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

coastal willow, dune willow, Hooker's willow

Tyrrell's willow

Habit Shrubs or trees, (0.6–)2–8 m, (sometimes forming clones by layering or stem fragmentation). Shrubs, 0.6–3.5 m, (sometimes forming clones by layering).
Stems

branches (highly brittle at base), yellow-brown, gray-brown, red-brown, or violet, not or weakly glaucous, glabrous, tomentose, woolly, or sparsely villous to glabrescent (nodes hairy);

branchlets gray-brown, red-brown, or yellow-brown (sometimes color obscured by hairs), glabrous, pilose, moderately densely villous, tomentose, or woolly, scale with inner membranaceous layer free, (not separating from outer layer).

branches and branchlets red-brown, not to strongly glaucous, glabrous, (buds caprea-type or intermediate).

Leaves

stipules rudimentary or absent on early ones, foliaceous (early deciduous) or rudimentary (sometimes obscured) on late ones, (2.5–7.8–18 mm), apex acuminate, acute, or rounded;

petiole convex to flat, or shallowly grooved adaxially, 4–29 mm, villous, woolly, pilose, or tomentose adaxially;

largest medial blade (sometimes hemiamphistomatous), narrowly to broadly elliptic, oblanceolate, or obovate to broadly obovate, 36–123 × 18–63 mm, 1.5–4.2 times as long as wide, base convex, rounded, subcordate, cordate, or cuneate, margins slightly revolute, crenate, serrate, shallowly serrulate, sinuate, or entire, apex acuminate, acute, or convex, abaxial surface glaucous, pilose, moderately densely tomentose, villous, or woolly, midrib hairy, hairs (white, sometimes also ferruginous), wavy or straight, adaxial highly or slightly glossy, glabrous, pilose, villous, or moderately densely tomentose, midrib and veins hairy (hairs white, sometimes also ferruginous);

proximal blade margins entire or shallowly serrulate;

juvenile blade yellowish, reddish green (sometimes obscured by hairs), pilose or sparsely to densely long-silky, tomentose, woolly, or villous abaxially, hairs white, sometimes also ferruginous, or yellowish.

stipules rudimentary or foliaceous (often brownish) on early ones, foliaceous or rudimentary on late ones, (ca. 4 mm), apex acute;

petiole convex to flat, or shallowly grooved adaxially, 1–3.4–16 mm, glabrous, pilose, or short-silky adaxially;

largest medial blade (amphistomatous), narrowly elliptic, elliptic, oblanceolate, or obovate, 15–29–65 × 3.5–8.8–18 mm, 2.3–3.3–4.4 times as long as wide, base cuneate or convex, margins strongly to slightly revolute, entire, or very shallowly serrulate or shallowly serrulate-crenulate, apex acute, acuminate, or convex, abaxial surface glaucous, sparsely long-silky to glabrescent, hairs (ferruginous), straight, adaxial highly glossy, glabrous or sparsely short-silky (hairs white, sometimes also ferruginous);

proximal blade margins entire;

juvenile blade yellowish green or sometimes reddish, sparsely long-silky abaxially, hairs white and ferruginous.

Staminate flowers

adaxial nectary oblong, ovate, or narrowly oblong, 0.5–1.4 mm;

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

anthers yellow, cylindrical or ellipsoid, (0.5–)0.7–1 mm.

adaxial nectary oblong, 0.8–1.1 mm;

filaments distinct, glabrous or hairy basally;

anthers purple turning yellow, ellipsoid, 0.4–0.7 mm.

