Salix humboldtiana |
Salix delnortensis |
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Humboldt's willow |
Del Norte willow |
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Habit | Shrubs, 1–2 m, (sometimes forming clones by stem fragmentation). | |
Stems | branches (highly brittle at base), red-brown, not glaucous, tomentose or velvety to glabrescent; branchlets red-brown or yellow-brown, densely velvety, (buds caprea-type). |
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Leaves | stipules absent or rudimentary on early ones, rudimentary or foliaceous on late ones, apex acute; petiole convex to flat, or shallowly grooved adaxially, 6–16 mm, velvety or tomentose adaxially; largest medial blade elliptic or obovate, 53–102 × 29–54 mm, 1.3–2.8 times as long as wide, base cuneate or convex, margins slightly revolute, entire or sinuate, apex convex, rounded, or acute, abaxial surface glaucous (sometimes obscured by hairs), densely to sparsely velvety, tomentose, villous, or short-silky, hairs erect or spreading, wavy, adaxial dull, sparsely tomentose or short-silky; proximal blade margins entire; juvenile blade green, very densely velvety or long-silky abaxially, hairs white or gray. |
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Staminate flowers | adaxial nectary narrowly oblong to oblong, 0.5–1 mm; filaments distinct or slightly connate, glabrous; anthers purple turning yellow, ellipsoid, 0.6–0.7 mm. |
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Pistillate flowers | adaxial nectary narrowly oblong to oblong, 0.4–0.9 mm, longer than stipe; stipe 0–0.3 mm; ovary obturbinate, short-silky or densely pubescent, beak gradually tapering to styles; ovules 14–18 per ovary; styles 0.6–1.2 mm; stigmas flat, abaxially non-papillate with rounded tip, or 2 plump lobes, 0.2–0.32–0.4 mm. |
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Capsules | 4 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 before leaves emerge; staminate stout, 25–30 × 6–13 mm, flowering branchlet 0–5 mm; pistillate moderately densely flowered, slender to stout, 17–53 × 6–8 mm, flowering branchlet 1–3 mm; floral bract brown, 1.2–2.2 mm, apex rounded, abaxially hairy, hairs straight. |
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Salix humboldtiana |
Salix delnortensis |
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Phenology | Flowering late Mar-early May. | |
Habitat | Streamshores, gravel to boulder substrates, serpentine soils | |
Elevation | 90-500 m (300-1600 ft) | |
Distribution |
Mexico to central Chile |
CA; OR
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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.) |
The origin of the serpentine endemics Salix breweri and S. delnortensis is still unresolved (G. W. Argus 1997; R. D. Dorn 2000). The possibility that they are of hybrid origin, perhaps involving S. lasiolepis and S. sitchensis (Dorn 1976), cannot be resolved by field and herbarium studies alone; cytological and experimental methods need to be employed. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 34. | FNA vol. 7, p. 161. |
Parent taxa | Salicaceae > Salix > subg. Protitea > sect. Humboldtianae | Salicaceae > Salix > subg. Vetrix > sect. Sitchenses |
Sibling taxa | ||
Synonyms | S. breweri var. delnortensis | |
Name authority | Willdenow | C. K. Schneider: J. Arnold Arbor. 1: 96. (1919) |
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