Salix hookeriana |
Salix ovalifolia |
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coastal willow, dune willow, Hooker's willow |
arctic seashore or oval-leaf willow, oval-leaf willow |
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Habit | Shrubs or trees, (0.6–)2–8 m, (sometimes forming clones by layering or stem fragmentation). | Plants 0.02–0.05 m, not clonal or 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). |
trailing; branches yellow-brown, gray-brown, or red-brown, glabrous or hairy; branchlets yellow-green, yellow-brown, or red-brown, glabrous or pilose. |
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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 usually absent or rudimentary, rarely foliaceous; petiole (deeply to shallowly grooved adaxially), 1.1–16 mm, (glabrous); largest medial blade hypostomatous, narrowly to broadly elliptic, circular, subcircular, or obovate, 13–46 × 7–20 mm, 1–3.4 times as long as wide, base subcordate, cordate, rounded, or convex, margins slightly revolute or flat, entire, sometimes ciliate, apex convex, rounded, acuminate, acute, or retuse, abaxial surface glabrous, villous, long-silky, pubescent, or pilose, hairs wavy or straight, adaxial highly glossy, usually glabrous; proximal blade margins entire; juvenile blade (reddish or yellowish green), pilose, villous, or long-silky abaxially. |
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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. |
abaxial nectary 0.6–1 mm, adaxial nectary oblong or ovate, 0.6–1.6 mm, nectaries distinct or connate and cup-shaped; filaments distinct or connate less than 1/2 their lengths (glabrous); anthers elliptic, short-cylindrical, or globose, 0.3–0.5(–0.6) mm. |
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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. |
abaxial nectary (0–)0.4–0.6 mm, adaxial nectary longer than stipe; stipe 0.2–1.4 mm; ovary obclavate or pyriform, glaucous or not, usually glabrous or tomentose, sometimes pubescent or villous, beak abruptly tapering to styles; ovules 10–15 per ovary; styles 0.2–0.8 mm; stigmas flat, abaxially non-papillate with pointed tip, or slenderly cylindrical, 0.32–0.41–0.64 mm. |
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Capsules | 5–10 mm. |
5.2–9.6 mm. |
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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. |
staminate 4.8–46 × 5–11 mm, flowering branchlet 1.5–24 mm; pistillate moderately densely flowered, stout, subglobose, globose, or slender, 6.3–50 × 5–28 mm, flowering branchlet 2.5–22 mm; floral bract brown, greenish, or bicolor, 1.2–2 mm, apex rounded, entire or, sometimes, 2-fid, abaxially hairy, hairs straight or wavy. |
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2n | = 114. |
= 38. |
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Salix hookeriana |
Salix ovalifolia |
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Phenology | Flowering mid Apr-mid Jun. | |||||||||||||
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 | |||||||||||||
Elevation | 0-1800 m (0-5900 ft) | |||||||||||||
Distribution |
AK; CA; OR; WA; BC
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AK; NT; YT; Asia |
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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.) |
Varieties 4 (4 in the flora). The varieties of Salix ovalifolia are relatively minor variants; their ranges overlap and their differences in leaf shape and ovary indumentum intergrade (G. W. Argus 1969, 1973). The only one with a more or less distinctive geographical distribution is var. cyclophylla; where its range overlaps with var. ovalifolia there is intergradation. Variety arctolitoralis, which is characterized by larger leaves and catkins, may be an ecotype. Variety glacialis is known only from near Point Barrow, Alaska. E. Hultén (1968) suggested, probably based on its often tomentose ovaries, that it is S. arctica × S. ovalifolia. All varieties of the species have some plants with hairy ovaries, but the suggestion that this character is an indication of hybridization deserves study. Hybrids: Salix ovalifolia forms natural hybrids with S. arctica and S. fuscescens. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 7, p. 127. | FNA vol. 7, p. 77. | ||||||||||||
Parent taxa | Salicaceae > Salix > subg. Vetrix > sect. Cinerella | Salicaceae > Salix > subg. Chamaetia > sect. Ovalifoliae | ||||||||||||
Sibling taxa | ||||||||||||||
Subordinate taxa | ||||||||||||||
Synonyms | S. amplifolia, S. hookeriana var. laurifolia, S. hookeriana var. tomentosa, S. piperi | |||||||||||||
Name authority | Barratt ex Hooker: Fl. Bor.-Amer. 2: 145, plate 180. (1838) | Trautvetter: Nouv. Mém. Soc. Imp. Naturalistes Moscou 2: 306, plate 13. (1832) | ||||||||||||
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