New Zealand mustard cress Rorippa divaricata

Key Features

  • A hairless, perennial, deeply tap-rooted, rosette herb with erect stems up to 1.5 cm tall. Leaves are up to 15 cm long and are variously lobed (especially the lower leaves) and toothed. Flowers and seed pods are borne at the top of the stem with mature seed pods projecting at right angles. Plants often die back in winter.

Distribution and Habitat

  • North Island (including offshore islands) and northern South Island, but very few mainland populations now exist.
  • Occurs locally on the margins of the Rotorua lakes. Formerly widespread in forests where it occupies clearings, slips, track margins and damp banks. Also inhabits coastal forest and scrub, and disturbed areas on lake margins.

Threats

  • Habitat modification and loss.
  • Competition from weeds.
  • Trampling.
  • Browsing animals (pigs, possums, rodents and stock).
  • Insect pests.
  • Disease.
  • Succession to closed canopy forest.

Management Opportunities

  • Survey for new locations.
  • Mark known sites.
  • Protection of habitat.
  • Weed and pest control.
  • Reintroduce to appropriate sites in plantation forests.

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
  • Weed and pest management - Department of Conservation, Regional Councils
  • References
    • Dopson, S.R.; de Lange, P.J.; Ogle, C.C.; Rance, B.D.; Courtney, S. & Molloy, J. (1999). The conservation requirements of New Zealand’s nationally threatened vascular plants. Threatened Species Occasional Publication 13. Department of Conservation, Wellington.
    • Peter de Lange, Peter Heenan, David Norton, Jeremy Rolfe and John Sawyer (2010). Threatened Plants of New Zealand. Canterbury University Press, Christchurch. 472 pp.