Heteranthera mexicana S. Watson Heteranthera mexicana S. Watson in Proc. Amer. Acad. Arts 18: 166. 1883 sec. Olvera & Lot 2013=Eurystemon mexicanum (S. Watson) Alexander, N. Amer. fl. 19: 55. 1937 syn. sec. Olvera & Lot 2013