Acacia microcalyx is a shrub belonging to the genus Acacia and the subgenus Phyllodineae that is endemic to western Australia.
The dense pungent shrub typically grows to a height of 1.5to. It has ash-grey to pale green coloured, rigid, erect to ascending branchlets that are generally straight and are sparingly divided with obscure ribs. Like most species of Acacia it has phyllodes rather than true leaves. The evergreen phyllodes are few and distant from each other with a linear shape and a length of and a width of and an obscure midrib. It blooms from February to June and produces cream flowers.
It is native to an area in the Mid West and Goldfields-Esperance regions of Western Australia where it is commonly situated on floodplains and stony plains growing in sandy, loamy and clay loam soils. The bulk of the population is found around Shark Bay but the range extends to the east as far as Mount Magnet in the north east and Belele Station in the south east where it is commonly found as a part of Acacia scrubland communities or with species of Atriplex or Halosarcia.[1]