Rumex aquaticus, L.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1964, Flora Europaea - Volume 1. Lycopodiaceae to Platanaceae, Cambridge University Press : 86

24. R. aquaticus L. , Sp. Pl. 336 (1753) .

Perennial. Stem (50-) 100-200 cm, erect. Basal leaves triangular, acute, deeply cordate at base, 1 ^-21 times as long as wide; petiole at least as long as lamina. Panicle large, dense; pedicels filiform, up to 2| times as long as the valves. Valves (5-)6-8- 5 mm, ovate-triangular, more or less acute, longer than wide, margins entire. 2n = c. 200. Wet places. N., C. & E. Europe. Au Be Br Cz Da Fe Ga Ge He Ho Hu Ju No Po Rm Rs (N, B, W, E) Su.

Many records for S. Europe are erroneous. The hybrid with R. hydrolapathum (described under that species) is frequent and fairly fertile. The hybrid with R. longifolius is frequent, especially in N. Sweden.