Tuesday, 7 November 2017

Mueller's warty, smelly and very Victorian plant


The Forest Boronia grows mostly in forests, or woodlands, of eucalypts and banksias. It started flowering in the Melbourne Gardens in late September and will stay in bloom across its range right through to the end of summer and even sometimes into autumn and early winter. Next to the National Herbarium of Victoria building, where I took these photos, it is now finishing.

From Sydney (and once Melbourne) botanist, Marco Duretto's 116 pages of 'notes' on Boronia from eastern and northern Australia (that is, leaving out the Western Australian bounty), we learn a bit about this species.


As expected, Boronia muelleri was named after the first Director of Royal Botanic Gardens Victoria, Ferdinand von Mueller, who collected the 'type' specimen from the upper reaches of Bunyip River in western Victoria. It was at first, in 1863, considered a variety of Boronia pinnata but eventually granted species status in 1924.  

Boronia muelleri pops into New South Wales, as far north as Eden, but is primarily a Victorian species, extending east from Buchan but also found in the Otway Range and central Gippsland. A more recently discovered population of 20 or so plants between Bacchus Marsh and Woodend is doubtfully native. (Boronia pinnata is a pure New South Welsh, from north of Eden.)

Our boronia - Victorian by geography and era of scientific discovery - can be a small tree up to 7 metres high. Although in its incursion into New South Wales it reaches only 3 metres at most. 

Like many Boronia species it has fern-shaped leaves, which we call pinnate. Also like many Boronia species, the leaves smell. In this case not unpleasantly so.

I can detect notes of pine, cardamon and perhaps guava, although I haven't eaten a guava for a while. I asked my colleague Neville Walsh, who has a better botanical nose, and he thought 'a background of citrus (leaning toward grapefruit), maybe a bit of camphor, possibly turpentine, with a slight flush of honey'. Either that, he said, or that 'general Australian Rutaceae (Boronieae) kinda smell'.


You'll note the warty glands on the leaf surface above. I presume these contain volatile oils such as 'elemicin', which has been extracted from the species. And these oils are what presumably combine to create the difficult-to-describe odour. 

The Aniseed Boronia, Boronia galbraithiae, was chipped off our species in 1993 by Neville Walsh and his colleague David Albrecht. It's a true Victorian endemic, only growing on the slopes of mountains near Mount Difficulty, north of Sale in the mid-east of the State. Compared to Boronia muellerii it has smaller leaves (the 'leaflets' sticking out the side are shorter) with finely toothed or ragged margins. Oh and it smells different, like fennel rather than that rather eclectic perfume we might call Eau De Boronia.


2 comments:

Lauren said...

Growing up, I always hated the smell of the Boronias in my mum's garden (probably Boronia heterophylla, in hindsight). I'll have to give Forest Boronia a whiff next time I meet it to see if I've changed my mind.

Tim Entwisle said...

Some - such as the Brown Boronia - are not very nice but this one is OK. It might never be used as a perfume but it's 'interesting' rather than 'unpleasant'.
Tim