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 subcapitata Simmons

Brassicaceae (Cruciferae), Draba family.

Published in Vasc. Pl. Fl. Ellesmereland 87. 1906.

Type: Canada: Nunavut, Ellesmere Island: "Ad litus orientale sinus Goose Fjord Ellesmerelandiae meridionalis, Yellow Hill", 23.08.1901, leg. H.G. Simmons 3591, selected by G.A. Mulligan (1971). Lectotype: O.

Vegetative morphology. Plants (1.5–)2–6(–10) cm high; perennial herbs; caespitose. Taproot present. Ground level or underground stems vertical; elongate, or compact. Horizontal stems at ground level, branching extensively to shape plant habit as mats (small and hemispherical). Caudex present (well developed with congested branching). Aerial stems erect. Aerial stem trichomes spreading. Leaves mainly basal, or basal in a rosette; alternate, or whorled; marcescent. Petioles absent. Leaf blades simple. Leaf blade bases attenuate and truncate. Blades (3.5–)5–7(–8) mm long, 3–5 mm wide, oblanceolate or obovate, appearing single-veined (with a prominent midrib) or with inconspicuous veins. Blade adaxial surface glabrous (predominantly) or hairy (with isolated, occasional hairs), hairs simple, hairs sparse (if applicable), hairs white, or translucent. Blade abaxial surface glabrous (predominantly) or hairy, hairs pilose, hairs sparse (if applicable), hairs white, hairs straight or curved, hairs spreading or erect. Blade margins entire, with non-glandular hairs (that are simple and 0.5–0.7 mm long); apices acute.

Reproductive morphology. Flowering stems two or more per plant; without leaves. Flowering stem hairs branched (irregularly); shorter than the diameter of the flowering stem; white or translucent. Inflorescences racemose and head-like; dense; globose or sub-globose; 4–6 cm long; 4–6 mm wide; not elongating as the fruit matures. Pedicels with non-glandular hairs. Flowers per inflorescence 2–6(–8); small (small for a Draba); radially symmetrical (actinomorphic). Sepals conventional; 4; free; 0.5–0.9 mm long; 1.5–1.8 mm wide; brown; herbaceous. Calyx hairy. Calyx hairs pilose; non-glandular; white or translucent (conspicuously long, 0.5–0.7 mm). Petals conventional; free; 4; white; without contrasting markings; obovate, or oblanceolate, or spatulate; slightly lobed or undulating, or unlobed; 2–2.5 mm long; 0.7–1 mm wide (at the top, tapering evenly to 0.2–0.3 mm wide at the base). Stamens 6; stamen filaments markedly unequal in length; stamen filaments glabrous; free of the corolla. Anthers yellow; sub-globose; 0.3–0.5 mm long. Ovary superior; carpels 2; syncarpous. Ovaries sub-globose; hairy. Ovary hairs straight and branched. Styles 1; 0.05–0.1 mm long; straight. Stigmas per ovary 1. Placentation parietal. Ovules per ovary 12–16(–18). Fruit stalked; stalk 2–4 mm long; dry; a silique; ovoid, or oblong (narrowly or broadly so); purple (slightly, a drab purplish grey); 4–6(–7) mm long; 2–2.5(–3) mm wide; glabrous; surface appearing veinless; 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 0.05–0.1 mm long (short, stubby). Seeds 8–14; 0.9–1.1(–1.5) mm long; brown; surfaces smooth (at 10×), rugose (at 40×).

Chromosome information. 2n = 16.

2n = 16. Holmen (1952, Greenland); Jørgensen et al. (1958, Greenland); Zhukova (1967a, northeastern Asia); Zhukova and Tikhonova (1971, Chukotka); Mulligan (1974, northern Canada); Engelskjøn (1979, Svalbard); Zhukova and Petrovsky (1984, northeastern Asia); Brochmann et al. (1993, Svalbard); Grundt (unpublished many areas, diploid in cytometry); Mulligan (2003).

Ploidy levels recorded 2x.

