Flora of the Canadian Arctic Archipelago
Brassicaceae (Cruciferae), Draba family.
Published in Fl. Bor.-Amer. 1: 51. 1830.
Type: Described from Canada: Mackenzie River, lat. 68°.
Vegetative morphology. Plants 3–12 cm high; perennial herbs; caespitose. Taproot present. Ground level or underground stems horizontal; elongate. Horizontal stems at ground level, branching extensively to shape plant habit as mats (moss-campion-like). Caudex present. Aerial stems erect. Leaves mainly basal; alternate; marcescent. Petioles absent. Leaf blades simple. Leaf blade bases truncate, or attenuate. Leaves not grass-like. Blades 4–9 mm long, 0.7–1 mm wide, appressed to the stem or spreading, linear or oblanceolate (narrowly), appearing single-veined or with inconspicuous veins. Blade adaxial surface hairy, hairs woolly, hairs stellate, hairs moderately dense or dense (in the upper part of the leaf), hairs white, or translucent. Blade abaxial surface hairy, hairs woolly, hairs moderately dense or very dense, hairs white, hairs straight or irregularly branched, hairs appressed or spreading. Blade margins entire, with non-glandular hairs (especially at the apex); apices acute.
Reproductive morphology. Flowering stems two or more per plant; without leaves. Inflorescences racemose; diffuse (more so in fruit); elongating as the fruit matures. Pedicels glabrous, or with non-glandular hairs (sparse). Flowers per inflorescence 5–12(–15); small; radially symmetrical (actinomorphic). Sepals conventional; 4; free; 1–1.5 mm long; 1.5–2.5 mm wide; green. Calyx glabrous. Petals conventional; free; 4; yellow (a pale creamy yellow); ovate (on a short stalk); unlobed; 3–4(–5) mm long; 2.5–2.8 mm wide. Stamens 6; stamen filaments markedly unequal in length; stamen filaments glabrous. Anthers yellow; sub-globose; 0.6–0.8 mm long. Ovary superior; carpels 2; syncarpous. Ovaries ovate; hairy; pubescent. Ovary hairs white; appressed; straight (unbranched). Styles 1; thick and short; 0.7–1 mm long; straight. Stigmas per ovary 1. Placentation parietal. Ovules per ovary 10–16(–20). Fruit stalked; stalk (2.5–)3–10(–20) mm long; dry; a silique; spherical, or ovoid; yellowish; 3.5–6(–7) mm long; (2–)2.5–3 mm wide; glabrous; distinctly flattened; dehiscent; shedding the outer walls to expose a thin inner wall, with the seeds attached at the margins on either side. Styles persisting in fruit 0.5–1 mm long. Seeds 10–16(–20); 1.2–1.4 mm long; brown (rusty red); surfaces smooth (at 10×), verrucose (at 40×).
Chromosome information. 2n = 32, or 64.
2n (4x) = 32. Chinnappa and Chmielewski (1987, western North America);
2n (8x) = 64. Rollins (1966, 2n = about 60); Mulligan (1972, Yukon); Mulligan (2003).
Ploidy levels recorded 4x/6x.
Ecology and habitat. Substrates: slopes, ridges, barrens; dry; gravel, sand (shale). Gravel terraces, sandy and shale bluffs, ancient beach ridges.
North American distribution. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories. Range in the Canadian Arctic Archipelago limited. Rare. Arctic islands: Victoria (found at one site on Victoria Island, Wollaston Peninsula, Falaize Bay, about 15 km inland, quite far from its nearest known sites in the Yukon).
Northern hemisphere distribution. Cordilleran. Central Canada.
General notes. A Cordilleran species, which is a misfit in Tolmatchew's ser. Alpinae. Included in Petrovsky's draft, but at that time not known from the Arctic. Recently found in northwestern Canada (Victoria Island).
Illustrations. • Close-up of fruiting plant. Plant growing in a dry, calcareous rock crevice. Note the build-up of marcescent leaves, the cespitose growth, the linear leaves, and the leafless stem. The siliques are ovate and 2–5 mm long. The pedicels are up to twice the length of the siliques. Note the conspicuous style on some siliques. Alberta, Sulphur Mountain. 2000. No voucher. • 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..