Landoltia punctata
Common name
purple-backed duckweed
Synonyms
Spirodela punctata (G. Meyer) C. Thompson
Family
Araceae
Flora category
Vascular – Exotic
Structural class
Herbs - Monocots
NVS code
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.
LANPUN
Brief description
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.
Distribution
Widepsread and abundant in the North Island and northern South Island.
Habitat
Clear, still fertile water including, troughs, dams, drains and backwaters.
Features
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.
Similar taxa
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.
Flowering
November to March
Flower colours
Green
Fruiting
January to March
Life cycle
These tiny plants are readily spread by waterfowl.
Year naturalised
1929
Origin
Asia, Polynesia and Australiaa
Reason for introduction
Probably a contaminant of ornamental pond or aquarium plants.
Control techniques
Difficult to control once established.
Etymology
punctata: From the Latin punctatus ‘dotted’, referring to a patten of small round dots
Attribution
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.