by Juliet Bodycomb
This series, Know Your Park Lands Plants, showcases the myriad plant species that you can find in your Open, Green, Public Adelaide Park Lands.
Today, we bring you the drooping sheoak (Allocasuarina verticillata) – a small tree, endemic to south-eastern Australia.
Growing from four to 10 metres tall, it has dark grey, fissured bark, and drooping, grey-green branchlets. Though much of its inland environments have been destroyed by agricultural land-clearing, it is widespread along the South Australian coastline.
It can also be found in your Victoria Park / Pakapakanthi (Park 16), Veale Park / Walyu Yarta (Park 21), Golden Wattle Park / Mirnu Wirra (Park 21W), and Gladys Elphick Park / Narnungga (Park 25), plus other Parks too.
Image: Snow Dennis on iNaturalist.
You may recognise drooping sheoak by its unique, segmented branchlets. I, for one, have very fond memories of showing my brothers how you can snap a branchlet at one of its joins and ‘stick’ the pieces back together again.
Though these branchlets function as leaves, they closely resemble pine needles. In fact, the genus is named ‘casuarina’ because the species’ needle-like leaves resemble the feathers of a cassowary.
Image: smith_magnus on iNaturalist.
Accompanying these leaves are large, spiky appendages, which are found only on female trees. Though resembling a conifer cone, these acorn-sized adjuncts are woody fruits which grow from small, red flowers.
This is important when we consider the taxonomy of the drooping sheoak. Though it resembles a pine, pine trees don’t produce flowers or fruit, as the drooping sheoak does,
Image: davidsando on iNaturalist.
The drooping sheoak has drought-adapted foliage and nitrogen-fixing roots, which enables it to thrive in poor soil and semi-arid climates. However, the species is much less bushfire-tolerant than its neighbouring Eucalyptus species.
Animals, like the Kangaroo Island glossy black cockatoo, feed almost exclusively on the seeds of the drooping sheoak.
In the 2019-20 bushfires, drooping sheoak populations on Kangaroo Island were severely impacted.
Events like this not only jeopardise the populations of the plants themselves, but pose direct threats to a plethora of native South Australian fauna, which rely on them for food and habitat.
Image: Tour Kangaroo Island.
Want to know more about the plants in your Park Lands? Head over to iNaturalist, where you can record, share, and discuss your findings with fellow naturalists.
See the other plants featured in this series here:
https://www.adelaide-parklands.asn.au/know-your-park-lands-plants.
Main photo: deborod on iNaturalist.
