Inconspicuous pinkish flowers, only female are produced and all reproduction is vegetative. Transluscent dark-green leaves, usually in whorls of 3. Stems to 3m.
Still or slow-moving water to 3m+. Widespread, first Irish record 1836. Replaced in some locations by Nuttall's Waterweed.
An invasive plant in Ireland: Target 10 - Managing Invasive Alien species
My thanks to Dr. Michael Millane, Inland Fisheries Ireland for correcting the photographs previously shown, which were of Nuttall's Waterweed, E. nuttalli
Canadian Waterweed. All photographs: Dr. Michael Millane, Inland Fisheries Ireland