Do you mean Dryopteris x australis? (dixie wood fern)
A native natural hybrid fern of the southeast USA, as the common name might suggest.
'australis' refers to southern, not Australia as such.

It's actually Dryopteris australis (not australicus), though because it's believed to be a natural hybrid it is usually written Dryopteris x australis. It took me about half a minute's Googling to find this.

Australis is a Latin adjective that simply means 'southern', and presumably refers to southern USA, hence also the common name Dixie Wood Fern.