Acacia harpophylla, commonly known as brigalow, brigalow spearwood or orkor, is an endemic tree of Australia. The Aboriginal Australian group the Gamilaraay peoples know the tree as Barranbaa or Burrii. It is found in central and coastal Queensland to northern New South Wales. It can reach up to tall and forms extensive open-forest communities on clay soils. Description The tree is root-suckering and has hard, furrowed and almost black coloured bark. The glabrous or hairy branchlets are angular at extremities. Like most species of Acacia it has phyllodes rather than true leaves. The coriaceous, sericeous and evergreen phyllodes have a falcate shape with a length of and a width of and have many closely parallel nerves with three to seven of the nerves are more prominent than the others. When it blooms, between July and October, it produces condensed inflorescences in groups of two to eight on racemes, usually appearing as axillary clusters. The spherical flower-heads have a diameter of and contain 15 to 35 golden coloured flowers. After flowering crustaceous and glabrous seed pods form that are subterete and straight to slightly curved. The pods are raised over and constricted between seeds and have a length of up to and a width of with longitudinal nerves. The soft, dull, brown coloured seeds within the pods are arranged longitudinally and have an oblong or broadly elliptic shape and are flattened but thick with a length of and have a filiform funicle. Distribution and habitat Two species, brigalow (A. harpophylla) and gidgee (A. cambagei) form open woodlands on flat and gently undulating terrain on heavy and relatively fertile clay and clay-loam soils primarily in the 300-700mm annual rainfall region of Eastern Australia. These woodlands extend from a northern extreme of 20° S into northern New South Wales. Brigalow and gidgee occur as mixed communities in some regions and are commonly associated with several other woody species, including overstorey species such as Eucalyptus coolabah, E. cambageana, Casuarina cristata, and a range of understorey species. A. tephrina, A. georginae and A. argyrodendron also occupy similar habitats and have similar habits and growth forms, but are less widespread, while a number of other Acacia species also form structurally similar communities. Brigalow occurs from coastal regions receiving in excess of rainfall per year through to the semi arid rainfall region although it is primarily a semi-arid zone species. Gidgee (A. cambagei) replaces brigalow as rainfall