Balaustion quinquelobum is a species of flowering plant in the family Myrtaceae and is endemic to the south-west of Western Australia. It is low-growing to fairly erect shrub with narrowly egg-shaped or narrowly oblong to linear leaves, and white or pale pink flowers with 18 to 25 stamens.
Balaustion quinquelobum is a low-growing or fairly erect shrub that typically grows to high and wide, the flowering branchlets with usually one pair of flowers. Its leaves are narrowly egg-shaped or narrowly oblong to linear, mostly long and wide, the lower surface keeled near the tip with usually one or two rows of oil glands each side of the midvein. The flowers are in diameter on a peduncle long, each flower on a pedicel long. The floral tube is long and wide and is distinctively five-lobed. The sepals are broadly egg-shaped, long, wide and reddish, sometimes with a whitish border. The petals are white or pale pink, long, with 18 to 25 stamens. Flowering has been recorded from August to November, mainly in September and October.
Balaustion quinquelobum was first formally described in 2022 by Barbara Lynette Rye in the journal Nuytsia from specimens collected west of Southern Cross in 1978. The specific epithet (quinquelobum) means 'five lobes' referring to the distinctive hypanthium.
This species of Balaustion grows in sandy soil in a range of vegetation associations between Welbungin, south to Lake Grace and to the east of Lake King in the Avon Wheatbelt, Coolgardie and Mallee bioregions in the south-west of Western Australia.
Balaustion quinquelobum is listed as "not threatened" by the Government of Western Australia Department of Biodiversity, Conservation and Attractions.