Nymphaea mexicana
Common names
Mexican water lily
Biostatus
Exotic
Category
Vascular
Structural class
Herbs - Dicotyledons other than Composites
Simplified description
Floating leaved aquatic plant with ‘lily’ shaped leaves and yellow flowers, that can develop dense stands in still and slow flowing waters.
Flower colours
Yellow
Detailed description
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.
Similar taxa
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.
Distribution
Locally naturalised, mostly Auckland and Waikato.
Habitat
Still and slow flowing water bodies
Conservation status
Not applicable
Detailed taxonomy
Family
Nymphaeaceae
Ecology
Flowering
October, November, December
Fruiting
Summer-autumn
Year naturalised
1982
Origin
Native to Southern United States and Mexico.
Reason for introduction
Ornamental pond plant
Life cycle and dispersal
Reproduces by rhizomes, tubers, and seed. Dispersed by water movement and deliberate plantings.
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland). If you have suggestions for the Wetland Indicator Status Rating, please contact: [Enable JavaScript to view protected content]
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
Other information
National Pest Plant Accord species
This plant is listed in the 2020 National Pest Plant Accord. The National Pest Plant Accord (NPPA) is an agreement to prevent the sale and/or distribution of specified pest plants where either formal or casual horticultural trade is the most significant way of spreading the plant in New Zealand. For up to date information and an electronic copy of the 2020 Pest Plant Accord manual (including plant information and images) visit the MPI website.
Environmental Weed (2024)
This plant is named in a list of 386 environmental weeds in New Zealand 2024 prepared by DOC. 759 candidate species were considered for inclusion on this new comprehensive list of environmental weeds in New Zealand. The species considered were drawn from published lists of weed species, lists of plants that must be reported or managed by law if observed, existing national and regional programmes and agreements for pest management, and species already managed by the Department of Conservation (DOC). Candidate species were then assessed to see if they were fully naturalised and whether they have more than minor impacts in natural ecosystems. Read the full report here.
Referencing and citations
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).
Attribution
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA).