Flora of the Canadian Arctic Archipelago


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

Astragalus alpinus L.

English: Alpine milk-vetch,

French: Astragle alpin.

Fabaceae (Leguminosae), Pea family.

Published in Sp. Pl. 760. 1753.

Type: Scheuchzer (1723), Uredif. Helv. f. 7, selected by Podlech, in Turland and Jarvis, Taxon 46: 463. 1997. Lectotype.

Epitype: Schweiz: Joch-Alpe prope Churwalden, 07.1863, leg. Brügger BM. Elven (personal communication, 2005) noted that a specimen in Linnaean Lapland Herbarium (LAPP) was indicated as a possible holotype by Gillett et al. (1999 onwards), but as several elements are cited in the protologue, there can be no holotype. The chosen lectotype and neotype decide one question. If there is a taxonomical difference between the central European plants and the northern and arctic ones, the name A. alpinus from now on belongs to the central European plants.

Synonymy. Atelophragma alpinum (L.) Rydberg, Bull. Torrey Bot. Club 55: 130. 1928.

Astragalus arcticus Bunge, Mém. Acad. Imp. Sci. Saint Pétersbourg, sér. 7, 15, 1: 27. 1869, non A. arcticus Willd. 1813.

Astragalus alpinus subsp. arcticus (Bunge) Lindm., Sv. Fanerogamfl., ed. 2, 384. 1926

Astragalus subpolaris Boriss. and B. Schischk., Fl. URSS, 12: 44. 1946.

Astragalus alpinus subsp. alaskanus Hultén, Acta Univ. Lund., n. s., sect. 2, 43, 1: 1082. 1947.

Astragalus alpinus var. alaskanus (Hultén) Lepage, Amer. Midl. Nat. 46: 757. 1951. No type designated, but 15 collections at NY and US cited by Hultén (Barneby 1964). Hultén (1947, not 1944!) wrote on p. 1084: "Type locality ... subsp. alaskanus: "Yukon district" June 18, 1898 (Five Finger Rapids) Andersson (S)". This specimen (seen by Elven in S, before 2005) is then the holotype.

Phaca astragalina Hooker, Fl. Bor.-Amer. 1: 145. 1831. Non DC., Astragalogia 64. 1802.

Astragalus astragalinus (Hooker) Á. Löve and D. Löve, Bot. Not. 128: 515. 1976. Non (DC.) E.Sheld., Minnesota Bot. Stud. 1: 65. 1894.

Vegetative morphology. Plants 2–25 cm high (low and matted); perennial herbs; not caespitose. Taproot present. Well developed on older plants. Ground level or underground stems horizontal; rhizomatous; elongate; 0.4–0.8 mm wide. Horizontal stems at ground level, branching extensively to shape plant habit as mats (loosely formed from weak branches). Ground level or underground stems scales absent (stipules present). Caudex absent. Aerial stems branching from a tap at or near ground level into two or more branches; erect (small plants), or decumbent (larger plants with creeping freely branched weak stems). Aerial stem trichomes appressed. Leaves distributed along the stems; alternate (larger plants), or opposite (semi-opposite; compact plants); dying annually and non-persistent. Stipules present; persisting for 2 or more years; 3–4 mm long; 2–2.5(–3) mm wide (at base, side view); sheathing (connate, collar-like around the stem); black from hairs (when young), or brown (with age); hairy (when young, glabrescent); villous (towards the apex); apex acute, or rounded. Petioles (5–)10–25(–35) mm long; hairy (glabrescent); villous. Petiole hairs shorter than the diameter of the petiole; appressed; straight; smooth (flattened, whitish, approaching strigose). Leaf blades compound. Leaves not grass-like. Blades 15–55 mm long, 8–20 mm wide, spreading, appearing single-veined. Blade adaxial surface hairy (when young, glabrescent with age) or glabrescent, hairs pilose (on some leaves) or strigose, hairs simple, hairs sparse or moderately dense, hairs white, or translucent. Blade abaxial surface without sessile glands or glandular hairs, hairy, hairs short-silky or long-silky (on the central vein) or strigose, hairs moderately dense, hairs white, hairs straight, hairs appressed. Blade apices acute, or rounded. Leaflet arrangement pinnate (odd-pinnate). Leaflets 9–23; 3–12 mm long; 3–4.5 mm wide; oblong, or elliptic, or lanceolate (broadly); veins inconspicuous.

