Acacia effusifolia is a shrub or tree belonging to the genus Acacia and the subgenus Juliflorae. It is native to an area in the Mid West and the Wheatbelt regions of Western Australia.
The shrub or tree typically grows to a height of and has few to many stems that have shallow or deep longitudinal flutings along their length. The grey to brown coloured bark is mostly smooth but can occasionally be fissured toward the base. The new shoots tend to be encrusted in resin and have a few red glandular hairlets while the resin ribbed branchlets are hairy between the ribs. Like most species of Acacia it has phyllodes rather than true leaves. The green to grey-green, flat and sub-rigid phyllodes have a narrowly linear shape and are straight to shallowly curved with a length of and a width of and are glabrous or with tiny hairs between the many, fine longitudinal nerves. It mostly blooms between July and September producing yellow coloured flowers. The simple inflorescences are often found in pairs in axils with short-obloid to cylindrically shaped flower-heads with a length of and a diameter of packed with golden coloured flowers. Following flowering thinly coriaceous-crustaceous seed pods that are straight to slightly curved form. the terete pods have a length of and a width of that have obscure longitudinal nerves. The shiny brown seeds found within the pods have an oblong shape and a length of with a white aril.[1]
The bulk of the population is found from around Mullewa to the south west with its range extending north to around Meekatharra and east out as far as Goongarrie with several outlying populations. It is usually situated on low hills, around granite outcrops, flats and sandplains where it grows in sandy or loamy soils that can contain a substantial amount of clay as a part of shrubland and spinifex communities that usually contain a number of Eucalyptus and other Acacia species.[1]