923 Rorippa palustris (L.) Bess. complex

The following main taxa within the widespread R. palustris complex are mapped, viz. R. palustris subsp. palustris in the main part of N. and C. Europe and Asia (introduced in N. America), subsp. palustris var. williamsii (Britt.) Hult. in northwestern N. America, subsp. fernaldiana (Butt. & Abbe) Jonsell and subsp. hispida (Desv.) Jonsell, both occurring in eastern and central N. America, and subsp. occidentalis (Wats. in A. Gray) Abrams in western N. America. The detailed distribution in N. America of the taxa mapped here is insufficiently known. R. palustris belongs to the circumpolar plants (Hultén, Circumpol. Il, p. 236 and map 227). Outside the map area it is widely spread, for instance to Ethiopia, V ietnam, Australia, New Zealand and S. America. R. islandica (Oeder) Borb. has been distinguished as a separate species (cf. Jonsell in Symb. Bot. Ups. 19:2, 1968). This name was, however, frequently used for the whole R. palustris complex (e. g. Hultén, Circumpol. Il). R. islandica s. str. has a scattered distribution from Greenland through Europe to C. Asia. The W. European and Greenlandic R. islandica belongs to subsp. islandica, the Russian and Asiatic populations to subsp. dogadovae (Tzvel.) Jonsell.