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

Oxytropis arctica R. Br.

English: Arctic oxytrope.

Fabaceae (Leguminosae), Pea family.

Published in Chlor. Melvill. 20, 1823.

Type: Canada: Melville Island, Mr. Beverley, selected by Welsh, Great Basin Naturalist 55. 1995. Lectotype: K.

Synonymy. Astragalus arcticus (R. Br.) Spreng., Syst. Veg. 4: 288. 1827.

Spiesia arctica (R. Br.) Kuntze, Rev. Gen. Pl. 205. 1891.

Aragallus arcticus (R. Br.) Greene, Pittonia 3: 211. 1897.

Oxytropis coronaminis Fernald, Rhodora 30: 151, pl. 175. 1928. Type: "Richardson s.n.". Holotype: GH.

Vegetative morphology. Plants (5–)10–15(–20) cm high; perennial herbs; caespitose. Taproot present. Ground level or underground stems absent. Horizontal stems at ground level, branching extensively to shape plant habit as cushions. Caudex present (and freely branched). Aerial stems erect. Aerial stem trichomes present; dense; spreading. Leaves mainly basal; alternate; dying annually and non-persistent, or marcescent. Stipules present; persisting for 2 or more years; 4–8 mm long; 2–3 mm wide; sheathing (margins with clavate processes mixed with cilia); white (greyish or pale brown, strongly adnate to the petiole); hairy; pilose, or villous; apex acuminate. Petioles (5–)10–20(–35) mm long; hairy; villous. Petiole hairs longer than the diameter of the petiole; spreading; straight, or curved. Leaf blades compound. Leaves not grass-like. Blades 20–45(–60) mm long, 6–15 mm wide, with inconspicuous veins. Blade adaxial surface without sessile glands, hairy (sparsely hairy or glabrescent), hairs pilose (wavy) or short-silky, hairs simple, hairs dense, hairs white, or translucent. Blade abaxial surface hairy, hairs pilose or short-silky, hairs very dense, hairs white, hairs wavy (almost crinkly), hairs appressed or spreading. Blade apices acute. Leaflet arrangement pinnate. Leaflets 9–13; (4–)6–8(–10) mm long; 1.5–3 mm wide; oblong, or lanceolate; veins inconspicuous.

Reproductive morphology. Flowering stems about as high as the leaves, or conspicuously taller than the leaves; without leaves. Flowering stems hairy. Flowering stems villous, or tomentose. Flowering stem hairs simple; longer than the diameter of the flowering stem; white or translucent, or black. Inflorescences spicate and head-like; dense; globose or sub-globose; 1.5–2.5 cm long (flowers arising very close together at the top of the subumbelate inflorescence); 20–30 mm wide; not elongating as the fruit matures. Pedicels present (short). Floral scales hairy all over (pilose stipules). Flowers per inflorescence 1–5; medium-sized, or large (sweetly perfumed); bilaterally symmetrical (zygomorphic). Sepals conventional; 5; fused (about half their length); 10–15 mm wide; brown, or black. Calyx tubular; 5-lobed (teeth spathulate); hairy. Calyx hairs pilose, or villous; non-glandular; white or translucent. Calyx teeth equal or nearly so; 2.5–3 mm long. Petals conventional; both free and fused; 5; purple (vivid in young petals), or blue (fading in drying); with contrasting markings (colour gradation from deep colour on the tips to pale at the base of the petals; prominent veins on the banner petal act as guidelines); unlobed (4 petals), or slightly lobed or undulating (banner petal); 20–30 mm long. Corolla papilionaceous; keel with a pointed tip. Stamens 10. Anther filaments 9 fused into a tube, plus 1 free. Nectaries present. Ovary superior; carpels 1; monomerous. Stigmas per ovary 1. Ovules per ovary 10–15. Fruit stalked (within the calyx); with calyx persisting; dry; a legume; oblong (crescent shaped like a wide ulu); green at maturity, or yellowish (a dark olive green); 20–25(–30) mm long (with a long beak); 5–6 mm wide; hairy (with black hairs); not distinctly flattened; dehiscent; splitting to the base into separate segments. Legume unilocular; valves straight. Styles persisting in fruit 6x, 10x, and 12x. Cypselas surface This taxon has been collected as far north as Melville Island, Ibbett Bay, 75°54'N. Seeds 3–12; 2.5–3 mm long (in the longest dimension); brown; surfaces smooth.

Chromosome information. 2n = 48, 80, 96.

2n (6x) = 48. Murray and Kelso (1997, western Alaska);

2n (10x) = 80. Mosquin and Hayley (1966, northern Canada, 2n = about 80);

2n (12x) = 96. Mosquin and Hayley (1966, northern Canada, 2n = about 96); Löve and Löve (1975).

Ploidy levels recorded 6x, 10x, 12x.

Taxon as an environmental indicator. This taxon has been collected as far north as Ibbett Bay, 75°54'N.

Ecology and habitat. Substrates: hummocks, river terraces, tundra, slopes, ridges (dry, open, flat, tundra); solifluction slopes, moderately well-drained areas; gravel, sand, silt, till; with high organic content; calcareous.

North American distribution. Range in the Canadian Arctic Archipelago limited. Common (western arctic).

Northern hemisphere distribution. Amphi-Beringian (subsp. arctica and subsp. barnebyana in America, subsp. taimyrensis in northern Siberia (Elven et al. 2003)). Yamal–Gydan, Taimyr – Severnaya Zemlya, Anabar–Olenyok, Kharaulakh (subsp. taimyrensis), West Alaska, North Alaska – Yukon, Central Canada, Labrador – Hudson Bay (subsp. arctica).

General notes. In this treatment we have used the species name Oxytropis arctica because the subspecific circumscription is disputed on a circumarctic basis (Elven and Murray personal communication, 2005). However, all of the plants in the Flora region appear to fall under the typical subspecies O. arctica subsp. arctica. According to investigations of Jorgensen (2001) and Jorgensen et al. (2003), this typical subspecies is purple-flowered and appears to be distributed in Canada and northern Alaska. Their studies suggested that the white-flowered "barnebyana" entity of western and northern Alaska is best considered a variety of O. arctica.

The northern Canadian plants have been counted as decaploid and dodecaploid, Siberian plants (different subspecies) are counted as octoploid, and western Alaskan plants as hexaploid (incl. O. koyukukensis).

Illustrations. • Close-up of inflorescence. Note the deep magenta-purple standard banner petal that is lighter towards the base and the hairy sepals. Banks Island, Sachs Harbour. 27 July, 1981. J.M. Gillett 18867. CAN. • Close-up of plant. Plants growing on the bank above the beach. Banks Island, Sachs Harbour. 27 July, 1981. J.M. Gillett 18867. CAN. • Close-up of flower. Note the deep magenta-purple standard banner petal that is lighter towards the base, and the hairy sepals. J.M. Gillett 18867. • 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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