A shrub or small tree up to 4 m (13 ft) high, it has prickly foliage and pink and cream flowerheads which appear in late Spring (October to December).

First collected in 1984 near the wheatbelt town of Wagin, Banksia oligantha was officially described in 1987 by Australian botanist Alex George.

Several scattered populations survive in fragments of remnant bushland in a region which has been mostly cleared for agriculture.

Banksia oligantha grows as a single-trunked small tree or as an erect shrub with few main stems.

[2] Appearing from October to December (late spring), the flowers occur in dome-shaped heads from 2.5 to 3 cm (0.98 to 1.18 in) in diameter, growing at the ends of branches.

These comprise just 20 to 35 individual flowers, enclosed at the base by a whorl of furry involucral bracts 2 to 4 mm (0.079 to 0.157 in) long.

[6] Banksia oligantha was discovered by Ken Wallace of the Government of Western Australia's Department of Conservation and Land Management (now the Department of Environment and Conservation) in September 1984, during a survey of Wangeling Gully Nature Reserve (Nature Reserve 9098), about 28 km (17 mi) northwest of Wagin.

[7] A 1996 cladistic analysis of the genus by botanists Kevin Thiele and Pauline Ladiges based on morphology yielded no information about the circumscription of B. subg.

[9] George largely discarded Thiele and Ladiges' changes in his 1999 arrangement, but again B. oligantha's placement was unaffected, and the placement of B. oligantha there can be summarised as follows:[2] Since 1998, American botanist Austin Mast and co-authors have been publishing results of ongoing cladistic analyses of DNA sequence data for the subtribe Banksiinae, which then comprised genera Banksia and Dryandra.

[10][11][12] Early in 2007, Mast and Thiele rearranged the genus Banksia by merging Dryandra into it, and publishing B. subg.

Further complicating the situation is the southernmost (and closest) population of B. cuneata, which has both genetic and phenetic affinities with B. oligantha.

[14] Banksia oligantha occurs over a range of about 100 kilometres (62 miles) in southern parts of the Avon Wheatbelt region of the Southwest Botanical Province of Western Australia.

[1] Six species of honeyeater have been observed feeding at its flowers, as have insects including honeybees, ants, butterflies, beetles and native bees.

Firstly, the higher density of disturbed populations leads to greater rates of mating between neighbouring plants, resulting in more genetic structure and thus more effective selfing.

[16] Like many plants in south-west Western Australia, B. oligantha is adapted to an environment in which bushfire events are relatively frequent.

[3] Threats include grazing by sheep and rabbits, drought, the drift of aerosol chemicals from surrounding farmland, invasion by weeds, and rising salinity.

However, its prickly foliage makes it unsuitable for growth near paths, it is prone to lose branches in strong wind, and it is often attacked by woodboring beetles.