Acacia rigens

Plants typically grows to a height of 1 to 6 m (3 ft 3 in to 19 ft 8 in) and have rigid, terete phyllodes that are between 3 to 13 cm (1.2 to 5.1 in) in length. The bright yellow flowerheads appear in groups of up to four in the axils of the phyllodes. The simple inflorescences have resinous and spherical flower-heads with a diameter of 4 to 7 mm (0.16 to 0.28 in) and contain 20 to 30 bright yellow coloured, 5-merous flowers that appear between July and December in the species' native range, followed by curled, twisted or coiled seed pods which are 4 to 10 cm (1.6 to 3.9 in) long and 2 to 3 mm (0.079 to 0.118 in) wide.[2][3]

The species was first formally described in 1832 by botanist Allan Cunningham.[1] It resembles Acacia havilandiorum but has longer phyllodes and 4-merous flowers. The specific epithet is thought to be a reference to the rigidity of the pjhyllodes.[3]

The species occurs on red earth, sandy or shaly soils in mallee and woodland in southern Western Australia, South Australia, Victoria, New South Wales and Queensland.[3][4]

The species is fast-growing and is both frost and drought tolerant, rarely requiring watering after establishment. It is adaptable to most soils and is best suited to a position in full sun or light shade.[5]

The larvae of the double-spotted lineblue butterfly feed on this species.[4]

• List of Acacia species