Salix humboldtiana |
Salix prolixa |
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Humboldt's willow |
Mackenzie willow, Mackenzie's willow |
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Habit | Shrubs, 1–5 m. Stems: branches gray-brown or red-brown, not or weakly glaucous, (with sparkling wax crystals), glabrous or moderately villous; branchlets yellow-green, or yellow-brown to red-brown, glabrous or sparsely to moderately densely velvety, (inner membranaceous bud-scale layer free, separating from outer layer). | |
Leaves | stipules foliaceous, apex acuminate to rounded; petiole convex to flat adaxially, 6–12 mm, glabrous or pilose adaxially; largest medial blade narrowly oblong, narrowly elliptic, lanceolate, or obovate, 50–150 × 10–53 mm, 2.4–4.5 times as long as wide, base cordate, subcordate, rounded, or convex, margins flat, serrate, serrulate, or spinulose-serrulate, apex acuminate to acute, abaxial surface glaucous, glabrous, adaxial dull, glabrous, pilose, or sparsely pubescent, (sometimes adaxial stomata only along veins or apically); proximal blade margins entire; juvenile blade reddish or yellowish green, glabrous, pilose or sparsely long-silky abaxially, hairs white. |
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Staminate flowers | adaxial nectary oblong to narrowly oblong, 0.8–1 mm; filaments distinct or connate less than 1/2 their lengths, glabrous; anthers purple turning yellow, (ellipsoid), 0.5–0.6 mm. |
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Pistillate flowers | adaxial nectary oblong, square, or flask-shaped, 0.3–0.8 mm, shorter than stipe; stipe 1.3–4.2 mm; ovary pyriform, glabrous, beak sometimes slightly bulged below styles; ovules 12–22 per ovary; styles 0.3–0.7 mm; stigmas flat, abaxially non-papillate with rounded tip, or 2 plump lobes, or slenderly cylindrical, 0.16–0.28–0.4 mm. |
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Capsules | 4–6 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 | flowering as leaves emerge; staminate slender or stout, 16–41 × 8–12 mm, flowering branchlet 0.5–3 mm; pistillate moderately densely to loosely flowered, slender or stout, 19–66 × 8–18 mm, flowering branchlet 0.5–6 mm; floral bract brown, 0.8–1.6 mm, apex acute or rounded, abaxially hairy mainly proximally, hairs straight or wavy. |
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Salix humboldtiana |
Salix prolixa |
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Phenology | Flowering late Mar-late Jun. | |
Habitat | Along streams, lakes, springs, marsh margins, sandy-gravel, sandy or silty substrates | |
Elevation | 100-2300 m (300-7500 ft) | |
Distribution |
Mexico to central Chile |
AK; CA; ID; MT; NV; OR; WA; WY; AB; BC; NT; YT
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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.) |
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Source | FNA vol. 7, p. 34. | FNA vol. 7, p. 125. |
Parent taxa | Salicaceae > Salix > subg. Protitea > sect. Humboldtianae | Salicaceae > Salix > subg. Vetrix > sect. Cordatae |
Sibling taxa | ||
Synonyms | S. cordata var. mackenzieana, S. eriocephala subsp. mackenzieana, S. mackenzieana, S. mackenzieana var. macrogemma, S. rigida var. mackenzieana, S. rigida var. macrogemma | |
Name authority | Willdenow | Andersson: Monogr. Salicum, 94, plate 5, fig. 52. (1867) |
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