B plants

"Most genetic studies including Baldellia species have focused on general patterns in Alismataceae and Alismatales phylogeny. The order Alismatales is indeed of great interest because it has often been regarded as one of the most ancient group of the monocotyledons and therefore centers several studies investigating the systematics, biogeography and evolutionary processes of flowering plants."

"Our ITS phylogeny clearly places Baldellia in a clade composed of Alisma and Luronium. This result corroborates several recent molecular, chromosomal and anatomical studies suggesting that Baldellia is actually closely related to Alisma, Damasonium and Luronium. Our study definitively ends the long standing discussion about the relationship of Baldellia with the predominantly neotropical genera Echinodorus and Helanthium, as suggested by Cook in his influential book on the aquatic plants of the world (Cook, 1990). Therefore, morphological similarities of these genera probably result from convergences and not from genetic relatedness."

From: "Phylogenetics and phylogeography of the monocot genus Baldellia (Alismataceae): Mediterranean refugia, suture zones and implications for conservation" (PDF) by Nils Arrigo et. al."