Pistillate flowers

adaxial nectary narrowly oblong, oblong, or square, 0.5–1.4 mm, shorter than stipe;

stipe 0.5–1.8(–2.8) mm;

ovary obclavate or pyriform, glabrous, tomentose, villous, or woolly (hairs wavy), beak sometimes abruptly tapering to styles;

ovules 12–20 per ovary;

styles 0.6–2.3 mm;

stigmas broadly to slenderly cylindrical, 0.3–0.8 mm.

adaxial nectary oblong or flask-shaped, 0.6–1.1 mm, equal to or shorter than stipe;

stipe 0.2–1 mm (–1.4 mm in cultivation);

ovary pyriform, long-silky, beak gradually tapering to styles;

ovules 12–16 per ovary;

styles 0.6–1.2 mm;

stigmas flat, abaxially non-papillate with rounded tip, or slenderly cylindrical, 0.44–0.55–0.75 mm.

Capsules

5–10 mm.

3.6–5 mm.

Catkins

flowering before or as leaves emerge; staminate slender or stout, 26–73 × 10–27 mm, flowering branchlet 0–10 mm; pistillate densely flowered, slender or stout, 36–92(–140 in fruit) × 10–25 mm, flowering branchlet 0–20 mm;

floral bract brown, black, or bicolor, 1.1–3.6 mm, apex convex, rounded, or acute, abaxially hairy, hairs straight or wavy.

flowering before leaves emerge; staminate stout, 14–35 × 12–16 mm, flowering branchlet 0 mm; pistillate densely flowered, stout, 17–51 × 10–13–22 mm, flowering branchlet 0–4 mm;

floral bract brown, black, or bicolor, 1–3.7 mm, apex acute to acuminate or rounded, abaxially hairy, hairs long, straight.

2n

= 114.

Salix hookeriana

Salix tyrrellii

Phenology Flowering mid Apr-mid Jun. Flowering mid Jun-mid Jul.
Habitat Marine coastal beaches and sand dunes, interdunal depressions, coastal marshes, pine barrens, floodplains, ravines, wet sedge meadows, lakeshores, morainal flats, sandy or gravelly substrates Active sand dunes, shrubby tundra
Elevation 0-1800 m (0-5900 ft) 200-600 m (700-2000 ft)
Distribution
from FNA
AK; CA; OR; WA; BC
[WildflowerSearch map]
[BONAP county map]
from FNA
AB; NT; NU; SK
[BONAP county map]
Discussion

Salix hookeriana is primarily a coastal species occurring from northern California northward to Oregon, Washington, and southern Vancouver Island, with disjunct populations on Queen Charlotte Islands, British Columbia, and northward to Yakatut Bay, Turnagain Arm, and Kodiak, Alaska. It was treated by G. W. Argus (1973) and R. D. Dorn (2000) in a broad sense because of an absence of strong distinguishing characters and intergradation in characters that could be used to divide it. It is highly variable and three very similar taxa have been named: S. amplifolia, S. hookeriana (including vars. tomentosa and laurifolia), and S. piperi. Although extremes of these taxa sometimes are recognizable, the intergradation displayed is so great that even attempts to recognize them as varieties are thwarted. The amplifolia variant in Alaska is characterized by having only white leaf hairs, hairy ovaries, no stipules, and catkins often borne on distinct flowering branchlets, but variation can occur within the same population, and typical S. hookeriana on Vancouver Island sometimes displays the same characteristics. The piperi variant, an inland population in western Oregon and Washington, is usually recognized by local botanists as different from coastal populations. It is characterized by leaves and branchlets soon becoming glabrate and stipules prominent. These characteristics, however, sometimes appear in northern California coastal populations, and some inland populations in Oregon include very hairy individuals that are indistinguishable from coastal variants of S. hookeriana. In general, very hairy populations of S. hookeriana are probably an adaptation to marine coastal environments, but some variation may be due to hybridization and introgression with S. scouleriana. Inland populations suggest the influence of S. lasiolepis. Two hexaploid chromosome numbers reported for S. hookeriana from Vancouver Island (R. L. Taylor and S. Taylor 1977) and Queen Charlotte Islands (R. L. Taylor and G. A. Mulligan 1968), British Columbia, indicate that hybridization has played a role in the evolution of this complex. It is possible that each variant of S. hookeriana has had a different, possibly even recurrent, polyploid origin. Further cytological and genetic study is indicated.

