Flora of the Canadian Arctic Archipelago
Brassicaceae (Cruciferae), Draba family.
Published in Novon 13: 396. 2003.
Type: Russian Far East: Kamtchatka, leg. Friedrich, E.L. von Fischer s.n. Holotype: G-DC.
Synonymy. Nasturtium bursifolium DC., Syst. Nat. 2: 194. 1821.
Arabidopsis bursifolia (DC.) Botsch. Bot. Mater. Gerb. Bot. Inst. Komarova Akad. Nauk SSSR 19: 106. 1959.
Beringia bursifolia (DC.) R.A. Price, Al-Shehbaz and O'Kane, Novon 11: 334. 2001.
Turritis mollis Hooker, Fl. Bor.-Amer. 1: 40. 1829.
Arabis hookeri Lange, Consp. Fl. Groenl. 50. 1830.
Arabis trichopoda Turcz., Bull. Soc. Naturalistes Moscou 8, 1: 63. 1840.
Arabidopsis mollis (Hooker) O.E. Schulz, Bot. Jahrb. 66: 97. 1933.
Halimolobus mollis (Hooker) Rollins, Rhodora 43: 480. 1941.
Arabidopsis trichopoda (Turcz.) Botsch.,Bot. Mater. Gerb. Bot. Inst. Komarova Akad. Nauk SSSR 18: 104. 1957.
Vegetative morphology. Plants 15–50 cm high; biennial herbs. Taproot present. Caudex present (unbranched). Aerial stems erect. Leaves mainly basal, or basal in a rosette and distributed along the stems; alternate; dying annually and non-persistent. Petioles absent (smaller leaves; long attenuated blade bases may appear petiole-like on some large leaves). Leaf blades simple. Leaf blade bases attenuate, or hastate. Blades 30–40(–50) mm long (plus up to 15 mm attenuated leaf base), 4–10 mm wide, oblanceolate, appearing single-veined. Blade adaxial surface without sessile glands, hairy, hairs simple and branched, hairs moderately dense or dense, hairs white, or translucent. Blade abaxial surface dull, hairy, hairs very dense. Blades not lobed. Blade margins dentate, with non-glandular hairs, with teeth all around the blade. Hydathodes present and conspicuous. Blade apices acute.
Reproductive morphology. Flowering stems two or more per plant; conspicuously taller than the leaves; with leaves. Flowering stem hairs simple, or branched (some irregularly forked); shorter than the diameter of the flowering stem; white or translucent. Inflorescences racemose. Pedicels present; with non-glandular hairs. Flowers per inflorescence (10–)30–50; small; radially symmetrical (actinomorphic). Sepals conventional; 4; free; 1–1.3 mm long; (2–)2.5–3 mm wide; green and purple; herbaceous. Calyx hairy. Calyx hairs with sparse, scattered simple and branched hairs; non-glandular; white or translucent. Petals conventional; free; 4; white; without contrasting markings; obovate, or spatulate (narrowly clawed); slightly lobed or undulating; 4.5–6(–6.5) mm long; 1.5–2 mm wide. Stamens 6; stamen filaments markedly unequal in length; stamen filaments glabrous; free of the corolla. Anthers yellow; 0.4–0.5(–0.6) mm long. Ovary superior; carpels 2; syncarpous. Ovaries glabrous. Styles 1; thick and short; 0.1–0.3(–0.4) mm long. Stigmas per ovary 1. Placentation parietal. Ovules per ovary 60–80. Fruit stalk 4–10 mm long; dry; a silique; elongate-cylindrical (slightly flattened parallel to septum); yellowish, or green at maturity; 25–40 mm long; 1–1.5 mm wide; glabrous; surface venation reticulate (strongly nerved, nearly to apex); dehiscent; shedding the outer walls to expose a thin inner wall, with the seeds attached at the margins on either side. Styles remaining straight; persisting in fruit 0.2–0.3 mm long. Seeds (40–)60–80; 1–1.2 mm long; brown; surfaces verrucose.
Chromosome information. 2n = 16, 20.
2n (2x) = 16. Jørgensen et al. (1958, Greenland, 'mollis'); Mulligan (1964, Canada, 'mollis'); Berkutenko and Gursenkov (1976, northeastern Asia, Magadan area, 'bursifolia'); Zhukova et al. (1977, northern Siberia, 'bursifolia'); Dawe and Murray, in Löve (1981a, Alaska, 'mollis'); Zhukova and Petrovsky (1984, northeastern Asia); Mulligan (2003, as Halimolobos mollis);
2n = 20. Dawe and Murray, in Löve (1981a, 'mollis'); Mulligan (2003).
Ploidy levels recorded 2x.
