Flora of the Canadian Arctic Archipelago

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S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, L.J. Gillespie, A.K. Brysting, H. Solstad, and J.G. Harris

Salix planifolia Pursh

English: Tea-leaf willow, flat leaf willow,

French: Saule saule à feuilles planes,

Inuktitut: Uqaujaq (Nunavik).

Salicaceae, Willow family.

Published in Fl. Lam. Sept. 2: 611. 1814.

Synonymy. Salix phylicifolia L. subsp. planifolia (Pursh) Hiitonen, Mem. Soc. Faun Fl. Fenn. 25:82. 1950.

Vegetative morphology. Plants 150–900 cm high; shrubs; low shrubs, or mid shrubs, or tall shrubs; not colonial, or forming colonies by layering. Aerial stems erect, or decumbent. Branches yellow-brown, or red-brown, or violet, or brownish (dark); not glaucous, or weakly glaucous, or strongly glaucous; glabrous, or glabrescent, or hairy (pubescent). Branchlets yellow-brown, or red-brown, or violet, or brownish (dark); not glaucous (rarely weakly glaucous); glabrous, or hairy, or glabrescent; pubescent, or pilose, or villous, or with short-silky hairs. Branchlet hairs sparse, or moderately dense (rarely very dense); appressed, or spreading. Buds caprea-type. Leaves distributed along the stems; alternate; dying annually and non-persistent, or marcescent. Stipules present; on first leaves rudimentary, or foliaceous; on leaves formed later in the season rudimentary, or foliaceous; early deciduous, or deciduous in autumn, or persisting for 2 or more years; brown, or green; apex acute. Petioles 2–5–13 mm long; shallowly concave in cross section; glabrous, or hairy; pilose, or short-silky. Juvenile leaves reddish, or yellowish green; glabrous, or hairy; abaxial surfaces puberulent, or pubescent, or hairs long-silky; abaxial hairs sparse, or moderately dense, or very dense; abaxial hairs white (or white and rust-coloured). Leaf blade bases cuneate, or obtuse (slightly decurrent). Blades 20–36–65 mm long, length-width ratio 1.7–2.8–4.7, 5–12–22 mm wide, oblong (narrowly) or elliptic (to narrowly elliptic) or oblanceolate. Blade adaxial surface highly glossy, glabrous or hairy or glabrescent, hairs short-silky, hairs sparse, hairs white, or translucent. Blade abaxial surface glaucous, glabrous or hairy or glabrescent, hairs short-silky or long-silky, hairs sparse, hairs white or a mixture of white and rust-coloured or rust-coloured, hairs straight or wavy, hairs appressed. Blade margins slightly revolute or flat. Blade margins entire and glandular-dotted (or not glandular-dotted) or serrulate or crenate, with 2–8 glands per cm (4), with teeth toward the base or all around the blade; apices acuminate, or acute, or obtuse.

Reproductive morphology. Plants dioecious. Inflorescences catkins. Pedicels absent. Catkins flowering before leaves emerge. Male catkins 12–41 mm long; 10–12 mm wide; stout, or sub-globose, or globose; peduncles 0–3 mm long; sessile, or borne on a flowering branchlet; flowering branchlets 0–4 mm long. Female catkins 16–67 mm long; 8–18 mm wide; slender, or stout, or sub-globose, or globose; peduncles 1–8 mm long; sessile, or borne on a flowering branchlet; flowering branchlets 0–6 mm long. Floral bracts brown, or black; 1–3.2 mm long; hairy all over; hairs moderately dense, or very dense; hairs straight; apices acute, or convex, or rounded; apices entire, or bifid. Flowers unisexual. Sepals absent. Petals absent. Stamens 2; stamen filaments glabrous, or hairy at base only (sparsely so). Anthers purple becoming yellow; short-cylindrical; 0.5–0.7 mm long. Male flowers abaxial nectaries absent. Male flowers adaxial nectaries narrowly oblong, or oblong; 0.4–1.1 mm long. Female flowers abaxial nectaries absent. Female flowers adaxial nectaries oblong, or square, or ovate (tapering to slender tip); 0.4–1.3 mm long; shorter than stipes, or equal to stipes, or longer than stipes. Ovary carpels 2. Stipes 0.3–0.8 mm long. Ovaries pear-shaped; slightly bulged below style, or gradually tapering to style; hairy; short-silky, or long-silky. Ovary hairs moderately dense, or very dense; white, or white and rust-coloured; appressed, or spreading; straight; flattened. Styles 0.5–2 mm long. Stigma lobes 0.36–0.52–1.1 mm long. Ovules per ovary 10–16. Fruit a capsule; (2.5–)5.5–6 mm long; hairy.

