Flora of the Canadian Arctic Archipelago
English: Purple rockcress,
French: Braya glabre,
Brassicaceae (Cruciferae), Draba family.
Published in Can. Field.-Natural. 108: 93. 1964.
Type: Canada: Melville Island., leg. J. Ross. Probably holotype: BM.
Synonymy. Platypetalum purpurascens R. Br., Chlor. Melvill. 9.1823.
Platypetalum dubium R.Br., Parry, 1st Voy. Suppl. 266. 1823.
Braya arctica Hooker, Parry, Voy. App. 387. 1825.
Braya purpurascens (R. Br.) Bunge ex Ledeb, Fl. Ross. 1: 195. 1842.
Braya purpurascens R. Br. var. dubia (R. Br.) O.E. Schulz, in Engler. Das Pflanzenreich 86 (IV, 105), 235. 1924.
Braya henryae Raup, Contr. Arnold Arbor. 6: 167. 1934.
Vegetative morphology. Plants 3.5–10.5(–12.8) cm high; perennial herbs; caespitose. Taproot present. Ground level or underground stems vertical. Caudex present. 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; erect, or ascending. Aerial stem trichomes appressed, or spreading. Leaves mainly basal (older plants), or basal in a rosette; erect; alternate; dying annually and non-persistent. Petioles absent. Leaf blades simple. Leaf blade bases truncate, or attenuate. Leaves not grass-like. Blades (4–)8–40 mm long, 1.2–2 mm wide, appressed to the stem or spreading, linear or oblanceolate, with inconspicuous veins. Blade adaxial surface shiny (see image library), glabrous. Blade abaxial surface glabrous. Blade margins entire (usually, rarely weakly toothed with 1 or 2 teeth per side, often fleshy), glabrous (usually) or with non-glandular hairs (sparse, simple or forked, often limited to a few short hairs at the apex); apices acute, or rounded.
Reproductive morphology. Flowering stems two or more per plant; with leaves (occasionally), or without leaves. Flowering stems hairy. Flowering stems pilose. Flowering stem hairs simple, or branched; white or translucent. Inflorescences head-like (in flower), or racemose, or head-like (in fruit); dense; not elongating as the fruit matures. Pedicels glabrous (almost), or with non-glandular hairs. Flowers per inflorescence 5–12; small. Sepals conventional; 4; free; 1–1.5 mm long; 2–3.5 mm wide; green, or purple, or pink. Calyx glabrous, or hairy (very sparsely). Calyx hairs pilose; white or translucent. Calyx margins ciliate (sometimes, as a tuft of hairs at the tip). Petals conventional; free; 4; white, or pink (purplish tinged); spatulate; unlobed; 2.9–3.1 mm long; 2–2.5 mm wide (at the apex, 0.4–0.6 mm wide at the base). Stamens 6; stamen filaments markedly unequal in length; stamen filaments glabrous. Anthers yellow; sub-globose; 0.4–0.6 mm long. Ovary superior; carpels 2; syncarpous. Ovaries pear-shaped; hairy; woolly (with tangled stiff hairs). Ovary hairs white; spreading; straight, or wavy, or branched (2-forked). Styles present (but very short); 1; completely fused; thick and short; (0.35–)0.5–1.2(–1.5) mm long. Stigmas per ovary 1. Placentation parietal. Ovules per ovary 5–20. Fruit stalked; stalk 2–4 mm long; dry; a silique; ellipsoid, or ovoid, or elongate-cylindrical, or oblong (usually straight); yellowish (green); (3–)5–10 mm long; 1.5–3 mm wide (2.5–3.7 times longer than broad); hairy; surface venation ribbed (slightly); 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 (0.35–)0.5–1.6(–2) mm long. Seeds 5–20; 0.9–1.1 mm long; brown; surfaces smooth.
Chromosome information. 2n = 48, 56, 64, and 84.
2n = 48. Zhukova and Petrovsky (1984, north and northeastern Asia).
2n (8x) = 56. Holmen (1952, Greenland, the arctic entity); Löve and Löve (1956); Jørgensen et al. (1958, Greenland, the arctic entity); Mulligan (1965b, central Alaska, the 'henryae' entity); Böcher (1966a); Zhukova (1966, Wrangel Island); Johnson and Packer (1968, northwestern Alaska, the arctic entity); Zhukova and Petrovsky (1971, Wrangel Island, the arctic entity); Zhukova et al. (1973, northeastern Asia, the arctic entity); Dawe and Murray, in Löve (1979, northern Alaska, the arctic entity); Petrovsky and Zhukova (1981, Wrangel Island, the arctic entity); Zhukova and Petrovsky (1984, northeastern Siberia, 1987b, the arctic entity);
2n = 64. Sørensen and Westergaard, in Löve and Löve (1948, Greenland);
2n (12x) = 84. Krogulevich (1976a, northern Siberia, Putorana).