Ecology and habitat. Substrates: wet meadows, slopes, ridges, cliffs; imperfectly drained moist areas, seepage slopes, dry; rocks, gravel, sand, clay; with low organic content, with high organic content; calcareous, or nitrophilous. Transberginia bursifolia is a continental, essentially subarctic plant of ruderal strategy [see Yurtsev, in Tolm. 1975, Fl. Arct. URSS 7: 53–59]. Its favourite habitats in the Arctic are tors and other dining places of birds of prey. Local populations usually have very few individuals. A large gap separates the marginal populations of T. bursifolia in the Asian and American Arctic, between the lower reaches of the Amguema River in the isthmus of Chukchi Peninsula and the lower reaches of Mackenzie River (or the upper reaches of Koyu River, in subarctic central Alaska). This gap was most probably brought about by the Holocene increase in climatic humidity that followed the flooding of the shelf in Central Beringia. Near the centre of this gap, two dwarfish, strongly isolated populations have been discovered. They deviate from a rather variable T. bursifolia. One of them corresponds to the rank of variety, whereas the other is species-level distinct. They may be the result of genetic drift in very small populations under marginal climatic conditions. Both isolated taxa have plants with many features in common such as the following: monocarpic to oligocarpic life cycles; erect stems with sagittate oblanceolate acutish leaves that have long auricles; caducous sepals covered by simple hairs without any branched ones; siliques widest in the middle part with thick midveins; and a septum with a very thin median vein, and without perforations (Yurtsev, personal communication, 2001). Confined to dry, continental areas and sites with sparse vegetation and low competition. This species is often dispersed by animals and humans.
North American distribution. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories, Nunavut Islands. Range in the Canadian Arctic Archipelago limited. Arctic. Arctic islands: Baffin, Banks.
Northern hemisphere distribution. Amphi-Beringian (broadly), or North American. Taimyr Severnaya Zemlya, Kharaulakh, YanaKolyma, West Chukotka, East Chukotka, West Alaska, North Alaska Yukon, Central Canada, Ellesmere Land Peary Land, West Greenland.
General notes. After Rollin's (1941) monograph of western North American Arabis, North American authors referred Arabis hookeri to the North American Cordilleran oligotypic genus Halimolobus Tausch, comprising robust perennials (some of them sub-shrubs), densely pubescent with soft branched hairs (including siliques) and with very thin and long styles. Typical representatives of the genus Halimolobus are H. patula Tausch and H. stricta Tausch (isotypes in LE!), whereas the Cordilleran H. virgatus (Nutt.) O.E. Schulz is closely related to H. mollis (according to Rollins 1941 and A.E. Porsild 1957) and may belong to the genus Arabidopsis as well (Yurtsev, personal communication, 2001).
A high inter-population polymorphism is notable in this taxon, more or less similar throughout the range. Transberginia (Arabidopsis [Beringia] bursifolia) and A. mollis are both variable species, but the ranges of their variability are practically identical. Comparison of anatomical structure of some parts of siliques, kindly performed by E. Velitschkin, in plants from the lower reaches of Kolyma River (A. bursifolia) and western Greenland (A. mollis), revealed some distinctions, for example, in the shape of cells in the mechanical tissue of the inner walls of valves (almost round in A. mollis, multiangular in A. bursifolia), but it is not known if these distinctions are stable. Elven et al. (2003) chose to synonymise the taxa.
This species was recently found genetically distinct from both Arabidopsis and Halimolobus by Price et al. (2001) and assigned to its own genus Beringia.
Their chosen name of the genus had to be changed because the name Beringia belongs to an algal genus, described by P. Perestenko, Bot. Zhurn. 60: 1183. 1975. The name Transberginia for the genus was published in Novon 13: 396. 2003.
Price et al. (2001) have recognised two subspecies, a non-arctic Cordilleran subsp. virgata (Nutt. ex Torrey and A. Gray) R.A. Price, Al-Shehbaz, and O'Kane, and an amphi-Beringian subsp. bursifolia, which includes the entities named as 'mollis', 'tschuktschorum', and 'beringensis.'
Illustrations. • Plant in flower. Coarse weedy biennials, 15–50 cm high, usually with several erect-ascending branched stems, leaves oblanceolate, 30–40(-50)mm long, moderately, or densely hairy, blade margins, dentate; petals white, obovate, or spatulate, narrowly clawed, shallowly lobed, 4.5–6(-6.5) mm long, 1.5–2 mm wide. Nunavut, Ellesmere Island, near Lake Hazen. J.M. Powell 454. 27 June, 1959. CAN 483661. • Plant in fruit. Inflorescence has elongated as the siliques developed. Siliques are much longer than wide and slightly flattened parallel to septum. Nunavut, Ellesmere Island, near Lake Hazen. J.H. Soper 8303. 31 July, 1958. CAN 483682. • Close-up of fruits in previous image. Inflorescence has elongated as the siliques developed. Siliques are glabrous, much longer than wide, slightly flattened parallel to septum. Nunavut, Ellesmere Island, near Lake Hazen. J.H. Soper 8303. 31 July, 1958. CAN 483682. • 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..