Prostrate to ascending perennial
herbs. Leaves opposite, sessile or shortly petiolate, ±
elliptic. Stipular sheath bearing several fimbriae. Flowers bisexual in dense heads surrounded by an involucre of 4 leaves. Calyx lobes
persistent. Corolla funnel-shaped, lobes 3-5. Ovary 3-4-locular.
Capsule composed of 3-4 cocci, crowned by the persistent calyx,
eventually splitting into separate cocci. Worldwide: 15 species in tropical America; naturalised elsewhere |
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