Oxalis species are difficult to ID even in the hand. Sightings of Oxalis need to include good photos of the whole plant, of the stem showing the hairs, and the stipules (outgrowths) at the bases of the leaf stalks. In some cases, a definite ID requires knowing whether the plant has a taproot or not, or bulbils that form underground or not. Not a good idea to check by pulling up the plant if you do not have a collecting permit from the relevant NSW department.