1. Rumex acetosella Linnaeus, Sp. Pl. 1: 338. 1753.
小酸模 xiao suan mo
Acetosa acetosella (Linnaeus) Miller; Acetosella vulgaris (Koch) Fourreau; Rumex acetosella var. vulgaris Koch.
Herbs perennial, dioecious. Rhizomes horizontal, ligneous. Stems usually numerous from rhizome, erect or ascending, 15-35(-45) cm tall, slender, finely grooved, branched above middle. Basal leaves hastate, rarely without basal leaves, 2-4 cm × 3-6(-10) mm, glabrous, central lobe ovate-lanceolate, lanceolate, or linear, basal lobes spreading or curved, sometimes multifid, margin above basal lobes entire, apex acute or obtuse; cauline leaves smaller upward. Petiole short or in upper cauline leaves nearly absent; ocrea fugacious, white, membranous. Inflorescence terminal, paniculate. Flowers unisexual. Pedicel 2-2.5 mm, articulate near base of tepals. Male flower: outer tepals small; inner tepals elliptic, ca. 1.5 mm. Female flower: outer tepals lanceolate, ca. 1 mm, not reflexed in fruit; inner tepals slightly enlarged in fruit; valves ovate, 1-1.6 mm, without tubercles, net veined, base rounded to broadly cuneate, margin entire, apex acute. Achenes brown, shiny, broadly ovoid, trigonous, 1-1.5 mm. Fl. Jun-Jul, fr. Jul-Aug. 2n = 14, 42.
Hilly grasslands, forest margins, moist valleys; 400-3200 m. Fujian, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangxi, Nei Mongol, Shandong, Sichuan, Taiwan, Xinjiang, ?Yunnan, Zhejiang [India, Japan, Korea, Kazakhstan, Mongolia, Russia; Europe, North America; widely introduced elsewhere].
Rumex acetosella s.l. is a variable and taxonomically complicated, polyploid complex represented by several more or less distinct entities (subspecies and/or segregate species). Despite several painstaking efforts (see Nijs, Feddes Repert. 95: 43–66. 1984; Löve, Bot. Helv. 93: 145–168. 1986; and Akeroyd, Bot. J. Linn. Soc. 106: 97–99. 1991), their taxonomy remains rather confused. At least two of these taxa are represented in China: gymnocarpous R. acetosella subsp. acetosella and angiocarpous forms referred to subsp. angiocarpus (Murbeck) Murbeck (R. angiocarpus Murbeck) or subsp. pyrenaicus (Pourret ex Lapeyrouse) Akeroyd (R. pyrenaicus Pourret ex Lapeyrouse). The distribution and taxonomic relationships of these taxa of R. acetosella s.l. in China is still insufficiently known, and because of that no attempt has been made to distinguish them in the present treatment.