Botanic Gardens Trust, Sydney, Australia

She-oaks - tough survivors

Karen Wilson, Senior Research Scientist

My research with Dr Lawrie Johnson (1925-1997), former Director of the Royal Botanic Garden, has led to new views on relationships in the She-oak family, Casuarinaceae. There are 96 species, grouped in four genera. Studying differences in appearance, DNA, insect predators, and the bacteria that live in their roots, helps us understand the species - in the past as well as the present - and predict their future survival. The Swamp-oaks, Casuarina glauca, in the Royal Botanic Garden, are part of the original shoreline vegetation of Farm Cove. They are all growing from the one rootstock.

Did you know?

  • Casuarinaceae is native to SE Asia, Australia and western Pacific Islands.
  • Fossils of Casuarinaceae up to 60 million years old have been found in Australia, New Zealand, Patagonia and southern Africa.
  • Many Casuarinaceae species have root nodules with filamentous bacteria that capture nitrogen from air. These plants can grow fast in poor soils.
  • The nuts from inside the cones are an important food for Black Cockatoos.
  • Casuarina species are grown for firewood, living fences, and erosion control on riverbanks and sand-dunes.
  • Find out more about She-oaks from our PlantNET website


  • D.A. Steane, K.L. Wilson and R.S. Hill (2003) Using matK sequence data to unravel the phylogeny of Casuarinaceae. Molecular Phylogenetics and Evolution 28: 47-59.
  • L.A.S. Johnson & K.L. Wilson (1993)  Casuarinaceae. Pp. 237–242 in K. Kubitzki (ed.), Families and Genera of Vascular Plants, vol. 2.
  • L.A.S. Johnson & K.L. Wilson (1989)  Casuarinaceae: a synopsis. Pp. 167-188 in P.R. Crane & S. Blackmore (eds), Evolution, systematics and fossil history of the Hamamelidae, vol. 2. (Clarendon Press: Oxford)
  • K.L. Wilson & L.A.S. Johnson (1989)  Casuarinaceae. Pp. 100-174 in A.S. George (ed.), Flora of Australia, vol. 3.