The small red flowers of Rumex lativalvis grow in whorls spaced at stem-tips. Each flower perianth has six segments in two whorls of three. There are six stamens and a three-angled ovary, enclosed in the persistent perianth. Flowering happens late in winter to mid-spring.

The fruits are red, the three-angled ovary enclosed by the perianth, the inner perianth segments enlarged (Bond and Goldblatt, 1984; Leistner, (Ed.), 2000; iNaturalist).