Salix pulchra Cham.
Diamond-leaf willow.
Linnaea 6: 543. 1831
Salix phylicifolia subsp. pulchra (Cham.) Hultén
Salix phylicifolia var. subglauca (Anderss.) Boivin
Salix phylicoides Anderss.
Salix planifolia subsp. pulchra (Cham.) Argus
Salix planifolia var. yukonensis (Schneid.) Argus
Salix pulchra var. looffiae Ball
Salix pulchra var. palmeri Ball
Salix pulchra var. yukonensis Schneid.
Plants low shrubs, or mid shrubs, or tall shrubs; more than 15 cm high, or less than 15 cm high; 10–30(–450) cm high; not colonial. Stems. Aerial stems erect. Branches red-brown, or brownish; not glaucous (rarely glaucous); glabrous, or hairy, or glabrescent; villous (in patches); epidermis flaky. Branchlets brownish; not glaucous (rarely glaucous); glabrous, or hairy; villous, or puberulent; hairs sparse, or moderately dense, or very dense; hairs spreading. Bud scale inner membrane free but not separating from outer membrane. Stipules. Stipules present (persist 2–4 yrs); leaf-like; apex acuminate. Petioles. Petioles 2.8–10(–15) mm long; glandular dots at the base of the leaf absent; convex to flat in cross-section; glabrous, or hairy. Petioles adaxial surface puberulent (sparse). Leaves. Juvenile leaves yellowish green; glabrous, or hairy; abaxial surface pubescent; hair sparse; hair white, or gray. Blades (2.2–)3.2–6(–7.5) cm long; (8–)10–23(–26) mm wide; length-width ratio (1.7–)2–3.6(–4.7); herbaceous, or leathery; elliptic (to narrowly elliptic), or obovate; flat, or revolute; secondary veins flat on adaxial surface, protruding on abaxial surface; secondary veins arising along midrib; stomata only on abaxial surface. Blades adaxial surface shiny, or highly glossy; glabrous. Blades abaxial surface glabrous (midrib with wh and ferr hairs); glaucous. Leaf bases acute, or cuneate. Leaf margins entire and glandular-dotted, or crenate; with teeth all around leaf, or toward base only; with teeth per cm 2–5 (3); with submarginal glands, or with marginal glands. Leaf margins with glandular hairs all around leaf, or toward base only. Leaf apices acute, or retuse, or acuminate.
Plants dioecious. Catkins. Catkins flowering before the opening of leaf buds; one to several catkins just below tip of previous year’s shoot, or numerous catkins just below tip of previous year’s shoot. Male catkins. Male catkins densely flowered; 15–45 mm long; 12–19 mm wide; stout; peduncles 0–5 mm long; sessile; flowering branchlets 0 mm long. Female catkins. Female catkins densely flowered; 25–80 mm long; 8–19 mm wide; stout, or subglobose; peduncles 0–8 mm long; sessile (sometimes 2–3 bracts); flowering branchlets 0 mm long. Floral bracts. Floral bracts brown, or black; widest at base; 1.6–2.8 mm long; hairy mainly at apex; hairs moderately dense; hairs straight; entire. Stamens 2; filaments glabrous. Anthers purple becoming yellow; ellipsoid, or stout-cylindrical; axis straight; 0.4–0.8 mm long. Male flowers. Male flowers abaxial nectaries absent; adaxial nectaries one; adaxial nectaries slender-rod, or broad-rod; adaxial nectaries 0.6–0.9 mm long. Female flowers. Female flowers adaxial nectaries absent; unlobed; slender-rod, or broad-rod; 0.4–1.6 mm long; longer than stipes. Stipes 0.2–0.8 mm long. Ovaries pear-shaped; ovary slightly bulged at the base of the style; hairy; ovary hairs long-silky. Ovary hair moderately dense, or sparse; white, or translucent, or mixture of white, or translucent, and rust-coloured; appressed; straight; flattened. Styles 1–1.8 mm long. Stigmas slender-cylindrical; lobes 0.44–0.63–0.96 mm long. Ovules 12–18. Fruit. Fruit 3.2–5.6 mm long; glabrescent.
Chromosome inforamtion. 2n = 76. Johnson & Packer 1968; Suda & Argus 1969. Russia Zhukova 1967, 1968, 1969; Zhukova et al. 1977; Petrovsky & Zhukova 1983b. Ploidy levels recorded 4x.
Distribution. Northern hemisphere: Canada, United States, Eurasia (Russia). Canada: B.C., N.W.T. (Frank.) (old), N.W.T. (Mack.) (old), Yukon, N.W.T. USA: Alaska.
Ecology and habitat. In our area this rare shrub forms low thickets along river, lake, and streams.
Notes. Salix pulchra is a shrubby species with prominent, persistent, linear stipules; the catkins are essentially sessile, the ovaries are glabrous, and the nectaries 2–3 times as long as the stipes.
It is closely related to S. planifolia which differs from it in having smaller, usually ovate or short-linear, non-persistent stipules. It similar to and sometimes difficult to separate from S. richardsonii based on vegetative material. The two overlap on Banks Island. They are easily separated there, however, by ovaries of Salix pulchra silky and those of S. richardsonii glabrous.
This species has been treated as S. planifolia subsp. pulchra (Argus 1973). Subspecies rank was proposed because where the ranges of the two taxa overlap in the Mackenzie Mountains and in northwestern British Columbia they appeared to intergrade. The intergradation, however, does not seem to extend beyond the overlapping populations. This situation is very similar to that found in S. lanata - S. richardsonii - S. calcicola, and S. brachycarpa - S. niphoclada. Trinomial nomenclature, in all of these cases, was used to show the close evolutionary relationship between these taxa. But in-as-much as such nomenclature is cumbersome to use and is therefore often ignored by the non-taxonomist, its information value is minimal. This taken together with the fact that evidence of intergradation, on which the decision to use subspecific rank was based, is often indistinct suggests that it is best to use binomial nomenclature.
This species, along with S. alaxensis and S. richardsonii, are the tallest growing willows in the Arctic Archipelago. In the Masik River valley, southwestern Banks Island, it forms a dominant shrub tundra in association with S. alaxensis and S. richardsonii (Kuc 1970, 1974).
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Illustrations. • Line drawing. Salix pulchra: A. Male catkins are sessile on the branch. B. Male flowers have 2 stamens, a floral bract with long straight hairs, and a single nectary. C. Female catkins are sessile on the branch. D. Female flowers have a villous ovary with a long style, a long hairy floral bract, and a single floral nectary that is longer than the stipe. E. Leaves are typically oblanceolate and have linear, leaf-like stipules. • Arctic Island Distribution.
Cite this publication as: G.W. Argus, C.L. McJannet and M.J. Dallwitz (1999 onwards). ‘Salicaceae of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval.’ Version: 2nd November 2000. http://http://www.mun.ca/biology/delta/arcticf/. Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993, 1995, 2000) should also be cited (see References).
