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mountain willow, Scouler willow, Scouler's willow

arroyo willow

Habit Shrubs or trees, 1–10(–20) m. Stems: branches gray-brown, yellow-brown, or red-brown, not glaucous, glabrous or tomentose; branchlets yellow-green or yellow-brown, sparsely to densely villous, tomentose, or velvety. Shrubs or trees, 1.5–10 m, (sometimes forming clones by stem fragmentation).
Stems

branches (sometimes flexible to highly brittle at base), yellow-brown to red-brown, not or weakly glaucous, glabrous, tomentose, pubescent (appearing dusty);

branchlets yellowish, yellow-brown, or red-brown, sparsely to densely villous, tomentose, or velvety to glabrescent, (inner membranaceous bud-scale layer free, separating from outer layer).

Leaves

stipules absent, rudimentary, or foliaceous on early ones, foliaceous on late ones, (1–16 mm), apex acute or acuminate;

petiole convex to flat adaxially, 2–13 mm, velvety or villous adaxially;

largest medial blade usually oblanceolate, sometimes narrowly elliptic, elliptic or obovate, 29–100 × 9–37 mm, 1.7–3.9 times as long as wide, base cuneate or convex, margins strongly to slightly revolute or flat, entire, remotely serrate, crenate, or sinuate, (glands submarginal or epilaminal), apex acuminate, convex, or rounded, abaxial surface glaucous, sparsely to densely short- to long-silky or woolly, hairs (white, sometimes also ferruginous), wavy or straight, adaxial slightly glossy, pilose or moderately densely short-silky, midrib velutinous or villous, (hairs white, sometimes also ferruginous);

proximal blade margins entire, serrulate, or crenulate;

juvenile blade reddish or yellowish green, sparsely to densely villous, short- or long-silky abaxially, hairs white, sometimes also ferruginous.

stipules usually foliaceous, or rudimentary or absent on early ones, foliaceous on late ones, apex acute;

petiole convex to flat, or shallowly grooved adaxially, 3–16 mm, tomentose or velvety adaxially;

largest medial blade lorate, narrowly oblong, narrowly elliptic, oblanceolate, or obovate to broadly obovate, 36–125 × 6–32 mm, 1.9–9.6 times as long as wide, base cuneate or convex, margins slightly to strongly revolute, entire or remotely or irregularly serrate, sinuate, (glands submarginal or epilaminal), apex acute, acuminate, convex or rounded, abaxial surface glaucous, sparsely pubescent, moderately densely tomentose or woolly-tomentose, short- or long-silky to glabrescent, hairs (white, sometimes also ferruginous), wavy, adaxial slightly or highly glossy, moderately densely tomentose or short-silky to glabrescent, (hairs white, sometimes also ferruginous);

proximal blade margins entire or serrulate;

juvenile blade color sometimes obscured by hairs, silky, tomentose or very densely woolly-tomentose abaxially, hairs white, sometimes ferruginous.

Staminate flowers

adaxial nectary oblong or square, 0.4–0.9 mm;

filaments distinct, glabrous or hairy on proximal 1/2;

anthers purple turning yellow, ellipsoid to shortly cylindrical, 0.7–1.2 mm.

adaxial nectary narrowly oblong, oblong, or ovate, 0.5–1.2 mm;

filaments distinct or connate less than 1/2 their lengths;

anthers purple turning yellow, ellipsoid or shortly cylindrical, 0.4–0.7 mm.

Pistillate flowers

adaxial nectary oblong or square, 0.2–0.8 mm, shorter than stipe;

stipe 0.8–2.3 mm;

ovary pyriform or obclavate, densely long-silky, beak slightly bulged below styles;

ovules 10–18 per ovary;

styles 0.2–0.6 mm;

stigmas slenderly cylindrical, 0.4–0.82–1.04 mm.

adaxial nectary oblong to flask-shaped, 0.2–1.1 mm;

stipe 1–1.7 mm;

ovary pyriform, beak slightly bulged below styles;

ovules 10–18 per ovary;

styles (sometimes slightly distinct distally), 0.1–0.6 mm;

stigmas flat, abaxially non-papillate with rounded or pointed tip, or 2 plump lobes, 0.1–0.3 mm.

Capsules

4.5–11 mm.

2.5–5.5 mm.

