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black willow

glaucous willow, gray willow, gray-leaf willow, grey-leaf willow

Habit Trees, 5–20+ m. Stems: branches highly brittle at base, red-brown to yellow-brown, glabrous; branchlets gray-brown to red-brown, glabrous or pilose to villous. Plants 0.2–6 m, not clonal.
Stems

erect or decumbent;

branches brownish, yellow-brown, gray-brown, or red-brown, villous or pilose to glabrescent;

branchlets yellow-brown or red-brown, sparsely to densely villous or tomentose to glabrescent.

Leaves

stipules rudimentary or foliaceous on early ones, usually foliaceous on late ones, (glands few or absent adaxially), apex acuminate, acute, or rounded;

petiole (margins covering groove, with spherical glands distally), (2–)3–10(–15) mm, glabrous or pilose adaxially;

largest medial blade (sometimes amphistomatous), very narrowly elliptic, lanceolate to narrowly lanceolate, or linear to lorate, (50–)70–103(–190) × (6–)7.5–17(–23) mm, 6–13 times as long as wide, base cuneate to convex, margins serrulate, apex acuminate, acute, or caudate, abaxial surface (not glaucous), glabrous or pilose, hairs white or ferruginous, wavy, adaxial slightly glossy, glabrous or pilose (especially on midribs);

proximal blade margins serrulate;

juvenile blade glabrous or pilose abaxially, hairs white and/or ferruginous.

stipules (marcescent or not), foliaceous or rudimentary on early and late ones;

petiole (usually deeply to shallowly grooved adaxially), 1–27 mm, (much longer than subtended bud);

largest medial blade usually hypostomatous, sometimes hemiamphistomatous or amphistomatous, usually narrowly elliptic, elliptic, usually oblanceolate or obovate, sometimes narrowly oblong or obovate, 27–82 × 6–39 mm, 1.4–4.8 times as long as wide, base usually cuneate or convex, sometimes rounded, rarely subcordate, margins slightly revolute or flat, usually entire, apex acute, acuminate, convex, or rounded, abaxial surface densely villous or villous-silky, tomentose, short- or long-silky, or pilose, hairs usually wavy or straight, sometimes curved, adaxial usually slightly glossy, sometimes dull, moderately densely villous, pilose, or long-silky to glabrescent;

proximal blade margins entire or serrulate;

juvenile blade sparsely or densely villous, tomentose, or long-silky abaxially.

Staminate flowers

abaxial nectary 0.3–1 mm, adaxial nectary oblong to ovate, 0.2–0.6 mm, nectaries distinct or connate and shallowly cup-shaped;

stamens 4–6;

filaments hairy on proximal 1/2 or basally;

anthers 0.4–0.6 mm, (axes strongly recurved).

abaxial nectary 0.1–1 mm, adaxial nectary narrowly oblong, oblong, square, ovate, or flask-shaped, 0.5–1.3 mm, nectaries distinct, or connate and cup-shaped;

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

anthers 0.4–0.8 mm.

Pistillate flowers

adaxial nectary oblong, (swollen), 0.2–0.5 mm;

stipe 0.5–1.5 mm;

ovary pyriform to obclavate, (rarely pilose), beak slightly bulged below styles;

ovules 12–16 per ovary;

styles 0.1–0.3 mm;

stigmas (sometimes 2 plump lobes), 0.2–0.28–0.36 mm.

abaxial nectary absent, adaxial nectary usually narrowly oblong, oblong, or ovate, sometimes flask-shaped, 0.4–1.8 mm, shorter to longer than stipe;

stipe 0.3–2.8 mm;

ovary pyriform or obclavate, densely villous, tomentose, short-silky, or pubescent, beak usually gradually tapering to styles, sometimes gradually tapering to or slightly bulged below styles;

ovules 6–22 per ovary;

styles connate to distinct 1/2 their lengths or more, 0.3–1.6 mm;

stigmas flat, abaxially non-papillate with rounded tip, or slenderly or broadly cylindrical, 0.2–0.8 mm.

Capsules

3–5 mm.

4.5–9 mm.

Catkins

staminate 35–83 × 7–13 mm, flowering branchlet 5–35 mm; pistillate 23–74(–80 in fruit) × 5–10 mm, flowering branchlet 6–35 mm;

floral bract 1–3 mm, apex acute or rounded, entire, abaxially sparsely hairy, hairs wavy; pistillate bract deciduous after flowering.

staminate 14–53 × 5–17 mm, flowering branchlet 1–25 mm; pistillate densely to sometimes loosely flowered, slender, stout, subglobose, or globose, 15–83 × 7–21 mm, flowering branchlet 2–37 mm;

floral bract tawny, brown, bicolor, or greenish, 1–3.4 mm, apex convex or rounded, entire, abaxially hairy, hairs wavy, crinkled, or straight.

2n

= 38.

= 76, 95, 114, 152.

