Ascending or decumbent, branching from the base, 6—15 inches high, slightly hairy or smooth. Leaves 2—5 inches long, with 13—25 oval or elliptic, obtuse or retuse leaflets, narrowed or rounded at the base, ¼—½ an inch long. Flowers ½ an inch or more long, pale violet, the keel commonly darker, in short rather open racemes; calyx about ⅓ the length of the corolla, with short black hairs. The most dainty of any of the vetches, frequent in rocky soil in slightly shaded situations throughout the Rockies at the lower altitudes; flowering during June and July. [Sidenote: =Astragalus convallarius= Greene. _Slender Milk-vetch._] Stems slender, ascending and rigid, 10—18 inches high, branching from the base; hairy throughout. Leaves 3—6 inches long with 9—17 narrowly linear, silky leaflets ½—1 inch long, remote. Flowers pale violet or mauve, half an inch or more long, scattered in a slender raceme 3—5 inches long; peduncles much longer than the leaves; calyx about ⅓ the length of the corolla with scattered white or brownish hairs. On the eastern slopes of the Rockies in dry stony ground at the lower altitudes; flowering in early June. [Sidenote: =Astragalus Macouni= Rydb. _Macoun’s Vetch._] Stems 18—24 inches high, stout and leafy, slightly striate and nearly smooth. Leaves 2—4 inches long, thin, odd-pinnate with 4—8 pairs of obtuse, oblong, or oval leaflets, ½—1 inch long. Flower scream-coloured, tinged with blue, in heads 1½—3 inches long, on peduncles 4—10 inches long, from the axils of the upper leaves; calyx ⅛ of an inch long, black-hairy, lobes very slender and short; corolla ¼ of an inch or more long. Frequent in more or less moist open ground throughout the Rockies at varying altitudes; flowering during June and early July. [Sidenote: =Phaca Americana= (Hook) Rydb. _Arctic Milk-vetch._] Erect, nearly simple and smooth, 1—2 feet high. Leaves 3—6 inches long with 7—17 oval or ovate-lanceolate obtuse leaflets, ¾—1½ inches long. Flowers white, ¾ of an inch long in loose racemes on peduncles equalling or exceeding the leaves; pedicels slender, ½ an inch long in fruit; pod membranous, inflated, an inch long. In moist or wet rocky shaded places throughout the Rockies; flowering during June and early July. [Illustration: Phaca americana (Hook.) Rydb. (½ Nat.) Arctic Vetch.] [Illustration: Homalobus aboriginorum (Richards) Rydb. (⅓ Nat.) Indian Vetch.] [Sidenote: =Homalobus aboriginorum= (Richards) Rydb. _Indian Vetch._] Stems erect and branching, 6—18 inches high, hairy throughout, from an enlarged root. Leaves pinnate with 7—11 linear leaflets; stipules ovate, acute, foliaceous. Flowers white, tinged with mauve, in a loose raceme 1—2 inches long; peduncles longer than the leaves, calyx black-hairy, about ⅛ of an inch long, with slender teeth nearly half as much longer; corolla more than twice the length of the calyx.