Catkins

flowering before leaves emerge; staminate stout or subglobose, 18–40.5 × 8–22 mm, flowering branchlet 0–4 mm; pistillate very densely flowered, slender or stout, 18–60(–90 in fruit) × 10–22 mm, flowering branchlet 0–8 mm;

floral bract brown, black, or bicolor, 1.5–4.5 mm, apex rounded or acute, abaxially hairy, hairs straight.

flowering before or just before leaves emerge; staminate slender or stout, 18–88 × 5–15 mm, flowering branchlet 0–5 mm; pistillate densely flowered, slender or stout, 18–72 × 7–12 mm, flowering branchlet 0–6 mm;

floral bract 1–2.4 mm, apex broadly rounded, abaxially hairy, hairs straight or wavy.

2n

= 76.

= 76.

Salix scouleriana

Salix lasiolepis

Phenology Flowering late Feb-mid Jun. Flowering mid Jan-mid Jun.
Habitat Dry conifer forests, mature woods on edges of streams and lakes, treed bogs, meadows, subalpine slopes, springs, pine barrens, openings in old burns, arroyos and disturbed sites, sandy, silty-clay, or gravelly, igneous substrates Streamshores, marshes, meadows, springs, coastal headlands, rocky bluffs, sand dunes, salt marshes, silty, sandy, gravelly, or rocky substrates, dolomite
Elevation 0-3500 m (0-11500 ft) 0-2800 m (0-9200 ft)
Distribution
from FNA
AK; AZ; CA; CO; ID; MT; NM; NV; OR; SD; UT; WA; WY; AB; BC; MB; NT; SK; YT; Mexico (Chihuahua, Sonora)
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; ID; NM; NV; OR; TX; UT; WA; Mexico (Baja California, Chiapas, Chihuahua, Coahuila, Durango, San Luis Potosí, Sonora)
[WildflowerSearch map]
[BONAP county map]
Discussion

Western Salix scouleriana and eastern S. humilis are closely related and are sometimes difficult to separate. Although there is an apparent range disjunction between them in western Manitoba, it may be a collecting gap. In general, S. scouleriana differs from S. humilis in being a taller shrub, sometimes even tree-like, with broader leaves and longer catkins, floral bracts, stigmas, and styles, but these quantitative characteristics all overlap. The apparent difference in anther length (S. scouleriana 0.7–1.2 mm; S. humilis 0.4–0.6 mm) may be correlated with a difference in chromosome number. Salix scouleriana is tetraploid (Y. Suda and G. W. Argus 1968); S. humilis has been reported to be both diploid (Suda and Argus; L. Zsuffa and Y. Raj, unpubl.) and tetraploid (R. D. Dorn 1976). The latter count was from the same population as the one by Suda and Argus. Further chromosome counts are indicated.

See 77. Salix hookeriana for comparative descriptions.

Hybrids:

Salix scouleriana forms natural hybrids with S. hookeriana, S. planifolia, and S. pulchra.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Salix lasiolepis is polymorphic. Variety bigelovii has been recognized in coastal California and Oregon (G. W. Argus 1993). It differs mainly in density of leaf indumentum and in having leaves tending to be slightly broader; it may be a coastal ecotype and is not formally recognized here.

Hybrids:

