Acacia lasiocalyx

The species is closely related to Acacia conniana which has nonpruinose branchlets, shorter phyllodes and smaller pods enclosing smaller seeds. Other relatives are A. anastema and A. longiphyllodinea.^[3]

The Noongar peoples know the tree as wilyurwur.^[4][5]

The open often weeping tree or shrub typically grows to a height of 1.5 to 7 metres (5 to 23 ft),^[1] although some specimens may reach 25 m.^[5] It blooms from July to October producing yellow flowers. The leaf-like phyllodes are 25 centimetres (10 in) and gently curving,^[1] each terminating in a hooked point. The inflorescences are simple, sometimes with a few rudimentary racemes interspersed with axes that are 0.5 to 1 millimetre (0.02 to 0.04 in) in length with paired peduncles paired that are 8 to 17 millimetres (0.3 to 0.7 in) long. They are pruinose with 20 to 40 millimetres (0.8 to 1.6 in) spikes and with a diameter of 6 to 7 millimetres (0.2 to 0.3 in) densely packed with a golden colour.^[3] The seed pods are linear and raised over seeds with a straight to slightly curved shaped and are up to 16 centimetres (6.3 in) long and 5.5 millimetres (0.2 in) wide. The seeds are longitudinal with an elliptic to oblong shape.^[3]

It is native to a large area in the Wheatbelt, Goldfields-Esperance, and Great Southern regions of Western Australia^[1] and is found as far north as Eneabba, as south as Bremer Bay, and as east as Kalgoorlie.^[3] It is typically found growing as a thicket amongst granite outcrops.^[6]

The tree is fibrous and copes well in arid conditions. It germinates prolifically after fire forming dense thickets of trees which are about 4 metres (13.1 ft) in height. These thickets thin out over the following decades, and trees my attain a height of 25 metres.^[5]

• List of Acacia species