NZ Myrtaceae Key - Online edition

Tristaniopsis laurina (Sm.) Peter G.Wilson & J.T.Waterh.


Common Names

kanooka, water gum

Origin

Eastern Australia: Queensland, New South Wales, Victoria.

Cultivation

Easily propagated from seed and available in nurseries. Present in New Zealand as street trees, shelter, and in parks or gardens; occasional records of naturalised seedlings.

Distribution

Recorded in main centres in lowland areas of the North Island, and from Richmond to Takaka in the South Island of New Zealand.

Distinguishing Features

Habit

Trees from 5–15(–35) m tall. Grows slowly in cultivation and rarely attains maximum size.

Bark and Stem/Trunk

Bark pale, smooth, papery, shedding in strips. Young branchlets and stems hairy, 4-angled.

Leaves

Leaves alternate, leathery, oval with a tapered base and broad tip, 65–120 mm long, 15–30 mm wide, upper surface dark, glossy green and paler below, leaf surface flat, not puckered, upper surface hairless, lower surface hairy, midrib raised; margins entire; tips acute; leaf stalks 3–8 mm long.

Flowers

Flower clusters 7–17 flowered. Flowers ± 10–15 mm in diam., flower stalks ± 1–2 mm long, petals 5, yellow, rounded with a narrow base, 4–5 mm long, 3–4 mm wide, hairy on the outside; sepals 5, brown, ± 1 mm long, triangular, tips free, persistent, hairy; stamens white to cream, united into 5 groups opposite the petals, shorter than the petals. Main flowering period: summer.

Fruit

Fruit dry, globular, 3-locular, smooth, 6–10 mm long, 4–6 mm wide, becoming hairless with age.

Similar Species

Leaves and flowers superficially similar to Laurus nobilis (bay leaf, or laurel tree), but in L. nobilis the stamens are not grouped in five groups opposite the petals, flowers are paired in inflorescences and fruit are fleshy berries.

Notes

Tristaniopsis laurina is susceptible to myrtle rust (caused by Austropuccinia psidii).

Tristaniopsis is a genus of about 40 species in Southeast Asia, New Guinea, New Caledonia, and Australia. There is one record of a cultivated T. collina Peter G.Wilson & J.T.Waterh. from Auckland, but mainly T. laurina is known to be present in New Zealand.

Creative Commons Attribution 4.0 International Licence (CC BY 4.0).