Flora of the Canadian Arctic Archipelago
Brassicaceae (Cruciferae), Draba family.
Published in Meddel. Grønl. 64: 176. 1923.
Type: Greenland: Gunnar Andersson Valley (82°28'N), 11.07.1917, leg. Th.Wulff. Holotype: C.
Synonymy. Braya purpurascens (R. Br.) Bunge subsp. thorild-wulffii (Ostenf.) Hultén, Kongl. Sv. Vetensk.-Akad. Handl. 13, 1: 1. 1971.
Braya pilosa Hooker subsp. thorild-wulffii (Ostenf.) V.V. Petrovsky, in Tolm., Fl. Arct. URSS 7: 52. 1975.
Braya purpurascens (R. Br.) Bunge var. thorild-wulffii (Ostenf.) B. Boivin, Le Natur. Canadien 94: 646. 1967.
Vegetative morphology. Plants (3–)5–9(–14) cm high; perennial herbs; caespitose. Taproot present. Ground level or underground stems vertical. Caudex present (simple or branching). Aerial stems a small transition zone between taproot and basal leaves, or branching from a tap at or near ground level into two or more branches; decumbent, or prostrate, or ascending (occasionally, often bent or wavy). Aerial stem trichomes spreading, or erect. Leaves mainly basal, or basal in a rosette; erect; alternate; dying annually and non-persistent and marcescent (slightly). Petioles absent. Leaf blades simple. Leaf blade bases attenuate (but broadly expanded at the point of attachment). Leaves not grass-like. Blades (5–)10–30(–40) mm long, 1–4 mm wide, appressed to the stem or spreading, oblanceolate (linear spatulate), appearing single-veined or with inconspicuous veins. Blade adaxial surface dull, without sessile glands, glabrous (on the surface) or hairy (often with a tuft of hairs on the margin at the apex), hairs white, or translucent. Blade abaxial surface glabrous. Blade margins entire, with non-glandular hairs (that are long and mostly simple, often with a tuft of hairs at the apex); blade apices rounded.
Reproductive morphology. Flowering stems conspicuously taller than the leaves (usually), or shorter than the leaves (when stems are prostrate); without leaves (usually), or with leaves (rarely, and then only a single leaf near the inflorescence). Flowering stems hairy. Flowering stems woolly. Flowering stem hairs simple (mainly); white or translucent. Inflorescences head-like (in flower), or racemose, or head-like (in fruit); dense (in flower), or diffuse (in fruit); elongating as the fruit matures. Pedicels present; with non-glandular hairs. Flowers per inflorescence 3–6(–9); small. Sepals conventional; 4; free; 1–2 mm long (obtuse, pilose or glabrous); 2–3.5 mm wide; purple, or green. Calyx hairy. Calyx hairs woolly; white or translucent. Calyx margins ciliate (sometimes, as a tuft of hairs at the tip). Petals conventional; free; same length as the calyx, or longer than the calyx; 4; white, or pink, or purple (rose-purple tinged, especially towards the base); without contrasting markings; obovate (tapering gradually from the base to the apex); unlobed; 2–3.7 mm long; 1–1.5 mm wide. Stamens 6; stamen filaments markedly unequal in length; stamen filaments glabrous. Anthers yellow; ovoid; 0.4–0.6 mm long. Ovary superior; carpels 2; syncarpous. Ovaries ovate; hairy; woolly. Ovary hairs white; appressed; wavy, or branched (bifid). Styles present (sometimes only just); 1; completely fused; thick and short; 0–0.75(–1) mm long. Stigmas per ovary 1 (sometimes broadly bilobed). Placentation parietal. Ovules per ovary 12–26. Fruit stalked; stalk (1–)2.5–4 mm long; dry; a silique; ovoid; green at maturity, or purple (grey from dense hairs); (4–)5–8(–10) mm long; (2.5–)3–5 mm wide; hairy (densely pubescent with simple or branched hairs); surface appearing veinless; 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 0.75–1 mm long. Seeds (12–)18–26; (1.1–)1.2–1.4(–1.5) mm long; brown, or yellowish; surfaces smooth.
Chromosome information. 2n = 28.
2n (4x) = 28. Holmen (1952, Greenland); Jakobsen in Jørgensen et al. (1956, Greenland); Mulligan (1965a, Canada?); Böcher (1966a, Greenland); Mulligan (2003, 4 counts).
Ploidy levels recorded 4x.
Ecology and habitat. Substrates: river terraces, slopes, cliffs; imperfectly drained moist areas, dry, moderately well-drained areas; gravel, sand, clay, till; with low organic content; acidic, or calcareous. Grows on dry substrates, often on south-facing slopes; on well-drained drumlin crests (CAN 522694); colonising species on well to moderately well-drained silt (CAN 533007); moist clay on stony plain (CAN 223286).
North American distribution. Northwest Territories Islands, Nunavut Islands. Range in the Canadian Arctic Archipelago limited. Uncommon. High Arctic. Arctic islands: Ellesmere, Axel Heiberg, Parry islands (Bathurst, Melville, and Prince Patrick), Cornwallis, Banks, Victoria.
Northern hemisphere distribution. Amphi-Beringian, or North American. Wrangel Island, East Chukotka (?), Central Canada, Ellesmere Land Peary Land, East Greenland.
General notes. Braya thorild-wulffii differs from B. purpurascens in several morphological characters and in ploidy level. Plants from Wrangel Island are confirmed as belonging to this species and are geographically connected to the 'type' area in Greenland by later finds through Arctic Canada. It is treated as a distinct species (Petrovsky, Murray, and Elven, in Elven et al. 2003).
Populations of Braya thorild-wulffii on Banks and Victoria Islands have essentially glabrous stems, inflorescences, and fruits, in striking contrast to the densely hairy plants from more northerly populations. This glabrous form may merit infraspecific recognition (Harris, unpublished, 2005).
Illustrations. • Habitat. Silty, barren, alkaline habitat. Nunavut, Ellesmere Island, Lake Hazen, Blister Hill. 1999. L.J. Gillespie 6486 and L.L. Consaul. • Close-up of plant in flower. Plants in late flower, starting to fruit. Remnants of white petals visible. Nunavut, Ellesmere Island, Lake Hazen, Blister Hill. 1999. L.J. Gillespie 6486 and L.L. Consaul. • Close-up of plant in fruit. Plant in fruit. Siliques are covered with a tomentum of fine hairs. Nunavut, Ellesmere Island, Lake Hazen, Blister Hill. 1999. L.J. Gillespie 6486 and L.L. Consaul. • Close-up of pressed plant. Plant with basal leaves, no leaves on the flowering stem, and a racemose inflorescence beginning to set seed. Nunavut, Ellesmere Island. 26 June, 1958. J.H. Soper, 8065. CAN 483700. • Close-up of developing fruits. Developing ovoid siliques that are densely hairy with bifurcate and simple hairs. Styles short, from almost non-existent to 0.75(-1) mm long. Nunavut, Ellesmere Island. 26 June, 1958. J.H. Soper 8065. CAN 483700. • Type specimen. Holotype of Braya thorild-wulffii var. glabrata. N.W.T., Banks Island, Bernard River. 6 August, 1963. W.J. Maher and S. MacLean 139. CAN 279211. • 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..