Robert Powell: Tree Pictures, South-Western Australia

Salt sheoak (Casuarina obesa)

As its English name implies, this species often grows in salty places, such as round estuaries; here, near the coast, the air can be quite salty too. It is a much tougher species than common sheoak (Allocasuarina fraseriana), and has a much wider distribution, including a large part of Western Australia and smaller occurrences in eastern Australia.  Its Aboriginal name is cooli.

In Perth salt sheoak occurs round the Swan Estuary and along the lower parts of the Swan and Canning rivers. Some of the sheoaks found here nowadays, however, are planted species from eastern Australia, particularly swamp oak (Casuarina glauca).  Salt sheoak is also found on some of the alluvial soils on the eastern side of the Swan Coastal Plain, especially where the soil is not well drained.

Salt sheoak commonly supports mistletoes, including slender-leaved mistletoe (Amyema linophylla) and sheoak mistletoe (Lysiana casuarinae).  These in turn support the mistletoebird (Dicaeum hirundinaceum), and two striking, brightly coloured species of butterfly, the spotted jezebel (Delias aganippe) and the satin azure (Ogyris amaryllis), whose larvae feed on the leaves.

© Text and photographs: Robert Powell