Mercurialis perennis L. is very rare outside the Calcareous District of the Netherlands. Two very small groups of plants have been found near Rhijnauwen (Bunnik, prov. Utrecht) and one near Middachten (Rheden, prov. Gelderland). In both cases only female plants were found. Cytological studies demonstrated that the plants from Rhijnauwen are tetraploid (2n=84), those of Middachten triploid (2n=63).