Ploidy levels recorded 4x/8x/12x.
Ecology and habitat. Barren calcareous soils and gravels on lake and sea shores, gravel bars, scree slopes, solifluction lobes and disturbured sites.
North American distribution. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador. Range in the Canadian Arctic Archipelago widespread. Common. Arctic (northern coast of continental North America north through the Canadian Arctic Archipelago to the limits of land). Arctic islands: Baffin, Devon, Ellesmere, Axel Heiberg, Amund Ringnes, Ellef Ringnes, Parry islands (Bathurst, Melville, Prince Patrick), Cornwallis, Banks, Victoria, Prince of Wales, Somerset, King William, Southampton, Coats (and Boothia Peninsula).
Northern hemisphere distribution. Circumpolar. Northern Fennoscandian, Svalbard Franz Joseph Land, Polar Ural Novaya Zemlya, Taimyr Severnaya Zemlya, AnabarOlenyok, Kharaulakh, YanaKolyma, West Chukotka, Wrangel Island, East Chukotka, West Alaska, North Alaska Yukon, Central Canada, Labrador Hudson Bay, Ellesmere Land Peary Land, West Greenland, East Greenland.
General notes. See under B. glabella subsp. glabella for a discussion of the species and its infraspecific taxa.
Elven et al. (2003) noted that Rollins (1993) synonymised B. glabella, B. purpurascens (and B. henryae), and B. bartlettiana without any arguments and without reference to other authors. It is difficult both to object to and to accept his point of view without comparison of types of all four entities.
Harris (1985), after examining the types of all four entities, considered B. henryae and B. bartlettiana to be synonyms of B. glabella var. glabella, and recognised B. purpurascens as a variety of B. glabella.
Braya henryae was accepted as a species by Porsild and Cody (1980), who commented that perhaps it should be considered a geographical race of B. purpurascens.
Illustrations. • colonising plant in disturbed habitat. Scattered plants with white flowers colonising a recently disturbed site beside a road. Nunavut, Baffin Island, Iqaluit, Road to Nowhere. 5 July, 2004. Aiken and LeBlanc 04–003. CAN 586475. • Plants in disturbed site. Plants between the markers, one with the remains of last year's fruiting stem. Aiken and LeBlanc 04–003. CAN. • Outline of siliques. Remains of last years's fruit that give an indication of the shape of the siliques. Aiken and LeBlanc 04–003. CAN 586475. • Habitat. Plant growing in a floodplain of a braided river. Nunavut, Ellesmere Island, Scoresby Bay. Aiken 98–034a. CAN. Photograph by Mollie MacCormac. • Plant with long taproot. Plant collected in floodplain of a braided river. Nunavut, Ellesmere Island, Scoresby Bay. Aiken 98–034a. CAN. Photograph by Mollie MacCormac. • Habitat. Scattered plants growing in a calcareous loam on upper beach. Norway, Svalbard, Gipsdalen. August, 1997. Photograph by R. Elven. • Close-up of plant. Plant collected in a floodplain of a braided river. Nunavut, Ellesmere Island, Scoresby Bay. Aiken 98–033. CAN. Photograph by Mollie MacCormac. • Close-up of flowering plant. Plant growing in a calcareous loam. Norway, Svalbard, Gipsdalen. 1997. Photograph by R. Elven. • Close-up of flowering plant. Large flowering plant with characteristic pale lilac petals. Norway, Svalbard, Gipsdalen. 24 July, 1985. Voucher at TROM. Photograph by R. Elven. • Close-up of flowering plant. Plant growing in calcareous loam on beach terrace. Norway, Svalbard, Gipsvika. July, 1997. Photograph by R. Elven. • Close-up of flowering plant. Flowering plant with the remains of last year's siliques attached. Note the fruits are shorter and thicker than those in B. glabella s.s., i.e. less than 3x long than they are wide. Norway, Svalbard, Gipsdalen. August, 1997. Photograph by R. Elven. • 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..