Herbaceous or suffrutescent, counterclockwise twining vines. Stems articulated when young, glabrous or pubescent with simple or stellate, glandular and eglandular trichomes; cystoliths lacking. Leaves opposite, simple, entire, exstipulate, petiolate. Inflorescences of solitary or clustered flowers in leaf axils, each pedicellate and subtended by 2 large, flat or keeled, spathelike bracteoles (= bracts previously used by this and other authors); bracteoles green, variously shaped and vestured, often equaling corolla tube, valvate, often partially connivent or connate, remaining closed around flower, often widely spreading during fruiting. Flowers zygomorphic, bisexual; calyx inconspicuous, annular or cupular, truncate to irregularly dentate or lobed; corolla sympetalous, ± hypocrateriform, not inflated above, contorted, whitish, greenish, or reddish, often with purplish markings within, tube cylindric to funnelform, limb subequally 5-lobed or 2-lipped with upper lip 2-lobed and lower lip 3-lobed, lobes spreading or reflexed; stamens 4, didynamous, included, attached to corolla tube alternate with lobes, anthers 2-thecouswith parallel, subequal to unequal thecae, ± pubescent at base, dehiscing longitudinally or by subapical pores or slits; pollen spherical, 5-6-colporate; staminode, if present, 1, inconspicuous; nectar-disk prominent, cupular, around base of ovary; ovary superior, 2-locular, or one locule more or less reduced or even suppressed, ovules 2 in each locule, or 2 in one fertile locule, collateral, funiculus of ordinary type, neither thickened nor otherwise much modified, style filiform, stigma shallowly and unequally 2-lobed. Fruits drupaceous, ovoid to ellipsoid, mesocarp fleshy, endocarp osseous; seeds 1-2, embryo dicotyledonous, cotyledons twice folded, endosperm wanting.