Identification of a Small, Spring Water-associated Duckweed with Special Reference to the Taxonomy of Sect. Uninerves of the Genus Lemna (Lemnaceae) in Japan

抄録

Species-level identification of aquatic plants, such as duckweeds (Lemnaceae), can be challenging due to reduced morphological features and high phenotypic plasticity. A taxonomic study of sect. Uninerves of the genus Lemna in Japan based on morphological observations and DNA analyses is reported. Two non- indigenous species, L. minuta and L. valdiviana, were confirmed to occur in Japan. Excessively small, enigmatic plants of Lemna apparently specialized to grow in spring-fed waterbodies was determined to be a form of L. minuta. It could not be concluded whether the miniature Lemna represents an ecotype adapted to cool water or an example of phenotypic variation under low temperature conditions.