Herbs or shrubs [lianas], perennial or, rarely, annual; taprooted or rhizomatous. Stems woody stocks, acaulescent, or erect to prostrate, nodes swollen; indument of simple hairs, capitate glands that may secrete water or calcium salts, or multicelled glandlike structures. Leaves often basal, alternate, spiralled; stipules absent; petiole present or absent; blade linear to broadly obovate, ovate, or round, margins entire or lobed. Inflorescences terminal or axillary cymes, panicles, racemes, or corymbs, or solitary heads; bracts herbaceous, scarious, sometimes absent; involucral bracteoles (epicalyces) immediately subtending calyces usually present. Pedicels absent or present (short). Flowers bisexual, radially symmetric; perianth and androecium hypogynous; sepals persistent in mature fruits, 5, connate into 5- or 10-ribbed tube, mostly dry and membranous, sometimes petaloid, toothed or with distinct simple or lobed limbs; petals 5, nearly distinct, connate at bases or for most of their length (corolla salverform); blade clawed or claw absent, margins entire; corona absent; stamens 5; filaments adnate to bases of petals or free; ovary superior, 1-locular, placentation basal; ovules 1 per ovary, anatropous, bitegmic, crassinucellate; styles 1 with apically lobed stigma, or 5, each with linear stigma. Fruits utricles, achenes, or capsules. Seeds 1, embryo straight, endosperm present or absent.