The following comparisons may help to distinguish Salix hookeriana, S. lasiolepis, and S. scouleriana.

Vegetative specimens of Salix hookeriana can be distinguished from S. lasiolepis by having floral buds ellipsoid, beaks distinctly long-tapered, densely long-hairy (villous), red-brown, blades usually pilose, villous, or woolly on abaxial surfaces, usually 18–63 mm wide, and 1.5–4.2 times as long as wide; S. lasiolepis has floral buds ovoid, beaks inconspicuous and blunt, sparsely to moderately densely short-hairy (velvety), yellowish to red-brown, blades usually tomentose on abaxial surfaces, usually 6–32 mm wide, and 3.2–9.6 times as long as wide.

Salix hookeriana is distinguished from S. scouleriana by having branchlets with spreading hairs (woolly or tomentose to glabrate), petioles usually pilose to tomentose, blades typically narrowly elliptic but variable, stigmas 0.3–0.74, short in relation to styles (0.6–2.3 mm), and pistillate nectaries 0.5–1.4 mm, shorter or longer than stipes; S. scouleriana has branchlets usually with short, erect hairs (velutinous), sometimes spreading (villous or tomentose), petioles velvety or villous adaxially, blades typically oblanceolate but variable, stigmas 0.4–1.04 mm, long in relation to styles (0.2–0.6 mm), and pistillate nectaries 0.2–0.8 mm, shorter than stipes.

Hybrids:

Salix hookeriana forms natural hybrids with S. barclayi and S. scouleriana. Variation in some S. hookeriana populations suggests hybridization with S. lasiolepis but no positive identifications have been made. R. D. Dorn (2000) doubted that hybridization in California between these species with different chromosome numbers was possible, but species with different chromosome numbers do hybridize [for example, S. athabascensis (4x) × S. pedicellaris (2x)]; synthetic hybridization studies are indicated.

Salix hookeriana × S. scouleriana: Plants from southern British Columbia with leaves similar to S. hookeriana but with prominent stipules, catkins both erect and recurving, and relatively long stigmas were thought by J. K. Henry (1915) to be this hybrid.

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

Salix tyrrellii, first described from Lake Athabasca sand dunes in northwestern Saskatchewan and adjacent Alberta, is characterized by slender, amphistomatous leaves and relatively long, slender branchlets (G. W. Argus and J. W. Steele 1979). It probably evolved, in the past 10,000 years, from the widespread boreal S. planifolia. Originally, it was thought to be endemic to Lake Athabasca but recent collections from Nunavut and the Northwest Territories suggest that it may have a much wider range. Plants from Nunavut and the Northwest Territories do not have the long, slender branchlets found in sand dune populations, and identification is primarily based on the presence of amphistomatous leaves. This character, however, may be unreliable. For example, S. planifolia from 2610 m in the Glass Mountains, California, have amphistomatous leaves, suggesting that this character may be under environmental influence. The appropriate rank for this taxon remains uncertain.

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

Source FNA vol. 7, p. 127. FNA vol. 7, p. 140.
Parent taxa Salicaceae > Salix > subg. Vetrix > sect. Cinerella Salicaceae > Salix > subg. Vetrix > sect. Phylicifoliae
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. 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
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. 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. uva-ursi, S. vestita, S. viminalis, S. wolfii, S. ×fragilis, S. ×jesupii, S. ×pendulina, S. ×sepulcralis, S. ×smithiana
Synonyms S. amplifolia, S. hookeriana var. laurifolia, S. hookeriana var. tomentosa, S. piperi S. planifolia subsp. tyrrellii
Name authority Barratt ex Hooker: Fl. Bor.-Amer. 2: 145, plate 180. (1838) Raup: J. Arnold Arbor. 17: 231, plate 192. (1936)
Web links