Cabbage Tree

Cordyline australis

Family: Asparagaceae    Origin: New Zealand

In its native habitat, the Cabbage Tree is an interesting yet much appreciated tree by native animal and human populations. This tree was cultivated by an endemic people of New Zealand as a source of fibers used for clothing, shoes, baskets, and fishing gear. The fruits are a welcome and favorite food of a pigeon that lives in New Zealand, as well as many other native birds of the island. This tree is very popular as a landscape plant not only in its native homeland, but also in Australia. Fast growing and very tough, this tree is a welcome urban addition for its toughness and interesting appearance.

Arboriculture

Growth Form

This is a large tree when fully grown, reaching heights of 20 metres or more. Its single trunk can be sizeable, around 2 metres in diameter. Typically, its naked trunk is topped with a round and open form of foliage. Its base sometimes flares out with fascinating buttressing roots, and its bark and branch structure is gnarled and twisting, making this tree architecturally very attractive. There are of course, many cultivars and variances on this theme, with some kinds growing multi-branched, or with shorter mature heights.

Trunk

The texture of the trunk is fissured and gnarled, and feels like cork when you touch it. Normally it’s dark grey in color. Its base can reach gigantic girth which should be allowed for when choosing a site for planting.

Flowering

In spring and summer, Cabbage Trees bloom with large panicles (up to 100cm) of very pleasant smelling sweet and densely packed flowers, which are usually white. Before they open, some cultivars have pink tinges on the bracts, and some may also be green. The smell and nectar inside of the flowers are very attractive to wildlife and pollinators.

Foliage

Swords shaped green leaves, typical of many cordyline species, form from crowded clusters at the ends of branches and they sometimes droop slightly in older specimens. Each leaf measures around 60cm in length, sometimes shorter and sometimes longer. They have a very pronounced center midrib running through each leaf.

Cultivars have been developed with purple hues similar to Cordyline fruiticosa, for which it is easy to mistake them. Development of cultivars is ongoing.

Fruits

Fruits are white and berry-like, measuring around 6cm in length. They are edible for various animals, especially some birds. The fruit are a valuable source of food for many birds, especially in their native habitat. Much care has to be taken in their country of origin to ensure this tree is preserved as a native food source for wildlife.

Management

Propagation

Cabbage Tree is started from seed that may require some amount of physical scarification for germination, as the seeds inside of the fruits depend on native birds of New Zealand to eat and spread the seed around through their feces. The seeds themselves have a protective layer to help them not become digested in the digestive tract of these birds, but germination may happen faster if this protective substance is removed, simulating the natural scarification the seeds undergo in the bodies of animals.

While most Cordylines can be planted from cuttings, C. australis, cabbage tree, is not usually successfully propogated this way. Transplanting is also usually unsuccessful.

Cultivation

Because of the hardiness of this tree, it grows naturally in many varying conditions. Cultivars that have occurred naturally and in captivity have more specialized needs but overall, this tree is a tough customer and does well in most environments. They are fire resistant and excellent trees for stabilizing banks, as their roots are fibrous and spreading.

They enjoy full bright sun exposure in temperate climates and well-draining soil, but they can also be grown in soils that are slightly boggy and water retentive. Being cold-loving plants, they should have at least partial shade in the sub-tropics.

Feeding isn’t necessary except for when planting new Cabbage Trees. They do benefit from liberal organic matter, especially during establishment.

David’s field notes

I regularly see two issues with Cordyline australis. The first is people thinking it’s a native. I guess having the specific epithet, “australis” is understandably confusing. It’s latin for ‘south’ and probably refers to New Zealand’s south island, since that’s where the orginal type was collected from.

If wanting to plant a native Cordyline in Brisbane I suggest considering C. fruiticosa. Actually, over half of the 14 known species of Cordylines are native to Australia.

The other, and more important issue I see is cabbage trees being planted near buildings. They have underground rhyzomes and a solid trunk which can cause grevious damage to even concrete. The International Cordyline Association recommends they not be planted within 4-5 metres of any structure.