Mexican water lily
Vascular – Exotic
Herbs - Dicotyledons other than Composites
Floating leaved aquatic plant with ‘lily’ shaped leaves and yellow flowers, that can develop dense stands in still and slow flowing waters.
Locally naturalised, mostly Auckland and Waikato.
Still and slow flowing water bodies
Stout erect rhizome with creeping stolons, often ending with distinctive ‘brood-bodies’ which look like miniature hands of bananas. Leaves are almost round to elliptical in shape, with a deep narrow basal sinus. Leaves are up to 20 cm across, green or pink on the lower surface, and with brown blotches on the upper surface. Flower is yellow and up to 15 cm across. Seeds 2-3 mm long. New Zealand plants are likely to be of hybrid origin, but have the characters of the parent species.
Common water lily (Nymphaea alba), marshwort (Nymphoides geminata), and fringed water lily (Nymphoides peltata). Common water lily has a horizontal rhizome distinguishing it from Mexican water lily, which has an erect rhizome and also often has brown blotches on the upper surface of leaves, which don’t occur on the leaves of common water lily. Marshwort and fringed water lily have thin stolons which loop across the sediment surface or lie just beneath the water surface, whereas water lilies have thick rhizomes.
October, November, December
Reproduces by rhizomes, tubers, and seed. Dispersed by water movement and deliberate plantings.
Native to Southern United States and Mexico.
Reason for introduction
Ornamental pond plant
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA).
References and further reading
Champion et al (2012). Freshwater Pests of New Zealand. NIWA publication. http://www.niwa.co.nz/freshwater-and-estuaries/management-tools/identification-guides-and-fact-sheets/freshwater-pest-species.
Johnson PN, Brooke PA (1989). Wetland plants in New Zealand. DSIR Field Guide, DSIR Publishing, Wellington. 319pp.
DiTomaso JM, EA Healy (2003). Aquatic and riparian weeds of the west. University of California Agriculture and Natural Resources Publication 3421, 462pp.
Hofstra, D.E.; Champion, P.D.; Dugdale, T.M.; Fridman, M.; Baker, R; Finlay 2013 Journal of Aquatic Plant Management (accepted for publication).