Annual or perennial herbs or subshrubs. Stems 4-angled. Leaves opposite or sometimes in whorls of 3. Flowers bracteate, terminal, in simple spikes or panicles of spikes. Calyx tubular, distinctly and ± unequally (4-)5-toothed, 5-ribbed. Corolla funnel- or salver-shaped; limb 5-lobed, ± spreading. Stamens (2-)4(-5), included, didynamous. Ovary entire or 4-lobed, 4-locular with 1 ovule per loculus. Fruit splitting into 4 nutlets at maturity, enveloped in the persistent calyx. Worldwide: 200 species in tropical and temperate America, incl 2-3 in temperate Europe; others weeds elsewhere Zimbabwe: 6 taxa. Insects associated with this genus:
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| Species | FZ divisions | Content |
| aristigera S. Moore | W,C,E | Description, Image |
| bonariensis L. | N,W,C,E,S | Description, Image |
| brasiliensis Vell. | C,E,S | Image |
| litoralis Kunth | W | |
| officinalis L. subsp. africana R. Fern. & Verdc. | N,W,C,E | Description, Image |
| rigida Spreng. | C,E | Image |