93 Hydrocharis morsus-ranae L.

This species occurs in W. and C. Eurasia. The closely related H. asiatica Miq. (syn.: H. dubia [Bl.] Backer) is known from large parts of C., SE. and E. Asia. It was introduced at least into one place in eastern America in 1958. Cf. also Meusel et al. 1965, map p. 30.