37. Rumex confertus Willdenow, Enum. Pl. 397. 1809.
Rumex alpinus Linnaeus var. subcalligerus Boissier
Plants perennial, glabrous or weakly papillose-pubescent espe-cially when young, with fusiform, vertical to oblique rootstock or short rhizomes. Stems erect, branched above middle, 50-100(-130) cm. Leaves: ocrea mostly deciduous or rarely partially persistent at maturity; blade ovate-triangular, broadly ovate, or ovate-elliptic, 20-30 × 15-25 cm, base deeply and broadly cordate, margins entire to obscurely repand, usually slightly crisped or undulate, apex obtuse to subacute. Inflorescences terminal, occupying distal 2 of stem (branches often slightly arcuate at base), rather dense, widely paniculate. Pedicels articulated in proximal 3, filiform, 4-10 mm, articulation distinctly swollen. Flowers 15-30 in whorls; inner tepals orbiculate-reniform or broadly scutate, 6-9 × 6-11 mm, as long as wide or nearly so, base cordate to subcordate, margins entire or subentire, occasionally irregularly erose near base, apex abruptly acute to acute; tubercles usually 1, small, 1-2 mm, normally less than 2 times as wide as inner tepals, rarely absent or indistinct. Achenes reddish brown, 3-3.5 × 1.7-2.5 mm. 2n =40.
Flowering late spring-summer. Roadsides, waste places, meadows, river valleys; 300-700 m; introduced; Alta., Man.; N.Dak.; e, ec Europe; w Asia (the Caucasus, Siberia); introduced elsewhere.
Rumex confertus was placed in subsect. Conferti Rechinger f. This species is common and ecologically successful in central and eastern Europe; it may be expected elsewhere in temperate regions of North America.