The New Zealand Plant Conservation Network

Species

Utricularia australis

Etymology

Utricularia: a small bladder
australis: southern

Common Name(s)

yellow bladderwort

Current Conservation Status

2012 - Threatened - Nationally Critical

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 - Threatened - Nationally Endangered
2004 - Gradual Decline

Qualifiers

2012 - RF, RR, SO
2009 - RR, SO

Authority

Utricularia australis R.Br.

Family

Lentibulariaceae

Flora Category

Vascular - Native

Structural Class

Dicotyledonous Herbs other than Composites

Synonyms

Utricularia protrusa Hook.f., U. mairii Cheeseman

Distribution

Indigenous. In New Zealand known only from the North Island, from Te Paki to Lake Taupo, and near Paekakariki. Also present in Australia and Europe.

Habitat

Coastal to lowland. Peat lakes, peaty pools and slow-moving streams draining peat bogs. Often found floating near or amongst spikerush (Eleocharis sphacelata R.Br.). U. australis appears to prefer shallow, still water, in sunny situations with little or no competition from other submerged aquatic plants.

Features

Wholly submerged, floating carnivorous aquatic plants dying down to turions (resting buds) in winter. Stems green to greenish-yellow, 400 mm or more long, filiform, sparingly branched. Leaves submerged, numerous, green to greenish-yellow, multifid 30-40 mm long, segments capillary up to 10 mm long. Bladders numerous and conspicuous, 1-4 mm long when mature, obliquely ovoid, mouth with 2 long setae, whole structure coloured dark blue to purple when mature and attached by short stalk near base of leaf segments. Inflorescence rarely seen, when present borne on a dark-green 2-4(-5)-flowered scape up to 170 mm long, this broad at base and tapering. Calyx lobes oblong to ellpitic. Flowers dark yellow sometimes with a dark orange blotch on palate. Corolla upper lip 3-lobed, lower entire, 7-9 mm wide, broad, palate protruded; spur short, obtuse. Capsule 1.5-2 mm diameter, globose. Seeds not known in New Zealand.

Similar Taxa

Utricularia gibba L. is an introduced species that has smaller, less divided floating stems and entire leaves. The upper lip of the corolla in this species is entire rather than 3-lobed as is seen in U. australis. U. gibba forms massive mats floating at the water surface and is usually always flowering while U. australis produces feathery, wholly submerged, floating stems and is very rarely found flowering. New Zealand examples of the naturalised U. geminiscapa Benj. differ from U. australis by their terminal leaves bearing small hairs, the internal portions of their bladders bearing bearing quadrifid trichomes whose arms are in parallel, and by their cleistogamous flowering condition. Utricularia australis could be confused with the fully submerged, aquatic state of Myriophyllum propinquum A.Cunn., with which it sometimes grows. However, Myriophyllum can be readily distinguished from U. australis because it bears roots and the foliage lacks bladders

Flowering

Flowers, December-March(-April), though some populations may never flower.

Flower Colours

Orange,Yellow

Fruiting

Seed has not yet been seen in New Zealand plants.

Propagation Technique

Difficult and should not be removed from the wild.

Threats

Now seriously at risk throughout most of its northern North Island range through competition from Utricularia gibba which occupies the same habitat and has a more aggressive growth form and also by other introduced aquatic weeds. It is also vulnerable to habitat loss through modification and drainage. There is some evidence which suggests it is selectively browsed by Canadian Geese and Black Swans

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

This page last updated on 13 May 2014