1) Dicot genus 2) Freshwater plant 3) Genus myriophyllum 4) Magnoliopsid genus 
These submersed aquatic plants are perhaps most commonly recognized for having elongate stems with air canals and whorled leaves that are finely, pinnately divided, but there are many exceptions. For example, the North American species M. tenellum has alternately arranged scale like leaves, while many Australian species have small alternate or opp...
[n] - chiefly monoecious and usually aquatic herbs (as the milfoils)
genus Myriophyllum noun chiefly monoecious and usually aquatic herbs (as the milfoils)