I have very little knowledge of the weeds of Oz but that looks a lot like the foliage of Alstroemeria psittacina. If you wait a bit you will know when it flowers.

It's a delightful garden plant where it behaves itself but like many introduced species it's gone bonkers in parts of Australia.

Here is a link that might be useful: Alstroemeria psittacina

This post was edited by floral_uk on Thu, Apr 17, 14 at 13:37