Shrubs deciduous. Leaves opposite, simple or divided to trifoliolate, entire or serrate, ovate to lanceolate. Flowers pedicellate, 1-6 in axillary fascicles, heterostylous. Calyx 4-lobed. Corolla yellow, deeply 4-lobed; lobes oblong, 1-2 cm long. Stamens attached at the base. Style slender, with 2-lobed stigma. Fruit a 2-celled, dehiscent capusle with many winged seeds. Flowers early in spring, before the leaves appear.