Spirodela punctata (G. Meyer) C. Thompson
Vascular – Exotic
Herbs - Monocots
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
Tiny, surface floating aquatic plant with bright green plate-like leaves (5 x 3 mm) that have a purple underside and more than one root per leaf.
Widepsread and abundant in the North Island and northern South Island.
Clear, still fertile water including, troughs, dams, drains and backwaters.
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).
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
Platelets usually with bright green uppersides, red-purple undersides and two or more roots per platelet. The leaves are generally thicker than those of Lemna. Flowers are small enclosed in a spathe within a lateral pouch on the platelet. Seeds are ribbed in a network with a prominent operculum.
The native Lemna disperma is very similar but the root does not arise from a winged sheath. Landoltia has two or more roots arising from each platelet. Watermeal (Wolffia australiana) is much smaller and lacking roots. Azolla is an aquatic fern and has scale like leaves that overlap.
November to March
January to March
These tiny plants are readily spread by waterfowl.
Asia, Polynesia and Australiaa
Reason for introduction
Probably a contaminant of ornamental pond or aquarium plants.
Difficult to control once established.
punctata: From the Latin punctatus ‘dotted’, referring to a patten of small round dots
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA).
References and further reading
Johnson PN, Brooke PA (1989). Wetland plants in New Zealand. DSIR Field Guide, DSIR Publishing, Wellington. 319pp.
Aston, H (1977). Aquatic plants of Australia. Melbourne University Press, 367PP.; Popay et al (2010). An illustrated guide to common weeds of New Zealand, third edition. NZ Plant Protection Society Inc, 416pp.