Reproductive morphology. Flowering stems two or more per plant; about as high as the leaves, or conspicuously taller than the leaves; without leaves. Flowering stems hairy. Flowering stems pilose, or strigose. Flowering stem hairs simple; black and white or translucent. Inflorescences racemose; terminal; dense (in flower); oblong, or globose or sub-globose; 0.5–1.5 cm long; 20–30(–35) mm wide; not elongating as the fruit matures. Bisexual spike(s) with empty bracts at the base (stipule-like). Flowers per inflorescence 3–9(–11); medium-sized, or large; bilaterally symmetrical (zygomorphic). Sepals conventional; 5; fused; 4–5 mm wide; green, or brown, or black (from hairs on the surface). Calyx tubular, or funnel-form; 5-lobed; hairy. Calyx hairs pilose; black. Calyx teeth equal or nearly so; 1.3–1.5 mm long. Petals conventional; both free and fused; 5; purple, or blue; with contrasting markings (some flowers have magenta coloured banner and keel petals and whitish wing petals), or without contrasting markings (flowers uniformly whitish); unlobed (4 petals), or slightly lobed or undulating (banner petal); 6–10 mm long. Corolla papilionaceous; keel blunt. Stamens 10; stamen filaments all equal in length (or slightly unequal). Anther filaments 9 fused into a tube, plus 1 free. Stamens free of the corolla. Anthers yellow (orange); 0.3–0.5 mm long. Nectaries present. Ovary superior; carpels 1; monomerous. Stipes 1.5–3 mm long (in fruit). Stigmas per ovary 1. Ovules per ovary 5–10. Fruit stalked (on a short stalk and hanging downwards); with calyx persisting; dry; a legume; ellipsoid, or ovoid (sometimes crescent or ulu-shaped in outline especially when pressed: hirsute, drying yellowish); brown (pale and yellowish); (5–)6–10(–12) mm long (more than 10 mm long when fully mature, and in this character distinct from A. eucosmus); 2.5–4 mm wide; hairy (with obvious black or brown hairs); distinctly flattened (sometimes); dehiscent; splitting to the base into separate segments. Legume nearly 2-locular by intrusion of placenta; valves straight. Styles persisting but not modified. Seeds 3–5(–8); 1–2 mm long (i.e., the longest dimension); yellowish; surfaces smooth.

Chromosome information. 2n = 16 and 32.

2n = 16. The chromosome number information is here roughly sorted according to source region, as a sorting on 'taxa' yet is difficult:

2n = 16. Central and southern and northern Europe: Favarger (1949b, 1965a); Favarger and Küpfer (1968); Küpfer (1974); Murín (1992);

2n = 16. Northern Europe and Russia: Sokolovskaya and Strelkova (1960); Laane (1965); Hedberg and Hedberg (1964); Knaben and Engelskjøn (1967); Sokolovskaya (1970); Lavrenko et al. (1990);

2n = 16. Central and southern and northern Siberia: Krogulevich (1971, 1976a, 1977, 1978); Belaeva and Siplivinsky (1976);

2n = 32. Northern Siberia: Yurtsev and Zhukova (1982); Zhukova and Petrovsky (1983b, northeastern Siberia and Chukotka, 13 counts, by Yurtsev as subsp. alpinus); Krogulevich (1984).

2n = 16. Beringian northeastern Asia: Zhukova and Petrovsky (1976); Gurzenkov and Pavlova (1983, 1984); Zhukova and Petrovsky (1983b, southern Chukotka, two counts, by Yurtsev as subsp. alaskanus).

2n = 32. Zhukova (1966); Zhukova and Petrovsky (1983b, northeastern Siberia and Chukotka, 13 counts, by Yurtsev as subsp. alpinus, 1983, Wrangel Island, by Yurtsev as subsp. arcticus); Sokolovskaya (1963, 1968); Zhukova et al. (1973); Zhukova and Tikhonova (1973); Zhukova et al. (1977); Zhukova and Petrovsky (1980); Pavlova et al. (1989);

2n = 32. Beringian northwestern America (Alaska-Yukon): Holmen (1962); Hedberg (1967); Johnson and Packer (1968); Mulligan and Porsild (1969); Packer and McPherson (1974);

2n = 16. Northern Canada and Rockies: Spellenberg (1976);

2n = 32. Mosquin and Hayley (1966, Northern Canada, Prince Patrick and Melville islands); Löve and Löve (1982a, Arctic Canada, Churchill). Hedberg (1967, northern Canada, Ungava, Victoria and Baffin islands);

Not sorted: Ledingham (1960 2n = 16 32); Ledingham and Fahselt (1964 2n = 16–32).

