Salix humboldtiana |
Salix arctophila |
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Humboldt's willow |
arctic willow, northern willow |
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Habit | Plants 0.03–0.15 m, (dwarf), forming clones by layering. | |
Stems | prostrate, long-trailing; branches yellow-brown, red-brown, or green-brown, glabrous; branchlets yellow-green or yellow-brown to red-brown, (sometimes weakly glaucous), glabrous, (inner membranaceous bud-scale layer free, not separating from outer layer). |
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Leaves | stipules rudimentary, absent, or foliaceous on early ones, foliaceous or rudimentary on late ones; petiole 3–7.8–15 mm; largest medial blade hypostomatous or hemiamphistomatous, elliptic, obovate, broadly elliptic, broadly obovate, subcircular, or oblanceolate, 15–31–60 × 6.5–16–35 mm, 1.2–3–4.3 times as long as wide, base cuneate, convex, or rounded, margins slightly revolute, inconspicuously crenulate or entire, apex usually acute or convex, sometimes rounded, abaxial surface glaucous, glabrous, adaxial slightly or highly glossy, glabrous; proximal blade margins entire or serrulate; juvenile blade glabrous. |
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Staminate flowers | abaxial nectary absent, adaxial nectary oblong, square, narrowly oblong, or ovate, 0.4–1 mm; filaments distinct or connate less than 1/2 their lengths, glabrous, or hairy on proximal 1/2; anthers ellipsoid or long-cylindrical, 0.5–0.7 mm. |
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Pistillate flowers | abaxial nectary absent, adaxial nectary oblong or narrowly oblong, 0.5–0.9 mm, shorter than stipe; stipe 0.8–1.4 mm; ovary pyriform or obclavate, pubescent or short-silky, (refractive), hairs (white, grayish, or ferruginous), crinkled, often refractive, ribbonlike, beak gradually tapering to styles; ovules 8–16 per ovary; styles connate or distinct 1/2 their lengths, 0.6–1.4 mm; stigmas slenderly or broadly cylindrical, 0.24–0.47–0.72 mm. |
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Capsules | 5–9 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 19–54 × 7–16 mm, flowering branchlet 4–20 mm; pistillate densely to moderately densely flowered, slender to subglobose, 30–79(–130 in fruit) × 10–20 mm, flowering branchlet 8–57 mm; floral bract brown, black, or bicolor, 0.8–2.4 mm, apex rounded or acute, entire, abaxially densely hairy, hairs straight. |
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2n | = 76. |
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Salix humboldtiana |
Salix arctophila |
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Phenology | Flowering late May-late Jul. | |
Habitat | Arctic-alpine, subarctic, hummocks in wet, mossy, grass or sedge meadows, margins of streams or ponds, among granite boulders, on alluvial plains, sometimes in snowbeds | |
Elevation | 40-600 m (100-2000 ft) | |
Distribution |
Mexico to central Chile |
AK; ME; MB; NL; NT; NU; ON; QC; SK; YT; Greenland
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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 arctophila occurs in western Greenland. Hybrids: Salix arctophila forms natural hybrids with S. arctica, S. glauca var. cordifolia, and S. uva-ursi. Salix arctophila × S. glauca var. cordifolia: Plants with villous leaves and moderately densely hairy branchlets and branches suggest this hybrid. Putative hybrids are rare but have been seen from Kuujjuaq and Ivujivik, Quebec (G. W. Argus, unpubl.), and are reported to be common in West Greenland (T. W. Böcher 1952). Salix arctophila × S. uva-ursi is a rare hybrid. The plants often have ovaries with patches of hairs, some of which are ribbonlike, as in S. arctophila, but their habit is compact, as in S. uva-ursi, rather than long-trailing as in S. arctophila. Some specimens are infertile and are evidently hybrids, but there is little to confirm S. uva-ursi as the second parent. N. Polunin (1940b) also expressed some uncertainty about plants intermediate between S. arctophila and S. uva-ursi, and A. K. Skvortsov (1971) discounted this hybrid but noted that there were a few somewhat doubtful specimens. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 34. | FNA vol. 7, p. 73. |
Parent taxa | Salicaceae > Salix > subg. Protitea > sect. Humboldtianae | Salicaceae > Salix > subg. Chamaetia > sect. Myrtosalix |
Sibling taxa | ||
Synonyms | S. arctophila var. lejocarpa, S. groenlandica var. lejocarpa | |
Name authority | Willdenow | Cockerell ex A. Heller: Cat. N. Amer. Pl. ed. 3, 89. (1910) |
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