Drooping Sheoak Tree
Separate male and female trees.
Murray Grey beef cattle were looking at us inquisitively as we walked past their paddock. The lady cattle farmer was showing me around the property, saying “We have a special place down here, and the cows like it as well” as she led me into a stand of drooping sheoak trees.
Immediately you could feel the calm difference, the other worldliness, the dreamy atmosphere from the whistling of the leaves so characteristic of sheoaks. The Murray Greys enjoyed the sense of shelter and protection as well.
The farmer said she doesn’t leave the cattle in amongst the trees for too long, even though they were adult trees and quite robust with thicker bark, too much rubbing by cows would damage the trees. But as a shelter on hot days or in cold windy conditions it was ideal.
Drooping sheoaks occur across south eastern Australia, in coastal sand soils and inland rocky sites, generally mixed with other species or sometimes as exclusive stands, as on the cattle farmers property.
The trees common name, drooping sheoak, refers to its well-defined habit of drooping branchlets, she meaning its female form, and oak referring to its semi durable wood, not quite as durable as the European oak.
The Genus and species names are Allocasuarina verticillata (Lam.) L.A.S. Johnson.
In Latin Allo means other, casuarina from Malay for Casuari meaning the foliage habit is similar to the cassowary birds feathers, and Latin verticillata refers to the leaves being arranged in a ring around the stem.
The abbreviated name in brackets (Lam.) refers to the author of the original plant name, Jean Baptiste Antoine Pierre Monnet de Lamarck,1744–1829, who named this plant Casuarina verticillata.
The second name is the author, Lawrence Alexander Sidney Johnson, 1925–1997, who renamed it with the accepted plant name of Allocasuarina verticillata.
The drooping sheoak is a rough barked tree often around 5 metres high, of rounded compact form, although the females can be more spreading because of the weight of the cones pulling the branches downwards.
Its foliage is unusual as what we see as leaves are stems or branchlets with chlorophyll, and the actual leaves are reduced to a ring of minute sheaths around each stem.
The flowers are unisexual with male flowers, a segmented golden spike 4 to 10cm long, on male trees, and female flowers are condensed into a rounded head or small cone on female trees, flowers often appearing in winter. The habit of having separate male and female plants is called dioecious. Sheoaks are dioecious.
The fruit is a cylindrical shaped woody cone, quite large, (larger cones in the photograph below are 4 cm x 2.5 cm) with prominent pointed valves releasing large winged seed, enabling dispersal by wind.
It is a frost resistant plant making it suitable for establishment in inland areas. It produces considerable amounts of pollen, useful for bees, but no nectar. The seed in the woody cones is sought after by yellow tailed black cockatoos and the endangered red-tailed black cockatoo.
The sheoak is very palatable to stock, especially at the seedling stage, and requires tree guards when revegetating to prevent grazing by rabbits, kangaroos and sheep.
Sheoak used to be much more common but has been cleared for agriculture and been eaten out by stock, feral rabbits and hares.
I remember many years ago talking to an older farmer who had been told about the conditions of the 1918 drought in southern Australia. He pointed to a distant hill side saying it used to be covered in sheoaks, but they were cut down during the drought to feed the sheep because the grasses had been eaten out and not regrown under the dry conditions.
He said he was told after the drought, the side of the hill appeared to move, but it was really the rabbits moving, there were so many of them.
Any regrowth from the sheoak stumps or seedling germination would have been eaten by sheep or rabbits, resulting if far fewer adult sheoak trees.
The sheoak, Allocasuarina verticillata is a beautiful medium size tree suitable for urban parks, shopping centre carparks, revegetation projects, home gardens and especially farms with Murray Grey cattle.
References:
Australian Plant Census Vascular Plants APC — Allocasuarina verticillata (Lam.) L.A.S.Johnson (biodiversity.org.au)
Coombes, A (ed.) 2009, Dictionary of Plant Names, The Timber Press., Oregon. Book.
National Arboretum Canberra (n.d.) Allocasuarina verticillata Search — National Arboretum (act.gov.au)
Native Trees of South Australia Bulletin №19 (1972) Woods & Forests Department, South Australia. Book.
Sharr, FA 1978, Western Australian plant names and their meanings, University of Western Australia Press. Book.
