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Salix key for mature vegetative material
See list of 30 species in this subkey-
1a. Leaf blades at least somewhat grayed or whitened on the abaxial surface by hairs or bloom (note: in some species the bloom is very thin)
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2a. Leaf blade margins entire, undulate, or crenate, the teeth (when present) rounded at the apex and often somewhat irregular from leaf to leaf [Figs. 889,896]
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3a. Dwarf, trailing, colonial shrubs not exceeding 0.2 m in height, of alpine habitats exceeding 1000 m elevation
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4a. Leaf blades 0.5–2 (–2.5) cm long, 1.7–3.6 times as long as wide; petioles 2–4 (–6) mm long; winter buds 1–3 (–4) mm long (in part)
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4b. Leaf blades 2–4 cm long, mostly 1.2–2 times as long as wide; petioles mostly 5–12 mm long; winter buds 3–8 mm long
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3b. Upright or low-spreading shrubs or small trees (0.3–) 1–15 m tall, of various habitats
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5a. At least some leaves on a given plant opposite or subopposite
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5b. Leaves alternate throughout
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6a. Fresh leaf blades with revolute margins
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7a. Leaf blades very soon glabrous, with strictly entire margins (in part)
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7b. Leaf blades pubescent on one or both surfaces, though sometimes becoming glabrate in late season, with entire to crenate margins
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8a. Leaf blades 1.5–3 times as long as wide
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9a. Decorticated wood (i.e., with the bark removed) of 1- to 4-year-old branches with many prominent ridges, some longer than 20 mm
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10a. Shrubs 1–2.5 m tall; stipules foliaceous, persistent
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10b. Shrubs or small trees 2–12 m tall; stipules small and caducous to foliaceous and persistent (in part)
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9b. Decorticated wood smooth, with small points, or with a few short ridges generally shorter than 10 mm
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11a. Leaf blades 2.5–8 cm wide, 2–3 times as long as wide, pubescent with only white hairs; stems 8–15 m tall
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11b. Leaf blades 0.3–2.3 (–3.4) cm wide, 2.3–9 times as long as wide, often with some red-brown hairs intermixed with the white hairs; stems 0.3–3 m tall
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12a. Leaf blades 3–10 ×1–2.5 cm, stipulate (at least on later leaves); petioles 3–7 mm long; branchlets 2–5 mm thick; generally upright shrubs 0.3–3 m tall (in part)
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12b. Leaf blades 2–5 ×0.3–1.2 cm, exstipulate; petioles 0.5–3 mm long; branchlets usually 2 mm thick or thinner; decumbent shrubs 0.3–0.7 m tall
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8b. Leaf blades 3–40 times as long as wide
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13a. Leaf blades elongate-linear, 1–8 mm wide, mostly 17–40 times as long as wide
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13b. Leaf blades narrow-lanceolate or narrow-oblong to oblanceolate or obovate, 7–30 mm wide, mostly 3–17 times as long as wide
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14a. Leaf blades 2–5 cm long; dwarf shrubs up to 0.7 m tall; stipules absent
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15a. Unfolding leaves densely sericeous with lustrous white hairs; red-brown hairs absent; alpine shrubs of elevations exceeding 1000 m
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15b. Unfolding leaves pubescent with dull hairs that are bent, curled, and tangled; red-brown hairs frequently present on leaves, winter buds, and/or branchlets; shrubs of dry, well-drained soils of lower elevations (in part)
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14b. Leaf blades 4–17 cm long; shrubs or small trees to 5 m tall; stipules commonly present
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16a. Unfolding leaves pubescent with straight, neatly aligned, and lustrous hairs; stipules usually lacking (sometimes present in S. viminalis and then linear to narrow-lanceolate, mostly more than 7 times as long as wide)
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17a. Branchlets brittle at base, breaking ± cleanly at the junction of yearly growth, becoming glaucous later in season; native plants of north-temperate and boreal shores
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17b. Branchlets flexible at base, tearing when bent to failure, not glaucous; introduced plants more common near civilization
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16b. Unfolding leaves pubescent with bent, curled, and tangled hairs that are gray to white, but not lustrous; stipules usually present, lanceolate to narrow-ovate, mostly less than 7 times as long as wide
