Oxytropis nigrescens (Pall.) Fisch. ex DC. var. uniflora (Hook.) Barneby
Proc. Calif. Acad. Sci. Ser. 4. 27: 209. 1952.
Oxytropis arctica var. uniflora Hook. Append. Parry's Second Voyage, 396. 1825.
Type: Nunavut: Barrow River, E. coast Melville Peninsula, lat. 67°21'N, on Parry's Second Voyage. Isotypes GH, NY.
Oxytropis arctobia Bunge Gen. Oxytr. 114: 1874. Oxytropis nigrescens subsp. arctobia (Bunge) Hultén, Arkiv för Botanik, Andra Serien 7: 80. 1968. Oxytropis nigrescens var. arctobia (Bunge) Gray, Proc. Amer. Acad. 20: 3. 1884.
Plants cushion-like (velvety-grey and up to 30 cm in diameter), or with leaves or spreading stems arising from a caudex; 1–5 cm high. Aerial stems erect; densely hairy (not easily visible between the appressed leaves). Leaves distributed along the stems (that are very compact); alternate; marcescent. Stipules sheathing (base of petiole expanded, stipules surrounding the stem); white (or pale grey from numerous hairs, stipule margins ciliate, sometimes with clavate processes). Petioles 5–15 mm long (not very obvious). Blades 5–8 cm long; 3–6 mm wide; with pinnate veins; hairy (densely so); with hairs equally dense on both surfaces. Leaflet arrangement pinnate; leaflets (3–)5–9(–13); leaflets 3–4.5 mm long (often conduplicate, i.e. margins rolled inwards, and with dense grey hairs).
Flowering stems 0.5–1.5 cm long (flowers are borne, just above the leaves, on the plant cushion); without leaves; hairy. Flowers solitary, or in inflorescences (of two flowers, often numerous on the plant cushion). Inflorescence 0.1–0.2 cm long (when applicable). Flowers per inflorescence 2 (when applicable); medium-sized, 5–15 mm in diameter or length. Floral scales hairy all over (pilose). Calyx green, or brown, or black (because of black hairs); tubular; 5-lobed. Petals 5; purple (at the tips of the petals, fading to light brown); unlobed (4 petals), or 2-lobed (banner petal); 8–12 mm long. Corolla papilionaceous. Corolla keel with a pointed tip. Stamens 10. Stigmas per style 1. Ovules 15–25. Fruit with calyx persisting; a legume (sessile within the calyx); ellipsoid, or elongate-cylindrical; (15–)25–30 mm long; 6–9 mm wide; sessile; dehiscent; black; hairy. Legume unilocular. Seeds 10–20; 1.2–1.6 mm long (i.e., the longest dimension); brown.
Chromosome information. 2n = 16.
Distribution. Low arctic (endemic to the central Canadian arctic from Banks Island to Baffin Island, also on Melville Peninsula and the south coast of Baffin, Southampton and adjacent islands in Hudson Bay). Range in the Canadian Arctic Archipelago limited. Arctic Islands: Baffin, Parry Islands (Eglinton), Banks, Victoria, King William, Southampton.
Ecology and habitat. Substrate hummocks (uncommonly), river terraces, ridges (very often); moderately well drained; calcareous; gravel, silt, clay; with high organic content (locally). At anthesis this species is strikingly handsome when the firm grey cushions of large individuals may be covered with several hundred flowers. In fruit the legumes are large and black and show up against the ashy-grey foliage, which otherwise tends to blend in with the grey gravel on which it grows.
Taxon as an environmental indicator. Polunin (1940) reported the northernmost record as Baffin Island, Arctic Bay, 73°05'N. Since that time, it has been collected further north, on Eglinton Island, Kuc, 8 July 1968, 75°48'N.
Notes. Polunin (1940) noted that there is a specimen of this species in the Gray Herbarium among a collection that has often been referred to as coming from Melville Island, but actually was made far to the southeast during Parry’s second voyage. He indicated that the Arctic Bay material differs from all other specimens that he had examined in having seeds that are light brown instead of almost black when ripe, and having the insides of the pods essentially glabrous instead of flocculent-pubescent. The pubescence on the outside also tends to be less dense and spreading. On these characters he recognized O. arctobia var. hyperarctica Polunin. This taxon has not been widely taken up.
Prevost and Bal Arya (1994) studied the early stages of nodulation in roots of what they called O. arctobia induced by the arctic rhizombial strain N31.
