Salix humboldtiana |
Salix arbusculoides |
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Humboldt's willow |
little-tree willow, northern bush willow |
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Stems | branches gray-brown to red-brown, not glaucous, glabrous; branchlets red-brown, glabrous or puberulent. |
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Leaves | stipules rudimentary on early ones, apex acute; petiole shallowly grooved adaxially, 3–11 mm, puberulent to glabrescent adaxially; largest medial blade very narrowly elliptic to elliptic, 38–78 × 7–18 mm, base cuneate or convex, margins slightly revolute, serrulate, apex acuminate, acute, or convex, abaxial surface glaucous (sometimes obscured by hairs), sparsely to densely long-silky, hairs (white, sometimes also ferruginous), straight, adaxial highly or slightly glossy, glabrous; proximal blade margins entire; juvenile blade yellowish green, very densely long-silky abaxially, hairs white, sometimes also ferruginous. |
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Staminate flowers | adaxial nectary oblong, 0.6–0.9 mm; filaments distinct; anthers purple turning yellow, ellipsoid to globose, 0.3–0.6 mm. |
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Pistillate flowers | adaxial nectary oblong or ovate, 0.6–1 mm; ovary pyriform, beak gradually tapering to styles; ovules 16–18 per ovary; styles 0.3–0.5 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 or just before leaves emerge; staminate stout or slender, 17–43 × 5–10 mm, flowering branchlet 0–2.5 mm; pistillate densely to loosely flowered, stout to slender, 20–46 × 6–15 mm, flowering branchlet 0–6 mm; floral bract tawny or brown, 0.8–1.2 mm, apex convex to rounded, abaxially hairy, hairs straight or wavy. |
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2n | = 38. |
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Salix humboldtiana |
Salix arbusculoides |
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Phenology | Flowering mid May-early Jul. | |
Habitat | Stream margins, lakeshores, openings in white spruce forests, treed bogs, sedge fens, edges of alpine and arctic tundra | |
Elevation | 0-2000 m (0-6600 ft) | |
Distribution |
Mexico to central Chile |
AK; AB; BC; MB; NT; NU; ON; QC; SK; YT |
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.) |
Glands on leaf teeth of Salix arbusculoides are sometimes covered with fine crystals of sulphur, calcium, potassium, and silicon (R. Cooper, pers. comm.), indicating that they can function as hydathodes as well as resin glands. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 34. | FNA vol. 7, p. 141. |
Parent taxa | Salicaceae > Salix > subg. Protitea > sect. Humboldtianae | Salicaceae > Salix > subg. Vetrix > sect. Arbuscella |
Sibling taxa | ||
Name authority | Willdenow | Andersson: Monogr. Salicum, 147, plate 8, fig. 81. (1867) |
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