Mecardonia Ruiz & Pav.

Erect or creeping herbs, annual or perennial, much branched, mostly glabrous, sometimes blackening on drying, gland dotted, stems angled. Leaves opposite, mostly serrate, basally narrowed, the costa prominent; petiole indistinct. Inflo-rescence solitary axillary flowers, the pedicels elongate, subtended by 2 basal bracts, the bracts often leaflike. Flowers yellow or white, the calyx 5-lobed, mostly to the base, the lobes often equal in length, quite unequal in width, the outer sepals much wider; corolla yellow or white, campanulate and somewhat bilabiate, glabrous outside, bearded at the mouth within; stamens 4, didynamous, inserted on the corolla throat, the anthers with the 2 thecae held apart on short arms; stigma 2-lobed, lamelliform, the ovary 2-locular, many ovulate. Seeds numerous, oblong, reticulate.