Description from Flora of China
Shrubs deciduous. Branches hollow or with lamellate pith; branchlets ± 4-angled. Leaves opposite, simple, rarely 3-parted to 3-foliolate, petiolate; leaf blade serrate or entire. Flowers appearing before leaves, bisexual, heterostylous, 1 to several fascicled in leaf axils, pedicellate. Calyx deeply 4-lobed, persistent. Corolla yellow, 4-parted; tube campanulate; lobes longer than tube, imbricate in bud. Stamens 2, inserted at base of corolla tube, scarcely exserted. Ovules many in each locule, pendulous. Style slender; stigma 2-cleft. Fruit a loculicidal capsule. Seeds numerous in each locule, slightly winged; endosperm absent; radicle erect.
About 11 species: mainly in eastern Asia, one in SE Europe; six species in China.
Most species are grown as ornamental shrubs for early spring. The fruit of some species are used medicinally.