Achudemia japonica Maximowicz, Mélanges Biol. Bull. Phys.-Math. Acad. Imp. Sci. Saint-Pétersbourg 9: 627. 1876; A. insignis Migo; Nanocnide closii Léveillé & Vaniot.

Herbs monoecious. Stems 5-30(-60) cm tall, succulent, swollen above nodes, glabrous. Leaves opposite or subwhorled; stipules almost persistent, light green, oblong, 3-5 mm, membranous; petiole 0.5-2(-5) cm; leaf blade abaxially pale green, rhombic-ovate or ovate, rarely triangular-ovate or lanceolate, slightly asymmetric, unequal in size, 1-6(-10) × 0.8-3(-5) cm, 3-veined, lateral veins 2-3(-5) each side, both surfaces sparsely puberulent, base cuneate, rarely rounded or subtruncate, margin crenate-serrate or dentate, apex often acute, rarely obtuse or shortly acuminate. Inflorescences sometimes of mixed sexes; male inflorescence often a capitulum, 1-1.5 cm; pedunculate, female inflorescence long pedunculate, 1-3(-5) cm, subglabrous. Male flowers pedicellate, in bud ca. 1 mm in diam.; stamens 5; rudimentary ovary minute, narrowly conic. Female perianth lobes oblong-lanceolate; staminodes scale-like, oblong-lanceolate. Achene ovoid, 1-1.4 mm, slightly compressed, verrucose, enclosed by perianth lobes subequal to achene. Fl. Jul-Sep, fr. Aug-Nov.

The plants are used medicinally to relieve internal fever and as a diuretic.

Wet rocks in moist forests and near streams; 500-1900 m. Anhui, Fujian, S Gansu, N Guangdong, Guangxi, Guizhou, Hebei, Henan, Hubei, Hunan, Jiangxi, Jilin, Liaoning, S Shaanxi, Shanxi, Sichuan, Taiwan, E Yunnan, Zhejiang [Japan, Korea, Russia (E Siberia)].