Salix richardsonii Hook.
Richardson's willow.
Fl. bor-amer. 2: 147. 1838
Salix lanata subsp. richardsonii (Hook.) Skvort.
Salix richardsonii var. mckeandii Polunin
Plants low shrubs, or mid shrubs, or tall shrubs; more than 15 cm high; 30–650 cm high; not colonial. Stems. Aerial stems erect. Branches red-brown, or violet, or yellow-brown; not glaucous; glabrous, or hairy, or glabrescent (patches of hairs); villous; epidermis flaky. Branchlets red-brown, or yellow-brown; not glaucous; hairy; villous, or pilose; hairs sparse, or moderately dense, or very dense; hairs spreading. Bud scale inner membrane free and separating from outer membrane. Stipules. Stipules present; leaf-like; apex acuminate, or acute. Petioles. Petioles 2–27 mm long; glandular dots at the base of the leaf absent, or glandular dots at the base of the leaf present (sometimes); convex to flat in cross-section, or shallowly concave in cross-section; glabrous, or hairy. Petioles adaxial surface villous. Leaves. Juvenile leaves yellowish green; hairy; abaxial surface villous, or pilose (sometimes glabrous); hair sparse; hair white. Blades 23–100 cm long; 10–55 mm wide; length-width ratio 1.2–3.6; herbaceous, or leathery; elliptic (narrowly to broadly elliptic), or obovate; revolute, or flat; secondary veins protruding on adaxial and abaxial surfaces; secondary veins arising along midrib; stomata only on abaxial surface. Blades adaxial surface shiny; glabrous, or hairy, or glabrescent; hairs villous, or pilose; hairs moderately dense, or sparse; hairs white and translucent, or a mixture of white and rust-coloured. Blades abaxial surface glabrous, or hairy, or glabrescent; glaucous; pilose; hairs sparse; hairs white, or translucent, or mixture of white, or translucent, and rust-coloured; hairs spreading; hairs curved. Leaf bases acute, or cuneate, or obtuse (narrowly rounded). Leaf margins entire and glandular-dotted, or serrulate; with teeth all around leaf (rarely only toward base); with teeth per cm 2–13 (6); with submarginal glands. Leaf margins with glandular hairs all around leaf (rarely only towards the base). Leaf apices acute (abruptly), or obtuse.
Plants dioecious. Catkins. Catkins flowering before the opening of leaf buds; one to several catkins just below tip of previous year’s shoot. Male catkins. Male catkins densely flowered; 22–38 mm long; 16–20 mm wide; stout; peduncles 0 mm long; sessile; flowering branchlets 0 mm long. Female catkins. Female catkins densely flowered, or moderately densely flowered; 24–80 mm long; 13–19 mm wide; slender, or stout; peduncles 0–7 mm long; sessile; flowering branchlets 0 mm long. Floral bracts. Floral bracts black, or brown; widest at middle; 2.4–3.2 mm long; hairy all over; hairs moderately dense; hairs straight; entire. Stamens 2; filaments glabrous. Anthers purple becoming yellow; ellipsoid, or stout-cylindrical; axis straight; 0.5–0.8 mm long. Male flowers. Male flowers abaxial nectaries absent; adaxial nectaries one; adaxial nectaries slender-rod; adaxial nectaries 0.5–1.2 mm long. Female flowers. Female flowers adaxial nectaries absent; unlobed; slender-rod; 0.6–1.1 mm long; shorter than stipes (rarely equal). Stipes 0.4–1 mm long. Ovaries pear-shaped; ovary gradually tapering to style; glabrous (rarely sparsely sericeous). Styles 1.6–2.8 mm long. Stigmas slender-cylindrical, or broad-cylindrical; lobes 0.32–0.63–0.86 mm long. Ovules 30–34 (rarely 20–40). Fruit. Fruit 4.5–6.8 mm long; glabrous (rarely sparsely hairy).
Chromosome inforamtion. 2n = 38. Russia, Zhukova 1969, 1980; Zhukova & Petrovsky 1972; Petrovsky & Zhukova 1983b. Ploidy levels recorded 2x.
Distribution. Northern hemisphere: Canada, United States, Eurasia (Russia). Canada: B.C., Man., Yukon, N.W.T., Nunavut. USA: Alaska.
Ecology and habitat. Forming thickets 0.3–1 m tall on calcareous or sometimes igneous substrates. Growing on sand and gravel terraces, silty river beds, drumlin fields, gravel ridges, cliff ledges, and snow beds.
Notes. Salix richardsonii is a shrubby species with persistent, prominent, slender stipules with a long attenuate tip and a broader, inequilateral base; the catkins are sessile or with a few green bracts at the base; the ovaries are glabrous and the nectaries 2–3 times as long as the stipes. It similar to S. pulchra but because the latter species is known in our area only on Banks Island their separation will not often pose a problem. On Banks Island they are easily separated by the hairiness of their ovaries.
This species is often treated as S. lanata subsp. richardsonii (Argus 1973, Skvortsov 1968). Subspecies rank was proposed by Skvortsov because the two taxa apparently intergrade where their ranges overlap in the Ural Mts., Russia (Skvortsov 1968, 1999). The intergradation, however, does not seem to extend beyond the overlapping populations. This situation is very similar to that found in S. planifolia - S. pulchra, 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. I have decided to treat these taxa as distinct species because the area of overlap between in relatively small, and because the use of trinomial nomenclature in taxa with widely separated ranges is unnecessarily cumbersome.
Polunin (1940) described S. richardsonii var. mckeandii as differing from the species in having smaller leaves [1–3 (4) cm long and 0.4–1.3 (1.5) cm wide] and capsules borne on short, hairy stipes. The type, which is in the British Museum, and the specimens he cites (1940: 169) require study. It is treated here as a synonym of S. richardsonii.
This species, along with S. alaxensis and S. pulchra, are the tallest willows in the Arctic Archipelago. Plants up to 8 ft tall have been reported from the south coast of Victoria Island (Holm 1922). In the Masik River valley, southwestern Banks Island, it form a dominant shrub tundra in association with S. alaxensis and S. pulchra (Kuc 1970, 1974).
Hybrids
Salix calcicola × richardsonii. Polunin (1940) described S. richardsonii var. mckeandii and S. calcicola var. nicholsiana which he thought were hybridizing and intergrading on Baffin and Southampton Islands. I have not seen the types of either of these varieties. I have seen some suggestion of hybridization between S. calcicola and S. richardsonii on Southampton Island, but I have not seen clear evidence of hybridization elsewhere. This problem requires field study.
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Illustrations. • Female fruiting plant. Salix richardsonii: female fruiting plant. Capsules have opened releasing seeds surrounded by copious hairs (fluff). Photo taken at Cambridge Bay, Victoria Island, Nunavut, by Laurie Consaul, July 1997. Voucher specimen: Laurie Consaul and Lynn Gillespie 1103, CAN. • Habit. Salix richardsonii: habit. Photo taken at Cambridge Bay, Victoria Island, Nunavut, by Lynn Gillespie, July 1997. Voucher specimen: Laurie Consaul and Lynn Gillespie 1105, CAN. • Habitat. Salix richardsonii: habitat. Photo taken at Cambridge Bay, Victoria Island, Nunavut, by Laurie Consaul, July 1997. Voucher specimen: Laurie Consaul and Lynn Gillespie 1138 & 1139, CAN. • Close-up of female catkin. Salix richardsonii: close-up of female catkin. Catkins are sessile on the branch; there may be two or three small, green bracts (white arrow) at base. The ovaries are glabrous. Some capsules on the right side of the catkin have opened to release seeds surrounded by hairs (fluff). Photo taken at Cambridge Bay, Victoria Island, Nunavut, by Laurie Consaul, July 1997. Voucher specimen: Laurie Consaul and Lynn Gillespie 1103, CAN. • Female catkin and vegetative shoot. Salix richardsonii: female catkin and a short vegetative shoot. Photo taken at Cambridge Bay, Victoria Island, Nunavut, by Lynn Gillespie, July 1997. Voucher specimen: Laurie Consaul and Lynn Gillespie 1105, CAN. • 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).
