The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

Humboldt's willow

Alaska willow, felt-leaf willow

Habit Shrubs or trees, 1–7 m. Stems: branches yellow-brown or red-brown, not glaucous, glabrous or villous; branchlets gray-brown or red-brown, glabrescent or villous.
Leaves

stipules (sometimes marcescent), foliaceous, (3–23 mm), apex acuminate to acute;

petiole convex to flat, or shallowly grooved adaxially, 3–20 mm, tomentose adaxially, (strongly ventricose around floral buds);

largest medial blade broadly oblong, narrowly oblong, narrowly elliptic to elliptic, narrowly oblanceolate, oblanceolate, obovate, or broadly obovate, 50–110 × 13–35 mm, 2–4 times as long as wide, base cuneate or convex, margins strongly revolute, entire or crenate, apex acuminate, acute, or convex, abaxial surface glaucous or not (usually obscured by hairs, midrib yellowish), densely tomentose or villous-tomentose, hairs wavy, adaxial dull, sparsely or moderately densely villous (floccose) to glabrescent, (hairs white or gray);

proximal blade margins entire;

juvenile blade reddish or yellowish green (color often obscured by hairs), very densely woolly-tomentose abaxially, hairs white.

Staminate flowers

adaxial nectary narrowly oblong to oblong, 0.5–1.4 mm;

filaments distinct;

anthers purple turning yellow, long-cylindrical, 0.6–0.9 mm.

Pistillate flowers

adaxial nectary narrowly oblong, 0.6–1.6 mm;

stipe 0–0.4 mm;

ovary pyriform, (hairs refractive, wavy), beak gradually tapering to styles;

ovules 14–18 per ovary;

styles 1.3–2.8 mm;

stigmas 0.4–0.99–1.28 mm.

Capsules

4–5 mm.

Salix

humboldtiana Willdenow: Humboldt willow is not known to occur in the flora area.

It

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.

Catkins

flowering before leaves emerge;

staminate stout, 23–55 × 13–27 mm, flowering branchlet 0–6 mm;

pistillate densely flowered, slender to stout, 33–103 × 8–22 mm, flowering branchlet 0–13 mm;

floral bract brown or black, 1.5–2–2.5 mm, apex acute to convex, abaxially sparsely hairy, hairs straight.

Salix humboldtiana

Salix alaxensis

Distribution
from USDA
Mexico to central Chile
[BONAP county map]
from FNA
AK; AB; BC; MB; NT; NU; QC; YT; Asia (n, e Siberia)
[WildflowerSearch map]
[BONAP county map]
Discussion

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.)

Varieties 2 (2 in the flora).

Salix alaxensis is often used in northern regions for revegetation of disturbed sites and for wildlife habitat restoration (R. A. Densmore et al. 1987).

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

Key
1. Branchlets not noticeably glaucous, very densely villous; largest medial blades: midrib evident, moderately densely tomentose to sparsely pubescent, abaxial surface not noticeably glaucous.
var. alaxensis
1. Branchlets strongly glaucous, glabrescent or sparsely villous; largest medial blades: midrib prominent, sparsely pubescent to glabrescent, abaxial surface noticeably glaucous or not.
var. longistylis
Source FNA vol. 7, p. 34. FNA vol. 7, p. 146.
Parent taxa Salicaceae > Salix > subg. Protitea > sect. Humboldtianae Salicaceae > Salix > subg. Vetrix > sect. Villosae
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. 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. 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
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. 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
Subordinate taxa
S. alaxensis var. alaxensis, S. alaxensis var. longistylis
Synonyms S. speciosa var. alaxensis
Name authority Willdenow (Andersson) Coville: Proc. Wash. Acad. Sci. 2: 280. (1900)
Web links