Calyx small, equally 5-cleft. Standard roundish, silky outside, wings coherent; keel erect, gibbous or spurred at base. Stamens diadelphous; connective gland-like. Pod 1–several-seeded, septate within between the seeds.—Herbs or shrubs, mostly canescent with appressed hairs fixed by the middle, with odd-pinnate faintly-nerved leaves, and pink or purplish flowers in naked axillary spikes. (So named because some of the species yield the indigo of commerce.)
1. I. leptosépala, Nutt. A perennial herb, ½–2° high; leaflets 5–9, oblanceolate; spikes very loose; pods linear, 6–9 seeded, obtusely 4-angled, reflexed, 1´ long.—Kan. to Tex. and Fla.
Calyx short, 5-toothed, slightly 2-lipped. Standard large and rounded, turned back, scarcely longer than the wings and keel. Stamens diadelphous. Pod linear, flat, several-seeded, margined on the seed-bearing edge, at length 2-valved.—Trees or shrubs, often with prickly spines for stipules. Leaves odd-pinnate, the ovate or oblong leaflets stipellate. Flowers showy, in hanging axillary racemes. Base of the leaf-stalks covering the buds of the next year. (Named in honor of John Robin, herbalist to Henry IV. of France, and his son Vespasian Robin, who first cultivated the Locust-tree in Europe.)
1. R. Pseudacàcia, L. (Common Locust or False Acacia.) Branches naked; racemes slender, loose; flowers white, fragrant; pod smooth.—S. Penn. to Ind., Iowa, and southward. Commonly cultivated as an ornamental tree, and for its valuable timber; naturalized in many places. June.
2. R. viscòsa, Vent. (Clammy L.) Branchlets and leaf-stalks clammy; flowers crowded in oblong racemes, tinged with rose-color, nearly inodorous; pod glandular-hispid.—Va. to N. C. and Ga., in the mountains. Cultivated, like the last, and often escaped. June.
3. R. híspida, L. (Bristly L. or Rose Acacia.) Shrub 3–8° high; branchlets and stalks bristly; flowers large and deep rose-color, inodorous; pods glandular-hispid.—Varies with less bristly or nearly naked branchlets; also with smaller flowers, etc.—Mts. of Va. to N. C. and Ga. May, June.
20. WISTÀRIA, Nutt.
Calyx campanulate, somewhat 2-lipped; upper lip of 2 short teeth, the lower of 3 longer ones. Standard roundish, large, turned back, with 2 callosities at its base; keel scythe-shaped; wings doubly auricled at the base. Stamens diadelphous. Pods elongated, thickish, knobby, stipitate, many-seeded, at length 2-valved. Seeds large.—Woody twiners, climbing high, with minute stipules, pinnate leaves of 9–13 ovate-lanceolate leaflets, with or without minute stipels, and dense racemes of large and showy lilac-purple flowers. (Dedicated to the late Professor Wistar, of Philadelphia.)
1. W. frutéscens, Poir. Downy or smoothish when old; wings of the corolla with one short auricle and an awl-shaped one as long as the claw.—Alluvial grounds, Va. to Fla., west to S. Ind., Kan. and La. May.—Sometimes cultivated for ornament, as is the still handsomer Chinese species.