Atlas of North European vascular plants
925 Rorippa nasturtium-aquaticum (L.) Hayek complex
Syn.: Nasturtium officinale R. Br. complex
This widespread complex originates from Eurasia. It has been introduced into northern parts of Europe (casual in several places not marked here), E. Asia and N. America as well as a great many places outside the map area (C. and S. Africa, Java, Australia, New Zealand, S. America etc.). The recently distinguished R. microphylla (Boenn.) Hyl., occurring mainly in W. Europe, is too little known for separate mapping and therefore included in the total map area of this complex. In areas where it is possible to distinguish this species it is marked separately on the map by open dots. It is also introduced in C. and S. Africa, C. Asia and N. America. Hybrids between R. nasturtium-aquaticum and microphylla occur occasionally (crosses). With its present distribution this complex belongs to the discontinuous circumpolar plants (Hultén, Circumpol. Il, p. 204 and map 195).