Whorls of 4 small dull-reddish flowers, bracts shorter than flowers. Erect flowering spikes. Leaves usually in whorls of 4, with 8-15 segments on each side.
Ponds, lakes, canals, rivers, usually base-rich. Widespread throughout Ireland, can be locally abundant. Identified by Paul Green
Spiked Water-milfoil. The Gearagh, County Cork. August 2008