Acacia williamsiana

The tall shrub or tall tree with a spreading to erect habit^[1] and typically grows to a height of 2 to 8 m (6 ft 7 in to 26 ft 3 in) and has angular and glabrous branchlets that can be covered in a fine white powdery coating. Like most species of Acacia it has phyllodes rather than true leaves. On juvenile plants the phyllodes have a broadly elliptic to obovate shape with a length of 1.3 to 7.5 cm (0.51 to 2.95 in) and a width of 13 to 25 mm (0.51 to 0.98 in). As the plant matures the pale-green to grey green phyllodes have a more oblanceolate, narrowly elliptic or linear shape and are 5 to 12 cm (2.0 to 4.7 in) in length and 4 to 11 mm (0.16 to 0.43 in). The generally glabrous phyllodes have many longitudinal nerves that are closely parallel with three to five nerves that are more prominent than the others.^[2] It flowers between September and December^[1] and produces simple inflorescences form cylindrical flower-spikes with pale yellow flowers. After flowering linear to moniliform seed pods form that are 3.5 to 9 cm (1.4 to 3.5 in) in length and 2 to 4 mm (0.079 to 0.157 in) wide that are wrinkled and curved. The black to dark brown seeds inside are arranged longitudinally and have an ellipsoid shape.^[2]

The specific epithet honours John Beaumont Williams who was a botanist and teacher who had worked at New England University in Armidale and first noticed the distinctiveness of this species.^[1]