Acacia: Many Trees, One Name

click image to zoomFamily Name
Acacia melanoxylon of the Family Fabaceae (Leguminosae)

Common Names
Australian blackwood, black wattle

Height/Weight
The average height is 80 to 100 feet, but some trees grow to 120 feet tall with diameters of 3 feet or more. The average weight is 41 pounds per cubic foot.

Properties
Blackwood is a fairly heavy, dense wood with medium bending strength and stiffness.
The wood has a deep, lustrous grain and is resilient but easy to work, with moderately high blunting effect on cutting tools.
The wood turns very well. It holds nails and glues satisfactorily.
Experts recommend a reduced cutting angle when planing interlocked or wavy grain. Acacia is a widely used name for trees, most probably because the genus Acacia includes some 1,200 species worldwide, in addition to numerous trees outside the genus, which also are known as acacia. This column will focus on Acacia melanoxylon, also known as Australian blackwood, but will also recognize some of the other famous — and not so famous — trees that share the name acacia.

The Encyclopedia of Wood describes Australian blackwood as a “highly decorative timber, in great demand for high-quality furniture, cabinets and paneling.” Other uses include: billiard tables, tool handles, office and bank fittings, interior joinery, gunstocks, ornamental turnery, boat building and flooring. The book contends there are “hundreds of species of wattle belonging to the Acacia genus found in India, South Africa and South America, but (Australian blackwood) is one of the most attractive.” Also one of the largest of the “wattles,” it is found in New South Wales, Queensland, southeastern Australia, Victoria and Tasmania.

Acacia melanoxylon, which sometimes closely resembles Hawaiian koa, is commonly called blackwood although it has nothing to do with its color and should not be confused with African blackwood, a truly black species. Australian blackwood’s sapwood is straw colored with a reddish brown to dark brown heartwood and bands of gold to dark brown. While the grain is usually straight, it can sometimes be interlocked or wavy, producing a beautiful fiddleback figure. Australian blackwood is gaining popularity in part because koa, one of the most-prized acacias, is limited in production. To mimic koa, the most-prized look is quarter-cut, with as much contrast and figure as possible.

Known to some as Tasmanian blackwood or black wattle, Australian blackwood grows fast and tall. Ranging in height from 80 to 120 feet with a three-foot diameter. It has a wide ecological tolerance, occurring over an extensive range of soils and climatic conditions, but develops better in colder climates. Although efforts to control its “invasion” of natural vegetation, commercial timber plantations and farmlands can result in considerable costs, the timber value and nursing of natural forest succession provides a positive contribution.

Article excerpted from Wood of the Month archives.