Herbaceous or weakly woody perennials. Leaves opposite or alternate, linear to broadly hastate, mealy when young. Flowers small, in clusters arranged in racemose or open panicles; pedicels constricted at apex. Terminal flower of cluster bisexual; lateral flowers female, without staminodes. Tepals 5, rarely 4. Stamens 1–3, glabrous; disc absent. Ovary glabrous; stigmas 2, slender. Fruit with the pericarp either membranous or succulent, not enveloped by perianth. Seed horizontal, lenticular with rounded margin; embryo annual; perisperm central and copious.