Plants perennial, glabrous, with vertical rootstock [and, according to Rechinger f. (1937), with fusiform-incrassate root fibers]. Stems ascending or decumbent, usually producing axillary shoots below 1st-order inflorescence or at proximal nodes, 50-60(-70) cm. Leaf blades with lateral veins forming angle of ca. 80° with midvein especially near base, ovate or ovate-elliptic, 10-25 × 4-12 cm, usually ca. 2 times as long as wide, fleshy, coriaceous, base rounded or truncate-cuneate, occasionally indistinctly cordate, margins entire, flat, apex acute. Inflorescences terminal and axillary, terminal usually occupying distal 3- 2 of stem, usually lax, interrupted in proximal part, broadly paniculate. Pedicels articulated in proximal part, distinctly thickened distally 8-13 mm, (2.5-)3-4 times as long as inner tepals, articulation slightly swollen. Flowers 10-20 in whorls; inner tepals orbiculate or rounded-triangular, 4-5 × 4-5 mm, base truncate or subcordate, margins entire, or rarely indistinctly erose, apex acute or acuminate (with broadly triangular tip); tubercles 3, equal or subequal, minutely punctate and/or rugose in proximal part. Achenes brown or dark brown, 2-2.5(-3) × 1.8-2.5 mm. 2n = 60. Flowering spring-early summer. Swamps, marshes, wet meadows, shores of lakes and rivers; 0-100 m; Fla. Rumex fascicularis was mentioned for North Carolina (Á. Löve 1986). It is closely related to and sometimes treated as a subspecies of R. verticillatus.