When it blooms between July and October,[4] it produces condensed inflorescences in groups of two to eight on racemes, usually appearing as axillary clusters.

The soft, dull, brown seeds within the pods are arranged longitudinally and have an oblong or broadly elliptic shape.

[3] 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.

[6][7] Gidgee (A. cambagei) replaces brigalow as rainfall drops in western regions and extends from 650 to 300 mm (26 to 12 in).

[9] In the north-western regions black gidgee (A. argyrodendron) replaces brigalow in many areas, while in Central-Western districts boree (A. tephrina) forms woodlands and shrublands, frequently on cracking clay soils and often in association with A. cambagei.

It was reclassified as Racosperma harpophyllum by Leslie Pedley and subsequently transferred back the genus Acacia in 2001.

[11] Fire in any brigalow or gidgee woodland would be a rare event under natural circumstances, since pasture is at best sparse in these communities, consisting of Chloris, Setaria (syn.