Perennial climbers with slender stems and often tuberous roots or rhizomes. Lvs ± succulent, alternate, entire, exstipulate. Fls usually ☿, actinomorphic, in spikes, racemes or panicles; each fl. subtended by a small bract and 2 or 4, sometimes petaloid bracteoles. Perianth segments (tepals) 5, almost free to connate and forming a tube, persistent in fr., imbricate. Petals 0. Stamens 5, inserted opposite to tepals and on or near their bases; filaments free, short; anthers dehiscing lengthwise or by apical pores or slits. Ovary superior, 1-locular, with 1 basal ovule; style usually simple or 3-branched, sometimes 3. Fr. indehiscent, surrounded by the persistent, sometimes fleshy perianth or winged bracteoles. Seed globular or nearly so; endosperm copious.