Description from Flora of China
Lapathum crispum (Linnaeus) Scopoli.
Herbs perennial. Roots large. Stems erect, 50-120(-150) cm tall, simple or branched above, glabrous, grooved. Basal leaves shortly petiolate, lanceolate or narrowly lanceolate, 10-25 × 2-5 cm, glabrous or indistinctly papillose along veins below, base usually cuneate to truncate, margin strongly crisped and undulate, apex acute; cauline leaves shortly petiolate, narrowly lanceolate, small; ocrea fugacious, membranous. Inflorescence terminal, paniculate, narrow; branches erect or ascending. Flowers bisexual. Pedicel slender, articulate in proximal third, articulation distinctly swollen. Inner tepals enlarged in fruit; valves broadly ovate, 3.5-6 × 3-5 mm, all with tubercles, rarely only 1 valve bearing a tubercle, conspicuously net veined, base nearly truncate, margin entire, rarely weakly erose, apex obtuse to subacute; tubercle ovate, 1.5-2 mm. Achenes dark brown, shiny, ovoid, trigonous, ca. 2 mm, apex acute. Fl. May-Jun, fr. Jun-Jul. 2n = 60.
The typical variety, Rumex crispus var. crispus, has valves with 3 tubercles; the less common variety with 1 tubercle, R. crispus var. unicallosus Petermann, also sporadically occurs in China. Forms currently recognized as R. crispus subsp. fauriei (K. H. Rechinger) Mosyakin & W. L. Wagner (R. fauriei K. H. Rechinger) probably also occur in China (see Mosyakin & Wagner, Bishop Mus. Occas. Pap. 55: 39–44. 1998), but their distribution is insufficiently known.
Field margins, streamsides, waste areas; sea level to 2500 m. Gansu, Guizhou, ?Hainan, Heilongjiang, Hebei, Henan, Hubei, Hunan, Jilin, Liaoning, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xinjiang, Yunnan, ?Zhejiang [Japan, Kazakhstan, Korea, Kyrgyzstan, Mongolia, Myanmar, Russia, Thailand; Europe, North America; widely naturalized elsewhere].