Allocasuarina portuensis (Nielsen Park She-oak)

© Allocasuarina portuensis (Nielsen Park She-oak)

Allocasuarina portuensis is a slender shrub, 3-5 m high with branchlets drooping to spreading and dark green in colour. It is a dioecious species; that is, it has separate male and female plants, with the female plants bearing the characteristic fruit-bearing cones.

The Nielsen-Park She-oak Allocasuarina portuensis is one of Australia’s most endangered plants and only found in Nielsen Park, a small area of Sydney Harbour National Park.

They were discovered as a new species in 1986, when there were 10 specimens at the site. Six years later, only one single female plant was left.

The population is threatened by low recruitment (male plants have been reintroduced into the population), an inappropriate fire regime, weed invasion, habitat degradation due to recreational use, and possible contamination by landfill.

A management plan was implemented to save Allocasuarina portuensis from extinction. Fortunately She-oaks propagate readily from collected seed and this rare Australian native plant is now cultivated in Mount Annan Botanic Garden near Sydney and the Australian National Botanic Gardens in Canberra. About 100 trees from those collected seeds have been planted in Nielsen Park.

With Foundation for National Parks & Wildlife funds the NSW National Parks and Wildlife Service conducted weed control work in Nielsen Park, Vaucluse, to promote the regeneration of rare native plants in Sydney Harbour National Park.

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