Richard,

We had a few of those iris in our front garden. We were told they were
natives. That may be so, but not of Australia.

They grew into large clumps and if they are not dead-headed after
flowering, the seeds sprout up everywhere.

In my opinion, they're as weed-like as the bloody-awful agapanthus. Both
should be banned (though I hear there is a new aga out which is not as
invasive).

Mark.