Salix lasiolepis forms natural hybrids with S. irrorata and S. breweri. Hybrids with S. hookeriana are suspected but unconfirmed. The distinctly serrate leaves in some specimens from Arizona and New Mexico may be part of the species variability, but could also be due to hybridization.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 7, p. 131. FNA vol. 7, p. 156.
Parent taxa Salicaceae > Salix > subg. Vetrix > sect. Cinerella Salicaceae > Salix > subg. Vetrix > sect. Mexicanae
Sibling taxa
S. alaxensis, S. alba, S. amygdaloides, S. arbusculoides, S. arctica, S. arctophila, S. argyrocarpa, S. arizonica, S. athabascensis, S. atrocinerea, S. aurita, S. babylonica, S. ballii, S. barclayi, S. barrattiana, S. bebbiana, S. bonplandiana, S. boothii, S. brachycarpa, S. breweri, S. calcicola, S. candida, S. caprea, S. caroliniana, S. cascadensis, S. chamissonis, S. chlorolepis, S. cinerea, S. columbiana, S. commutata, S. cordata, S. daphnoides, S. delnortensis, S. discolor, S. drummondiana, S. eastwoodiae, S. elaeagnos, S. eriocephala, S. euxina, S. exigua, S. famelica, S. farriae, S. floridana, S. fuscescens, S. geyeriana, S. glauca, S. gooddingii, S. hastata, S. herbacea, S. hookeriana, S. humboldtiana, S. humilis, S. interior, S. irrorata, S. jejuna, S. jepsonii, S. laevigata, S. lasiandra, S. lasiolepis, S. lemmonii, S. ligulifolia, S. lucida, S. lutea, S. maccalliana, S. melanopsis, S. monochroma, S. monticola, S. myricoides, S. myrsinifolia, S. myrtillifolia, S. nigra, S. niphoclada, S. nivalis, S. nummularia, S. orestera, S. ovalifolia, S. pedicellaris, S. pellita, S. pentandra, S. petiolaris, S. petrophila, S. phlebophylla, S. planifolia, S. polaris, S. prolixa, S. pseudomonticola, S. pseudomyrsinites, S. pulchra, S. purpurea, S. pyrifolia, S. raupii, S. reticulata, S. richardsonii, S. rotundifolia, S. sericea, S. serissima, S. sessilifolia, S. setchelliana, S. silicicola, S. sitchensis, S. sphenophylla, S. stolonifera, S. taxifolia, S. thurberi, S. tracyi, S. triandra, S. turnorii, S. tweedyi, S. tyrrellii, S. uva-ursi, S. vestita, S. viminalis, S. wolfii, S. ×fragilis, S. ×jesupii, S. ×pendulina, S. ×sepulcralis, S. ×smithiana
S. alaxensis, S. alba, S. amygdaloides, S. arbusculoides, S. arctica, S. arctophila, S. argyrocarpa, S. arizonica, S. athabascensis, S. atrocinerea, S. aurita, S. babylonica, S. ballii, S. barclayi, S. barrattiana, S. bebbiana, S. bonplandiana, S. boothii, S. brachycarpa, S. breweri, S. calcicola, S. candida, S. caprea, S. caroliniana, S. cascadensis, S. chamissonis, S. chlorolepis, S. cinerea, S. columbiana, S. commutata, S. cordata, S. daphnoides, S. delnortensis, S. discolor, S. drummondiana, S. eastwoodiae, S. elaeagnos, S. eriocephala, S. euxina, S. exigua, S. famelica, S. farriae, S. floridana, S. fuscescens, S. geyeriana, S. glauca, S. gooddingii, S. hastata, S. herbacea, S. hookeriana, S. humboldtiana, S. humilis, S. interior, S. irrorata, S. jejuna, S. jepsonii, S. laevigata, S. lasiandra, S. lemmonii, S. ligulifolia, S. lucida, S. lutea, S. maccalliana, S. melanopsis, S. monochroma, S. monticola, S. myricoides, S. myrsinifolia, S. myrtillifolia, S. nigra, S. niphoclada, S. nivalis, S. nummularia, S. orestera, S. ovalifolia, S. pedicellaris, S. pellita, S. pentandra, S. petiolaris, S. petrophila, S. phlebophylla, S. planifolia, S. polaris, S. prolixa, S. pseudomonticola, S. pseudomyrsinites, S. pulchra, S. purpurea, S. pyrifolia, S. raupii, S. reticulata, S. richardsonii, S. rotundifolia, S. scouleriana, S. sericea, S. serissima, S. sessilifolia, S. setchelliana, S. silicicola, S. sitchensis, S. sphenophylla, S. stolonifera, S. taxifolia, S. thurberi, S. tracyi, S. triandra, S. turnorii, S. tweedyi, S. tyrrellii, S. uva-ursi, S. vestita, S. viminalis, S. wolfii, S. ×fragilis, S. ×jesupii, S. ×pendulina, S. ×sepulcralis, S. ×smithiana
Synonyms S. scouleriana var. poikila S. bakeri, S. bigelovii, S. franciscana, S. lasiolepis var. bracelinae, S. lasiolepis var. sandbergii, S. lutea var. nivaria
Name authority Barratt ex Hooker: Fl. Bor.-Amer. 2: 145. (1838) Bentham: Pl. Hartw., 335. (1857)
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