Echinodorus L.C. Richard ex Engelmann. Burhead.
A genus of about 27 species, herbs, primarily of the American tropics and subtropics. Christenhusz, Fay, & Byng (2018) propose splitting Echinodorus into two genera, Echinodorus (of E. berteroi only), and Aquarius Christenhusz & Byng (of all other species of Echinodorus), allegedly based on the results of Lehtonen & Myllys (2008). Lehtonen & Myllys's (2008) results are ambiguous, however, and it is unclear that this split is well-founded.
Ref: Christenhusz, Fay, & Byng (2018); Haynes & Hellquist (2000a) In Flora of North America Editorial Committee (2000); Haynes, Les, & Holm-Nielsen In Kubitzki (1998b); Lehtonen (2008); Lehtonen (2009); Lehtonen & Myllys (2008). Show full citations.