Description from Flora of China
Rumex cardiocarpus Pampanini; R. crispus Linnaeus subsp. japonicus (Houttuyn) Kitamura; R. crispus var. japonicus (Houttuyn) Makino; R. hadroocarpus K. H. Rechinger; R. regelii F. Schmidt.
Herbs perennial. Stems erect, 50-100 cm tall, branched above, grooved, glabrous. Basal leaves: petiole 6-15 cm; leaf blade oblong or lanceolate-oblong, 8-25 × 3-8 cm, abaxially minutely papillate along veins, adaxially glabrous, base rounded, cordate, or broadly cuneate, margin slightly undulate, apex acute or obtuse; cauline leaves shortly petiolate, narrowly oblong, small; ocrea fugacious, white, membranous. Inflorescence paniculate. Flowers bisexual. Pedicel slender, articulate below middle, articulation distinct. Inner tepals enlarged in fruit; valves broadly cordate, 4-5 × 5-6 mm, all valves with narrowly ovate tubercles, conspicuously net veined, base cordate, margin irregularly denticulate, apex acute; denticles 0.3-0.5 mm. Achenes dark brown, shiny, broadly ovoid, sharply trigonous, ca. 2.5 mm, base narrow, apex acute. Fl. May-Jun, fr. Jun-Jul.
This species is used medicinally.
Field margins, stream banks, wet valleys; sea level to 3400 m. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Nei Mongol, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Zhejiang [Japan, Korea, Russia (Far East)].