All of Europe has only diploids, and diploids are also the only ones counted in south and central Siberia. They also occur, together with tetraploids, in the Russian Far East and perhaps in Cordilleran North America. Tetraploids occur eastwards from central northern Siberia, and may be more frequent in the Russian Far East. They are the only counts from Beringian northwestern America and northern Canada.

Ploidy levels recorded 2x.

Taxon as an environmental indicator. This is a phenotypically plastic taxon that is able to occupy a variety of habitats. The size of the plants is an indication of the exposure, water, and mineral availability of a site. In adverse conditions plants are only 5 cm tall, in favourable conditions they may be 15–25 cm tall. The northernmost records are from Lichutin Island, approx. 76°N in Novaya Zmelya, Russia, and Melville Island, Marie Bay, 76°15'N, in Canada. In North America, the range extends from Alaska south to the mountains of New Mexico, with extensions eastwards to the Canadian Arctic Islands, across the northern portion of the prairie provinces to James Bay, northern Quebec and Labrador, southern Quebec and New Brunswick to Newfoundland.

Ecology and habitat. Substrates: hummocks, snow patches, river terraces, lakeshores, tundra, slopes, seashores; imperfectly drained moist areas (rarely), dry (commonly), moderately well-drained areas; rocks, gravel, sand, silt (often forming patches); with low organic content; acidic. This species may be locally abundant and form large mats in areas that are rather dry and exposed, sandy or gravelly. It often occurs with grasses as a colonising species. Plants flower and fruit profusely and usually produce numerous root nodules.

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 (where it occurs). Arctic, Low Arctic. Arctic islands: Baffin, Parry islands (Eglington, Melville and Prince Patrick), Banks, Victoria, Somerset, King William, Southampton, Coats (Bylot and Digges islands, Boothia and Melville peninsulas).

Northern hemisphere distribution. Circumpolar, or circumboreal. Northern Fennoscandian, Kanin–Pechora, Polar Ural – Novaya Zemlya, Yamal–Gydan, Taimyr – Severnaya Zemlya, Anabar–Olenyok, Kharaulakh, Yana–Kolyma, West Chukotka, Wrangel Island, South Chukotka, East Chukotka, West Alaska, North Alaska – Yukon, Central Canada, Labrador – Hudson Bay, East Greenland.

General notes. Barneby (1964) recognised this species as being in the section Astragalus. He stated that ‘the alpine milk-vetch is the most widely dispersed of all astagali, yet when due allowance has been made for the diversity of soils, climates, and environments to which it has become adapted, it is a comparatively little variable species.’ He recognised two varieties as occurring in North America. The arctic plants are A. alpinus var. alpinus. A second variety, A. alpinus var. brunetianus, occurs on river and lake shores in New England, Newfoundland, and southeastern Quebec.

Barneby (1964) discussed another variant of A. alpinus, "... confined to the highest latitudes around the pole, that has been described as A. arcticus Bunge." It was maintained by Gontscharov (1946), as a distinct species under the epithet subpolaris, and recognised by Hultén (1944) as a subspecies coordinate with subsp. alaskanus. Barneby (1964) whom we follow found no reason to recognise variants such A. arcticus Bunge or A. subpolaris Gontascharov at species level.

Polunin (1940, p. 288) noted that the little ‘alpine milk-vetch varies considerably in robustness and general appearance; also varies in the colour of the flowers and the size, shape and hairiness of the leaflets’.

Elven et al. (2003) proposed three subspecies: subsp. alpinus in northeastern Siberia, Russian Far East, and North America; subsp. arcticus in northern Europe, northern Asia, North America, and northeastern Greenland; and subsp. alaskanus in eastern and southern Chukotka and in Alaska. Only subsp. alpinus is in the Flora region.

