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Boronia algida

Alpine Boronia

Family: Rutaceae

A shrub to growing to 1.5 metres tall and may reach about 1 metre wide.

It occurs naturally in the higher tablelands (alpine) as well as lower regions of NSW. There are several disjunct populations; one in the northern tablelands in the Armidale-Tenterfield region, then with a few records around Bathurst and Lithgow-Newnes area; and then with much of the population from Wollongong through to Canberra, down to Kosciuszko National Park and the south coast area, into the alpine areas of north-eastern Victoria.

It typically grows on granite and sandstone in heath, shrubby woodland and dry sclerophyll woodland to forest.

It has red, hairy and warty branchlets.

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, leaves are compound-imparipinnate with 5 to 9 leaflets. Overall leaves are up to 20 mm long, with obvious oil glands, aromatic when crushed.
The leaflets are broad-spathulate to rounded with a small point (mucro), about 7 mm long and 4 mm wide.

Boronia 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 white to bright pink and borne either singly or in groups of up to three on the ends of branches, occurring from September to February.

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, capsules are smooth, to 3 mm long and to 2 mm wide.
This species is not currently well-known in cultivation. It may be difficult to grow or may not have been trialled.

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.

In the garden

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.

Propagation

Other information

Boronias can be propagated from cuttings but with limited success with most but not all species.

Is a genus of about 160 species of flowering plants in the citrus family Rutaceae. Most species are endemic to Australia and species can be found in all states. There are also some 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.

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.
algida – Latin meaning “cold” or “chilly”, named by Ferdinand von Mueller in 1855 as he noted that this plant grows in alpine regions.

Not considered at risk in the wild.

Australian Native Plants Society Australia – Boronia profile page
http://anpsa.org.au/boronia9.html

Wikipedia – Boronia algida and Boronia profile pages
https://en.wikipedia.org/wiki/Boronia_algida
https://en.wikipedia.org/wiki/Boronia

Gardening with Angus – Boronia for Beginners
https://www.gardeningwithangus.com.au/boronias-for-beginners-2/

Plants of South Eastern NSW – Boronia algida profile page
https://apps.lucidcentral.org/plants_se_nsw/text/entities/boronia_algida.htm

By Jeff Howes, edited Dan Clarke