Tristaniopsis spp.

water gum

Myrtaceae

Southeast Asia, Australia, and the western Pacific

Attracts Pollinators Drought Tolerant

SunFull Sun – Part Shade

WaterMedium · drought-tolerant

HardinessZones 9–11

Overview

Tristaniopsis spp. is a genus of about 40 species of evergreen trees and shrubs in the myrtle family (Myrtaceae), native to Southeast Asia, Malesia, eastern Australia, New Caledonia, and the western Pacific. Plants range from multi-stemmed shrubs to single-trunked trees 15-100 feet (4.5-30 m) tall, many with smooth bark that peels in patches to reveal pale, mottled underbark. The leaves are simple, alternate or clustered at branch tips, leathery and glossy dark green, often turning red before they drop individually. Clusters of small flowers, each with five yellow petals and tufts of stamens, open in summer and are followed by small woody capsules. Several species grow along watercourses and tolerate seasonal flooding, while others occupy heath and forest on poorer soils. Tristaniopsis laurina, the water gum, is widely cultivated as a street and shade tree for its dense crown and tolerance of urban conditions. Growth is moderate, and most species are frost-sensitive when young.

Native Range

Native to Southeast Asia, Malesia, eastern Australia, New Caledonia, and islands of the western Pacific, growing in rainforest, along watercourses, and in heath and open forest.

Suggested Uses

Grown as street, shade, and specimen trees and as screening shrubs in mild climates. Streamside species are used for bank stabilisation and in rain gardens that flood periodically.

How to Identify

Evergreen tree or shrub with leathery, glossy leaves clustered toward the branch tips and smooth bark that sheds in patches to expose paler underbark. Small five-petalled yellow flowers form in branched clusters, followed by woody capsules. Old leaves often turn red before dropping singly.

Appearance

Size & Dimensions

Height15' - 100'

Width/Spread10' - 30'

Colors

Flower Colors

yellow

Foliage Colors

green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

Summer

Flowering occurs mainly in summer, roughly December to February in the Southern Hemisphere. The yellow flowers open in clusters and draw nectar-feeding insects. Woody seed capsules develop over the following months and persist on the branches.

Detailed Descriptions

Foliage Description

glossy dark green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.5(Neutral)

357912

Soil Types

clay loam sand

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

tender

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Most species grow in full sun to part shade in moist, free-draining soils and tolerate a range of textures from sand to clay. Streamside species withstand periodic flooding and wet ground, while established plants of Tristaniopsis laurina also tolerate dry spells and compacted urban soils. Young plants are frost-sensitive and grow without damage where hard freezes are absent. Propagation is by seed or semi-hardwood cuttings. Pests are few, though leaf-spot fungi and scale insects appear on stressed plants.

Pruning

Little pruning is needed beyond removing dead or crossing branches in late winter. Street and specimen trees can be shaped when young to a single leader, and shrubs trimmed lightly after flowering to keep a compact form.

✓ Toxicity

Non-toxic

Tree