Description from Flora of China
Botryopleuron Hemsley; CalorhabdosBentham; Leptandra Nuttall.
Herbs, perennial. Roots usually densely yellow tomentose when young. Rhizomes short to long, rarely absent. Stems erect or arching and rooting at apex. Leaves alternate, opposite, or whorled. Inflorescences terminal or axillary, spicate. Flowers usually crowded. Calyx 5-lobed, upper lobe slightly smaller than others. Corolla 4-lobed; tube tubular, straight or slightly curved, usually with a ring of villous hairs inside, rarely glabrous; limb actinomorphic or 2-lipped; lobes unequal in width, upper widest, lower narrowest. Stamens 2; filaments usually basally villous, rarely glabrous, adnate to upper part of corolla tube; anther locules connivent, not confluent. Stigma small, slightly dilated. Capsule ovoid to ovoid-globose, slightly compressed laterally, 2-grooved, 4-valved. Seeds numerous per capsule.
About 20 species: E Asia, North America; 13 species in China.