Description from
Flora of China
Triosteospermum Miller.
Herbs, perennial, with underground rhizomes. Stem erect, with white pith becoming hollow. Leaves simple, opposite, obovate,
entire, undulate to deeply pinnatifid. Inflorescence of sessile 6-flowered whorls; bracts and bracteoles lanceolate, shorter than flowers. Calyx 5-lobed, persistent. Corolla yellow-green, yellow, or purple; lobes 5, imbricate, bilabiate, upper lip 4-lobed, lower lip entire and recurved at anthesis. Nectary of compact glandular hairs, forming a bulge at base of corolla tube. Stamens 5, inserted in corolla tube; anthers introrse. Ovary 3-5-locular; ovule 1 per locule sometimes aborted, pendulous; style filiform; stigmas discoid, 3-5-lobed. Fruit a drupe, subglobose to pyriform, ± fleshy; pyrenes 2-4, black, with a thick stony endocarp, sometimes ribbed; endosperm fleshy, embryo small.
About six species: C and E Asia, North America; three species in China.