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18a. Decorticated wood (i.e., with the bark removed) of 1–4 year old branches with many prominent ridges, some longer than 20 mm (in part)
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18b. Decorticated wood smooth, with small points, or with a few, short ridges generally less than 10 mm in length
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19a. Branchlets pubescent largely with gray or brown villose-tomentose hairs; red-brown hairs sometimes present on leaves, winter buds, and/or branchlets; plants mostly of dry, well-drained soils (in part)
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19b. Branchlets usually pubescent with conspicuous white, yellow-white, or gray-white tomentum; red-brown hairs absent; plants of high-pH fens and swamps
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6b. Fresh leaf blades plane, the margins not rolled under
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20a. Branchlets frequently becoming glaucous later in season; plants of alpine habitats exceeding 1000 m elevation
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20b. Branchlets glabrous to pubescent, but not glaucous; plants of lower elevation
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21a. Winter branchlets red, glabrous, and lustrous; leaf blades glabrous, thin and somewhat translucent, especially in early season, rounded to cordate at the base, persistently fragrant in drying for many years (in part)
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21b. Winter branchlets either pubescent or of color other than red; leaf blades glabrous to pubescent, membranaceous to coriaceous, cuneate at the base (rounded to rarely cordate in S. myricoides), not fragrant in drying
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22a. Leaf blades strictly entire [Fig. 896], very soon glabrous; branchlets glabrous; petioles 2–7 mm long; low shrubs up to 1.5 m, of organic soil wetlands (in part)
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22b. Leaf blades usually with some form of dentition, pubescence, or both; branchlets often pubescent, minimally retaining patches of hairs near the nodes in most species; petioles 3–17 mm long; shrubs or small trees to 5 m, of various habitats
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23a. Leaf blades coriaceous, prominently glaucous on the abaxial surface, tending to be more regularly toothed, the teeth numbering 5–9 per cm; leaves broad-cuneate to rounded or less frequently subcordate at base (in part)
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23b. Leaf blades membranaceous to herbaceous, obscurely to prominently glaucous on the abaxial surface, tending to have fewer coarser, less regular teeth numbering 1–3 (–5) per cm; leaves narrow- to broad-cuneate at the base
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24a. Leaf blades usually impressed-veiny above and rugose-veiny below [Fig. 889]; branchlets persistently pubescent, even on second-year branches; herbage lacking red-brown hairs; winter branchlets and buds red to red-brown
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24b. Leaf blades not notably veiny; branchlets commonly glabrate with small patches of hairs near the nodes, the second-year branches usually glabrous; herbage frequently with red-brown hairs, these often persisting along the midrib on the adaxial surface; winter branchlets brown to yellow-brown; winter buds yellow to yellow-brown or red-brown
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2b. Leaf blade margins denticulate to serrulate, the teeth sharply pointed at the apex and, in most species, ± uniform through the margin [Figs. 893,895]
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25a. Trees to 25 m tall; apex of petiole with one or more dark glands, these often ± paired on opposite sides of the petiole (glands often absent in S. amygdaloides) [Fig. 895]
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26a. Winter buds with a sharply pointed apex, the margins distinct and overlapping; leaf blades somewhat abruptly tapering to a long, thin apex; branchlets flexible at base, tearing when bent to failure
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26b. Winter buds blunt at apex, the margins connate; leaf blades gradually tapering to the apex; branchlets brittle at base, breaking ± cleanly at the junction of yearly growth
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25b. Shrubs to 4 m tall; apex of petiole lacking a pair of dark glands (present in S. serissima) [Fig. 893]
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27a. Winter branchlets red, glabrous, and lustrous; leaves thin and somewhat translucent, especially in early season, persistently balsam-fragrant in drying for many years (in part)
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27b. Winter branchlets usually yellow-brown, red-brown, green-brown, or brown, varying from glabrous to pubescent, dull to sublustrous (lustrous in S. serissima); leaves thick-herbaceous to coriaceous, not fragrant in drying
