Source:
SSA
Description:
Annual or occasionally perennial herbs, erect or prostrate, usually thickened at nodes, pubescent. Leaves opposite, sessile or subsessile, entire. Inflorescences terminal or axillary, capitate to spicate, sessile or pedunculate, solitary or glomerate, often subtended by a pair of sessile leaves, bracteate with bract persistent in fruit, axis frequently thickened. Flowers bisexual, solitary in axils of bracts; bracteoles 2, concave, or laterally compressed with a dorsal longitudinal keel or wing, or crested, falling with fruit. Tepals 5, erect, similar or dissimilar, free or almost so, +/- lanate dorsally, at least inner 2 usually +/- indurate at base in fruit. Stamens 5, hypogynous; filaments monadelphous, tube shortly 5-dentate with entire to very deeply bilobed teeth; with or without free pseudostaminodes; anthers 1-thecous. Ovary turbinate or subglobose; ovule solitary, pendulous; style short or long; stigmas 2 or 3, linear or short and thicker. Capsule a compressed, thin-walled, irregularly rupturing utricle. Seed compressed-ovoid, brown, smooth or faintly reticulate, shining. x= 13 (8, 9, 10, 11) (polyploidy) .
Distribution:
Species +/- 120, tropics and subtropics of the New World and in Australia, some introduced and naturalised in the Old World; 2 in sthn Afr., widespread weeds.
Classification:
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