Stalked adder’s tongue fern Ophioglossum petiolatum

Many of New Zealand’s threatened ferns are found in warmer climates on landmasses north of New Zealand, with New Zealand representing their southern distribution limits. These species tend to be restricted to northern areas of the country and occupy coastal and geothermal sites. Other species are restricted to habitats such as wetlands, which have suffered drastic modification and loss, or are palatable to stock and feral animals.

Key Features

  • Perennial, often forming extensive patches. Leafy in summer, but dying down in autumn and winter.
  • Leaves broad and with a distinct petiole up to 3 cm long.
  • Mature stipe with the sporophore can be up to 20 cm long.
  • P. coriaceum usually has a narrower, smaller leaf that lacks a petiole and the mature stipe is much shorter (up to 9 cm long).

Distribution and Habitat

  • Northern half of North Island. Once more widespread in North Island and northern South Island.
  • Moist coastal and lowland sites such as ephemeral wetlands, lake and lagoon margins, and damp hollows in forest.


  • Wetland drainage.
  • Habitat modification and loss.
  • Natural succession by taller vegetation can shade it out.
  • Competition with exotic plants.
  • Browsing by slugs and snails.

Management Opportunities and Methods

  • Survey for new locations.
  • Protection of habitat.
  • Weed control.

Monitoring Options

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

Further Information and Support

  • New Zealand Plant Conservation Network (NZPCN).
  • Weed management - Department of Conservation, Regional Councils.
  • References
    • Brownsey, P.J. & Smith-Dodsworth, J.C. (2000). New Zealand Ferns and Allied Plants. David Bateman, Auckland.
    • Peter de Lange, Peter Heenan, David Norton, Jeremy Rolfe and John Sawyer (2010). Threatened Plants of New Zealand. Canterbury University Press, Christchurch. 472 pp.