Family Code: CERATO Genus Code: CERAT Genus CN: hornwort Genus Authority: L. Genus Summary: A genus of about F6 species, aquatic herbs, of cosmopolitan distribution. Genus Identification: Identification notes: Ceratophyllum is sometimes mistaken for other, superficially somewhat similar aquatics, such as Cabomba (Cabombaceae), Utricularia (Lentibulariaceae), and Myriophyllum (Haloragaceae). Cabomba has the leaves opposite (rather than whorled), dichotomously divided (like Ceratophyllum), but the divisions lacking the marginal denticles of Ceratophyllum, and on a 1-3 cm long petiole (vs. sessile or on a petiole 0-2 mm long). Utricularia has the leaves sometimes dichotomously divided, but the divisions are usually irregular, the leaves are alternate (in most species), and bladder traps are present. Myriophyllum has the leaves pectinately rather than dichotomously divided. Genus References: Les in FNA (1997); Les (1985, 1986, 1988a, 1988b, 1988c, 1989)=Z; Les in Kubitzki, Rohwer, & Bittrich (1993). Key adapted from Les. Last Updated: 2019-11-29 Publish: 1