Acacia tetragonocarpa

The shrub can have a prostrate, straggling or erect and slender habit and has a rush like appearance. It typically grows to a height of 0.05 to 0.5 metres (0.16 to 1.64 ft) but can grow as high as 1.5 m (5 ft). The branches are slender and wiry as well as finely striated with yellow ribs. The phyllodes have a continuous, thin, horizontally flattened, narrowly triangular scale-like appearance and are only 1.5 to 3 millimetres (0.06 to 0.12 in) in length. Often there are bipinnate leaves found at the base of the stems. It blooms between March and June or October and November producing yellow flowers. The simple inflorescences contain between one and four flowers but usually have two, the petals are finely flabellate-striate. Following flowering reddish brown and glabrous seed pods form . The pods are shallowly curved with a length of 2 to 6 centimetres (0.8 to 2.4 in) and 4 to 5 mm (0.16 to 0.20 in) wide with winged margins that are 1 to 2 mm (0.04 to 0.08 in). The seeds within are oblong-conical with a length of 5 mm (0.20 in) and arranged longitudinally. conical.

It has a discontinuous distribution and is found as far north as Perth and south through the Peel, South West and Great Southern regions as far south as Albany and east as Tambellup. It is found in swampy areas, along creeklines and on rocky hillsides where it grows in damp sandy or loamy soils and in gravelly lateritic soils. The shrub is often part of the understorey of paperbark or jarrah woodland communities but can be found in regenerating heath land communities.