SelecTree: Tree Detail
BLACK WATTLE
Acacia mearnsii
Photo Locations: San Luis Obispo, CA and Hawaii
General Notes
Originally introduced as a forestry tree to Hawaii, 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 (Hawaii Pacific Weed Risk Assessment) score of 15 (High Risk).
Has fragrant Flower.
Native to Southeastern Australia and Tasmania.
Family: Fabaceae
Synonyms
Acacia mollissima
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, Gray Green, No Change, Evergreen.
Flowers Showy. Fragrant Yellow to Cream-colored. Flowers in Spring or Winter. Has perfect flowers (male and female parts in each flower).
Few, Brown Pod, 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. Apr 6, 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.