A shrub to 2 metres tall with hairy younger branches.
It has a very restricted distribution, only found in the Woodsreef area, east of Barraba, growing in and around Woodsreef State Conservation Area.
It grows in dry eucalypt woodland on soils derived from serpentinite rock.
It is a listed threatened species under State legislation.
The stems are covered with dense star-shaped (stellate) hairs.
Boronia spp. produce opposite leaves which can be simple or compound (sometimes on the same plant) and are usually aromatic (sometimes strongly-so).
In this species, the leaves appear simple (or unifoliolate) or compound with 3 to 7 leaflets, each leaflet to 30 mm long and to 12 mm wide.
When crushed, the leaves have a strong scent.
Boronia spp. have complete flowers (bisexual and with all whorls present). The flowers are produced either solitarily or in groups, in the leaf axils, or, at the branch terminals. There are usually four sepals, four petals and generally eight stamens, surrounding one female part (carpel). Flowers are often pink to purple, which makes them easily identifiable in NSW bushland.
In this species, flowers are pale to bright pink and are arranged singly in or in groups of up to 3 in leaf axils, produced in all months, yet blossom primarily during July to November.
The fruit of Boronia are described as a schizocarp-capsule; a capsule that splits into even segments, which each segment called a coccus. In this species, the fruit is smooth to 6 mm long and to 4 mm wide.
Not much is known currently about the cultivation of this species and it is not commonly grown. It may be that it is difficult to grow or has not been trialled sufficiently to verify cultivation potential. It is threatened with extinction in the wild and has a very small natural distribution. It may become more readily cultivated in the future.
Growing boronias can be a frustrating experience and they have a reputation for being difficult. Their attractiveness has led to substantial efforts to cultivate them. One tip is to try to grow forms that are local to your area, rather than attempting to grow those species from interstate. There are certainly some species that have proven easier to grow than others.
Most boronias have a short life span of two to three years in a garden situation but are a rewarding plant while healthy as they provide lovely fragrance and flowers in Spring.
For them to grow at their best, select a position with dappled sunlight and especially protection from hot afternoon sun in summer, as well as from wind, which they dislike.
The soil must be well drained and have an even supply of moisture. If they dry out, they will surely die.
Planting on a slight slope is said to work well.
For a longer life, the best way to grow them is in a medium sized pot, say 30 cm in diameter where drainage and moisture can be controlled. A sheltered patio or courtyard that receives at least a few hours sunlight a day would be ideal.
Fertilise after flowering.
The conventional wisdom is, think deeply about which species to plant and the location to plant it.
Boronias can be propagated from cuttings, but the process can be challenging.
In the past, B. ruppii was considered to occur more widely in the Hunter Valley of N.S.W, but these records are now recognised as a separate species – Boronia rubiginosa.
Boronia is a genus of about 150 species in the citrus family Rutaceae. Most species are endemic to Australia and species can be found in all states. There are also 4 species in New Caledonia, which were previously placed in the genus Boronella. In 2020, several species of Boronia have been transferred to the genus Cyanothamnus (meaning “blue shrub or bush”), as these species have been found to be more closely related to other Rutaceae genera rather than other Boronia species. After the move of some species to Cyanothamnus, there are about 30 Boronia spp. in NSW.
Boronias are likely killed by fire and regenerate from the seedbank.
Boronia – after Francesco Borone (1769-1794), an 18th century Italian botanist who assisted John Sibthorpe. Allegedly, he died at age 25, due to falling out a window whilst collecting plant specimens.
ruppii – honours the Rev. Herman Rupp (1872-1956), a clergyman and very active botanist who contributed much knowledge on the study of native plants, mainly, orchids. Rupp was the collector of the type specimen at Wollombin in Sept 1912.
This species is listed with being threatened with extinction in the wild at the State level with a category of Endangered.
NSW Flora Online (PlantNET) – Boronia ruppii profile page https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Boronia~ruppii
Australian Native Plants Society Australia – Boronia Family Profile Page
Gardening with Angus Website – Boronia for Beginners
Wikipedia – Boronia ruppii and Boronia profile pages
NSW Office of Environment and Heritage – Threatened Species Profile Page