Flora of the Canadian Arctic Archipelago
English: Smooth whitlowgrass,
French: Drave glabre.
Brassicaceae (Cruciferae), Draba family.
Published in Fl. Amer. Sept. 2: 434. 1814.
Synonymy. Draba daurica DC., Syst. Nat. 2: 350. 1821.
Draba hirta L., nom. rejic. prop., Syst. Nat. 2: 350. 1759.
Vegetative morphology. Plants (5–)10–20(–25) cm high; perennial herbs; caespitose (small compact plants), or not caespitose. Taproot present. Horizontal stems at ground level, branching extensively to shape plant habit as mats (loosely). Caudex present (loosely branching). Aerial stems erect (branched or unbranched). Aerial stem trichomes spreading. Leaves mainly basal; alternate; dying annually and non-persistent, or marcescent. Petioles absent. Leaf blades simple. Leaf blade bases truncate and attenuate (sometimes petiole-like). Leaves not grass-like. Blades 10–45(–50) mm long, 2.5–6(–7) mm wide, oblanceolate or obovate, appearing single-veined or with inconspicuous veins. Blade adaxial surface hairy, hairs stellate or simple, hairs sparse (at the base, more towards the leaf apex), hairs white, or translucent. Blade abaxial surface hairy, hairs sparse (sometimes almost absent), hairs white, hairs irregularly branched, hairs spreading. Blade margins entire and dentate (very slightly, especially on the flowering stem leaves), with non-glandular hairs; apices acute.
Reproductive morphology. Flowering stems with leaves. Flowering stem hairs simple, or branched (irregularly); white or translucent. Inflorescences racemose; dense (in flower), or diffuse (in fruit); globose or sub-globose (in flower); elongating as the fruit matures. Pedicels glabrous (or with a few hairs). Flowers per inflorescence (4–)5–10(–12); small; radially symmetrical (actinomorphic). Sepals conventional; 4; free; 1–1.5(–1.8) mm long; 2–3 mm wide; green and purple. Calyx hairy (with a few simple hairs). Calyx hairs non-glandular; white or translucent. Petals conventional; free; 4; white (sometimes fading cream on herbarium specimens); without contrasting markings; obovate; slightly lobed or undulating; 3.5–4.5 mm long; 1–2 mm wide (at the apex, narrowing down to 0.2 mm wide at the base). Stamens 6; stamen filaments markedly unequal in length; stamen filaments glabrous. Anthers yellow; sub-globose; 0.3–0.4 mm long. Ovary superior; carpels 2; syncarpous. Ovaries ovate; glabrous (usually), or hairy (sometimes densely so, often with a few glabrescent hairs). Styles 1; 0.3–0.5 mm long; straight. Stigmas per ovary 1. Placentation parietal. Ovules per ovary 24–32. Fruit stalked; stalk 2–7(–10) mm long; dry; a silique; ellipsoid, or ovoid; green at maturity (a greyish green), or purple and green at maturity; (8–)9.5–11(–12.5) mm long; 3–4 mm wide; glabrous, or hairy (glabrous or pubescent with unbranched or forked trichomes (CAN 295533)); 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 0.4–0.7 mm long. Seeds 24–28; 1–1.3 mm long; brown; surfaces smooth, rugose (at 40×).
Chromosome information. 2n = 64, or 80.
2n (8x) = 64. Heilborn (1927, Greenland; 1941, Greenland and Norway); Böcher and Larsen (1950, Greenland); Löve and Löve (1956, Iceland); Holmen, in Jørgensen et al. (1958, Greenland); Böcher (1966a, Canada and Greenland); Holmen in Böcher (1966a, Greenland); Knaben and Engelskjøn (1967, Norway); Zhukova (1967a, northeastern Asia); Mulligan (1970, Yukon); Zhukova and Tikhonova (1971, 1973, Chukotka); Löve and Löve (1982, Arctic Canada); Zhukova and Petrovsky (1980, western Chukotka; 1984, 1987b, northern and northeastern Asia); Yurtsev and Zhukova (1982, northern Siberia); Brochmann et al. (1993, Svalbard); Murray and Kelso (1997, Alaska); Mulligan (2003);
2n = about 75. Rollins (1966, Alaska, as D. 'hirta', identification questioned);
2n (10x) = 80. Heilborn (1927, Greenland); Jørgensen et al. (1958, Greenland); Böcher (1966a, Greenland); Johnson and Packer (1968, northwestern Alaska, as D. 'hirta'); Mulligan (1970, Yukon).
The deviant chromosome number of 2n = about 75 from Alaska (Rollins 1966) should be checked against the voucher specimen. There seems, however, to be good evidence for the occurrence of two ploidy levels (2n = 64 and 80) in this very widespread and polymorphic species.
