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

Draba corymbosa R. Br. ex DC.

English: Flattop whitlowgrass,

French: Drave en corymbe.

Brassicaceae (Cruciferae), Draba family.

Published in Syst. Nat. 2: 343. 1821.

Type: Canada: Nunavut, Baffin Land, Bylot Island, Possession Bay, leg. E. Sabine. Mulligan, Can. J. Bot. 52: 792. 1974. Holotype: BM.

Synonymy. Draba macrocarpa Adams, Nouv. Mém. Soc. Imp. Naturalistes Moscou 3: 249. 1834.

Draba bellii Holm, Feddes Repert. 3: 338. 1907.

Draba barbata Pohle, Izv. Imp. Bot. Sada Petra Velikago 14: 467. 1914.

Draba kjellmanii Lid ex E. Ekman, Svensk Bot. Tidskr. 25: 478. 1931.p.m.p.

Vegetative morphology. Plants (1–)4–8 cm high; perennial herbs; caespitose. Taproot present. Ground level or underground stems vertical. Horizontal stems at ground level, branching extensively to shape plant habit as cushions. Caudex present (stout, branching from a strong taproot and covered with marcescent leaves). Aerial stems erect. Aerial stem trichomes spreading, or erect. Leaves basal in a rosette (small to large, narrow to broad, entire and shorter and more slender than leaves of D. alpina); alternate, or whorled; marcescent (with several years of leaves built up). Petioles absent. Leaf blades simple. Leaf blade bases attenuate. Blades 9–12 mm long, 2.5–3.5 mm wide, spatulate, appearing single-veined, midvein conspicuously larger than the lateral veins (this vein and the margins often strengthened, especially in western plants approaching D. pilosa in morphology). Blade adaxial surface hairy, hairs stellate, simple, and branched (a mixed indumentum of stiff simple and often forked hairs and shorter and more slender, regularly, or irregularly branched to stalked cruciform hairs), hairs moderately dense or dense (sufficient to give the leaves a grey appearance), hairs white, or translucent. Blade abaxial surface hairy, hairs unbranched and long-stalked branched trichomes, hairs moderately dense, hairs white, hairs straight or irregularly branched or stellate, hairs spreading or erect. Blade margins entire, with non-glandular hairs; apices acute.

Reproductive morphology. Flowering stems two or more per plant; without leaves. Flowering stem hairs simple, or branched (irregularly); white or translucent. Inflorescences racemose; not elongating as the fruit matures (remaining subcorymbose), or elongating as the fruit matures (more rarely). Pedicels with non-glandular hairs. Flowers per inflorescence 4–10; small; radially symmetrical (actinomorphic) (usually relatively large for a Draba and wide open, cf. D. alpina). Sepals conventional; 4; free; (0.8–)1.2–1.5 mm long; 2.5–3 mm wide; green; herbaceous and scarious. Calyx hairy. Calyx hairs non-glandular; white or translucent. Petals conventional; free; 4; yellow; without contrasting markings (broader than sepals); obovate; slightly lobed or undulating; 4.5–5.5 mm long; 2.5–3 mm wide. Stamens 6; stamen filaments markedly unequal in length; stamen filaments glabrous. Anthers yellow; short-cylindrical; 0.4–0.5 mm long. Ovary superior; carpels 2; syncarpous. Ovaries ovate; hairy. Styles 1; 0.2–0.4 mm long; straight. Stigmas per ovary 1. Placentation parietal. Ovules per ovary 8–12. Fruit stalked; stalk 4–9 mm long; dry; a silique; ovoid, or broadly lanceolate (rather variable in shape from almost round to lanceolate); yellowish, or purple; 7–9 mm long; 2.5–4 mm wide; hairy (pubescence of short stiff usually unbranched but occasionally forked trichomes); surface appearing veinless; distinctly flattened (so that it appears long and distinct in mature fruit, but not so in all specimens); 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 0.4–0.6 mm long. Seeds 8–12; 1–1.3 mm long; brown; surfaces verrucose.

