Salix humboldtiana
Salix wolfii
Humboldt's willow
Idaho willow, wolf willow, Wolf's willow
stipules rudimentary or foliaceous on early ones, foliaceous on late ones, apex rounded, acuminate, or acute;
petiole convex to flat, or shallowly grooved adaxially, 3–12 mm, pubescent, long-silky, or villous adaxially;
largest medial blade narrowly oblong, narrowly elliptic, elliptic, or oblanceolate, 26–56 × 8–16.5 mm, 2.5–3.7–5.6 times as long as wide, base cuneate, convex, or rounded, margins flat, entire, apex acute, acuminate, or convex, abaxial surface not glaucous, pubescent, short-silky, or villous, hairs appressed or spreading, straight or wavy, adaxial dull, sparsely to densely silky or villous;
proximal blade margins entire;
juvenile blade yellowish green, densely short- or long-silky or villous abaxially, hairs white.
(abaxial nectary 0–0.2 mm), adaxial nectary oblong, 0.4–1.1 mm, (nectaries distinct);
filaments distinct, glabrous;
anthers yellow, 0.3–0.5 mm.
adaxial nectary oblong, ovate, or flask-shaped, 0.4–1.1 mm, shorter to longer than stipe;
stipe 0.2–0.9 mm;
ovary pyriform, glabrous or hairy, beak gradually tapering to or slightly bulged below styles;
ovules 8–16 per ovary;
styles 0.3–1 mm;
stigmas flat, abaxially non-papillate with rounded or pointed tip, or slenderly or broadly cylindrical, 0.24–0.3–0.4 mm.
3–5 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.
flowering as leaves emerge;
staminate stout or subglobose, 9.5–16 × 6–12 mm, flowering branchlet 1–5.5 mm;
pistillate moderately or very densely flowered, stout, subglobose or globose, 8.5–38 × 5–12 mm, flowering branchlet 1–11 mm;
floral bract brown, black, or bicolor, 0.8–2 mm, apex rounded or acute, abaxially hairy, hairs wavy, straight, or curly.
Salix humboldtiana
Salix wolfii
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.)
Varieties 2 (2 in the flora).
The two varieties of Salix wolfii are distinguished mainly by ovary hairiness; other characters in the key overlap. Ovaries of the typical var. wolfii are glabrous and those of var. idahoensis are hairy. In the latter variety, ovaries are sometimes hairy throughout, but most have hairs in streaks or in a patch at the base of the ovary and on the stipes. These plants usually do not set seed and may be infertile hybrids. Occasional occurrence of staminate flowers with abaxial nectaries suggests that this variety may be a hybrid with S. glauca or S. brachycarpa, although it could also be with S. eastwoodiae, as suggested by S. J. Brunsfeld and F. D. Johnson (1985). The presence of both abaxial and adaxial nectaries in staminate flowers of S. wolfii (staminate plants cannot be identified to variety) is an unusual character in subg. Vetrix; it rarely occurs in S. argyrocarpa, S. breweri, and S. orestera, but is common in S. wolfii. Both hairy ovaries and abaxial nectaries could have been acquired through hybridization and introgression, or polyploidy, with S. glauca or S. brachycarpa. Cytological study of S. wolfii may help answer this question.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Ovaries glabrous; pistillate adaxial nectaries 0.4-0.8 mm; stipes 0.2-0.9 mm. | var. wolfii |
1. Ovaries pubescent or tomentose (hairs in streaks or patches); pistillate adaxial nectaries 0.4-1.1 mm; stipes 0-0.4 mm | var. idahoensis |
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