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Acacia mearnsii

black wattle

Attracts Pollinators Drought Tolerant Fragrant (light)

Overview

Acacia mearnsii is a fast-growing evergreen tree reaching 6-15 m (20-50 ft) tall, with a spreading crown and dark fissured bark. Unlike many wattles, it keeps true bipinnate leaves throughout life rather than developing flattened phyllodes; the dark green feathery fronds are 8-12 cm (3-4.7 in) long with many small leaflets and a raised gland at each pair of pinnae. In late spring and summer it bears abundant rounded heads of pale yellow to cream flowers, each head 5-6 mm (0.2 in) wide, massed in branched sprays and lightly fragrant. Flat dark brown pods 5-10 cm (2-4 in) long follow, constricted between the seeds. It grows naturally in open forest and on disturbed ground in southeastern Australia and is cultivated worldwide for the tannin in its bark. The same vigour makes it a serious environmental weed outside its native range; A. mearnsii is listed among invasive species in South Africa, parts of Europe, and other regions, where it forms dense thickets. It is short-lived, often declining after 15-20 years.

Native Range

Native to southeastern Australia, including New South Wales, Victoria, Tasmania, and South Australia, in open forest, woodland, and along watercourses and disturbed margins. It has been planted and has naturalised widely in Africa, Asia, South America, and Europe.

Suggested Uses

Grown in forestry and farm plantings for tannin, fuel wood, and shelter, and used for quick shade and nitrogen-fixing on poor soils. Outside its native range its weed risk restricts where it is planted.

How to Identify

A wattle with dark green feathery bipinnate leaves kept throughout life, raised glands spaced along the leaf stalk between pinnae pairs, and dark fissured bark. The flowers are pale yellow to cream in small round heads, paler than the bright gold of many wattles, followed by constricted brown pods.

Appearance

Size & Dimensions

Height20' - 50'

Width/Spread13' - 26'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~8 weeks

Spring Summer

Pale cream to yellow globular flower heads appear in late spring and summer, roughly October to January, in large branched sprays. They are lightly fragrant and rich in pollen. Flowering is heavy in most years and followed by abundant seed pods.

Detailed Descriptions

Flower Description

Pale yellow to cream

Foliage Description

Dark green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-12 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 Range4.5 - 7.5(Neutral)

357912

Soil Types

clay loam sand

Drainagewell drained

Water & Climate

Water Needs

Low

Frost Tolerance

hardy

Time to Maturity

Fast; flowering size in 2-4 years, full height in 10-15 years, often declining after 15-20 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Grows quickly in full sun on a wide range of soils, including poor, acidic, and disturbed ground, and fixes nitrogen through root nodules. It tolerates drought once established and moderate frost but is damaged by severe freezes. Little watering or feeding is needed, and growth can be rapid on cleared sites. Its prolific seeding and suckering let it spread readily, so it can become weedy near bushland. Wind can break branches on older, brittle trees.

Pruning

Tolerates formative pruning when young to develop a single trunk and can be cut for tannin bark or fuel. Removing seed pods before they shed limits unwanted seedlings. Old trees respond poorly to hard pruning and are prone to dieback.