Chromosome information. 2n = 100–144.

2n = (about 14–18x).

2n = 110 – 130. Mulligan (2003);

2n = 128. Holmen (1952, Greenland);

2n = 120. Krogulevich (1976a, northern Siberia, as D. alpina, probably this species);

2n = 120±10. Mosquin and Hayley (1966, northern Canada);

2n = 128. Böcher (1966a, Greenland and Svalbard); Brochmann et al. (1993, Svalbard);

2n = 144. Mulligan (1974a, North America); Mulligan (2003).

Ploidy levels recorded 14–18x.

Ecology and habitat. Substrates: dry (more often in very dry habitats; this is a specialist of wind-swept ridges and plateaus (Elven, personal communication, 2005)); gravel, sand, clay, till; with low organic content; calcareous (almost always on very calcareous ground).

North American distribution. Common throughout the Arctic Archipelago. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec. Range in the Canadian Arctic Archipelago widespread. Common. High Arctic. Arctic islands: Baffin, Devon, Ellesmere, Axel Heiberg, Ellef Ringnes, Parry islands (Bathurst, Melville, and Prince Patrick), Cornwallis, Banks, Victoria, Prince of Wales, Somerset, King William, Southampton (Jenny Lind, Prince Charles, MacKenzie King, Queen Elizabeth islands, Hans and Stefansson islands).

Northern hemisphere distribution. Circumpolar. Svalbard – Franz Joseph Land, Polar Ural – Novaya Zemlya, Yamal–Gydan, Taimyr – Severnaya Zemlya, Anabar–Olenyok, Kharaulakh, Yana–Kolyma, 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. Draba corymbosa is a complex high-polyploid that may have received a large part of its genome, perhaps the majority, from other aggregates (perhaps the D. cinerea and the D. micropetala aggregates) (Elven et al. 2003).

Nearly all the material available for the typification (LE) of Draba barbata [Pohle, Bull. Jard. Bot. Petétersb. 14: 467. 1914] fits into the current concept of D. corymbosa. Its range from Taimyr, across Bering Strait, to Alaska is within that of D. corymbosa, as is its high-polyploid chromosome number (more than 100, Zhukova and Petrovsky 1972, cited after Löve and Löve 1975).

Brochmann et al. (1992a-d) investigated this species as one of three morphologically variable Nordic species and their possible progenitors using enzyme electrophoresis and restriction site analysis of chloroplast DNA (cDNA) and nuclear ribosomal RNA (rDNA) genes. They found the electrophoretic data showed high levels of fixed heterozygosity in the three polyploid taxa, showing that they are all genetic alloploids. Electrophoretic and rDNA data suggest that D. corymbosa is a polyphyletic polyploid. In experiments where plants were cross-pollinated the data also supported this conclusion. It is likely that D. corymbosa is polyphyletic and that this species has formed numerous times in different areas.

Brochmann (1992b), in a study of pollen and seed morphology of Nordic Draba, found that the pollen morphological data for D. corymbosa are consistent with the hypothesis that this 16-ploid is an intersectional allopolyploid derived from species in the sections Draba and Chrysodraba.

Brochmann et al. (1993) suggested that D. corymbosa is probably an intersectional, polyphyletic alloploid derived from D. alpina (10x) and various hexaploids of Sec. Draba.

Ekman (1931) rejected the name D. corymbosa because she found the type specimen of it (in BM) to be Cochlearia fenestrata R. Br. This rejection was unjustified and was caused by different sheets and erroneous labelling. One of the sheets annotated by Brown contains a very typical and well-preserved Cochlearia and is double-labelled Cochlearia fenestrata and Draba corymbosa. Another sheet, which Ekman probably did not see, contains a less well-preserved but 'typical' D. corymbosa, as currently understood. It is annotated as such by Brown and was chosen as lectotype by Mulligan (1974).