Illustrations. • Herbarium specimen. Flowering specimen originally with blue petals that have faded to yellowish, and with blackish sepals. Note leaflets less than 0.5 cm long. Nunavut, Victoria Island, Cambridge Bay, 27 July, 1949, A.E. Porsild, 17206. CAN 128009. • Herbarium specimen. Fruiting specimen with hairy pods to 2 cm long, the remains of petals and blackish calyx lobes. Note finely divided pale grey-green leaves. Nunavut, Victoria Island, Cambridge Bay, 20 July, 1962, S. Stephens, 1091. CAN 273711. • Herbarium specimen. Holotype specimen of Oxytropis arctobia Bunge var. hyparctica. Polunin Bot. Can. E. Arctic, p. 293. Nunavut, Baffin Island, Arctic Bay, 8–11 Sept 1936, N. Polunin, 2583. CAN 76863. • Habitat. Plants growing on south facing rocky sandy barren. N.W.T., Banks Island, Aulavik National Park near Shoran Lake 73°30'73 N; 120°21'.13 W. 1 July, 1999, Susan Aiken, no voucher. • Plants in habitat. Plants growing on south facing rocky sandy barren. N.W.T., Banks Island, Aulavik National Park near Shoran Lake 73°30'73 N; 120°21'.13 W. 1 July, 1999, Susan Aiken, no voucher. • Plant with flowers in bud. Note the very black sepals and the first sign of petal colour. The "black" is the result of hairs on the sepals that appear to aid in warming the developing flower. N.W.T., Banks Island in Aulavik National Park, near Green Cabin, June 29, 1999. Susan Aiken, SA99–015, CAN. • Flowers in bud. The "black" is the result of hairs on the sepals that appear to aid in warming the developing flower. N.W.T., Banks Island in Aulavik National Park, near Green Cabin, June 29, 1999. Susan Aiken, SA99–015, CAN. • Plants with buds. Plant with closed and opening buds growing on south facing rocky sandy barren. Note the very black sepals, and almost all of the flowers pointing in the same direction towards the sun. N.W.T., Banks Island, Aulavik National Park near Shoran Lake 73°30'73 N; 120°21'.13 W. 1 July, 1999, Susan Aiken 99–011, CAN. • Plant coming into flower. Plant coming into flower. Note the two colored standard or banner petal, and sepals covered with black hairs. These possibly aid in warming the developing flower. N.W.T., Banks Island in Aulavik National Park, near Green Cabin, June 29, 1999. Susan Aiken, SA99–015, CAN. Scale bar in cm. • Plant coming into flower. Note the two colored standard or banner petal, and sepals covered with black hairs. These possibly aid in warming the developing flower. N.W.T., Banks Island in Aulavik National Park, near Green Cabin, June 29, 1999. Susan Aiken, SA99–015, CAN. • Close-up of flower. Flower with contrasting markings on the standard or banner petal. N.W.T., Banks Island in Aulavik National Park, near Green Cabin, June 29, 1999. Susan Aiken, SA99–015, CAN. • Plant in habitat. Plant covered with a mass of flowers,growing with Dryas on south facing rocky sandy barren N.W.T., Banks Island, Aulavik National Park, confluence of Thomsen and Muskox Rives. 13 July, 1999, Susan Aiken 99–062, CAN. Scale bar in cm. • Plant habit. Flowers fading to blue and returning to more or less prostrate on the ground after being erect. N.W.T., Banks Island in Aulavik National Park, beside Muskox River. 9 July, 1999. Susan Aiken, 99–062, CAN. • Plant with seed pods. Previous season's seed pods lying on the tundra. Flowers in bud. N.W.T., Banks Island in Aulavik National Park, near Green Cabin, June 29, 1999. Susan Aiken. SA99–015, CAN. Scale bar in cm. • Close-up of seed pods. Previous season's seed pods lying on the tundra. N.W.T., Banks Island in Aulavik National Park, near Green Cabin, June 29, 1999. Susan Aiken. SA99–015, CAN. • Arctic island distribution.
Cite this publication as: J.M. Gillett, L.L. Consaul, S.G. Aiken and M.J. Dallwitz (1999 onwards). ‘Fabaceae of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval.’ Version: 15th November 2000. http://http://www.mun.ca/biology/delta/arcticf/. Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993, 1995, 2000) should also be cited (see References).
