Astragalus L.
Milk vetch.
Fabaceae (Leguminosae), pea family.
Vegetative morphology. Plants perennial herbs; 2–30 cm high; with single unbranched or with spreading stems. Taproot present. Caudex present (usually). Aerial stems erect, or decumbent; glabrous, or sparsely hairy, or densely hairy. Leaves distributed along the stems; alternate, or opposite (compact plants of Astragalus alpinus have leaves that may appear opposite); compound. Stipules present; leaf-like, or scale-like; sheathing, or not sheathing; brown, or green. Petioles 5–35 mm long. Blades 15–55 mm long; 8–25 mm wide. Blades veins pinnate. Blades adaxial surface glabrous, or hairy. Blades abaxial surface glabrous, or glabrescent, or hairy. Leaflet arrangement pinnate. Leaflets 7–23; 3–12 mm long; linear, or oblong, or elliptic, or lanceolate.
Reproductive morphology. Flowering stems present. Flowering stems without leaves; hairy. Inflorescence racemose; 0.5–9 cm long. Flowers per inflorescence 3–16; medium-sized, 5–15 mm in diameter or length; zygomorphic. Calyx sepals 5; fused. Calyx brown, or black; tubular, or funnel-form; 5-lobed; hairy. Petals both free and fused; longer than the calyx; 5; green, or white, or purple, or blue; with contrasting markings; tipped with an awn-like bristle, or not tipped with an awn-like bristle; 6–15 mm long. Corolla papilionaceous. Corolla keel blunt. Stamens 10; filaments all equal in length. Nectaries present. Gynoecia superior. Carpels monomerous. Stipes 0–8 mm long (in fruit). Stigmas per style 1. Ovules 3–12. Fruit stalked. Fruit with calyx persisting; dry; a legume; spherical (almost), or ellipsoid, or ovoid; dehiscent. Fruit 5–26 mm long; 2.5–6 mm wide; black, or brown; glabrous, or hairy. Legume nearly 2-locular by intrusion of placenta. Styles may persist until dehiscence but are not modified. Seeds 3–12; 1–2 mm long; brown, or yellowish; with surfaces smooth.
Chromosome information. 2n = 16, 32, 48.
Distribution. Northern hemisphere distribution: circumpolar, or amphi-Beringian, or North American. Arctic Islands: Baffin, Parry Islands, Banks, Victoria, Somerset, King William, Southampton, Coats.
Ecology and habitat. Substrates: imperfectly drained moist areas; acidic, or calcareous. Habitats: dry or moist sandy areas.
Notes. The name Astragalus is from the Greek for ankle-bone, used in ancient times as a form of dice. It has been supposed that word was applied to the plant, because of the rattle of seeds within the dry pods of some species.
Cite this publication as: ‘S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, L.J. Gillespie, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, A.K. Brysting and H. Solstad. 1999 onwards. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 29th April 2003. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993, 1995, 2000) should also be cited (see References).