Illustrations. • Habitat: Dorset, hillside. Plants with yellow flowers growing in the shelter of rocks on a hillside. Nunavut, Baffin Island, Cape Dorset. 4 August, 2005. Aiken. No voucher. • Habitat: Dorset. Plants with small yellow flowers, near the marker, growing near the beach with sea-shore chamomile. Baffin Island, Cape Dorset. 4 August, 2005. Aiken. No voucher. • Close-up of tussock. Plant in high mountain arctic environment, before anthesis. Note compact tussock and abundant coarse hairs on leaves. Norway, Svalbard, Coloradofjella Mountains. 1989. Photograph by R. Elven. • Three Draba species in the same habitat. Right, Draba corymbosa plant with yellow flowers (94–009). Centre, Draba micropetala (94–010). Left, Draba subcapitata (94–011). Nunavut, Cornwallis Island, Resolute Bay. Aiken vouchers. CAN. • Close-up of plant. Plant about 6 cm tall with yellow flowers growing with Saxifraga cernua. Cornwallis Island, Resolute Bay. Aiken 94–009. CAN. • Close-up of plant. Flowering plant with past year's stems. Note spreading, broad, bright yellow petals. Norway, Svalbard, Sassen. 6 August, 1987. Photograph by R. Elven. • Close-up of plant. Current season's flowering plants are 1 cm tall growing in a talus of medium-sized calcareous rocks and boulders. Note the previous season's fruiting stems are 3 cm tall. Nunavut, Victoria Island, Flagstaff Point, 69°03'N, 105°6'W. 26 July, 1997. L.L. Consaul 1119 and L.J. Gillespie. CAN. • Close-up of leaves. Leaves with prominent midvein. Nunavut, Baffin Island, Cape Dorset, 4 August. 2005. No voucher. • Close-up of flowering plant. Note pale yellow petals, saccate sepals, and abundant long simple and forked hairs on stems and leaves. Norway, Svalbard, Longyearbyen. 1989. Photograph by R. Elven. • Close-up of flowering plant. Large flowering tussock. Flowers have bright yellow petals. Norway, Svalbard, Longyearbyen. 1987. Photograph by R. Elven. • Surface view of flowering plant. Asymmetrical flowers (appearing to be compressed from the sides) are often typical of this species, as is the pale to bright yellow colour. Norway, Svalbard, Longyearbyen. 1989. Photograph by R. Elven. • Close-up of flowers. Flowers with four yellow petals, six anthers, and a gynoecium covered with branching hairs on the ovary. Nunavut, Victoria Island, Flagstaff Point, 69°03'N, 105°6'W. 26 July, 1997. L.L. Consaul 1119 and L.J. Gillespie. CAN. • Close-up of tiny plants. This very variable species may develop old but very tiny plants in extreme environments. The aboveground plant is approximately 0.5 cm high. The build-up of marcescent leaves underneath suggests that it is a very old plant. Nunavut, Stefansson Island. CAN 522751. • Close-up of tiny plants. Plant approximately 2 cm high with characteristically relatively large yellow flowers, and sepals conspicuously shorter than the spreading petals. Arrow A points to a rib on the leaf. Arrow B points to the hairs at the top of the leaf. CAN 499607. • Close-up of plant. Drawing by Mrs. S. Bergh and Mrs. L. Barstad based on a collection from Svalbard, Dickson Land, Austfjord, Wijde Bay, Simledalen. 20 August, 1924. O.A. Høeg. (as D. alpina x oblongata, det. D. corymbosa, R. Elven, 14 April 1992). O 204742. With permission of the Botanical Museum, University of Oslo, Norway. • Characteristic fruits. Fruit in this species are rather variable in shape from almost round to lanceolate. The surfaces are covered with short stiff, usually unbranched but occasionally forked trichomes. Each style appears distinct in mature fruit. Nunavut, Cornwallis Island. CAN 205406. • Fruit. Note the seeds are attached to the edges of the partition in the fruit and not to the ovary wall. Nunavut, Victoria Island, Flagstaff Point, 69°03'N, 105°6'W. 26 July, 1997. L.L. Consaul 1119 and L.J. Gillespie. CAN. • 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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