18. Rumex obtusifolius Linnaeus, Sp. Pl. 1: 335. 1753.
钝叶酸模 dun ye suan mo
Rumex obtusifolius subsp. agrestis (Fries) Danser; R. obtusifolius var. agrestis Fries.
Herbs perennial. Roots vertical, large, to 1.5 cm in diam. Stems erect, 60-120(-150) cm tall, grooved, branched above middle or in upper 2/3, glabrous. Basal leaves: petiole 6-12 cm, minutely papillate; leaf blade broadly ovate to oblong-ovate or narrowly ovate, 15-30 × 6-15 cm, base cordate, abaxially sparsely minutely papillate, adaxially glabrous; cauline leaves shortly petiolate, narrowly ovate, small; ocrea fugacious, membranous. Inflorescence broadly paniculate, large; branches ascending. Flowers bisexual, dense. Pedicel filiform, slender, articulate below middle (in proximal third, rarely near middle). Inner tepals enlarged in fruit; valves narrowly triangular-ovate, 4-6 × 2-3 mm, usually 1 valve with tubercles, sometimes 3 valves with tubercles, but then 1 tubercle distinctly larger than other 2, base truncate, each margin with 2 or 5 teeth, apex obtuse to subacute; teeth 0.8-1.5 mm, apex straight. Achenes dark brown, shiny, ovoid, sharply trigonous, ca. 2.5 mm. Fl. May-Jun, fr. Jun-Jul. 2n = 40.
Field margins, moist valleys; sea level to 100 m. Anhui, Gansu, Hebei, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Taiwan, Zhejiang [Japan, Russia; N Africa, Europe; introduced and naturalized in North America and other regions of the world].
One of us (Grabovskaya-Borodina) suggests that these plants may, in fact, be Rumex chalepensis.