Sheoaks are great bulokes

With leaves reduced to tiny scales (below), and petals disposed of almost entirely (female flowers above), the Sheoak must be one of the most thrifty plants around. A close competitor would be the spurges I mentioned last week, which have an equally dismissive attitude towards to leaves and petals.

In the case of the four genera in the family Casuarinaceae - named (as is the genus Casuarina and Allocasuarina) after the similarity of the fine branches to the feathers of a cassowary, called kasuari in Malaysia - the flowers consist of either a single ovary with two chambers and no petals (the female flower) or a single stamen (the male flower; with one or two scale-like 'tepals' on the male flowers falling off early).

In this next picture the male flowers are immature, and unopened, but you can see how they are arranged in whorls, just like those bract-like leaves.

The flowers are gathered together in what looks like a narrow bottle-cleaner (male) or a tuft (female; see picture at top of post), giving them a bit of visibility to animals like us. But that doesn't matter. These flowers are pollinated by wind, which means they don't have to attract bird nor bee.

In an evolutionary sense, the closest relatives to the casuarina family are the birches (Betulaceae) and an obscure South American tree called Tichodendron incognitum. The birches have flowers almost as reduced as those of the sheoaks, with a most a few scale-like bracts around the male or female floral parts. Like sheoaks, the male flowers are arranged around an elongate fine branch (catkin) and the females more clumped. Again the pollen is carried between flowers by the wind.

Their next closest relatives are things like cucumbers, roses and peas, all of which have big showy petals and more complicated flowers. And the 'first' flowers were most likely whorls of female bits, male bits and some petal-like outer layers. So the Cauarinaceae seems to have 'lost' those bits of its flowers unhelpful for their 'preferred' form of pollination. (You'll need to convert those words in inverted commas into proper scientific jargon to accurately reflect how evolution works but this blog post is already too long...)

The branches of some of the more well-known tree species swish around in the wind, hence the common name Sheoak, with the 'She' apparently the sound those branches make - sheeeeee. At least that's the story I've been told, but this topic is hotly debated, at least on the internet where almost anything is disputed by someone.

That wind though is presumably behind the reduced floral apparati. With that swishing habit, wind would remain an efficient way to move pollen around, as it was and is in conifers with a not dissimilar look and feel, albeit constructed differently (with for example needle-like leaves).

As for the oak part of the name, that's due to a propensity for early settlers to link any new plant they found back to something from their 'old country', this time the genus Quercus. It's said the timber of the Sheoak is similar in appearance to that of the English Oak, but not as good for construction.

That's all good and well but what about She-oke or Sheoke. You'll see that used occasionally, such as by J.W. Audas in his charming 1950 book, The Australian Bushland. Audas uses River Oak as most people do for Casuarina cunninghamiana, but Drooping She-oke for what we now call Allocasuarina verticillata (and usually Drooping Sheoak).

Interestingly, Audas uses Bulloak for what is now know as Allocasuarina luehmannii, where many (e.g. our VicFlora) prefer Buloke for that one. I can't find the origins of 'oke', but note that is a slang term in South Africa for a man. A little like 'bloke' I guess.

I do wonder if 'buloke' is just a take on 'b-loke', as a deliberate mispronunciation of Bull-oak, and perhaps even a dig at the 'She' part of the usual common name for a species that is a bit 'thicker' and scrappir than other more elegant Sheoaks. But that is 100% conjecture, and why 'Sheoke' or 'She-oke'?

That's as much as I know or can make up. And if all that 'allo' stuff in the botanical names is confusing, you can find out what is a Casuarina and what is an Allocasuarina in the Flora of Australia online. Read more about the third Australian genus, Gymostoma, in my own blog.

Thanks to Neville Walsh for bully-oking me into writing this piece. I don't know if it answers his questions but as always it was a fascinating diversion, as were these cockatoos in a Shee-oke growing in Melbourne Gardens. The other pictures are from Allocasuarina grampiana, a species Neville planted in the Victorian Rare and Threatened Species Collection, Melbourne Gardens. Both male and female plants together.