Acacia auriculiformis: Earleaf acacia

Introduction

Quickly reaching a height of 40 feet and a spread of 25 feet, earleaf acacia becomes a loose, rounded, evergreen, open shade tree. It is often planted for its abundance of small, beautiful, bright yellow flowers and fast growth. The flattened, curved branchlets, which look like leaves, are joined by twisted, brown, ear-shaped seed pods. Growing 6 to 8 feet per year, earleaf acacia quickly grows into a medium-sized shade tree. This makes it a popular tree. However, it has brittle wood and weak branch crotches, and the tree can be badly damaged during wind storms. Prune branches so there is a wide angle of attachment to help them from splitting from the tree. Also, be sure to keep the major branches pruned back so they stay less than half the diameter of the trunk. These techniques might increase the longevity of existing trees.

General Information

Scientific name: Acacia auriculiformis

Pronunciation: uh-KAY-shuh ah-rick-yoo-lih-FOR-miss

Common name(s): earleaf acacia

Family: Fabaceae

USDA hardiness zones: 10A through 11 (Figure 2)

Origin: native to northern Australia, Papua New Guinea, and Indonesia

UF/IFAS Invasive Assessment Status: caution, may be recommended but manage to prevent escape (Central, South); not considered a problem species at this time, may be recommended (North)

Uses: not recommended for planting

Description

Height: 35 to 40 feet

Spread: 25 to 35 feet

Crown uniformity: irregular

Crown shape: round

Crown density: moderate

Growth rate: fast

Texture: medium

Foliage

Leaf arrangement: alternate

Leaf type: simple

Leaf margin: entire

Leaf shape: linear and sickle-shaped

Leaf venation: 3-7 parallel veins

Leaf type and persistence: evergreen, broadleaf evergreen

Leaf blade length: 4 to 8 inches

Leaf color: dark to medium green

Fall color: no color change

Fall characteristic: not showy

Flower

Flower color: bright yellow

Flower characteristics: showy; emerges in cluster on 2-3" long, axillary spikes

Flowering: spring to fall

Fruit

Fruit shape: irregular; curved, twisted, compressed, and spiraling pod

Fruit length: 2 to 4 inches

Fruit covering: dry or hard

Fruit color: turns from green to brown when mature

Fruit characteristics: does not attract wildlife; showy; fruit/leaves a litter problem

Trunk and Branches

Trunk/branches: branches droop; not showy; typically one trunk; no thorns

Bark: greenish white and smooth, becoming greenish brown and vertically fissured with age

Pruning requirement: needed for strong structure

Breakage: susceptible to breakage

Current year twig color: green

Current year twig thickness: thin

Wood specific gravity: unknown

Culture

Light requirement: full sun

Soil tolerances: clay; sand; loam; alkaline; acidic; well-drained to occasionally wet

Drought tolerance: high

Aerosol salt tolerance: moderate

Other

Roots: not a problem

Winter interest: no

Outstanding tree: no

Ozone sensitivity: unknown

Verticillium wilt susceptibility: resistant

Pest resistance: free of serious pests and diseases

Use and Management

Seeds also germinate in the landscape and it has escaped cultivation in south Florida where it is becoming a mildly invasive weed in some areas. However, it is not as invasive as Australian pine or Brazilian pepper and probably will not become so. Despite this, many people consider this to be an undesirable tree.

Earleaf acacia grows in full sun on almost any soil including alkaline and is moderately salt-tolerant. It will withstand periods of water inundation but is also very tolerant of drought.

Pests and Diseases

No pests or diseases are of major concern. Occasionally anthracnose infects leaves.

Reference

Koeser, A.K., Friedman, M.H., Hasing, G., Finley, H., Schelb, J. 2017. Trees: South Florida and the Keys. University of Florida Institute of Food and Agricultural Sciences.