Ecology and habitat. Substrates: snow patches, depressions of low-centre polygons, river terraces, tundra, ridges, flood plains; imperfectly drained moist areas (moist peat, depressions), seepage slopes, dry, moderately well-drained areas (usually); gravel, moss; with low organic content, with high organic content, peat; acidic, or calcareous (generally a strong calciphile). This species occurs in open ground, both in snow patches and moist-wet areas with open soil and on ridges and exposed outcrops with open gravel, dry recently eroding gravelly terraces, both in modern floodplain and on edges of older raised terraces; disturbed terrain, (CAN 518537); well-drained slope of alkaline coluvium (CAN 502437); well-drained fluvial sand and silt (CAN 5024331); wet sandy area by creek (CAN 296126); linear ridge with sand and gravel beach. Predominantly carbonate rocks (CAN 526764); growing on the edge of a frost crack, side by side with D. cinerea and D. alpina (CAN 12784).

North American distribution. Alaska, Northwest Territories Islands, continental Northwest Territories, Nunavut Islands, continental Nunavut. Range in the Canadian Arctic Archipelago widespread. Common. High Arctic. Arctic islands: Baffin (Bylot and Prince Charles), Devon, Ellesmere, Axel Heiberg, Ellef Ringnes, Parry islands (Bathurst, Melville, and Prince Patrick), Cornwallis, Banks, Prince of Wales, Somerset, Southampton (King Christian, and Ward Hunt).

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, North Alaska – Yukon, Central Canada, Labrador – Hudson Bay, Ellesmere Land – Peary Land, West Greenland, East Greenland.

General notes. Draba subcapitata is a diploid, 2n =16. It is quite distinct morphologically, in indumentum, petal morphology, and silique shape and seems to be quite closely related to D. fladnizensis (RAPD analysis; Grundt et al.2004).

Draba subcapitata (in ser. Pilosae) and D. fladnizensis (in ser. Lacteae) are genetically and morphologically close (Scheen 1999, Scheen et al. 2002) and must belong to the same series if the series shall have any taxonomic value. Both species are more different than D. lactea and D. pilosa than they are from each other (Elven et al. 2003).

Recent genetical investigations (Grundt 2001, unpublished) prove a close relationship between D. subcapitata, D. fladnizensis, and also the central Asian D. altaica Bunge (this name was applied for the arctic plants before Simmons' publication of D. subcapitata). If we apply the series concept, D. subcapitata therefore belongs in ser. Lacteae rather than ser. Pilosae or ser. 'Oblongatae'. This is also supported by the studies of Scheen (1999) and Scheen et al. (1999, 2001), investigating morphology, enzymes, and RAPD (Grundt and Elven, personal communication, 2002).

Illustrations. • Habitat. Left (94–011), plant with small white flowers, growing on a calcareous rocky slope with Draba micropetala (centre, 94–010) and Draba corymbosa (94–009). Nunavut, Cornwallis Island, Resolute Bay. Aiken vouchers. CAN. • Close-up of plant. Plant with tiny white petals that are slightly longer than the calyx, growing beside Draba corymbosa. Nunavut, Cornwallis Island, Resolute Bay. Aiken 94–011. CAN. • Habitat. Plant growing in calcareous soil with scars and strongly fragmented vegetation. Norway, Svalbard, Kolldalsnosa, Sassen Valley. August, 1998. Photograph by A.-C. Scheen. • Close-up of flowering plant. Compact cespitose plant with subcapitate inflorescences. Note small, narrow petals. Norway, Svalbard, Kolldalsnosa, Sassen Valley. August, 1998. Photograph by A.-C. Scheen. • Close-up of plant. Plant less than 5 cm high, with fading white petals and forming characteristically shaped siliques (short with very short styles). Aiken 094–011. CAN. Scale bar in cm. • Close-up of fruiting plant. Note the short fruits with very short styles. N.W.T., Banks Island, Parker River Valley. August, 1999. Voucher at CAN and O. Photograph by R. Elven. • Close-up of plant. Drawing by Mrs. S. Bergh and Mrs. L. Barstad based on a collection from Svalbard, Nordenskiöld Land, Green Harbour, Fuglefjell [bird-cliff] under Vardeborg. 15 July, 1924. J. Lid. O 204422. With permission of the Botanical Museum, University of Oslo, Norway. • 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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