Rumex aquaticus subsp. protractus (K. H. Rechinger) K. H. Rechinger; R. protractus K. H. Rechinger.

Herbs perennial. Stems erect, 30-120 cm tall, usually branched above (in inflorescence), glabrous, grooved. Basal leaves: petiole 9-28 cm, glabrous or minutely papillate; leaf blade oblong-ovate to ovate-lanceolate, 10-30 × 4-13 cm, both surfaces glabrous or abaxially minutely papillate along veins, base cordate to nearly truncate, margin undulate, apex acute to nearly obtuse; cauline leaves shortly petiolate, oblong or broadly lanceolate, small; ocrea fugacious, membranous. Inflorescence terminal, paniculate, narrow; branches suberect. Flowers bisexual. Pedicel filiform, articulation indistinct, not swollen in fruit. Inner tepals enlarged in fruit; valves ovate, 5-8 × 4-6 mm, all without tubercles, base subtruncate, margin nearly entire, apex acute. Achenes brown, shiny, ellipsoid, trigonous, 3-4.5 mm, base narrow, apex acute. Fl. May-Jun, fr. Jun-Jul. 2n = 140.

Watersides in valleys, riverbanks; 200-3600 m. Gansu, Heilongjiang, Hubei, Jilin, Ningxia, Qinghai, Shaanxi, Shanxi, NW Sichuan, Xinjiang [Japan, Kazakhstan, Kyrgyzstan, Mongolia, Russia; Europe, North America].