Flora of the Canadian Arctic Archipelago


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 arctica J.Vahl

Brassicaceae (Cruciferae), Draba family.

Published in In Hornem., Fl. Dan. 13, 39: t. 2294. 1840.

Type: Described from Greenland and Svalbard. Böcher (1966: 14): Svalbard: Bellsound, [1838–1839], J. Vahl (C, S, O), "all three specimens serving as lectotypes". However, this is not sufficient as a lectotypification (Elven, personal communication, 2005).

Vegetative morphology. Plants 10–25 cm high; perennial herbs; caespitose. Taproot present. Ground level or underground stems horizontal (if applicable), or absent; rhizomatous (between rosettes); compact. Horizontal stems at ground level, branching extensively to shape plant habit as cushions. Caudex present (loosely branching). Aerial stems erect. Aerial stem trichomes spreading. Leaves mainly basal, or basal in a rosette; alternate; marcescent (with limited build-up at the base of the plant). Petioles absent (long attenuated bases may appear petiole-like). Leaf blades simple. Leaf blade bases truncate, or attenuate. Leaves not grass-like. Blades (7–)10–20 mm long, (0.6–)2–5 mm wide, spreading, obovate (basal leaves) or ovate (leaves on the flowering stems), appearing single-veined or with inconspicuous veins. Blade adaxial surface hairy (sometimes almost glabrous), hairs simple or branched or stellate, hairs sparse, hairs white, or translucent. Blade abaxial surface hairy, hairs moderately dense, hairs white, hairs irregularly branched or stellate, hairs appressed or spreading. Blade margins entire or dentate (with 1–6 dentations in the upper part of the leaf), with non-glandular hairs (similar to those on the leaf); apices acute.

Reproductive morphology. Flowering stems with leaves ((1-)2(-3) leaves). Flowering stem hairs branched (irregularly); shorter than the diameter of the flowering stem; white or translucent. Inflorescences head-like (in bud), or racemose, or cymose (before elongating); dense (in bud), or diffuse (soon elongating in flower); globose or sub-globose (in bud), or lanceolate (in fruit); elongating as the fruit matures. Pedicels present; with non-glandular hairs. Flowers per inflorescence (2–)5–12; small. Sepals conventional; 4; free; (0.7–)0.8–1.1 mm long; 2.5–3 mm wide; green, or yellow, or purple (tinged, without conspicuous hyaline margins); herbaceous. Calyx without sessile glands; hairy (with irregularly branched hairs). Calyx hairs non-glandular; white or translucent. Petals conventional; free; 4; white (fading to cream on herbarium specimens); without contrasting markings; ovate, or spatulate (cf. a table-tennis paddle, upper end slightly convex); unlobed; 4–6 mm long; 2–2.5 mm wide (at the apex tapering to 0.2–0.3 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 ovate; hairy. Ovary hairs very dense; white; spreading; branched (irregularly). Styles 1; thick and short; 0.4–0.5 mm long; straight. Stigmas per ovary 1, or 2. Placentation parietal. Ovules per ovary 24–32. Fruit stalked; stalk 5–9 mm long; dry; a silique; ovoid, or elongate-cylindrical; purple (yellowish), or green at maturity; 8–11 mm long; 2–3 mm wide; hairy (densely so, with irregularly forked hairs); 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 (0.5–)0.6–0.8 mm long. Seeds (20–)24–32; 1–1.1 mm long; brown; surfaces rugose.

Chromosome information. 2n = 80.

2n (10x) = 80. Heilborn (1927, Svalbard, as D. cinerea); Flovik (1940, Svalbard); Jørgensen et al. (1958, Greenland, as D. cinerea); Böcher (1966a, Svalbard); Holmen, in Böcher (1966a, Greenland); Mulligan (1971a, North America); Löve and Löve (1982, Arctic Canada); Brochmann et al. (1993, Svalbard).

Ploidy levels recorded 10x.

Ecology and habitat. Substrates: tundra, dry meadows, flood plains (with Dryas); dry; rocks, sand, silt; with low organic content; acidic, or calcareous, or nitrophilous (CAN 205026), near old Eskimo ruins (CAN 296014).

North American distribution. Nunavut Islands. Range in the Canadian Arctic Archipelago widespread. Uncommon. Arctic. Arctic islands: Baffin, Ellesmere, Axel Heiberg, Parry islands (Melville), Banks, Victoria, King William, Southampton (Melville Peninsula).

Northern hemisphere distribution. Amphi-Atlantic. Svalbard – Franz Joseph Land, Polar Ural – Novaya Zemlya, Central Canada, Ellesmere Land – Peary Land, West Greenland, East Greenland.

