Cabbage tree at sunset, Alligator Head, Marlborough Sounds

The distinctive cabbage tree (Cordyline spp.) is an iconic New Zealand species, its primitive flax-like foliage and often deeply weathered branches and trunks giving an almost prehistoric touch to it environment. Cabbage trees are relatively fast growing and are remarkably resilient to harsh, salt-laden winds, thriving in exposed localities where many other species may find it difficult to get established. As such cabbage trees are widespread throughout New Zealand, except in the far south of the South Island where their natural range is limited by colder temperatures.

In recent years cabbage trees throughout New Zealand have begun dying suddenly for no apparent reason, in a phenomenon known as ‘Sudden Decline’. Theories abounded as to the cause, ranging from trees over-expending themselves by flowering too heavily, through to attack by insects, viruses or fungi. Sudden Decline has eventually been linked to a native sap-dwelling bacterium, Phytoplasma australiense, whose spread through native flax populations in the Manawatu contributed to the collapse of the once vibrant flax fibre industry. Phytoplasma has decimated populations of large cabbage trees in some areas, but early fears that cabbage trees might be wiped out completely by this disease now appear to be unfounded.

Nevertheless, Sudden Decline continues to claim cabbage trees throughout New Zealand and the reasons for its spread are still not well understood. Landowners are encouraged to fence off existing cabbage tree groves to encourage natural regeneration, while the planting of cabbage trees in gardens and reserves will also help to ensure that they keep their place as a classic feature of the New Zealand landscape.