A revision of the genus Limnobium including Hydromystria (hydrocharitaceae)

A taxonomic revision of the genus Limnobium (Hydrocharitaceae) is presented with full descriptions, diagnoses, synonyms with typifications, distribution maps and illustrations and including information on ecology, floral biology, anatomy, morphology, chromosomes and variation with a rather extensive bibliography. Two well-defined and allopatric species are recognized: L. spongia (Bosc) Steudel, eastern North America and L. laevigatum (Humboldt & Bonpland ex Willd.) Heine, Central and South America. The genus Hydromystria is not considered to be worthy of recognition and is included within Limnobium. New chromosome counts are reported.