Boronia grandisepala is a plant in the citrus family Rutaceae and is endemic to northern parts of the Northern Territory. It is an erect shrub with elliptic leaves and white, pink or -coloured, four-petalled flowers.
Boronia grandisepala is an erect shrub that grows to high and wide. Its branches and leaves are covered with star-like hairs. The leaves are elliptic to almost lance-shaped, long and wide with a petiole long. The flowers are usually arranged singly in leaf s on a pedicel up to long. The four sepals are larger than the petals, white, pink or burgundy coloured, broadly egg-shaped, long and wide but increase in size as the fruit develops. The four petals are long and wide. Flowering occurs from December to June.
Boronia grandisepala was first formally described in 1859 by Ferdinand von Mueller who published the description in Fragmenta phytographiae Australiae. The specific epithet (grandisepala) is derived from the Latin words grandis meaning "large" and sepalum meaning "sepal", giving "large sepaled Boronia".
In 1997, Marco Duretto described two subspecies in the journal Australian Systematic Botany and the names have been accepted by the Australian Plant Census:
Subspecies grandisepala grows in heath and woodland from near Jim Jim Falls to the Nitmiluk National Park. Subspecies acanthophida grows in sandstone heath and woodland between Jim Jim Falls and Deaf Adder Falls north.
This boronia is classed as of "least concern" under the Northern Territory Government Parks and Wildlife Conservation Act.