SelecTree: Tree Detail

BLACK WATTLE
Acacia mearnsii

Acacia mearnsii Acacia mearnsii Acacia mearnsii Acacia mearnsii Acacia mearnsii Acacia mearnsii Acacia mearnsii Acacia mearnsii Acacia mearnsii Acacia mearnsii Acacia mearnsii Acacia mearnsii Acacia mearnsii Acacia mearnsii Acacia mearnsii

Photo Locations: San Luis Obispo, CA and Hawaii

General Notes

This plant is weedy. We do not recommend planting it in Hawai’i.

Originally introduced as a forestry tree to Hawai'i, black wattle has become a naturalized weed on several islands, particularly Maui. It grows from seed and root suckers, forming dense thickets. Hardwood timber from this species is used worldwide for building materials, fuelwood, charcoal, poles, fencing posts and tool handles. Acacia mearnsii has a HPWRA (Hawai'i Pacific Weed Risk Assessment) score of 15 (High Risk).

Has fragrant Flower.

Native to Southeastern Australia.

Family: Fabaceae

Synonyms

Acacia mollissima

Additional Common Names

BLACK WATTLE, LATE BLACK WATTLE

Tree Characteristics

Spreading with a High Canopy.

Rounded or Vase Shape.

Has Evergreen foliage.

Height: 50 feet.

Width: 40 - 50 feet.

Growth Rate: 36 Inches per Year.

Longevity Less than 50 years.

Leaves Bipinnately Compound, Bluish Green or Silver or Gray Green, No Change, Evergreen.

Flowers Showy. Fragrant Yellow or Cream. Flowers in Spring or Winter. Has perfect flowers (male and female parts in each flower).

Few, Brown Legume, Large to Very Large (1.50 to 3.00 or more inches), fruiting in Spring, Summer or Fall.

Bark Dark Gray, Furrowed or Smooth.

Shading Capacity Rated as Moderate to Dense in Leaf.

Litter Issue is Dry Fruit.

Tree Site Conditions & Constraints

Sunset Zones 8, 9 and 14 - 24; H1, H2.

USDA Hardiness Zones 8 - 11.

Exposure Full Sun to Partial Shade.

Moist to Dry and Well Drained Soil.

Clay, Loam or Sand Texture.

Slightly Acidic to Highly Alkaline Soil pH.

Seaside Tolerance is Good in Mild Zone.

Pests & Disease Information

Resistant to Armillaria. Susceptible to Invasive Shot Hole Borer and Beetle Borers, Root Rot.

Health, Safety & Environmental Concerns

Branch Strength Rated as Weak.

Root Damage Potential Rated as High.

Allergy Health Hazard.

Attracts Birds.

Not Deer Palatable.

Special Uses & Values

Hedged.

Cite this tree:
SelecTree. "Acacia mearnsii Tree Record." 1995-2020. Sep 29, 2020.
< https://selectree.calpoly.edu/tree-detail/acacia-mearnsii >

This tree is not part of the SelecTree Nursery Connection. If you would like to see this tree listed, or know of a nursery that sells it, please contact us at ufei@calpoly.edu.