Sopubia

Annual or perennial herbs or undershrubs, hemiparasitic on roots; stems usually erect, rigid, branched, often ribbed because of decurrent leaf bases, glabrous, scabrid, woolly or tomentose, sometimes in longitudinal bands. Leaves opposite or verticillate, or upper alternate, linear to linear-lanceolate, entire or dissected with linear or filiform segments. Flowers solitary in axils of bracts, in racemes or spikes; pedicellate or not; bracteoles 2, close to calyx. Calyx campanulate or hemispherical, 5-lobed; variously hairy without and within; lobes valvate in bud, linear-triangular to broadly deltate, longer or shorter than tube. Corolla usually short, at times exserted, sometimes subrotate, 5-lobed; tube short to very short, subcampanulate, enlarged at throat; limb spreading; lobes broad, elliptical, subequal, entire, longer than tube, 2 upper lobes inside in bud. Stamens 4, didynamous, arising in throat of corolla tube, exserted or shortly included; filaments linear; anthers bithecate, all coherent or together in pairs; thecae unequal with one perfect, ovoid or ellipsoid, the other much smaller, linear or clavate, shortly stalked, +/- barren. Ovary bilocular, subglobose or elliptical; ovules many on thick, planoconvex placentas; style elongated; stigma simple or subclavate. Fruit an oblong, ovoid, subglobose or ellipsoid capsule, rounded or compressed and retuse, emarginate or obtuse at apex, loculicidal. Seeds subglobose, oblong to obovoid, sometimes linear and curved; testa membranous, reticulate or ribbed, rather loose. x = 9.