Species

Landoltia punctata

Etymology

punctata: From the Latin punctatus 'dotted', referring to a patten of small round dots

Common Name(s)

purple-backed duckweed

Authority

Landoltia punctata (G. Meyer) Les & DJ Crawford

Family

Araceae

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.

Flora Category

Vascular - Exotic

NVS Species Code

LANPUN

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.

Structural Class

Monocotyledonous Herbs

Synonyms

Spirodela punctata (G. Meyer) C. Thompson

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

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.

Life Cycle and Dispersal

These tiny plants are readily spread by waterfowl.

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.

This page last updated on 31 Jul 2014