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

Astragalus australis (L.) Lam.

English: Richardson's milk-vetch, Indian milk-vetch.

Fabaceae (Leguminosae), Pea family.

Published in Fl. Fr. 2. 637. 1778.

Type: "Habitat in alpinis Helvitiae, Italiae, Gallo Provinciae". S.L. Welsh (1998), illustration of "Astragaloides Alpina supina glabra, foliis auctioribus" in Tilli, Cat. Pisani 19.5.14.f.1, 1723. Lectotype.

Synonymy. Phaca australis L., Mant. Pl. 103. 1767.

Astragalus aboriginum Richardson, in Franklin, Jour. Append. 746. 1823. ("aboriginorum"). Type: Canada: above Prince Albert, on the North Saskatchewan River. "Sandy plains in the neighbourhood of Carlton." Presumed holotype labelled ‘N. America, 1819–22, Richardson’, BM (Barneby 1964).

Homalobus aboriginum (Richardson) Rydberg, Mem. N.Y. Bot. Gard 1. (Fl. Mont.): 246. 1900.

Atelophragma aboriginum (Richardson) Rydberg, Bull. Torrey Bot. Club 32: 660. 1905.

Astragalus richardsonii Sheldon, Minn. Bot. Stud. 1: 126. 1894, a new name for Astragalus vaginatus (sheathing of the stipules) sensu Richardson ex Hooker, Fl. Bor.-Amer. 1: 149.1831 (non Pallas, 1800, tab. 36.) "Woody country between lat. 54° and 64°, Dr. Richardson." No holotype identified as such, specimen labelled simply Astragalus vaginatus. BM. Specimen at GH labelled "284."

Astragalus aboriginum var. richardsonii (Sheldon) B. Boivin, Phytologia 15: 383. 1967.

Astragalus vaginatus. Richardson's Arctic Plants (ex herb. Lowell), probably a duplicate of the preceeding." (Barneby 1964).

Vegetative morphology. Plants 10–25 cm high (coarse); perennial herbs; not caespitose. Taproot present. Well developed on older plants. Ground level or underground stems vertical. Caudex present (branching and subligneous in older plants). Aerial stems erect. Aerial stem trichomes appressed, or spreading. Leaves distributed along the stems; alternate (sometimes almost opposite in smaller plants); dying annually and non-persistent (leaf blades), or marcescent (petioles). Stipules present; persisting for 2 or more years; (3–)4–5 mm long; 2–3 mm wide (at base); sheathing (subconnate, i.e., joined at the base or free); black from hairs (when young), or brown (with age); hairy (when young, glabrescent); pilose (at the point of attachment to the stem); apex acute. Petioles 5–15(–20) mm long (slender); hairy (when young, glabrescent to almost glabrous with age); pilose. Petiole hairs longer than the diameter of the petiole (in young leaves); spreading, or erect; straight; smooth (flattened, whitish, approaching strigose). Leaf blades compound. Leaves not grass-like. Blades (25–)30–40 mm long, 10–20 mm wide, spreading, appearing single-veined. Blade adaxial surface glabrous (on the midrib) or hairy (for the most part), hairs pubescent, hairs simple, hairs moderately dense or dense, hairs white, or translucent. Blade abaxial surface hairy, hairs pubescent or villous (midvein prominent, other veins obscure), hairs very dense, hairs white (giving an ash-grey appearence), hairs straight or wavy, hairs appressed or spreading. Blade apices acute. Leaflet arrangement pinnate (odd-pinnate). Leaflets 7–15; 7–15(–17) mm long; 2–4.5 mm wide; linear and 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 pilose. Flowering stem hairs simple; black and white or translucent. Inflorescences racemose; terminal; dense (in flower); oblong, or globose or sub-globose; 1.5–4 cm long (in flower); 20–30 mm wide; elongating as the fruit matures. Bisexual spike(s) with empty bracts at the base (stipule-like). Flowers per inflorescence 7–15; medium-sized (without scent); bilaterally symmetrical (zygomorphic). Sepals conventional; 5; fused; 5–6 mm wide; brown (or black). Calyx tubular, or funnel-form; 5-lobed; hairy (densely so). Calyx hairs pilose; black. Calyx teeth equal or nearly so; 1.3–1.6 mm long. Petals conventional; both free and fused; 5; green, or white, or purple (banner and wing petals white or pale pink with prominent green veins, tips of the keel petals purplish, without any appendage; wing petals toothed); with contrasting markings (a blot of colour on the tip of the keel); unlobed (four petals), or slightly lobed or undulating (banner petal, wing petals toothed); 10–15 mm long (usually longer than the petals of plants of this species growing south of 60°N). 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. Anthers yellow; 0.3–0.5 mm long. Nectaries present. Ovary superior; carpels 1; monomerous. Stipes 2.5–8 mm long (in fruit). Stigmas per ovary 1. Ovules per ovary 3–12. Fruit stalked (within the calyx, borne on a stipe that is as long or almost twice as long); with calyx persisting; dry; a legume; ellipsoid (more or less inflated); red (becoming dark wine red, and somewhat translucent when mature); 10–26 mm long; 3–6(–10) mm wide (pods from southern plants usually 3.5–6 mm wide); glabrous (even when young); distinctly flattened; dehiscent; splitting to the base into separate segments. Legume nearly 2-locular by intrusion of placenta; valves straight. Styles persisting but not modified. Seeds 3–12; 1.5–2 mm long (i.e., the longest dimension); brown (pale and yellowish); surfaces smooth.

