Utricularia arenaria, u. gibba, u. livida and u. sandersonii

Bladderwort species

Also known as:

Humped bladderwort

Family: Lentibulariaceae

Origin: Various

Stalks of bladderwort flowers coming out of the water.
Bladderwort is submerged just below the surface of the water or entangled with other plants.

Regional Pest Management Plan (RPMP) status

  • National Pest Plant Accord Species
  • Whole region — Sustained control

View more about the RPMP statuses

General description

Perennial (sometimes annual for u. livida) aquatic herbs. Roots are absent. Stolons are long, branched, filamentous, bear tiny round bladders, and form dense sprawling mats. Bladders suck insect and zooplankton prey in when external hairs triggered. Flowers are submerged and borne in summer. u. gibba flowers are yellow and held above water. Seeds are small and ripen summer – autumn.

What you need to know

To help protect our environment:

  • you must not breed, distribute, release or sell bladderwort species - As bladderwort species are National Pest Plant Accord species, these restrictions apply within the Auckland region and across the whole of New Zealand
  • you must not plant bladderwort species within the Auckland region
  • you must destroy any bladderwort species on land that you occupy if it has been planted in breach of the above rules and you are directed to do so by an authorised person.

Habitats

Still and slow-moving water bodies, seasonally inundated water body margins.

Dispersal

Seeds dispersed by water movement. Vegetative spread from stem fragments, dispersed by attachment to waterfowl. Human-mediated dispersal through contamination of boats, equipment and aquarium/ornamental pond plants.

Impact on environment

Spreads aggressively and forms dense mats, threatening small turf-forming species and native bladderwort species in freshwater ecosystems. May shade submerged vegetation and alter sediment chemistry.

Control

Site management

Consider an aquatic pest plant control operator. Contact Auckland Council for control options.

Recommended approaches

Physical control

Method: Dig out.

Disposal options: Remove to greenwaste or landfill if practical.

Biocontrol

Biocontrol is currently not available for this species.

Community agrichemical control recommendations

Certified Handler/Experienced agrichemical user: Foliar spray of 100 ml glyphosate green per 10 L of water.

Caution: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.

Slightly submerged bladderwort with yellow flowers and tall stalks.
Rotting vegetation affects water quality.
Photo credit: Rohan Wells, NIWA
Lots of bladderwort flowers growing in shallow water.
Flowers protrude above the water surface.
Photo credit: Jackie Miles and Max Campbell
Close up of bladderwort flowers.
Prefers still or slow-moving water.
Photo credit: Rohan Wells, NIWA
Close up of the yellow bladderwort flowers.
Reproduces freely and disperses widely.
Photo credit: Rohan Wells, NIWA
Bladderwort with yellow flowers sticking up above the surface.
Displaces native species.
Small white and purple bladderwort flowers.
Bladders are used to trap insects.