Endangered Plants

Great Barrier Island is at risk from a range of invading plant pests. Many are already on the island and people could easily introduce others. Often this occurs accidentally. Seeds find their way to the bottom of people's dirty boots or attached to clothing or packs.

Marram Grass (Ammophila arenaria) This plant is a serious threat to coastal dune and sandy areas. It competes with native species such as pingao taking over large areas of dunes with its extensive foliage and roots systems.

Apple of Sodom (Solanum linnaeanum) This introduced plant grows on coastal sand dunes. It has a poisonous yellow fruit like an apple and wavy leaves with prickles. The flowers are large and purple. It grows into a shrub about 2m in height and is found in the top half of the North Island including Great Barrier Island.

GBI has 50 plants that are threatened including the endemic (found only on) Great Barrier Island tree daisy. The DoC programme of work includes learning more about the habits and habitat of these plants and designing ways to look after them.

Some of the plants under threat are sand tussock, prostrate kanuka, coastal cress and northern mistletoe. Facts about each endangered plant are summarised in the tables below.

Sand Tussock
Austrofestuca littoralis

Picture of native New Zealand sand tussock - Image: RJ Stanley

Once found throughout the Auckland area, now only on Great Barrier Island.

Habitat

  • found on sandy beaches, rear dunes
  • close to pohutukawa forest
  • east coast of Great Barrier Island

Threats

  • pampas
  • marram
  • people using dunes for recreational driving
  • stock grazing

Great Barrier Tree Daisy
Olearia allomii

Picture of Great Barrier Island tree daisy - Image: RJ Stanley

Endemic to Great Barrier Island.

 

Habitat

  • higher sites
  • often logged area

Threats

  • only occurs on Great Barrier Island

Prostrate Kanuka
Kunzea sinclairii

Picture of prostrate kanuka - Image: RJ Stanley

Habitat

  • higher altitudes
  • rocky outcrops
  • acidic soils
  • low shrubland
  • often with Great Barrier Island tree daisy

Threats

  • hybridisation with upright kanuka

Coastal Cress
Lepdium oleraceum

Photo of coastal cress - Image: Peter de Lange

Captain Cook used this to prevent scurvy with his crew.

 

Habitat

  • off shore islands of Great Barrier
  • on privately owned land

Threats

  • habitat destruction
  • grazing
  • exotic plants invading habitat
  • diseases such as white rust

Northern Mistletoe
Trilepidea adamsii

Sketch of northern mistletoe - Image: Fanny Osborne, Heineman

Once found throughout the Auckland area, now only on Great Barrier Island.

 

Habitat

  • coastal
  • open shrubland, lowland forest
  • grows on hosts - mapou, mamangi and wharangi

Threats

  • over collecting
  • habitat destruction
  • (possum browse on mainland sites)

© Heurisko Ltd www.learnz.org.nz/2001