Hi Phillip
Entering just the generic name brings up both sysirinchium species and also Lampranthus "Hunter Gullying". The date naturalised is on the information page for those species. No idea about Lampranthus "yellow"
The book " An illustrated Guide to Common Weeds of New Zealand" says that both the sysirinchiums are unnamed entities which may turn out to be subspecies of S. Iridifolium.
Cheers