Salix nigra |
Salix glauca |
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black willow |
glaucous willow, gray willow, gray-leaf willow, grey-leaf willow |
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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. |
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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. |
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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. |
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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. |
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Capsules | 3–5 mm. |
4.5–9 mm. |
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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. |
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2n | = 38. |
= 76, 95, 114, 152. |
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Salix nigra |
Salix glauca |
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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 |
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)
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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)
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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.) |
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Key |
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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 | ||||||||||||
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Subordinate taxa | ||||||||||||||
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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