nor notably veined, and capsule valves relatively thin and strongly recurved. Both species occur in Chihuahua, Mexico. The report by R. I. Lonard et al. (1991) that specimens identified as Salix nigra from the lower Rio Grande, Texas, resemble S. humboldtiana in having strongly veined capsules suggests that S. humboldtiana, or intergrades with that species, may occur in Texas. Attempts to locate a voucher specimen were unsuccessful; because strongly veined capsules are diagnostic, further field study is indicated. An earlier name, Salix chilensis Molina, has been applied to this species; it does not seem to pertain to this taxon (C. K. Schneider 1918). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Varieties 2 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 7, p. 34. | FNA vol. 7, p. 54. | ||||
Parent taxa | Salicaceae > Salix > subg. Protitea > sect. Humboldtianae | Salicaceae > Salix > subg. Longifoliae | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | S. fluviatilis var. exigua, S. longifolia var. exigua | |||||
Name authority | Willdenow | Nuttall: N. Amer. Sylv. 1: 75. (1842) | ||||
Web links |
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