Atlas of North European vascular plants
814 Nymphaea tetragona Georgi
This variable species occurs m Eurasia and N. America. Hybrids with N. alba subsp. candida are also included. In E. Asia at least two varieties are distinguished. The N. American population is considered as a subspecies, subsp. leibergii (Morong) Pors. It is also reported from S. Vietnam and (erroneously?) Queensland. The species belongs to the circumpolar plants (Hultén, Circumpol. Il, p. 116 and map 108).