1) Genus ceratophyllum 2) Magnoliid dicot genus 
Ceratophyllum is a cosmopolitan genus of flowering plants, commonly found in ponds, marshes, and quiet streams in tropical and in temperate regions. They are usually called hornworts, although this name is also used for unrelated plants of the division Anthocerotophyta. Ceratophyllum grows completely submerged, usually, though not always, floating...
[n] - constituting the family Ceratophyllaceae: hornworts
genus Ceratophyllum noun constituting the family Ceratophyllaceae: hornworts