4. Rumex thyrsiflorus Fingerhuth, Linnaea. 4: 380. 1829.
直根酸模 zhi gen suan mo
Acetosa thyrsiflora (Fingerhuth) A. Löve & D. Löve; Rumex acetosa Linnaeus subsp. thyrsiflorus (Fingerhuth) Celakovský; R. haplorhizus Czernjaev ex Turczaninow; R. thyrsiflorus var. mandshuricus A. Baranov & B. Skvortsov.
Herbs perennial, dioecious. Taproots large, thick, with remote secondary roots. Stems erect, 40-120 cm tall, glabrous, grooved. Basal leaves oblong-lanceolate to lanceolate, base sagittate, 4-13 × 1.5-4 cm, both surfaces glabrous or veins minutely papillate, margin entire, apex acute, basal lobes acute at apex; cauline leaves small; petiole short or nearly absent; ocrea fugacious, white, membranous. Inflorescence terminal, paniculate, dense, much branched. Flowers unisexual. Pedicel slender, articulate below middle. Male flowers: outer tepals erect, small; inner tepals elliptic, ca. 2 mm. Female flowers: outer tepals reflexed in fruit; inner tepals enlarged in fruit; valves orbicular to broadly ovate, 3-4 mm in diam., with small recurved tubercles at base of valves, base truncate to cordate, margin nearly entire, apex obtuse. Achenes brown, shiny, ellipsoid, trigonous, ca. 2 mm. Fl. May-Jun, fr. Jun-Jul. 2n = 14, 15.
Mountain slopes, moist valleys, water sides; 500-2200 m. Heilongjiang, Jilin, Nei Mongol, Xinjiang [Kazakhstan, Mongolia, Russia, Uzbekistan; Europe, North America].