Salix humboldtiana |
Salix lasiolepis |
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Humboldt's willow |
arroyo willow |
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Habit | Shrubs or trees, 1.5–10 m, (sometimes forming clones by stem fragmentation). | |
Stems | branches (sometimes flexible to highly brittle at base), yellow-brown to red-brown, not or weakly glaucous, glabrous, tomentose, pubescent (appearing dusty); branchlets yellowish, yellow-brown, or red-brown, sparsely to densely villous, tomentose, or velvety to glabrescent, (inner membranaceous bud-scale layer free, separating from outer layer). |
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Leaves | stipules usually foliaceous, or rudimentary or absent on early ones, foliaceous on late ones, apex acute; petiole convex to flat, or shallowly grooved adaxially, 3–16 mm, tomentose or velvety adaxially; largest medial blade lorate, narrowly oblong, narrowly elliptic, oblanceolate, or obovate to broadly obovate, 36–125 × 6–32 mm, 1.9–9.6 times as long as wide, base cuneate or convex, margins slightly to strongly revolute, entire or remotely or irregularly serrate, sinuate, (glands submarginal or epilaminal), apex acute, acuminate, convex or rounded, abaxial surface glaucous, sparsely pubescent, moderately densely tomentose or woolly-tomentose, short- or long-silky to glabrescent, hairs (white, sometimes also ferruginous), wavy, adaxial slightly or highly glossy, moderately densely tomentose or short-silky to glabrescent, (hairs white, sometimes also ferruginous); proximal blade margins entire or serrulate; juvenile blade color sometimes obscured by hairs, silky, tomentose or very densely woolly-tomentose abaxially, hairs white, sometimes ferruginous. |
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Staminate flowers | adaxial nectary narrowly oblong, oblong, or ovate, 0.5–1.2 mm; filaments distinct or connate less than 1/2 their lengths; anthers purple turning yellow, ellipsoid or shortly cylindrical, 0.4–0.7 mm. |
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Pistillate flowers | adaxial nectary oblong to flask-shaped, 0.2–1.1 mm; stipe 1–1.7 mm; ovary pyriform, beak slightly bulged below styles; ovules 10–18 per ovary; styles (sometimes slightly distinct distally), 0.1–0.6 mm; stigmas flat, abaxially non-papillate with rounded or pointed tip, or 2 plump lobes, 0.1–0.3 mm. |
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Capsules | 2.5–5.5 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 or just before leaves emerge; staminate slender or stout, 18–88 × 5–15 mm, flowering branchlet 0–5 mm; pistillate densely flowered, slender or stout, 18–72 × 7–12 mm, flowering branchlet 0–6 mm; floral bract 1–2.4 mm, apex broadly rounded, abaxially hairy, hairs straight or wavy. |
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2n | = 76. |
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Salix humboldtiana |
Salix lasiolepis |
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Phenology | Flowering mid Jan-mid Jun. | |
Habitat | Streamshores, marshes, meadows, springs, coastal headlands, rocky bluffs, sand dunes, salt marshes, silty, sandy, gravelly, or rocky substrates, dolomite | |
Elevation | 0-2800 m (0-9200 ft) | |
Distribution |
Mexico to central Chile |
AZ; CA; ID; NM; NV; OR; TX; UT; WA; Mexico (Baja California, Chiapas, Chihuahua, Coahuila, Durango, San Luis Potosí, Sonora)
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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.) |
Salix lasiolepis is polymorphic. Variety bigelovii has been recognized in coastal California and Oregon (G. W. Argus 1993). It differs mainly in density of leaf indumentum and in having leaves tending to be slightly broader; it may be a coastal ecotype and is not formally recognized here. Hybrids: Salix lasiolepis forms natural hybrids with S. irrorata and S. breweri. Hybrids with S. hookeriana are suspected but unconfirmed. The distinctly serrate leaves in some specimens from Arizona and New Mexico may be part of the species variability, but could also be due to hybridization. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 34. | FNA vol. 7, p. 156. |
Parent taxa | Salicaceae > Salix > subg. Protitea > sect. Humboldtianae | Salicaceae > Salix > subg. Vetrix > sect. Mexicanae |
Sibling taxa | ||
Synonyms | S. bakeri, S. bigelovii, S. franciscana, S. lasiolepis var. bracelinae, S. lasiolepis var. sandbergii, S. lutea var. nivaria | |
Name authority | Willdenow | Bentham: Pl. Hartw., 335. (1857) |
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