Acacia erioloba is an evergreen tree that ranges in size from a 2 m (6 foot) tall spiny shrub to a 16 m (~50 foot) tall but generally growing to 8 m (20 feet) tall (3, 4). The branches are a shiny reddish-brown when in adolescence but mature to form a grey to blackish-brown and deeply furrowed bark (2, 3). The branches are heavily protected by 60 mm long (~3 inch) straight, white-brown spines with bulbous bases which appear in pairs at the stem nodes (1, 3, 4). The leaves are twice divided (ie. bi-pinnately compound) with two to five pairs of pinnae per leaf (3, 4). Leaf surfaces are hairless and have a prominent underside vein on the undersurface (3, 4). The leaves have 8-18 leaflets on each pinnae (3, 4). After ten years of growth, the tree will produce brilliant yellow, puff-ball shaped, sweetly fragranced flowers in the winter (1). They are in bloom through spring and summer. The fruit is a legume pod approximately 130 mm (5 inches) long by 50 mm (2 inches) wide and 30 mm (1 inch) thick (4). They are externally woody and internally spongy, with varying shapes from cylindrical to flat, thick, semicircular or half-moon shaped (3). Current season’s pods are externally grey and velutinous and will persist on the tree with the more darkly colored older pods from the previous years (4). Further, the pods do not open until they fall to the ground in winter. Once opened, the pods reveal the thick, tough, 14mm x 10mm lens-shaped seeds embedded in the pod wall (3).