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28a. Leaves very soon glabrous, lustrous on the adaxial surface; petioles with one or more dark glands, these often ± paired on opposite sides of the petiole; plants restricted to high-pH wetlands
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28b. Leaves and branchlets pubescent when young and often remaining so until at least mid-season (or later); petioles lacking apical glands; plants of various habitats
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29a. Leaf blades cuneate at base, sometimes rounded in forms of S. sericea, with neatly aligned and appressed hairs (i.e., sericeous) at least when young, frequently darkening in drying; stipules absent or up to 4 mm long
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30a. Leaf blades 2.5–7 ×0.3–2 cm, sometimes nearly entire at the base, frequently with red-brown hairs intermixed with the white hairs; branches flexible, not breaking cleanly at the junction of yearly growth, commonly glabrate, sometimes glaucous; stipules usually wanting
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30b. Leaf blades 4–15 ×1–4 cm, serrulate to the base, lacking red-brown hairs; branches brittle at the base and breaking cleanly at the junction of yearly growth, usually puberulent, at least remaining so near the nodes, not glaucous; stipules often present, especially on vigorous shoots
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29b. Leaf blades rounded to cordate at the base (rarely broad-cuneate) [Fig. 893], with short, ascending and curving hairs (i.e., villous) at least when young, not prominently darkening in drying; stipules usually present and longer than 4 mm
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31a. Leaf blades lanceolate to more commonly narrow-ovate, ovate-oval, or obovate, with serrulate to crenate-serrate margins, prominently glaucous on the abaxial surface (in part)
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31b. Leaf blades lanceolate to oblong-lanceolate, with serrulate margins [Fig. 893], green to thinly glaucous on the abaxial surface (in part)
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1b. Leaf blades green beneath, sometimes paler than the adaxial surface but without bloom or dense hairs at maturity
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32a. Tree to 20 m tall; winter bud, sharply pointed at apex, with distinct and overlapping margins
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32b. Dwarf shrubs to small trees to 4 m tall; winter buds blunt, with connate margins
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33a. Leaf blades 0.5–3 cm long; dwarf shrubs to 15 cm tall of alpine habitats exceeding 1000 m elevation
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34a. Leaf blades 1–2.5 cm wide, oval to suborbicular, rounded to retuse at the apex, cordate to truncate at the base; plants commonly found in hydric, mossy areas
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34b. Leaf blades 0.2–1 (–1.7) cm wide, narrow-elliptic to obovate, acute to broad-obtuse at the apex, cuneate at the base; plants commonly found in gravels, cracks of bedrock, and folists (in part)
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33b. Leaf blades (2–) 3.5–17 cm long; shrubs or small trees much taller than 5 cm, primarily of low elevation habitats
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35a. Leaves elliptic to oblanceolate or obovate, usually widest above the middle [Fig. 896], sometimes revolute; low shrubs up to 15 dm tall, of organic soil wetlands (in part)
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35b. Leaves linear to narrow-ovate, widest below the middle, not revolute; shrubs of various sizes and habitats
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36a. Petioles 1–5 mm long; leaves amphistomatous (i.e., stomates present on both surfaces), somewhat remotely toothed, those teeth near the middle of blade margin often further than 3 mm apart
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36b. Petioles (3–) 5–16 mm long; leaves hypostomatous (i.e., stomates lacking on adaxial surface), finely and closely toothed, those teeth near the middle of the blade margin closer than 3 mm
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37a. Apex of petiole lacking dark glands [Fig. 893]; stipules mostly 4–10 mm long; branchlets usually flexible at base and tearing when bent to failure, infrequently brittle at base (in part)
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37b. Apex of petiole with one or more dark glands, these often ± paired on opposite sides of the petiole [Fig. 895]; stipules absent or up to 6 mm long; branchlets brittle at base, breaking ± cleanly at the junction of yearly growth
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38a. Leaf blades 5–17 cm long, frequently with red-brown hairs when unfolding, tapering to a long-acuminate to caudate apex on mature blades [Fig. 895]; stipules usually present, 1–6 mm long
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38b. Leaf blades 3.5–10 cm long, lacking red-brown hairs, tapering to an acuminate apex; stipules wanting
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Each photo represents one species in this subkey.