Salix humboldtiana
Salix raupii
Humboldt's willow
Raup willow, Raup's willow
erect;
branches gray-brown, glabrous;
branchlets yellow-brown, glabrous.
stipules foliaceous;
petiole 5–9 mm;
largest medial blade narrowly elliptic, 32–58 × 12–19 mm, 2–3.3 times as long as wide, base cuneate or convex, margins slightly revolute, entire, apex acute to acuminate, abaxial surface glabrous, adaxial slightly glossy, glabrous;
proximal blade margins shallowly serrulate;
juvenile blade glabrous.
abaxial nectary 0.3–0.8 mm, adaxial nectary narrowly oblong, 0.6–1 mm, nectaries distinct;
filaments distinct, glabrous;
anthers ellipsoid, shortly cylindrical, or globose, 0.4–0.7 mm.
abaxial nectary absent, adaxial nectary narrowly oblong or oblong, 0.5–1.1 mm, equal to or longer than stipe;
stipe 0.4–1.2 mm;
ovary pyriform, usually glabrous, rarely puberulent, beak slightly bulged below styles;
ovules 12 per ovary;
styles 0.6–0.8 mm;
stigmas flat, abaxially not papillate with rounded tip, or broadly cylindrical, 0.3–0.5 mm.
4.4–8 mm.
humboldtiana Willdenow: Humboldt willow is not known to occur in the flora area.
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.
staminate 17.5–42 × 5–13 mm, flowering branchlet 6–7 mm;
pistillate moderately densely flowered, stout, 20–40 × 6–12 mm, flowering branchlet 4–7 mm;
floral bract tawny or bicolor, 1.3–2.5 mm, apex rounded, entire, abaxially glabrous.
Salix humboldtiana
Salix raupii
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.)
Of conservation concern.
Salix raupii resembles glabrous S. glauca var. villosa. Thin-layer chromatography of leaf phenolics in S. raupii revealed a pattern similar to those of S. glauca vars. villosa and acutifolia and S. athabascensis (G. W. Argus, unpubl.). Based on overall similarity, its nearest neighbors are S. glauca, in a broad sense, and S. athabascensis (Argus 1997). The sectional placement of this species is uncertain. It is placed here in sect. Myrtilloides because it clusters with S. athabascensis, but it is evidently close to S. glauca and may be a species of intersectional hybrid origin.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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