Cyanothamnus bipinnatus, commonly known as rock boronia,[1] is a plant in the citrus family, Rutaceae and is endemic to Queensland. It is an erect shrub with bipinnate or tripinnate leaves and white, four-petalled flowers. A more widespread species previously known as Boronia pinnata and also occurring in New South Wales is now considered to be B. occidentalis.
Cyanothamnus bipinnatus is an erect shrub that grows to a height of about 1sigfig=2NaNsigfig=2 with pimply, glandular stems and bipinnate or tripinnate leaves. The leaves are mostly NaNsigfig=2NaNsigfig=2 long and NaNsigfig=2NaNsigfig=2 wide in outline with between seven and eleven leaflets, on a petiole NaNsigfig=2NaNsigfig=2 long. Between seven and twenty or more white flowers are arranged in groups in the leaf axils, the groups on a peduncle NaNsigfig=1NaNsigfig=1 long. The four sepals are elliptic to more or less circular, about 1sigfig=1NaNsigfig=1 long and wide. The four petals are NaNsigfig=1NaNsigfig=1 long and the eight stamens have hairy edges. Flowering occurs from September to June and the fruit are dull grey and wrinkled, about 2sigfig=2NaNsigfig=2 long and 1sigfig=2NaNsigfig=2 wide.[2]
This species was first formally described in 1848 by John Lindley who gave it the name Boronia bipinnata in Thomas Mitchell's Journal of an Expedition into the Interior of Tropical Australia.[3] [4] In a 2013 paper in the journal Taxon, Marco Duretto and others changed the name to Cyanothamnus bipinnatus on the basis of cladistic analysis.[5] The specific epithet (bipinnatus) is derived from the Latin prefix bi- meaning "two" or "double"[6] and pinnatus meaning "feathered", "plumed" or "winged".
Rock boronia grows in woodland, sometimes on steep slopes and is found in the central highlands of Queensland with disjunct populations on the Blackdown Tableland and near St George.