Perennial herbs or subshrubs; often procumbent or climbing. Leaves opposite in ± equal pairs, often fleshy. Inflorescences umbellate, whorled, irregularly branched or mixed, pedunculate. Bracts linear-lanceolate. Flowers bisexual. Perianth with lower part constricted above ovary with glands over surface (especially apex); upper part petal-like, coloured, funnel-shaped. Stamens 2-5(-6). Fruits variously shaped, ± 10-grooved, with variously arranged large sticky glands.