Illustrations. • Habitat in gravel: Cape Dorset. Plants growing with Dryas and fireweed on gravelly slope. Nunavut, Baffin Island, Cape Dorset. 2 August, 2005. Aiken. No voucher. • Habitat in dry gravel: Cape Dorset. Plants with darker than usual nearly purple flowers (colour not accurate in the image). Growing in the same area as the previous image. Nunavut, Baffin Island, Cape Dorset. 6 August, 2005. Aiken. No voucher. • Close-up of plants in gravel: Cape Dorset. Plants with pale blue flowers. Note white thread-like stolons that result in plants forming mats on the tundra. Nunavut, Baffin Island, Cape Dorset. 6 August, 2005. Aiken. No voucher. • Habitat: Banks Island. Plants growing on a bank above sandy beach. N.W.T., Banks Island, Sachs Harbour. 27 July, 1981. J.M. Gillett 18866. CAN. • Habitat: Banks Island. Plants growing on sandy bank. N.W.T., Banks Island, Aulavik National Park, Thomsen River. 11 July, 1999. Aiken 99–039. CAN. Scale bar in cm. • Close-up of plant with pink flowers. Plant with pink flowers growing on a pebble beach with driftwood. N.W.T., Tuktoyaktuk. 21 July, 1981. J.M. Gillett 18737. CAN. • Habitat: Rankin Inlet. Plant with white flowers growing on dry lichen tundra. N.W.T., Rankin Inlet, in the Head Lake area. 15 July, 1982. J.M. Gillett 15753. CAN. • Close-up of plant with white flowers. Plant with white flowers growing in Nunavut, near Rankin Inlet, Nipissak Lake, in patches on gravel. 20 July , 1973. J.M.Gillett 16122. CAN. • Close-up of underground rhizomes. Delicate underground rhizome with stipule scales persisting for more than one year. • Close-up of stipule at base of petiole. Hairy stipule at the base of a sparsely hairy petiole Note it is oblong in outline with a pointed tip. Photograph by Kathy Thornhill, 2005. • Contrasting stipules and leaves. Young leaf covered with white strigose hairs. Older leaf with sparse hairs. Young stipule covered with dark black hairs, older stipule brown, membranous, connate at the base and free in the upper part. N.W.T., Banks Island, Parker River Valley. CAN 583697. • Contrasting young and flowering inflorescences. Lower left, the youngest inflorescences is a small black ball, made black by the calyx tube hairs. Upper left, inflorescence is expanding to show the purple tips of the petals. Right, expanded spike-like racemose inflorescence with the flowers almost sessile, the calices expanded and a lighter colour, fused at the base with deltoid tips 1.5–2.5 mm long. Petals with the banner petal and keel petals purple and the wing petals a pale, orange cream. N.W.T. Banks Island, Thompson River. Aiken 99–039. CAN 582413. • Close-up of young and older leaf. Odd-pinnate compound leaf, that is one with pairs of leaflets up the rachis and a single terminal leaflet. Note almost glabrous mature leaf and densely pubescent young leaves that have black hairy stipules at the base of the petiole. N.W.T., Banks Island, Thompson River. Aiken 99–039. CAN 582413. • Inflorescence in bud. Note the dark colour of the bud petals and the sepals. N.W.T., Banks Island, Aulavik National Park. 11 July, 1999. Aiken 99–039. CAN. • Inflorescence coming into flower. Note the dark colour of the buds, the banner and keel petals and the light colour of the wing petals. N.W.T., Banks Island, Aulavik National Park. 11 July, 1999. Aiken 99–039. CAN. • Close-up of inflorescence: Baffin Island. Note relatively pale flowers each with a pale green calyx fused at the base with prominent teeth at the apex. Note banner petals with prominent guidelines. Aiken and Annie Archambault. 2005. No Voucher. • Side view of flower. Note the upper purplish banner, or standard petal, the white wing petals, and the deep purple blunt tip of the keel petals. Banks Island, Aulavik National Park. 11 July, 1999. Aiken 99–039. CAN. • Close-up of inflorescence with white flowers. Flowers with slightly pinkish white petals and green sepals. Nunavut, Rankin Inlet, Nipissak Lake. 20 July, 1973. J.M. Gillett 16122. CAN. • Plant in fruit. Plant mat covered with inflorescences that have set dark clusters of seed pods. Nunavut, Baffin Island, Cape Dorset. 6 August, 2005. Aiken. No voucher. • Close-up of fructescence. Close-up of infructescence with the white remains of the fused anther tubes around the developing legumes. Left, downward pointing developing legumes. Note that inflorescence does not elongate in fruit, and legumes with pointed beaks. N.T.W., Melville Island. CAN 489904. • 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.