Salix humboldtiana
Salix triandra
Humboldt's willow
almond leaf willow, almond willow
branches glabrous or glabrescent;
branchlets yellow-brown, red-brown, or brownish, usually glabrous, rarely pilose.
stipules rudimentary to foliaceous on early ones (absent on proximal ones);
petiole deeply grooved adaxially, margins covering groove, 4–26 mm, pubescent or puberulent to glabrescent adaxially;
largest medial blade oblong, narrowly oblong, narrowly elliptic, elliptic, or lanceolate to obovate, 53–114 × 14–35 mm, 2.7–6.3 times as long as wide, base convex or cuneate, margins flat or slightly revolute, crenate or serrulate, apex acuminate, acute, or ± caudate, abaxial surface glabrous or glabrescent, adaxial dull or slightly glossy, glabrous or glabrescent;
proximal blade margins crenate or crenulate;
juvenile blade reddish.
abaxial nectary 0.2–1.1 mm, adaxial nectary oblong, square, or ovate, 0.2–0.6 mm, distinct;
filaments distinct, hairy on proximal 1/2;
anthers ellipsoid.
adaxial nectary obovate to square, 0.3–0.5 mm;
ovary pyriform, beak gradually tapering to or slightly bulged below styles;
ovules 30–36 per ovary;
styles distinct 1/2 their lengths, 0.2–0.3 mm;
stigmas flat, abaxially non-papillate with rounded tip, 0.1–0.2 mm.
3–6 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.
staminate 20–60 × 5.5–10 mm, flowering branchlet 3–17 mm;
pistillate moderately to very densely flowered, slender to stout, 20–60 × 5–8 mm, flowering branchlet 5–31 mm;
floral bract 1–2.3 mm, apex rounded or acute, abaxially hairy (mainly proximally), hairs wavy.
= 38 (44), 57, or 88.
Salix humboldtiana
Salix triandra
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 triandra usually has been overlooked in North American floras. At one time, it was a very important basket willow and probably was introduced into North America for that purpose. Some authors treat the glaucous and nonglaucous forms as subspecies (F. Martini and P. Paiero 1988; K. H. Rechinger 1993); A. K. Skvortsov (1999) noted that, although the two have somewhat distinct ranges, both kinds occur throughout the species and sometimes can be found in the same population. His suggestion that genetic inheritance of this character should be studied has not been taken up. The species is characterized by bark that is dark gray, smooth, and flaking in large irregular patches, as in Platanus ×acerifolia. The ovary-style transition is so indistinct that styles are often described as absent, but there are two, distinct styles, each terminating in a short stigma. A color change, later in the season, between the styles and ovary suggests that the tip of the ovary and the two distinct styles are both stylar tissues. In general, it appears that the styles are connate proximally and distinct distally.
Collections of Salix triandra made in 1934–35 by H. Hyland along the Penobscot River, Orono, Maine, were labeled by him as “introduced,” but they could have spread from cultivation or have been naturalized (A. Haines, pers. comm.). Recent naturalized occurrences are known from Toronto, Ontario, and Wolfville, Nova Scotia. Specimens identified as S. triandra by C. R. Ball are from Virginia and the District of Columbia. Salix triandra is reported to occur in Ohio (T. D. Sydnor and W. F. Cowen 2000) but voucher specimens were not found.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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