Salix humboldtiana |
Salix maccalliana |
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Humboldt's willow |
Maccalla's willow, mccalla's willow |
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Stems | branches dark red-brown, slightly or highly glossy, glabrous; branchlets red-brown or yellow-brown, puberulent to glabrescent, hairs wavy, curved, straight, or geniculate. |
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Leaves | stipules absent or rudimentary on early ones; petiole convex to flat, or shallowly grooved adaxially, 4–15 mm, pilose or pubescent adaxially; largest medial blade lorate or narrowly oblong, 40–85 × 8–25 mm, 2.9–4.8(–5.7) times as long as wide, base convex or cuneate, margins flat, entire, serrulate, or crenate, apex acute to sometimes acuminate, abaxial surface (pale), glabrous or sparsely pubescent, hairs white and ferruginous, straight, relatively short and stiff, adaxial highly glossy, glabrous, puberulent, or sparsely tomentose, hairs white and ferruginous; proximal blade margins serrulate; juvenile blade reddish. |
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Staminate flowers | abaxial nectary (0–)0.6–0.9 mm, adaxial nectary oblong or narrowly oblong, 0.5–1 mm, nectaries distinct or connate and cup-shaped; filaments distinct, hairy on proximal 1/2; anthers (purple turning yellow), ellipsoid or shortly cylindrical. |
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Pistillate flowers | (abaxial nectary present), adaxial nectary oblong, 0.4–1 mm, (nectaries distinct); ovary pyriform; ovules 12–16 per ovary; styles connate or distinct 1/2 their lengths, 0.8–1.2 mm; stigmas flat, abaxially non-papillate with rounded tip, or slenderly cylindrical, 0.3–0.6 mm. |
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Capsules | 7–11 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 (stout or subglobose), 15.5–42 × 9–16 mm, flowering branchlet 1.5–11 mm; pistillate densely flowered, slender, stout, or subglobose, 25–50 × 10–20 mm, flowering branchlet 3–12 mm; floral bract 1.6–3.6 mm, apex rounded to truncate, entire, abaxially hairy throughout or proximally, hairs white and ferruginous, wavy. |
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2n | = ca. 190, ca. 228. |
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Salix humboldtiana |
Salix maccalliana |
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Phenology | Flowering early May-early Jul. | |
Habitat | Sedge meadows, shrubby fens, marly or bouldery lakeshores, string bogs, treed bogs, Calamagrostis grasslands | |
Elevation | 0-1500 m (0-4900 ft) | |
Distribution |
Mexico to central Chile |
MN; ND; WA; AB; BC; MB; NT; ON; QC; SK; 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.) |
The decaploid to dodecaploid chromosome number for Salix maccalliana, highest in the genus, suggests a complex origin. Relationships with subg. Chamaetia and subg. Salix were suggested by Rowlee and by H. M. Raup (1959). Staminate flowers with abaxial nectaries, tawny and persistent bracts, and villous ovaries suggest a link with S. glauca; leaves with coarse, ferruginous hairs and serrate margins suggest S. lucida (Rowlee). Although S. maccalliana is phenetically closer to sect. Salicaster than to (subg. Chamaetia) sect. Glaucae (G. W. Argus 1997), it is probable that because it incorporates genomes from more than one subgenus, its subgeneric placement is arbitrary. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 34. | FNA vol. 7, p. 49. |
Parent taxa | Salicaceae > Salix > subg. Protitea > sect. Humboldtianae | Salicaceae > Salix > subg. Salix > sect. Maccallianae |
Sibling taxa | ||
Name authority | Willdenow | Rowlee: Bull. Torrey Bot. Club 34: 158. (1907) |
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