Acacia horridula

Acacia horridula is a shrub belonging to the genus Acacia and the subgenus Phyllodineae that is endemic to south western Australia.

Description
The slender single-stemmed shrub typically grows to a height of 0.3 to 0.6 m and produces yellow flowers from May to August. It usually has red-brown to light brown coloured branchlets that are covered in a dense mat of woolly hairs and setaceous to narrowly triangular stipules with a length of 2.5 to 4 mm. Like most species of Acacia it has phyllodes rather than true leaves. The evergreen patent phyllodes are usually crowded on the branchlets and have a narrowly semi-trullate shape. The simple inflorescences occur singly in the axils with spherical heads containing four pale yellow flowers. The terete, red-brown and striated seed pods that form after flowering are curved and narrowed at both ends with a length of up to 7.5 cm and a width of around 3.5 mm. The oblong seeds inside are arranged longitudinally and are 4 to 5 mm in length with a conical and terminal aril.

Taxonomy
The species was first formally described by the botanist Carl Meissner in 1844 as part of the work Leguminosae in ''Plantae Preissianae'. It was reclassified as Racosperma horridulum by Leslie Pedley in 2003 and then transferred back to genus Acacia in 2006.

Distribution
It is native to an area along the south coast in the Peel and South West regions of Western Australia. It is often situated on rocky hillsides growing in sandy or gravelly soils over granite particularly in the Darling Range usually as a part of Eucalyptus woodland communities.