Species
Pistia stratiotes
Common Name(s)
Water lettuce
Authority
Pistia stratiotes L.
Family
Araceae
Brief Description
Free-floating aquatic plant, with thick pale green rounded leaves that form a rosette (lettuce like).
Flora Category
Vascular - Exotic
Structural Class
Monocotyledonous Herbs
Distribution
Nationally eradicated, previously known from Tauranga and Hokianga, Northland.
Habitat
Still and slow-flowing water bodies in warm areas.
Features
Free floating perennial herb. Plants are stoloniferous with daughter plants often attached. Leaves are velvety hairy, pale yellow-green, often with a spongy thickened base. Roots are long and finely divided. Flowers are small (about 1 cm long) and inconspicuous, arranged as a spike enclosed by a hairy green bract.
Similar Taxa
None.
Flowering
Late summer
Flower Colours
Green,White
Fruiting
Not seen in New Zealand
Year Naturalised
1975
Origin
Throughout the tropics.
Reason for Introduction
Ornamental pond and aquarium plant.
Control Techniques
Notify Ministry for Primary Industries if found.
Life Cycle and Dispersal
Older stolons between individual plants decay to release young plants. Also spreads by seed overseas.
Attribution
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.
DiTomaso JM, EA Healy (2003). Aquatic and riparian weeds of the west. University of California Agriculture and Natural Resources Publication 3421, 462pp.
Johnson PN, Brooke PA (1989). Wetland plants in New Zealand. DSIR Field Guide, DSIR Publishing, Wellington. 319pp.
Connor, H. E.; Dawson, M. I.; Keating, R. D.; Gill L. S. (1996).
This page last updated on 21 Aug 2013