Chromosome information. 2n = 57 and 76.

2n (3x) = 57. Suda and Argus (1968, 1969, North America);

2n (4x) = 76. Löve and Löve (1964); Löve and Löve (1966b, Mt. Washington, USA; 1982a, Churchill, Manitoba); Suda and Argus (1968, North America); Löve et al. (1971, western North America, as the alpine var. monica); Dorn (1975, North America).

Ploidy levels recorded 3x and 4x.

Ecology and habitat. A rare, but conspicuous, shrub, 0.6–4 m tall (Polunin 1940), of sheltered stream valleys and snowbeds.

North American distribution. Alaska (?), Yukon, continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador. Arctic islands: Baffin.

Northern hemisphere distribution. North American. Central Canada, Labrador – Hudson Bay.

General notes. Salix planifolia is a low shrubby species that has small, usually ovate, non-persistent stipules. The catkins are sessile, the ovaries are glabrous, and the nectaries 0–3 times as long as the stipes. It is closely related to Salix pulchra which differs from it in having prominent, linear, persistent stipules. This species has been treated as S. planifolia subsp. planifolia (Argus 1973). Subspecies rank was proposed because this taxon and S. pulchra appeared to intergrade where their ranges overlap in the Mackenzie Mountains and in northwestern British Columbia. The intergradation, however, does not seem to extend beyond the overlapping populations. This situation is very similar to that described for 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 inasmuch as such nomenclature is cumbersome to use and is therefore often ignored by the non-taxonomist, its information value is minimal. In addition, since the evidence of intergradation is indistinct, it appears more appropriate to use binomial nomenclature.

In Alaska, Salix planifolia was found to be an early coloniser of oil spills (Kershaw and Kershaw 1986).

Salix planifolia can be separated from the European S. phylicifolia by the following characters: branches and branchlets (twigs) often densely villous; juvenile and mature leaf blades and petioles often hairy with white and rust-coloured hairs; stipules usually present; and stipes (pedicels) usually shorter (0.3–0.8 versus 0.8–2 mm long). Salix pulchra differs from S. planifolia in its prominent, linear to lanceolate stipules (often persistent for 2 or more years), which generally equal or exceed the petioles, and in its juvenile leaves that are usually glabrous or sparsely pubescent. Salix phylicifolia differs from the other two species by having catkins that are usually borne on longer peduncles (3–6(-20) mm long versus 0–2.5(-5) mm). There also seems to be a difference in chromosome number. Salix phylicifolia usually has 2n = 114, although 2n = 38 has been reported, whereas S. pulchra and S. planifolia have 2n = 76. Where S. planifolia and S. pulchra overlap in the Mackenzie River basin (NWT and Yukon Territory), there is some evidence of hybridisation but species distinctions are not compromised.

In summary, our reasons for treating them as species are that they seem to be separated by a number of characters such that the area of overlap between them is small and that intergradation between them is limited even where they overlap (Argus and Elven 2000, in Elven et al. 2003).

Illustrations. • Willow "forest" from distance. Willow "forest" with trees over 3 m high. Baffin Island, Soper River Valley, Willow Creek tributary. Aiken and Iles 02–051. CAN. • Plant drawing. a. Vegetative branch. The swollen buds in the leaf axils are flower buds that will open the next spring. Scale bar = 1 cm. b. Female catkin. The catkin is sessile, lacking a flowering branchlet. Scale bar = 1 mm. c. Male flower. Scale bar = 1 mm. d. Base of male flower with the floral bract removed to show the adaxial nectary. Scale bar = 1 mm. e. Female flower. Scale bar = 1 mm. Coville 1901. • Arctic Island Distribution.


This publication is available on the internet (posted May 2011) and on CD-ROM (published in 2007). These versions are identical in content, except that the errata page for CD-ROM is accessible on the main index page of the web version.

Recommended citation for the web-based version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. NRC Research Press, National Research Council of Canada, Ottawa. http://nature.ca/aaflora/data, accessed on DATE.

Recommended citation for the CD-ROM version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. [CD-ROM] NRC Research Press, National Research Council of Canada, Ottawa.

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