1. E. álbida, Nutt. Climbing 8–12° high; leaves 3–5´ wide.—River-banks, S. Penn. and Va. to Ill., Mo., and Tex. July–Sept.
Calyx 5-parted. Corolla 5-parted, wheel-shaped. Crown flat and fleshy, disk-like, 5–10-lobed, simple. Anthers, smooth follicles and seeds much as in Asclepias.—Herbs, often twining. (Name from vincens, binding, and toxicum, poison.)
V. nìgrum, Moench. More or less twining, nearly smooth; leaves ovate or lance-ovate; flowers small, dark purple, in an axillary cluster, on a peduncle shorter than the leaves.—N. Eng. to Penn.; a weed escaping from gardens. (Adv. from Eu.)
6. GONÓLOBUS, Michx.
Calyx 5-parted. Corolla 5-parted, wheel-shaped, sometimes reflexed-spreading; the lobes convolute in the bud. Crown small and fleshy, annular or cup-shaped, in the throat of the corolla. Anthers horizontal, partly hidden under the flattened stigma, opening transversely. Pollen-masses 5 pairs, horizontal. Follicles turgid, mostly muricate with soft warty projections, sometimes ribbed. Seeds with a coma.—Twining herbs or shrubs (ours herbaceous), with opposite heart-shaped leaves, and corymbose-umbelled greenish or dark purple flowers, on peduncles rising from between the petioles. Our species belong to the typical section, with the crown simple and unappendaged, and the corolla nearly veinless. (Name composed of γωνία, an angle, and λοβός, a pod, from the angled follicles of some species.)
[*] Crown a low undulately 10-lobed fleshy disk; follicles unarmed, glabrous, 3–5-costate or angled.
1. G. suberòsus, R. Br. Leaves cordate with an open shallow or sometimes deeper and narrow sinus, pointed, glabrate or hairy (3–5´ long); umbels 3–9-flowered, much shorter than the petiole; corolla broadly conical in bud, abruptly pointed, twisted; lobes ovate or triangular-lanceolate, acute, pubescent inside; calyx half as long. (G. macrophyllus, Chapman.)—Near the coast, Va. to Fla.
2. G. læ̀vis, Michx. Leaves oblong-cordate with a deep and narrow open sinus, conspicuously acuminate (3–6´ long); umbels 5–10-flowered, barely equalling the petiole; corolla elongated-conical in bud, not twisted; lobes narrowly or linear-lanceolate, obtuse, glabrous inside, 3–4 times as long as the calyx.—South of our range.—Passes into var. macrophýllus, Gray, with larger broadly cordate leaves, the sinus often closed, finely pubescent beneath. (G. macrophyllus, Michx.)—River-banks, Va. to S. Ind., Mo., S. C., and Tex.
[*][*] Crown cup-shaped, as high as the anthers; follicles muricate, not costate.