Calyx 5-toothed or 5-cleft, the two upper teeth often higher united. Keel of the corolla, with the included stamens and style, spirally coiled. Stamens diadelphous. Style bearded along the upper side; stigma oblique or lateral. Pod scythe-shaped, several–many-seeded, tipped with the hardened base of the style. Seeds round-reniform, with very short hilum. Cotyledons thick and fleshy, rising out of the ground nearly unchanged in germination.—Twining herbs, with pinnately 3-foliolate stipellate leaves. Flowers racemose, produced in summer and autumn. (The ancient name of the Kidney Bean.)
1. P. perénnis, Walt. (Wild Bean.) Stem climbing high from a perennial root; leaflets roundish-ovate, short-pointed; flowers purple, handsome, but small; pods drooping, strongly curved, 4–5-seeded.—Copses, N. Eng. to Fla., west to Minn. and La.
Keel of the corolla with the included stamens and style elongated, strongly incurved, not spirally coiled. Pod linear, terete or flattish, straight or nearly so. Seeds quadrate or oblong with truncate ends, mealy-pubescent or glabrate; hilum linear. Flowers few, sessile and capitate clustered on the mostly long peduncles. Otherwise as Phaseolus.—Stems prostrate or climbing, more or less retrorsely hairy. Stipules and bracts striate. (Name from στροφή, a turning, and στῦλος, a style.)
1. S. angulòsa, Ell. Annual; stems branched, 1–6° long; leaflets ovate to oblong-ovate (rarely linear-oblong), with a more or less prominent rounded lobe toward the base (the terminal 2-lobed), or some or all often entire, about 1´ (6–20´´) long; corolla greenish-white and purplish; pod terete, 2–3´ long by 3´´ wide, 4–8-seeded, nearly glabrous; seeds oblong, about 3´´ long, usually very pubescent. (Phaseolus diversifolius, Pers. P. helvolus, L.)—Sandy shores and river-banks; coast of Mass. and southward, along the Great Lakes to Minn., and south to Kan. and Tex.
Var. Missouriénsis, Watson in herb. Climbing high (10–30°); leaves often 3´ long, rhombic-ovate, rarely at all lobed; seeds 3–4´´ long.—River-bottoms near Independence, Mo.; nearly two months later. (F. Bush.)
2. S. pedunculàris, Ell. Stems more slender, from a perennial rootstock, 2–4° long; leaflets ovate to oblong-linear, rarely at all lobed, 1´ long or less; pod 1½–2´ long and scarcely 2´´ wide; seeds much smaller, 1½–2´´ long, short-oblong to quadrate. (Phaseolus helvolus, Man., etc., not L.)—Sandy ground, Long Island and N. J. to Fla., west to S. Ind., Ky., and La.
3. S. pauciflòrus, Watson in herb. Annual, slender, low-climbing, pubescent; leaflets oblong-lanceolate or ovate-oblong to linear, not lobed, 1´ long; pod pubescent, 1´ long, flattish; seeds as in the last, very finely mealy, soon glabrate. (Phaseolus pauciflorus, Benth.)—River-banks, Ind. to Minn., south to Miss. and Tex.
35. CENTROSÈMA, DC. Spurred Butterfly-Pea.
Calyx short, 5-cleft. Corolla, etc., much as in Clitoria, but the spreading standard with a spur-shaped projection on the back near the base; keel broad. Style bearded at the apex around the terminal stigma. Pod long and linear, flat, pointed with the awl-shaped style, many-seeded, thickened at the edges, the valves marked with a raised line on each side next the margin.—Twining perennials, with 3-foliolate stipellate leaves, and large showy flowers. Stipules, bracts, and bractlets striate, the latter longer than the calyx. (Name from κέντρον, a spur, and σήμα, a standard.)