Annual or perennial herbs with entire, opposite leaves. Inflorescences of axillary heads or short spikes, bracteate. Flowers bisexual, solitary in the axil of each bract, subtended by 2 bracteoles. Tepals 5, glabrous and 1-nerved or barbed-pilose and 3-nerved, free, equal or unequal. Stamens 2-5, alternating with pseudostaminodes. Fruit an indehiscent capsule. Derivation of name: alterno meaning alternate, anthera meaning male flowers, referring to the alternation of stamens and pseudostaminodes. Worldwide: c. 200 species, mainly in the New World tropics; some worldwide weeds Zimbabwe: 4 taxa. |
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