Boronia crassifolia is a plant in the citrus family Rutaceae and is endemic to the south-west of Western Australia. It is a small, slender shrub with pinnate leaves, and yellowish green to brownish, four petalled flowers.
Boronia crassifolia is a slender, rounded shrub that grows to a height of about . It has pinnate leaves with three, five, or seven linear- to -shaped leaflets . The flowers are yellowish-green to brownish, about in diameter and hang from the leaf s on a pedicel long. The four sepals are red, more or less round and about long. The four petals are about long. The eight stamens alternate in length, with the four near the petals longer than those near the sepals.
Boronia crassifolia was first formally described in 1845 by Friedrich Gottlieb Bartling and the description was published in Plantae Preissianae. The specific epithet (crassifolia) is derived from the Latin words crassus meaning "thick", "fat" or "stout" and folium meaning "a leaf".
Boronia crassifolia grows on sandplains and sand dunes, often among rocks near Mount Lesueur and from near Perth to the Stirling Range and east to the Twilight Cove, in the Avon Wheatbelt, Esperance Plains, Geraldton Sandplains, Hampton, Jarrah Forest and Mallee biogeographic regions.