Azolla rubra


Azolla: From the Greek azo 'to dry' and ollo 'to kill', killed by dryness
rubra: red

Common Name(s)

Pacific azolla, azolla, red azolla

Current Conservation Status

2012 - Not Threatened

Conservation status of New Zealand indigenous vascular plants, 2012
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2012 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2009 and replaces all previous NZTCS lists for vascular plants. Authors: Peter J. de Lange, Jeremy R. Rolfe, Paul D. Champion, Shannel P. Courtney, Peter B. Heenan, John W. Barkla, Ewen K. Cameron, David A. Norton and Rodney A. Hitchmough. File size: 792KB

Previous Conservation Status

2009 - Not Threatened
2004 - Not Threatened


Azolla rubra R.Br.



Flora Category

Vascular - Native

NVS Species 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.

Structural Class



Azolla rubra R. Br.; Azolla filiculoides var. rubra (R.Br.) Strasb.; Azolla filiculoides Lam. auct. non. N.Z. authors


Indigenous. New Zealand: Kermadec (Raoul Island), North and South Islands. Widespread throughout the Pacific extending into Asia and India.


Coastal to lower montane. An aquatic plant frequenting shallow water bodies such as ponds, lake margins, dams and slow flowing streams. Also present in swamps on muddy ground. Occasionally establishing in cattle troughs. Azolla is most common in shallow eutrophic water bodies but it can also establish in more acidic wetland systems, where it is often a conspicuous plant of the lagg zone.


Aquatic, floating, dark-red (when exposed) or glaucous-green plants, usually forming ovate to ovoid patches on the surface of water bodies. Branching irregular; roots peg-like, simple (not branched). Leaves triangular; apex rounded; margins membranous, translucent; surface smooth, bright red or glaucous-green. Microsporangiate massulae spherical, surface conspicuously barbed. Megasporocarps brown, partially obscured by leaf lobe

Similar Taxa

Azolla pinnata which is presumably introduced in New Zealand (it could also have arrived naturally from Australia). Azolla pinnata is best distinguished from A. rubra by its pinnate rather than simple roots. Azolla pinnata is extremely invasive and has largely replaced A. rubra in Northland and Auckland.


Not applicable - spore producing

Flower Colours

No Flowers


Not applicable - spore producing

Propagation Technique

Easily grown (too easily!) in a pond or slow flowing stream. Plants tend to spread by fragmentation. Tolerant of shade but flourishes best in full sun. Inclined to be aggressive, especially in eutrophic water. Due to the cyanobacteria found within the plant, Azolla plants are able to fix atmospheric nitrogen. Azolla is also an important food source for the tadpole phase of the introduced Australian frogs Litoria raniformis and L. aurea


Not Threatened

Chromosome No.

2n = 44

Endemic Taxon


Endemic Genus


Endemic Family


Life Cycle and Dispersal

Minute spores are dispersed by wind, water and attachment (Thorsen et al., 2009).

Taxanomic notes

Azolla rubra has under gone a number of name changes over the last forty years. New Zealand plants have recently reverted back to A. rubra - for more information see Brownsey & Perrie (2013).


Description prepared by P.J. de Lange (1 August 2009). Description based on live plant material and herbarium specimens

References and further reading

Brownsey, P.J.; Perrie, L.R. 2013: Azolla rubra revisited. New Zealand Botanical Society Newsletter 111: 6-7.

Thorsen, M. J.; Dickinson, K. J. M.; Seddon, P. J. 2009. Seed dispersal systems in the New Zealand flora. Perspectives in Plant Ecology, Evolution and Systematics 2009 Vol. 11 No. 4 pp. 285-309


This page last updated on 10 May 2014