Yellow bladderwort Utricularia australis

Key Features

  • A submerged, free-floating aquatic plant with stems up to 40 cm long, and finely-divided, threadlike leaves. Many small bladders, used to trap tiny aquatic animals, are present among the leaves. Emergent flower stalks up to 15 cm long, bearing small yellow, lobed flowers. The introduced species Utricularia gibba is similar, but forms large floating mats and is almost always flowering, unlike U. australis which is submerged and flowers sporadically. Utricularia geminiscapa occurs in the Westcoast of South Island and is the correct name for plants from there previously treated as U. australis. Utricularia geminiscapa is distinguished by the tips of the leaves being sparsely hairy, the bladder having glands that are quadrifid with two pairs of parallel arms, and disk-shaped seeds.

Distribution and Habitat

  • North Island, Northland to Wellington.
  • Found in still, lowland waters such as pools and ponds in bogs, or slow-moving streams draining bogs.

Threats

  • Habitat modification and loss, including changes to hydrology.
  • Competition with aquatic weeds such as Utricularia gibba.

Management Opportunities

  • Survey for new locations.
  • Marking of known sites.
  • Protection of habitat.
  • Creation of new habitat and re-establishment in appropriate sites.
  • Ensuring that forest owners are aware of potential habitats and can recognise the species.

Monitoring Options

  • Check existing populations annually.
  • Report new locations to DOC and NZPCN.

Further Information and Support

  • New Zealand Plant Conservation Network (NZPCN). http://www.nzpcn.org.nz
  • References:
    • Johnson & Brooke (1989). Wetland plants in New Zealand. DSIR Publishing, Wellington.

    • Heenan P.B., de Lange P.J., Knightbridge P.I. 2004: Utricularia geminiscapa (Lentibulariaceae), a naturalised aquatic bladderwort in the South Island, New Zealand. New Zealand Journal of Botany 42: 247-251.

    • Peter de Lange, Peter Heenan, David Norton, Jeremy Rolfe and John Sawyer 2010: Threatened Plants of New Zealand. Canterbury University Press, Christchurch. 472 pp.