Littorella is a small, amphibious genus within the Plantaginaceae and is represented by three closely related, disjunct species, L. uniflora (L.) Ascherson in Europe including Iceland and the Azores, L. americana Fernald in North America, and L. australis Griseb. ex Bentham & Hooker in southern South America. A recent phylogeny (Rahn, 1996) based on morphological, embryological, and chemical data has resulted in the reduction of Littorella to Plantago subgenus Littorella (P.J. Bergius) Rahn and renaming of the included species to Plantago uniflora L. (= Littorella uniflora (L.) Aschers.), Plantago americana (Fernald) Rahn (= Littorella americana Fernald), and Plantago araucana Rahn (= Littorella australis Griseb.). We compared this phylogeny to one based on DNA sequence data from the nuclear ribosomal internal transcribed spacer region (ITS). A total of four outgroup taxa, three species of Littorella , and 44 species of Plantago were included in this analysis. Our molecular phylogeny supports the generic recognition of Littorella as it is clearly sister to Plantago . Our phylogeny also rejects the conspecific recognition of L. americana and L. uniflora as proposed by recent North American authors and suggests a European origin for Littorella .

Key words: Littorella, phylogeny, Plantaginaceae, Plantago