About Acacia harpophylla F.Muell. ex Benth.
Taxonomy and Common Name
Acacia harpophylla F.Muell. ex Benth., commonly known as brigalow, is a root-suckering tree that can reach heights of up to 20 m.
Bark Characteristics
It has hard, furrowed, almost black bark.
Branchlet Features
Its branchlets, which can be either glabrous or hairy, are angular at their tips.
Phyllode Presence
Like most Acacia species, it has phyllodes instead of true leaves.
Phyllode Texture and Shape
These evergreen phyllodes are coriaceous and sericeous, with a curved falcate shape.
Phyllode Size and Nerving
They measure 10 to 20 cm long and 7 to 20 mm wide, with many closely parallel nerves, of which three to seven are more prominent than the rest.
Flowering Period
Flowering occurs between July and October, when the tree produces condensed inflorescences.
Inflorescence Arrangement
These inflorescences grow in groups of two to eight on racemes, and usually appear as axillary clusters.
Flower Head Traits
The spherical flower heads are 5 to 8 mm in diameter, and each holds 15 to 35 golden flowers.
Seed Pod Development
After flowering, crustaceous, glabrous seed pods develop.
Seed Pod Shape
The pods are subterete, ranging from straight to slightly curved, and are raised over and constricted between individual seeds.
Seed Pod Size and Nerving
They can grow up to 20 cm long, 5 to 10 mm wide, and have longitudinal nerves.
Seed Appearance and Arrangement
The seeds inside the pods are soft, dull brown, and arranged longitudinally.
Seed Shape and Funicle
They have an oblong or broadly elliptic shape, and are flattened but thick, measuring 10 to 18 mm long, with a filiform funicle.
Brigalow Woodland Formation and Habitat
Brigalow, along with gidgee (Acacia cambagei), forms open woodlands on flat to gently undulating terrain with heavy, relatively fertile clay and clay-loam soils.
Woodland Distribution and Rainfall Range
These woodlands are primarily found in Eastern Australia's region that receives 300 to 700 mm of annual rainfall, and extend from a northern extreme at 20° S into northern New South Wales.
Mixed Community Composition
In some regions, brigalow and gidgee grow together in mixed communities, and are commonly associated with other woody species.
Associated Overstorey and Understorey Species
Overstorey associates include Eucalyptus coolabah, Eucalyptus cambageana, and Casuarina cristata, alongside a variety of understorey species.
Similar Acacia Habitat and Range
Acacia tephrina, Acacia georginae, and Acacia argyrodendron occupy similar habitats and share similar habits and growth forms, but have smaller ranges.
Structurally Similar Acacia Communities
A number of other Acacia species also form structurally similar communities.
Brigalow Rainfall Tolerance
Brigalow occurs across areas receiving from over 900 mm of annual rainfall in coastal regions to semiarid regions with 500 mm of annual rainfall, though it is primarily a species of the semiarid zone.
Gidgee Range and Rainfall
In drier western regions where rainfall is lower, gidgee (A. cambagei) replaces brigalow, and gidgee occurs across areas receiving 300 to 650 mm of annual rainfall.
Gidgee Size Comparison
Gidgee reaches a maximum height of around 12 m, making it somewhat smaller than brigalow.
Black Gidgee Distribution
In north-western areas, black gidgee (A. argyrodendron) replaces brigalow across many locations.
Boree Habitat and Associated Species
In Central-Western districts, boree (A. tephrina) forms woodlands and shrublands, frequently growing on cracking clay soils, and often found in association with A. cambagei.
Georgina Gidgee Distribution and Rainfall
Georgina gidgee (A. georginae) woodlands occur in more arid regions, within the annual rainfall belt of 200 to 250 mm.
New South Wales Distribution
Within New South Wales, brigalow is found from around Roto in the south to around Hungerford in the west, and to Willow Tree in the east along the Great Dividing Range.
Queensland Distribution
Within Queensland, it occurs as far north as Townsville.
