Aquatic macrophytes(Elodea canadensisRich, in Michx.,Lagarosiphon major(Ridley) Moss.,Potamogeton crispusL.,Potamogeton ochreatusRaoul,Pota‐mogeton cheesemaniiA. Cunn., andMyriophyllum elatinoidesGaud.) were collected from Lakes Rotoaira, Taupo, and Aratiatia, North Island, New Zealand, in November 1972 and analysed for 26 elements (nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, sodium, chlorine, silicon, aluminium, iron, titanium, vanadium, chromium, manganese, cobalt, nickel, copper, zinc, molybdenum, strontium, barium, lead, boron, gallium, and zirconium).ElodeaandLagaro‐spihonwere sampled again in March 1973, July 1974, and August 1974, to provide data on variability within a single stand, and change in element content during different seasons and different stages of growth. Surface water, plankton, and sediment samples were also collected at each sampling site in November 1972 and were analysed for the same range of elements.