Flora of the Canadian Arctic Archipelago

DELTA Home

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 micropetala Hooker

Brassicaceae (Cruciferae), Draba family.

Published in Trans. Linn. Soc. London 14: 385. 1825.

Type: Canada: Nunavut, Iglookik Island, leg. Parry, Mulligan (1974). Holotype: K.

Synonymy. Draba oblongata auct. subsp. minuta V.V. Petrovsky, Bot. Zhurn. (Moscow and Leningrad) 66, 3: 385. 1981.

Draba oblongata auct., non R. Br. ex DC., 1821.

Draba adamsii auct., non Ledeb. 1841.

Vegetative morphology. Plants 2–10 cm high; perennial herbs; caespitose. Taproot present. Ground level or underground stems absent (except within a cushion). Caudex present (a short, often branching zone close to the ground surface). Aerial stems erect. Aerial stem trichomes spreading. Leaves basal in a rosette; alternate, or whorled; marcescent (but not persisting as long as in D. corymbosa). Petioles absent. Leaf blades simple. Leaf blade bases attenuate and truncate. Blades (4–)8–24 mm long, (1–)2–4 mm wide, ovate, appearing single-veined. Blade adaxial surface glabrous or hairy, hairs simple or branched (if applicable), hairs sparse, hairs white, or translucent. Blade abaxial surface glabrous or hairy, hairs sparse or moderately dense (with long-stalked stellate hairs), hairs white, hairs straight or irregularly branched, hairs spreading or erect. Blade margins entire, with non-glandular hairs (unbranched to 0.5–1 mm long); apices acute.

Reproductive morphology. Flowering stems without leaves. Flowering stem hairs simple and stellate (denser towards the inflorescence, spreading, erect); shorter than the diameter of the flowering stem (stellate hairs), or longer than the diameter of the flowering stem (unbranched hairs to 1 mm long); white or translucent. Inflorescences racemose and head-like (in flower); globose or sub-globose; 6–10 cm long; 7–15 mm wide; elongating as the fruit matures (slightly), or not elongating as the fruit matures (fruits remaining in a capitate cluster). Pedicels with non-glandular hairs (similar to those on the peduncle). Flowers per inflorescence 3–7 (relatively small); small; radially symmetrical (actinomorphic). Sepals conventional; 4; free; (0.7–)1–1.3 mm long; 2–2.5 mm wide; purple (sometimes approaching lavender). Calyx hairy (with unbranched hairs, 0.75–1 mm long, and occasionally forked hairs). Calyx hairs non-glandular; white or translucent. Petals conventional; free; longer than the calyx (but not much longer); 4; yellow; oblanceolate (strap-like, tapering evenly from 0.4–0.5 mm wide at the base to the widest point at the apex); slightly lobed or undulating; 3–3.5 mm long; (0.8–)1–2 mm wide. Stamens 6; stamen filaments markedly unequal in length; stamen filaments glabrous. Anthers reddish, becoming yellow; triangular; 0.3–0.4 mm long. Ovary superior; carpels 2; syncarpous. Ovaries ovate; hairy; with conspicuous hairs. Ovary hairs white. Styles 1; 3–4(–5) mm long; straight. Stigmas per ovary 1. Placentation parietal. Ovules per ovary (12–)16–20(–24). Fruit stalked; stalk 1–8 mm long; dry; a silique; ovoid; green at maturity, or purple (drab olive or purplish); (6–)7–9(–10) mm long; 2–3 mm wide; hairy (sparsely so, with simple or stellate hairs); 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 0.2–0.5 mm long (appearing stubby and insignificant). Seeds (12–)16–20(–24); 1–1.2 mm long; brown; surfaces smooth (at 10×), rugose (slightly at 40×).

Chromosome information. 2n = 48.

2n (6x) = 48. Brochmann et al. (1993, Svalbard, 'adamsii'); Petrovsky and Zhukova (1981, Wrangel Island, as D. oblongata minuta); Zhukova and Petrovsky (1984, northeastern Asia, as D. oblongata minuta).

Ploidy levels recorded 6x.

Ecology and habitat. Substrates: along streams, flood plains, seashores, lakeshores; imperfectly drained moist areas and moderately well-drained areas; rocks, gravel, sand, silt. Rocky beach, Jenny Lind Island (CAN 273638); low swampy area near small lake adjacent to old Eskimo ruins, Cornwallis Island (CAN 206085); alkaline gravels and fines of floodplain, well-drained terrace crests and knolls, plants growing on siltier mudboils (CAN 518541).

North American distribution. Alaska, Yukon (?), Northwest Territories Islands, Nunavut Islands. Range in the Canadian Arctic Archipelago widespread. Uncommon. Arctic islands: Devon, Ellesmere, Axel Heiberg, Parry islands, Cornwallis, Banks (Elven record 2005; Melville, Jenny Lind).