Chromosome information. 2n = 16, 32, and 48.

2n = 16, 32, 48. For the collective species:

2n (2x) = 16. Gervais et al. (1999, eastern Canada, for Astragalus australis subsp. glabriuscula);

2n (4x) = 32. Favarger (1962b, 1965, central Europe, Astragalus australis s.s.); Küfer (1974, central and southwestern Europe, Astragalus australis s.s.)

2n (6x) = 48. Favarger (1959a, 1962b, 1964, 1965, central Europe, Astragalus australis s.s.); Pogan et al. (1982, southern Poland, Astragalus australis s.s.).

Ploidy levels recorded 2x, 4x, and 6x.

Indigenous knowledge. The root was gathered as a spring vegetable by Cree and Stone Indians (Barneby 1964) for whom the epithet 'aboriginum' was named.

Taxon as an environmental indicator. The northernmost record is from Banks Island, site B-14 of Scotter and Zoltai, 73°27'N. CAN.

Ecology and habitat. Substrates: slopes, ridges, seashores (most commonly collected from gravel ridges); dry, moderately well-drained areas; gravel, sand; with low organic content; calcareous. Calcareous dry and gravelly places.

North American distribution. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories, Nunavut Islands, continental Nunavut. Range in the Canadian Arctic Archipelago limited. Uncommon. Low Arctic. Arctic islands: Banks, Victoria.

Northern hemisphere distribution. Porsild (1957); not fitting any pattern in the wide sense Elven et al. (2003. Polar Ural – Novaya Zemlya, Taimyr – Severnaya Zemlya, Anabar–Olenyok, Kharaulakh, Yana–Kolyma, West Chukotka, Wrangel Island, South Chukotka, East Chukotka, West Alaska, North Alaska – Yukon, Central Canada.

General notes. Barneby (1964) recognised this species as being in section Hemiphragmium. Porsild (1964) identified the Arctic taxon as A. richardsonii Sheldon and indicated the species is closely related to the prairie species A. aboriginum Richardson from which it differs in having large flowers, glabrous legumes, and more densely tomentose leaves.

Barneby (1964) stated that ‘because of the variations in stature, vestiture, and amplitude of the foliage, the Indian milk-vetch, A. aboriginum, cannot be characterised in a few succinct words’. He placed A. richardsonii in synonymy under A. aboriginum because of the large, prominently veined, obtuse stipules at base of the stems and the toothed wing petals.

