Salix viminalis
Salix arizonica
basket willow, common osier, osier, osier willow, silky osier
Arizona willow
branches yellow-brown, gray-brown, or yellowish, not glaucous, glabrous or puberulent;
branchlets yellow-brown or yellowish (sometimes color obscured by hairs), glabrous, densely to sparsely villous, velvety, or puberulent.
branches red-brown or yellow-brown, not or weakly glaucous, glabrous or pilose at nodes;
branchlets yellow-green, red-brown, or brownish, pilose.
stipules (not adnate to petioles), rudimentary or absent on early ones, (late ones sometimes brownish, linear, 5.4–10.4 mm), apex acuminate;
petiole shallowly grooved adaxially, 4–13 mm, villous, puberulent, or velvety adaxially;
largest medial blade linear, lorate, narrowly oblong, or narrowly elliptic, 53–130 × 5–33 mm, base cuneate, margins strongly revolute, sinuate or apparently entire, (glands epilaminal), apex acuminate, acute, or convex, abaxial surface apparently glaucous (obscured by hairs), densely short-silky, woolly, or tomentose, (midribs prominent, yellowish, and hairy), hairs appressed, spreading or erect, straight or wavy, adaxial dull or slightly glossy, sparsely or moderately densely pubescent, hairs gray;
proximal blade margins entire;
juvenile blade yellowish green, very densely tomentose or short-silky abaxially, hairs white.
stipules foliaceous, apex convex or rounded;
petiole convex to flat, or shallowly grooved adaxially, 2–7.5 mm, villous or pubescent to glabrescent adaxially;
largest medial blade (sometimes amphistomatous), elliptic or broadly elliptic, 20–50 × 10–31 mm, 1.6–2–2.8(–3.6) times as long as wide, base convex, rounded, or cordate, margins flat, serrulate or entire, apex acute, convex, or acuminate, abaxial surface not glaucous, pilose or glabrous, hairs wavy, adaxial slightly glossy, pilose or glabrous;
proximal blade margins entire, serrulate, or crenulate;
juvenile blade green, glabrous or pilose abaxially, hairs white.
adaxial nectary narrowly oblong or oblong, 0.6–1.5 mm;
filaments distinct;
anthers purple turning yellow, ellipsoid to shortly cylindrical, 0.6–0.8 mm.
adaxial nectary narrowly oblong to oblong, 0.4–0.8 mm;
filaments distinct, glabrous;
anthers purple turning yellow, 0.4–0.6 mm.
adaxial nectary narrowly oblong or oblong, 0.9–1.4 mm;
ovary pyriform, beak gradually tapering to styles;
ovules 12–18 per ovary;
styles 0.6–1.8 mm.
adaxial nectary narrowly oblong to oblong, 0.4–1 mm, shorter to longer than stipe;
stipe 0.2–1 mm;
ovary pyriform, glabrous, beak gradually tapering to or slightly bulged below styles;
ovules 8–12 per ovary;
styles 0.5–1.2 mm;
stigmas broadly cylindrical, 0.14–0.21–0.36 mm.
4–6 mm.
3.2–4.5 mm.
flowering just before or as leaves emerge; staminate stout, 24–48 mm, flowering branchlet 0–2 mm; pistillate densely flowered, 23–55 mm, flowering branchlet 0–6 mm;
floral bract brown or tawny, 1.6–2.2 mm, apex convex or rounded, abaxially hairy, hairs straight.
flowering as leaves emerge; staminate stout, subglobose, or globose, 7–17 × 6–10 mm, flowering branchlet 1–3 mm; pistillate densely or moderately densely flowered, stout or subglobose, 12–38 × 6–12 mm, flowering branchlet 1.5–10 mm;
floral bract brown, black, or bicolor, 1–2 mm, apex acute or convex, abaxially hairy, hairs wavy.
= 38.
= 38.