The chromosome reports from Iceland (Löve and Löve 1956, 1975) are enigmatic, as the presence of this species in Iceland is discounted by Jalas et al. Suominen (1996) and Kristinsson (list, maps). The problem is that no octoploid Draba is currently known from Iceland. Vouchers of Löve counts are notoriously difficult to find, and the problem may be unsolvable (Elven et al. 2003).
Decaploid counts are reported from northeastern Asia. (Petrovsky, personal communication, May 2002).
Ploidy levels recorded 8x and 10x.
Ecology and habitat. Substrates: along streams, river terraces, lakeshores, slopes, ridges, cliffs; imperfectly drained moist areas, seepage slopes, dry; rocks, gravel, sand, till; with low organic content, with high organic content; calcareous, or nitrophilous. Sandy and gravelly beaches, sandy river margins. This species grows in lush stands near rich sources of animal dung, especially on bird islands below nesting cliffs (Burt 2002).
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 and alpine. Arctic islands: Baffin, Axel Heiberg, Banks, Victoria, Southampton (Boothia and Melville peninsulas).
Northern hemisphere distribution. Circumpolar, or circumboreal. Northern Iceland (?), Northern Fennoscandian, KaninPechora, Svalbard Franz Joseph Land, Polar Ural Novaya Zemlya, YamalGydan, Taimyr Severnaya Zemlya, AnabarOlenyok, Kharaulakh, YanaKolyma, West Chukotka, Wrangel Island, South Chukotka, East Chukotka, West Alaska, North Alaska Yukon, Central Canada, Labrador Hudson Bay, Ellesmere Land Peary Land, West Greenland, East Greenland.
General notes. This is a very common and variable species. It has large geographical and environmental ranges and responds with a wide range of growth forms and morphological variation.
Elven in Elven et al. (2003) noted that Russian sources almost uniformly have applied the name D. hirta L. to this species, whereas that name has long been out of use in northwestern Europe and Greenland. They note that "the material available for typification of D. hirta L. is LINN 823.12 with two specimens. The left-hand plant is marked "lapp" (Lapland, i.e., northern Scandinavia), is in acceptable condition, and may perhaps belong to D. glabella as currently understood [but this will be very difficult to decide absolutely]. The right-hand plant is in very bad condition and probably belongs to D. norvegica as currently understood." There is little help in the protologue, and there is no indication that Linnaeus had this, and only this, species in mind. The name has been applied and misapplied to too many diverse specimens to have any current use. It is therefore to be rejected, as it is not possible to make an unambiguous typification.
The chromosome reports from Iceland (Löve and Löve 1956, 1975) are enigmatic, as the presence of this species in Iceland is discounted by Jalas et al. (1996) and Kristinsson (list, maps). The problem is that no octoploid Draba is currently known from Iceland. Vouchers of Löve counts are notoriously difficult to find, and the problem may be unsolvable (Elven et al. 2003).
Decaploid counts have been found in northeastern Asia (Petrovsky, personal communication, May 2002).
Andersen (2003) found that D. glabella (Series Hirtae) is distinct enzymatically and especially morphologically from both D. arctica and D. cinerea. In morphology, it is intermediate between these two species (Series Cinereae) and D. arctogena (Series Rupestres). His results justify Tolmatchew (1939) separation of this complex into three series.
Illustrations. • Habitat: Dorset. Plant beside the marker growing among rocks near the beach with Saxifraga cernua, Poa glauca, and Trisetum spicatum. Nunavut, Baffin Island, Cape Dorset. 4 August, 2005. Aiken. No voucher. • Habitat Dorset. Plants often approaching 20 cm high growing in the shelter of buildings. Nunavut, Baffin Island, Cape Dorset. 2 August, 2005. Aiken. No voucher. • Close-up of plant. Plants growing among rocks at the base of a bird cliff. Nunavut, Baffin Island, Iqaluit. Aiken 2002. No voucher. • Close-up of leaves. Leaves with stellate hairs. Nunavut, Baffin Island, Iqaluit. Aiken and Mallory 02–008. CAN. • Habitat. Plant with white flowers in a south-facing favourable slope, together with yellow-flowered D. alpina. Norway, Svalbard, Odindalen. 1989. Voucher at 0. Photograph by R. Elven. • Close-up of plant. Plant infected by Puccinia drabae. Norway, Svalbard, Odindalen. 1989. Photograph by R. Elven. • Surface view of flowers. Flowers with four white petals. Nunavut, Baffin Island, Iqaluit. Aiken and Mallory 02–008. CAN. Scale bar in cm. • Close-up of fruits. Close-up of ripe and dehisced fruits with seeds on the partition of the siliques. Nunavut, Southampton Island, Duke of York Bay, Cleveland River. B.R. Irvine. 12 August, 1952. CAN 262001. • 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..