Najas guadalupensis (Sprengel) Magnus subsp. floridana (R. R. Haynes et W. A. Wentz) R. R. Haynes et C. B. Hellquist (Hydrocharitaceae) was recorded from a brackish pond in Ehime Prefecture, Shikoku, as the second locality of the species in Japan. A specimens of the species was proved to have been collected in 1923 from the same area. The origin of the species in Japan was discussed.
2016 The Japanese Society for Plant Systematics