Salix humboldtiana
Salix barrattiana
Humboldt's willow
Barratt's willow
stipules (sometimes marcescent), foliaceous, (resinous, 1.5–7.5 mm), apex acute;
petiole shallowly grooved, or convex to flat adaxially, 4–15 mm, villous or puberulent adaxially, (weakly ventricose around floral buds);
largest medial blade narrowly to broadly elliptic, oblanceolate, or obovate, 35–95 × 10–29 mm, 2.2–4.2(–5) times as long as wide, base usually convex, rounded, or cuneate, sometimes cordate, margins flat, entire, apex acute, convex, or acuminate, abaxial surface not glaucous, moderately to very densely long-silky tomentose to glabrescent, hairs wavy, adaxial slightly glossy, sparsely villous or pubescent to glabrescent;
proximal blade margins entire;
juvenile blade color sometimes obscured by hairs, very densely long-silky abaxially, hairs white.
adaxial nectary narrowly oblong to oblong, 0.4–1.8 mm;
filaments distinct;
anthers yellow or purple turning yellow, ellipsoid or shortly cylindrical, 0.4–0.6 mm.
adaxial nectary narrowly oblong to oblong, 0.6–1.3 mm;
stipe 0.2–0.6 mm;
ovary pyriform, (hairs refractive), beak gradually tapering to styles;
ovules 16–21 per ovary;
styles 0.6–1.8 mm;
stigmas 0.28–0.47–0.64 mm.
4.5–6 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 stout or subglobose, 20–57 × 13–18 mm, flowering branchlet 0–2 mm; pistillate densely flowered, slender to stout, 28–92(–105 in fruit) × 12–19 mm, flowering branchlet 0–5 mm;
floral bract brown or black, 2.8–5.2 mm, apex acute to convex, abaxially hairy, hairs straight.
Salix humboldtiana
Salix barrattiana
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 barrattiana has stipules and buds that are typically strongly oily or resinous, staining pressing sheets yellow. The Montana and Wyoming records are the basis for a conservation assessment by J. A. R. Ladyman (www.fs.fed.us/r2/projects/scp/assessments/salixbarrattiana.pdf). The Wyoming population is represented by three staminate specimens. Their buds and stipules are not conspicuously oily and further verification is needed.
Salix barrattiana is placed here in sect. Villosae, but it is morphologically similar also to members of sect. Lanatae. The most conspicuous difference is its hairy ovaries. Inconsistent phenetic clustering of this species (G. W. Argus 1997) shows the difficulty in determining its sectional placement. The suggestion that it may link the two sections by hybridization and introgression, or by alloploidy, still remains to be assessed.
Hybrids:
Salix barrattiana forms natural hybrids with S. barclayi, S. commutata, and S. pseudomyrsinites.
Salix barrattiana × S. commutata: This hybrid, known from Alberta and the Yukon, usually resembles S. barrattiana, but ovaries are hairy in patches, stipes at ca. 1 mm are long for that species, and buds and stipules are not oily. A British Columbia specimen has glabrous ovaries and oily stipules.
Salix barrattiana × S. pseudomyrsinites is a rare putative hybrid that combines characteristics of the two parents.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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