Annual erect herbs, glabrous-pubescent with simple hairs. Leaves well-developed, alternate or opposite, fleshy, with or without a mucro, semi-amplexicaul. Flowers bisexual, sessile, 1-few, axillary, almost enveloped in leaf axils or bases; bracts 2; perianth 5-partite, oblong, hyaline, free to base, slightly harder in fruit, not developing wings. Stamens 5, linear, with prominent vesicular appendages; appendages oblong-globose, yellow, stipitate. Styles 2, free to near base. At fruiting time the flower-subtending leaves and bracts indurate and expand forming a very hard nut-like structure, enclosing the 2 seeds; this disseminates as a single dispersal unit. Fruit compressed. Seeds vertical; embryo spiral.