Canadian pondweed

noun

a North American aquatic plant, Elodea (or Anacharis) canadensis, naturalized in Europe, having crowded dark green leaves: family Hydrocharitaceae. It is used in aquariums

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012