Salix humboldtiana
Salix caprea
Humboldt's willow
goat willow, hoary willow
stipules rudimentary on early ones, foliaceous on late ones, apex acute or convex;
petiole convex to flat adaxially, 7–25 mm, tomentose to glabrescent adaxially;
largest medial blade narrowly elliptic, broadly elliptic, oblanceolate, obovate, or broadly oblong, 50–130 × 25–80 mm, 2–3 times as long as wide, base cuneate or convex, margins slightly revolute, entire, crenate, or sinuate, (glands submarginal or epilaminal), apex acuminate or convex, abaxial surface glaucous, sparsely tomentose or pubescent, hairs erect, wavy, adaxial dull or slightly glossy, sparsely pubescent;
proximal blade margins entire;
juvenile blade green, densely tomentose abaxially, hairs white, sometimes also ferruginous.
adaxial nectary oblong or square, 0.4–0.7 mm;
filaments distinct, glabrous;
anthers yellow, ellipsoid or shortly cylindrical, 0.7–1.1 mm.
adaxial nectary oblong, narrowly oblong, or square, 0.4–0.9 mm, shorter than stipe;
stipe 2–2.5 mm;
ovary pyriform, densely short-silky, beak gradually tapering to styles;
ovules 12–14 per ovary;
styles 0.3–0.6 mm;
stigmas slenderly cylindrical, 0.4–0.55–0.6 mm.
6–12 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 before leaves emerge;
staminate subglobose or globose, 16–39 × 12–30 mm, flowering branchlet 0–3 mm;
pistillate densely flowered, stout or subglobose, 27–64 × 10–25 mm, flowering branchlet 0–7 mm;
floral bract dark brown or black, 2–4 mm, apex acute or rounded, abaxially hairy, hairs (white), straight.
= 38.
Salix humboldtiana
Salix caprea
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.)
Hybrids:
Salix ×smithiana Willdenow: S. caprea × S. viminalis is an introduced European hybrid commonly naturalized in eastern Canada (New Brunswick, Newfoundland, Nova Scotia, and Prince Edward Island), where it was introduced for coarse basketry. Only pistillate specimens are known and seed-set has not been noted. Its spread is apparently by cultivation and stem fragmentation. It is characterized by: shrubs or trees, 2–10 m; branches yellow-brown, brownish, or gray-brown, pubescent to glabrescent, ± brittle at base, peeled 3–5 year-old branches smooth or striate, striae few, 0–6 mm; branchlets not glaucous, moderately densely pubescent; largest medial leaf blades very narrowly elliptic, narrowly elliptic, or narrowly oblong, 2.8–4.9(–6.4) times as long as wide, margins entire or sinuate, adaxial surfaces pubescent; catkins flowering before leaves emerge; stipes 0.9–2 mm; ovaries pyriform to obclavate, moderately to very densely short-silky; styles 0.5–1.2 mm; stigmas slenderly cylindrical, lobes 0.6–1.2 mm; and capsules 5–7 mm.
Hybrids Salix caprea × S. viminalis and S. cinerea × S. viminalis are commonly recognized in North American floras. They are difficult to separate and their nomenclature is confusing. I am following G. Larsson (1995), who typified S. ×smithiana and cited S. ×sericans (formerly S. cinerea × S. viminalis) and S. caprea × S. viminalis as synonyms. These two S. viminalis hybrids are very similar. Salix caprea × S. viminalis has wood with striae 2–6 mm and leaves usually broadest in the middle; S. cinerea × S. viminalis has decorticated wood with striae 10+ mm and leaves usually broader toward the tip (B. Jonsell and T. Karlsson 2000+, vol. 1). Authentic S. cinerea × S. viminalis has not been seen from the flora area.
See 86. Salix pellita and 98. S. viminalis for more discussion of morphologies.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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