This is growing in a water way in hard to get to spraying what we can reach. (We dping ragwart and thistle spraying).
Wondering if this is purple loosestrife?
The rooting nodes seem to differentiate this species from wild celery. It is dominant for a 50m stretch in this roadside drain.
Under reveg
Area of ~100sqm along estuary edge by Hobson Bay Walkway, Thomas Bloodworth Park. No fls or fruit seen.