Acacia undoolyana (common names Sickle-leaf wattle, Undoolya wattle) is a species of wattle native to central Australia.
Acacia undoolyana is a shrub or small tree growing up to 15 m high and has persistent fissured bark. Both stems and phyllodes have a covering of minute flattened hairs, when young. The phyllodes are flat, linear to narrowly elliptic, and silvery when young but later a grey-green. They are sickle-shaped, are 120âÂÂ220 mm long by 5âÂÂ15 mm wide, and have a marginal basal gland and a prominent apical gland. They have multiple parallel nerves of which up to three are more prominent. The inflorescence is a yellow cylindrical spike on a hairy peduncle 3âÂÂ6 mm long. The pods are linear and 50âÂÂ110 mm long by 2âÂÂ3 mm wide, and the seeds have a white aril.
It flowers from June to September and fruits from August to December.
It is found in the MacDonnell Ranges Bioregion of Central Australia. The main population is on Undoolya station.
It is generally found on steep south facing slopes on skeletal soils.
It is listed as "vulnerable" under both Commonwealth and Territory legislation. The major threat to its survival is frequent bushfires.