Salix viminalis
Salix arizonica
Salix ×smithiana (S. caprea × S. viminalis) is distinguished from S. viminalis by having leaf blades usually broad, 2.8–4.9(–6.4) times as long as wide, stipes 0.9–2 mm, ovaries short-silky, branches ± brittle at base, and petioles flat to convex adaxially; S. viminalis has leaf blades usually very narrow, 4.7–13.7 times as long as wide, stipes 0.1–0.5 mm, ovaries long-silky, branches flexible at base, and petioles shallowly grooved adaxially.
See Salix ×smithiana [p. 132] and 86. S. pellita for further comparative descriptions.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
Salix arizonica is very similar to S. boothii. They were separated by Dorn on the presence of five flavonoid compounds identified in S. boothii not found in S. arizonica. Some morphological differences were noted but the characters used to separate them are quite variable. The most important feature seems to be the usually broader leaves of S. arizonica. In addition, the diploid chromosome number for S. arizonica separates it from the tetraploid S. boothii. Although the two are distinct species, the overlap in their morphological characters suggests that positive identification needs to be based on chromosome number or chromatographic analysis.
Salix arizonica is distinguished from S. boothii by having stipule apices convex to rounded, petioles 3–7.5 mm, juvenile blades glabrous or hairy, hairs white, largest medial blades elliptic or broadly elliptic, 20–50 mm, 1.6–3.6 times as long as wide, abaxial surfaces with white hairs, staminate catkins 1–1.7 times as long as broad, pistillate catkins 1.2–2.8 times as long broad, floral bract apices acute to convex, nectaries narrowly oblong to oblong, staminate nectaries 0.4–0.8 mm, anthers 0.4–0.6 mm, filaments distinct, glabrous, pistillate nectaries shorter to longer than stipes, stipes 0.2–1 mm, stigmas broadly cylindrical, and capsules 3.2–4.5 mm; S. boothii has stipule apices acuminate or acute to rounded, petioles 3–17 mm, juvenile blades hairy, hairs white, sometimes also ferruginous, largest medial blades lorate to narrowly or broadly elliptic, 26–102 mm, 2–5.2 times as long as wide, abaxial surfaces with white, sometimes also ferruginous, hairs, staminate catkins 1.2–3.1 times as long as broad, pistillate catkins 1.4–4.1 times as long as broad, floral bract apices rounded or retuse, nectaries narrowly oblong to ovate or flask-shaped, staminate nectaries 0.6–1.5 mm, anthers 0.48–0.8 mm, filaments distinct to connate about half their lengths, glabrous or hairy, pistillate nectaries shorter than stipes, stipes 0.5–2.5 mm, stigmas flat, abaxially non-papillate with rounded tip, slenderly cylindrical or plump, and capsules 2.5–6 mm.
Salix arizonica, originally known from Mt. Baldy in east-central Arizona, was proposed for listing under the United States Endangered and Threatened Wildlife and Plants Act, but the proposal was withdrawn when additional populations were discovered in southern Utah and in New Mexico; it is now listed as a “sensitive species” (K. Decker, www.fs.us/r2/projects/scp/assessments/salixarizonica.pdf). Major conservation concerns are from browsing by cattle and elk (J. Maschinski 2001) and Melampsora infection (M. L. Fairweather 1993; R. A. Obedzinski et al. 2001). The Arizona populations receive minimal protection from cattle and wildlife browsing by exclosures and by introduction into new localities. The Arizona and Utah populations have a genetic similarity of ca. 37%, which has been attributed to a period of panmixis followed by a long period of isolation in regions with different environments (J. T. Thompson et al. 2003).
Salix arizonica is in the Center for Plant Conservation’s National Collection of Endangered Plants.
Hybrids:
Salix arizonica forms natural hybrids with S. brachycarpa, S. eastwoodiae, and S. lutea.
Salix arizonica × S. brachycarpa var. brachycarpa occurs in southern Utah. Its parentage is supported by chromatographic data (E. D. McArthur, pers. comm.).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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