Salix nigra

Salix glauca

Phenology Flowering (south) early Feb-early May, (north) late Mar-early Jul.
Habitat Floodplains, edges of ponds and lakes, swamps, marshes, white cedar bogs, wet meadows, open fields, roadside ditches, mixed upland deciduous woods along streams
Elevation 10-1400 m (0-4600 ft)
Distribution
from FNA
AL; AR; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; NE; NH; NJ; NY; OH; OK; PA; RI; SC; TN; TX; VA; VT; WI; WV; NB; ON; QC; Mexico (Chihuahua)
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; CO; MT; NM; OR; UT; WA; WY; AB; BC; MB; NS; NT; NU; ON; QC; SK; YT; Eurasia (China [Altay Shan], Chukotka, Mongolia, Novaya Zemlya, Russian Far East, Sakhalin, Scandinavia, arctic, e, w Siberia)
[WildflowerSearch map]
[BONAP county map]
Discussion

Hybrids:

Salix nigra forms natural hybrids with S. alba, S. amygdaloides, S. caroliniana, S. gooddingii, and S. lucida.

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

Varieties 5 (4 in the flora).

Occurrence of Salix glauca is disjunct in western Siberia; var. glauca is known from Scandinavia.

Salix glauca is ubiquitous, highly polymorphic, and polyploid. It appears to have four major variations that are treated in different ways. European floras have treated it as an undivided polymorphic species(A. K. Skvortsov 1999), as several distinct species (K. H. Rechinger 1964b), or as comprising several subspecies (Rechinger 1993; G. W. Argus et al. 1999; B. Jonsell and T. Karlsson 2000+, vol. 1). In North America, Argus (1965) treated the four central tendencies as widely intergrading “phases” of a single species, later adopting varietal rank, whereas E. Hultén (1968) recognized them as subspecies. In view of the fact that the four elements are confluent over wide areas, there may be some merit in recognizing them as informal phases, but varietal rank is used here.

All specimens from Iceland named Salix glauca are S. arctica and those from Svalbard, Norway, are S. lanata Linnaeus.

The major reason for the high variability within Salix glauca seems to be high, and probably recurrent, polyploidy. Tetraploids, pentaploids, hexaploids, and octoploids are known in the species, and two of the subspecies include three ploidal levels. There also are intergrading geographical variations that are the basis for the recognition of infraspecific taxa.

Hybrids:

Salix glauca forms natural hybrids with S. arctica, S. arctophila, S. ballii, S. barclayi, S. boothii, S. brachycarpa, S. eastwoodiae, S. myricoides, S. niphoclada, S. pedicellaris, and S. planifolia.

The following key will help identify the varieties, but there are extensive areas of overlap among them and many intermediates.

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

Key
1. Stipules often marcescent, foliaceous on late leaves, usually prominent, linear, narrowly elliptic, or lanceolate, 2-17 mm; branches red-brown or gray-brown or brownish; branchlets densely villous to glabrescent; proximal blades: margins entire; floral bracts 1.2-2.5 mm; staminate flowering branchlets 1-14 mm; ovaries obclavate or pyriform; Alaska, Canada
→ 2
1. Stipules sometimes marcescent or rudimentary, if foliaceous, usually inconspicuous, oblong, elliptic, or ovate, 1-8(-10) mm; branches usually yellow-brown or red-brown; branchlets usually sparsely villous or tomentose; proximal blades: margins entire or serrulate; floral bracts 1-3.4 mm; staminate flowering branchlets 1.5-25 mm; ovaries pyriform; northern Canada east of Mackenzie River, Greenland, Rocky Mountains
→ 3
2. Shrubs, 0.3-1 m; branchlets densely villous; petioles 1-9 mm; largest medial blades: apex acute, sometimes acuminate, or convex, adaxial surface moderately densely villous, or long-silky to glabrescent; staminate catkins 14-26 mm; filaments distinct or partly connate, glabrous or hairy on proximal 1/2; pistillate catkins stout to subglobose, flowering branchlets 2-19 mm; stipes 0.4-1.8 mm; Alaska, Northwest Territories, w Nunavut, n Yukon.
var. stipulata
2. Shrubs, 0.3-6 m; branchlets soon becoming pilose or glabrescent; petioles 4-27 mm; largest medial blades: apex acuminate to convex, adaxial surface often sparsely long-silky or pilose; staminate catkins 19-45 mm; filaments distinct, glabrous; pistillate catkins slender to stout, flowering branchlets 3-37 mm; stipes 0.5-2.8 mm; c Alaska, British Columbia, Northwest Territories, Yukon.
var. acutifolia
3. Stipules 0.9-2.8-8(-10) mm, sometimes marcescent; floral bracts usually brownish; largest medial blades: petiole 3-14 mm; Alberta, British Columbia, Rocky Mountains, Saskatchewan to New Mexico.
var. villosa
3. Stipules 1-2.1-4 mm, usually deciduous (in autumn); floral bracts usually tawny; largest medial blades: petiole 2-9 mm; c, e Canada, Greenland, St. Pierre and Miquelon.
var. cordifolia
Source FNA vol. 7, p. 36. FNA vol. 7, p. 89.
Parent taxa Salicaceae > Salix > subg. Protitea > sect. Humboldtianae Salicaceae > Salix > subg. Chamaetia > sect. Glaucae
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. 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. 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. 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. glauca var. acutifolia, S. glauca var. cordifolia, S. glauca var. stipulata, S. glauca var. villosa
Synonyms S. nigra var. falcata, S. nigra var. lindheimeri
Name authority Marshall: Arbust. Amer., 139. (1785) Linnaeus: Sp. Pl. 2: 1019. (1753)
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