Calothamnus planifolius is a plant in the myrtle family, Myrtaceae and is endemic to the south-west of Western Australia. It is an erect shrub with many branches, growing to a height of about 1.5 metres (4.9 ft) with flat leaves and red flowers from September to November. The flowers have 4 petals and 4 narrow bundles of stamens. (In 2014 Craven, Edwards and Cowley proposed that the species be renamed Melaleuca planifolia.) Calothamnus planifolius occurs in the Avon Wheatbelt and Jarrah Forest biogeographic regions where it grows in gravelly clay over laterite.