Annual or perennial undershrub with hoary, tomentose stem; petioles and pedicels densely or sparsely covered with minute, stellate or simple hairs; petiole equal to or longer than leaf blade; leaves broadly cordate, nearly entire or irregularly toothed, minutely pubescent on both surfaces, often with few, closely felted longer hairs intermixed; stipules linear, deflexed; flowers yellow, 2-3 cm across, opening in the evening; solitary, axillary; pedicels longer than petioles, jointed near the tip; bracteoles absent; calyx lobes-5, valvate, united up to the middle, ovate, acute; petals-5, free above, connate below, spreading, broadly ovate, rounded or emarginate at apex, ciliate at base, yellow; staminal column short, divided at apex into numerous filaments, stellately hairy, basal part conical and upper tubular, glabrous; carpels 15-20, longer than calyx, glabrescent, truncate, shortly awned, spreading; styles as many as carpels; ripe carpels separating from the axis, awned, 1- or more seeded; seeds dark brown, minute with stellate hairs.