Acacia macdonnelliensis

Acacia macdonnelliensis, commonly known as the MacDonnell mulga or the Hill mulga, is a species of Acacia native to central Australia. The Indigenous Australians the Alyawarr peoples know the plant as irrar, the Kaytetye know it as arleth-arlethe or arwele arleth-arlethe and the Western Arrernte peoples know it as irrkwarteke.

Taxonomy
There are two subspecies:
 * Acacia macdonnelliensis subsp. macdonnelliensis Maconochie
 * Acacia macdonnelliensis subsp. teretifolia Maslin

Description
This bushy shrub or tree typically grows 3 to 6 m tall and has deeply fissured grey bark. It has sparsely hoary to glabrous branchlets with obscure, resinous ridges. It has erect, glabrous to hoary, grey-green phyllodes with a narrow elliptic to linear shape that are 4 to 15 cm in length and 0.8 to 5 mm wide. It produces yellow flowers in July. The dense golden flower spikes are 0.6 to 3 cm in length and have a width of 3 to 6 mm. After flowering linear pale brown seed pods form that are constricted between each seed. Each pod has a length of 3 to 9.5 cm and is 2 to 4 mm wide. The dark brown seeds within are arranged longitudinally and are 2.5 to 5 mm long.

Distribution and habitat
Acacia macdonelliensis is found in southern parts of the Northern Territory around Alice Springs and in far eastern Pilbara and north eastern Goldfields regions of Western Australia. It grows in areas of sandstone and quartzite along rocky ridges and creeklines. A. macdonnelliensis is drought and frost tolerant.