Cabbage trees, Cordyline australis, tē kōuka, with their tropical appearance may seem unlikely inhabitants of the Clutha basin, but they are in fact one of the few full size trees indigenous to this area. In Māori legend the name for the Cromwell basin was “Tirau”, many cabbage trees. They were a food source for both Māori and early European settlers.
On vineyards, they are hardy and easy to raise, happily surviving frosty winters. In the wild they are found on riverbanks, but they also occur on hill slopes, particularly if there is a spot where water seeps underground. Their water needs are no greater than those of a grapevine, making them attractive to plant between vine blocks where they can extend high above the vines without casting an excessive shadow. They flower in spring, and their summer fruits are eaten by many native and introduced birds. On our vineyard, the ground under the lower ring of dead leaves is a favourite nest-site for Mallard ducks.
Although they do not have true tap roots, cabbage trees grow long branches downwards into the ground, serving as tap roots and storing food reserves. True roots extend from these enlarged 'tap roots' enabling the trees to obtain water from deep in the soil. Cabbage trees also differ from most other trees by having multiple vascular bundles which extend right to the middle of the trunk, rather than a single external cambium supporting growth of xylem and phloem near the periphery of the trunk. Because of this, chips and fragments from any part of the tree may form roots and a leafy shoot and develop into a new adult tree. The food stores in both trunk and tap roots enabled Māori to use cabbage trees for food, fibre and medicine; early European settlers are said to have brewed beer from the roots.
Cabbage trees are still relatively abundant throughout New Zealand, although they are now rare in the Cromwell basin due to grazing stock, rabbits, possums and hares, all of which find the leaves of young trees attractive to eat. Mature trees are less attractive to these animals. A good ring of full-height rabbit netting is a great help in establishment.
There is speculation that cabbage trees provide shelter for vineyard yeasts during the winter - if so, these lovely natives provide a practical benefit for us by protecting the wild yeasts that contribute to the flavours and textures of our Pinot Noir.