Tristaniopsis laurina

Water Gum, Kannooka

Family: Myrtaceae

A very commonly planted tree, reaching 30 metres tall in its natural habitat. It has smooth brown-grey mottled bark.

It grows naturally along most of the entire coast of NSW, into the east of Victoria, and north into Queensland to around the Sunshine Coast. There are also a few record on the western slopes of NSW but these appear to be erroneous.

It is a common tree in rainforest and sclerophyll forest on freshwater creeklines in gullies, in sandstone and on other substrates, especially in places like the Royal National Park and elsewhere. It can be seen with its roots entirely in moving water. In some locations, it can completely dominate the bed of creeks and streams, creating a matrix of stems and branches in amongst sandstone boulders.

The leaves are alternate and somewhat resemble leaves of the exotic Oleander, oblanceolate, to about 12 cm long and 3 cm wide, dark green above and pale greyish white below, with scattered oil glands and a prominent midvein.

The flowers are produced in groups (dichasia – in opposite pairs) of 7-15, in leaf axils and near the terminals. Flowers are deep yellow in colour which is an attractive feature, 5-petaled, about 1 cm wide with stamens not overly showy but about 20 per flower.

The fruit is a capsule with a distinctive shape, about 10 mm long.

In the garden

A very hardy tree with an attractive canopy and overall form. It has been popular in parks and as a street tree for a long time.

Relatively easy to grow, although many Myrtaceae trees can take a while to establish and grow. But this is balanced by trees being very long-lived. This species can grow relatively quickly.

It will provide dense shade. Needs some room to grow as it will spread out. Expect a 20 m tree if grown in a garden over time, to about 10 m wide if not controlled.

It can be pruned heavily and turned into a dense topiary or hedging plant.

Likes a well-drained soil with some enrichment.

May be susceptible to Myrtle Rust.

The yellow flowers can be produced profusely, and the fruit are also ornamental.

Propagation

Propagation from seed or soft-wood cuttings.

Other information

Some cultivars are available. The most popular of these is called “Luscious” which is T. laurina ‘DOW 10’. This form is from the NSW north coast and has broader leaves, about 2 to 3 cm wide. It has been planted commonly since about 2013.

Another cultivar is called ‘Hot Tips’ with variegated leaves new bronze-red growth.

Can regenerate from seed bank after fire as well as branch shoots and suckering stems/trunks. Does not usually get burnt in fires as it grows almost purely on creeks.

Tristaniopsis – has its roots in the closely related genus Tristania which is named in honour of Jules Marie Claude de Tristan (1776-1861), a French botanist about whom not much information can be found. Tristaniopsis means “resembling Tristania” – the two genera have similar leaves and flowers.
laurina – having leaves resembling the genus Laurus – bay trees and other laurels.

Not considered to be at risk in the wild. Very common.

https://www.gardeningwithangus.com.au/tristaniopsis-laurina-water-gum/
https://www.gardeningwithangus.com.au/tristaniopsis-laurina-hot-tips-water-gum/
https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=tristaniopsis~laurina

By Dan Clarke