General notes. This species was included in D. cinerea in Flora Europea. During a visit to Canada in May, 2003, Elven separated many sheets of this species from among collections at CAN and DAO, most of which had previously been filed as Draba cinerea. Elven et al. (2003) noted that, morphologically and cytologically, this taxon is distinct from D. cinerea s.s. There are also consistent differences in genetic markers (Brochmann et al. 1992a, 1992c, 1993; Andersen et al. 1999; Andersen 2002). In recent decades this species has been accepted in Greenland, Svalbard, and partly in Russia, Siberia. In North America it was still included by implication in D. cinerea by Porsild and Cody (1980), Rollins (1993), and Cody (1996). The distribution in North America is therefore much less well known than in other areas. The treatment presented here is provisional pending further study.

The Greenland entity 'ostenfeldii' described and accepted by Ekman and Böcher was tentatively treated as a subspecies by Elven et al. (2003). Both Böcher (1966) and Andersen et al. (1999) found consistent differences between subsp. ostenfeldii and D. arctica s.s. that may justify treatment as a subspecies even if they are sympatric and both are decaploid. Species rank is out of the question for these 'close' entities, and there is no ecological difference that could justify ecotypical varieties.

Elven (personal communication, 2005) noted that Draba arctica subsp. ostenfeldii is also relevant for the Canadian Arctic Archipelago, as it was described from northeastern Canada in addition to northwestern Greenland. Three syntypes are cited: northwestern Greenland: Thule, Saunders' Island, 1914, leg. P.Freuchen (C); northwestern Greenland: Thule, "det høje Land paa Vejen til Uvdle", 1917, leg. Th.Wulff (C); and northwestern Canada: Ellesmere I., "sinu Goose Fjord", leg. H.G. Simmons 2894 (C, isotype in O).

Andersen (2003) studied morphological and isoenzymatic variation in Draba arctica and its relatives in the North Atlantic region and concluded that the patterns of variation do not indicate any taxonomic heterogeneity. The Svalbard plants belong to subsp. arctica as currently understood, but there is need for a lectotypification of D. arctica to make the application of this name unambiguous. Morphological evidence found species rank appropriate for at least D. glabella, D. cinerea, D. arctica, and D. arctogena/norvegica. For the first three, there is a supporting correspondence between evidence from cytology (ploidy levels), morphology, and genetic markers (isoenzymes) even if D. arctica and D. cinerea are more closely related than these two are to D. glabella.

Illustrations. • Inflorescences. Two inflorescences. Note the milky white petals and the small stellate hairs on everything except the petals. Norway, Svalbard, Sassen. 1987. Photograph by R. Elven. • Young inflorescence. Note milky white colour of large petals (flowers 4 to 8 mm across) and small stellate hairs covering all parts except petals. Norway, Svalbard, Longyearbyen. July, 1997. Photograph by R. Elven. • Hairs on the flowering stem. Grey coverage of small stellate hairs on scape. Norway, Svalbard, Longyearbyen. July, 1997. Photograph by R. Elven. • Close-up of small flowering plant. Caespitose plant with taproot, stiffly erect flowering stems with one well-developed leaf, and corymbose panicles with whitish flowers. Nunavut, Ellesmere Island, Van Hauen Pass. Brassard 3025. 14 July, 1962. CAN 320132. • Close-up of etiolated base of plant. Base of plant with widely spaced entire obovate leaves that have attenuated blade bases which may look like petioles. Note entire margins and light green leaves. Nunavut, Ellesmere Island, Vendom Fiord. Aiken and Maus. CAN 567884. • Close-up of inflorescence. Densely hairy flowering stem with a leaf near the compact paniculate inflorescence, relatively narrow sepals, one of which has been removed to show the very narrow base to the petals and a densely hairy ovary. Nunavut, Axel Heiberg Island. M. Kuc 466. 7 July, 1967. CAN 330992. • Close-up of fruiting plant. Plant in early fruiting stage. Note a greyish cover of small stellate hairs on almost all plant parts. Norway, Svalbard, Sassen. 6 August, 1987. Photograph by R. Elven. Voucher at 0. • Close-up of plant. Drawing by Mrs. S. Bergh and Mrs. L. Barstad based on a collection from Svalbard, Nathorst Land, Green Fyrkanten, fjellskråning. 13 July, 1920. J. Lid. (as D. cinerea, det. D. arctica, R. Elven, 11 April 1992.) (This is probably also the most frequent species in the Canadian Arctic islands.) O 204120. 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.