Vascular – Exotic
Dicotyledonous Herbs other than Composites
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.
Sprawling submerged plant often floating just under the waters surface, with finely divided thread-like leaves with tiny round bladders (often black). Usually many small yellow snapdragon-like flowers are held above the water surface in summer and autumn.
Abundant in Northland, Auckland and northern Waikato.
Most freshwater habitats, especially acidic and nutrient rich water.
Leaves are filamentous, up to 1 cm long, usually entire but occasionally branched. Bladders are up to 1.5 mm long and obliquely ovoid, situated on the leaves on short stalks. Small (c. 1 cm across) yellow flowers, with red stripes on the lower lip are commonly produced above the water surface either individually or in groups of up to 5 (8) on stems 3-20 cm long. Cleistogamous flowers are also produced on submerged stems. Capsules green, globose 2.5-3 mm across. Seed ovate, flattened with wing 0.75-1 mm x 0.7 mm.
Utricularia australis(rare native species mostly in northern North Island) and U. geminiscapa (introduced species found in Westland). Utricularia gibba has entire or nearly entire leaves, whereas the other Utricularia species have leaves divided many times into filiform segments with larger bladders.
December, January, February
Summer - autumn
Perennial. Reproduces freely by seeds, turions, stem fragments. Forms dense mats. Dispersed by Water movement, dumped aquaria contents, contaminated machinery, eel nets, boats and trailers. Seed spread by water fowl.
Widespread and almost cosmopolitan in tropical and warm temperate countries
Reason for introduction
Originally known from northwest Auckland, possibly introduced via the aquarium trade. In late 1990’s found in Northland and likely to have been introduced from Australia via water fowl. Has rapidly spread over the past decade.
Not usually controlled in New Zealand, but may be controlled manually, or mechanically.
Tolerant of clean or nutrient-rich, warm or cold, still or slow-moving water.
utricularia: A small bladder
gibba: From the Latin gibbus ‘humped’ or ‘hunched’, meaning gibbous, i.e. very convex or tumid
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA).
References and further reading
Champion et al (2012). Freshwater Pests of New Zealand. NIWA publication. http://www.niwa.co.nz/freshwater-and-estuaries/management-tools/identification-guides-and-fact-sheets/freshwater-pest-species.
Salmon, B. (2001). Carnivorous plants of New Zealand. Ecosphere Publications, Auckland. 303 pp.
Webb, C.J.; Sykes, W.R.; Garnock-Jones, P.J. (1988). Flora of New Zealand Volume 4: Naturalised pteridophytes, gymnosperms, dicotyledons. Botany Division, DSIR, Christchurch. 1365 pp.