Wolffia arrhiza var. australiana Benth.
Vascular – Native
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.
2n = 20, 40
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants. Authors: By Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley.
2012 | Not Threatened
Previous conservation statuses
2009 | Not Threatened
2004 | Not Threatened
Indigenous. North, South and Chatham Islands. Found throughout the Southern Hemisphere but exact distribution not clear
Coastal to lower montane (up to 400 m a.s.l.) in still, fertile, water in sunny situations. Often found in association with Lemna minor L., Landoltia punctata (G.Mey.) Les et D.J.Crawford, Azolla filiculoides Lam., Ricciocarpos natans (L.) Corda and Riccia fluitans L. Easily overlooked.
Bright green, minute aquatic summer-green herb without roots. Platelets 0.3-1 mm long, bearing one vegetative bud per platelet, ellipsoidal, dorsal surface weakly convex, the central green part merging into a colourless rounded shoulder; submerged portion much larger than that above water, pale, loosely cellular, more or less semi-circular in side view but laterally compressed. Inflorescence in a cavity opening on upper platelet surface; bearing one male and one female flower united without spathe. Ovule 1. Fruit spherical. Seed smooth with prominent operculum.
None. Could be confused with Lemna and Landlotia from which it differs by its much smaller size, absence of roots, uniformly green colour without red or purple pigmentation, and by the platelets bearing only one vegetative bud
November - February
December - April
Easily grown in a suitable pond, pool or aquarium. During winter it sinks to the bottom sediment, and becomes dormant, returning to surface during warmer weather in late spring and summer.
wolffia: Named after Johann Friedrich Wolff, 18th century German botanist and physician
australiana: From the Latin australis meaning southern
Where To Buy
Not commercially available
Description adapted from Moore and Edgar (1997).
References and further reading
Moore, L.B.; Edgar, E. 1970: Flora of New Zealand. Vol. II. Government Printer, Wellington.