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

General notes. Elven et al. (2003) noted that the D. micropetala aggregate is probably a natural group of taxa with very small and narrow pale yellow petals, very short styles, broad leaves with a rounded to subacute apex, and very coarse simple hairs and long-stalked branched hairs (forked, irregular, cruciform or few-branched stellate). Some of these features are also found in some more high-ploid species in the D. alpina aggregate, especially in D. corymbosa. The comparatively low-ploid D. micropetala aggregate may have furnished genomes or share parts of the same genomic stock as do parts of the D. alpina aggregate.

Most of the variation in Greenland, Svalbard, and northern Russia fits fairly well into two species: the hexaploid D. micropetala Hooker and the tetraploid D. pauciflora R.Br. The division is, however, less easy to apply on arctic American material (D. micropetala and D. pauciflora; both names based on North American types). There may be more than two taxa involved, and also the ploidy differences might be less clear-cut than implied by the investigations made to date. A revision combined with genetical investigations is needed. Elven did a preliminary revision of Arctic Canadian specimens at CAN and DAO in 2003, and separated the material on three groups, two representing these two species and a third that he referred to at the time as D. aff. micropetala.

The majority of the decaploid chromosome counts (2n = 80), grouped by Löve and Löve (1975) under the name D. micropetala, probably belong to D. alpina L. s.s. Their reasons for this strange treatment are unknown. Elven et al. (2003) knew of no high-ploid chromosome count of the 'micropetalous' Drabas and suggested that the octoploid chromosome counts (2n = 64) reported by Petrovsky in earlier drafts of the checklist might belong to D. oblongata R. Br. s.s., i.e., not D. micropetala.

The name D. oblongata was for a long time applied for this species. It has been proved to belong to, and have priority for, a white-flowered species in ser. Cinereae, later described and generally known as D. groenlandica E. Ekman (see Mulligan 1974a). The first valid name for the species seems to be D. micropetala Hooker (1825a). The lectotype of D. micropetala (K) chosen by Mulligan is unambiguous.

Illustrations. • Habitat. Centre, plant with white flowers (94–010) growing with Saxifraga cernua and with Draba subcapitata (94–011) and Draba corymbosa right (94–009). Nunavut, Cornwallis Island, Resolute Bay. Vouchers. CAN. • Close-up of flowering plant. Entire flowering plant showing the rosettes, the short stems before and during flowering, the yellow petals and the stems that elongate during fruit development. Norway, Svalbard, Longyearbyen. July, 1997. Photograph by R. Elven. No voucher. • Close-up of inflorescence. Plant in bud as seen from above. Note the scarcely exserted narrow petals, the coarse stellate hairs on the leaves, and the cabbage-like appearance of the rosette. Norway, Svalbard, Sassen. 5 August, 1987. Photograph by R. Elven. Voucher at 0. • Close-up of plant in bud. Cabbage-like plant in bud. Note very narrow petals and long-stalked and coarse stellate hairs on very obtuse leaves. Norway, Svalbard, Fjordnibba Mountain. 5 August, 1987. Voucher at 0. Photograph by R. Elven. • Close-up of inflorescence. Plant in bud. Note the very narrow, pale yellow petals and the cabbage-like rosette with large forked hairs on the leaves. Norway, Svalbard, Sabine Land, Fjordnibba. 5 August, 1987. Voucher at 0. Photograph by R. Elven. • Close-up of fruiting plant. Plant with immature fruits. Note fruit shape and indumentum and the coarse stellate hairs on the leaves. Norway, Svalbard, Sassen. 5 August, 1987. Photograph by R. Elven. Voucher at 0. • Close-up of flowers. Drawing by Mrs. S. Bergh and Mrs. L. Barstad based on a collection from Svalbard, Oscar II Land, Kapp Bohman, ved Signalet. 27 August, 1924. J. Lid. (as D. oblongata, confirm. A. Tolmatchew 1929, det. D. micropetala J. Lid 1932, det. D. adamsii S. Bretten and A.A. Frisvoll. 6 May, 1981. det. D. micropetatla R. Elven 1998). O 205780. With permission of the Botanical Museum, University of Oslo, Norway. • Close-up of fruiting bodies. Drawing by Mrs. S. Bergh and Mrs. L. Barstad based on a collection from Svalbard, Oscar II Land, Kapp Boheman, ved Signalet. 27 August, 1924. J. Lid. (as D. oblongata, confirm. A. Tolmatchew 1929, det. D. micropetala J. Lid 1932, det. D. adamsii S. Bretten and A.A. Frisvoll 6 May 1981, det. D. micropetala R. Elven 1998). O 205780. With permission of the Botanical Museum, University of Oslo, Norway. Scale bar in cm. • 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.

.

Contents