Barneby (1964) also noted that "the Arctic and sub-arctic races of A. aboriginum introduce three new features, petioled stem leaves, larger flowers, and broader pods than found in the Rocky Mountains." Barneby (1964) was not willing to equate A. aboriginum with the circumpolar A. australis (also the earlier name), however. This step was left to Welsh (1991).

Murray and Elven (personal communication, 2005) noted that this section, or alternatively as the A. australis aggregate, is perhaps the most controversial group of arctic Astragalus. The opinions differ strongly, both in general and among the collaborators on the Panarctic Flora Checklist (Elven et al. 2003). No consensus has been arrived at. It is one case, among many, of very widespread Eurasiatic and North American taxa with several allopatric to parapatric, morphologically distinguishable entities in different mountains and tundras. Such cases have been treated very differently in different families and by various authors. We are here treating A. aboriginum and A. richardsonii under A. australis (following Welsh 1991), pending further study in this group.

Astragalus australis was one of the taxa considered by Liston (1992) in a study of the variation in the chloroplast genes RPOC1 and RCOP2 of the genus.

Illustrations. • Habitat: Banks Island. Prostrate plant growing with Dryas, Draba and sedge. N.W.T., Banks Island, Aulavik National Park, beside the Thomsen River. 9 July, 1999. Aiken 99–035. CAN. Scale bar in cm. • Habit: Banks Island. Close-up of prostrate plant with hairy, compound leaves and flowers in bud. N.W.T., Banks Island, Aulavik National Park, beside the Thomsen River. 9 July, 1999. Aiken 99–035. CAN. Scale bar in cm. • Aboveground and belowground. Note well-developed, sub-ligneous caudex and plants flowering as the leaves are expanding. N.W.T., Banks Island. CAN 220055. • Contrasting stipules. Above, on either side of the petiole, the current season's sub-connate stipules are free for almost all their length and covered with black hairs. Note subtended pinnate young leaf folded in bud and covered with long hairs. Far left, stipules that have persisted overwinter and surround a previous season's stem. The leaf these stipules subtended has died. N.W.T., Banks Island. CAN 220055. • Close-up of young stipule in previous image. Black villous hairs on the stipules, long white villous hairs on the stem and leaf petiole. Hairs often wider than the diameter of the petiole. N.W.T., Banks Island. CAN 220055. • Close-up of young leaf. Inner (adaxial) surface of stipules glabrous, shown on folded back stipule near bottom of picture. Abaxial surfaces covered with black villous hairs, shown on other stipules. Leaves and petioles covered with white villous hairs, through which the midribs of the developing leaflets are dark brown, and the blade surfaces show green. Hairs often wider than the diameter of the petiole. N.W.T., Banks Island. CAN 220055. • Inflorescence in bud. Close-up of inflorescence showing buds with cream-coloured banner petals with vivid red tips. Note the hairy sepals that are black towards the tips. N.W.T., Banks Island, Aulavik National Park, beside the Thomsen River. 9 July, 1999. Aiken 99–035. CAN. • Side view of flowers. Side view of flowers showing teeth on the sepals covered with long black hairs. N.W.T., Banks Island, Big River. CAN 535974. • Close-up of developing inflorescence. Developing inflorescence in which buds are cream and slightly reddish towards the tips of the banner petal. N.W.T., Banks Island, Aulavik National Park, beside the Thomsen River. 9 July, 1999. Aiken 99–035. CAN. • Close-up of flower. Close-up of flower with a lobed banner petal and wing petals around the purplish keel petals. N.W.T., Banks Island, Aulavik National Park, beside the Thomsen River. 9 July, 1999. Aiken 99–035. CAN. • Herbarium specimen. Neotype of Astragalus richardsonii Sheld. Flowers with yellow petals and blackish fused sepals. Note the taproot with many shoots arising from the caudex or root crown. N.W.T., Banks Island, south-west coast north of Cape Lambton. 30 July, 1949. A.E. Porsild 17587. CAN 127991. • 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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