Acacia cassicula is a shrub of the genus Acacia and the subgenus Plurinerves that is endemic to an area of south western Australia.
The spreading shrub typically grows to a height of 1to. It can have glabrous or sparsely finely haired branchlets. Like most species of Acacia it has phyllodes rather than true leaves. The normally glabrous and thinly leathery evergreen phyllodes are inclined and more or less asymmetric with an oblong to oblong-elliptic shape and a length of and a width of and have two main distant longitudinal nerves.[1] It blooms from August to September and produces yellow flowers. It produces simple inflorescences that occur singly in the axils and have spherical flower-heads with a diameter of containing 22 to 30 flowers. Following flowering it produces glabrous and papery seed pods that have a linera shape and are strongly curved to coiled once or twice. The strongly resinous pods have a length of up to around and a width of The glossy dark brown seeds inside have an oblong shape with a length of .[1]
It is native to an area in the Wheatbelt and Great Southern regions of Western Australia where it is commonly situated on undulating plains growing in sandy loam soils. It has a disjunct scattered distribution from around Wagin in the north west to around Jerramungup in the south east growing in granitic based soils as a part of Eucalyptus occidentalis woodland communities.[1]