Landoltia (Lemnaceae), a new genus of duckweeds

Morphological, allozyme,and cpDNA (rbcL) sequence data provide evidence for the distinctness of Spirodela punctata from species in both Lemna and Spir odela (Lemnaceae). We propose the recognition of a new genus, Landoltia, to better reflect current phylogenetic concepts in the Lemnaceae. Landoltia i s distinguished by its reduced frond prophyllum, frond nerves (3 to 7), roo ts (up to 7), root tracheids, external anther locules, and also by well-sup ported molecular evidence provided by allozymes and cpDNA-sequences. The ne w combination Landoltia punctata is made to accommodate this taxonomic modi fication.