These don't produce runners. They do produce quite a mess from spent parts. Seedlings appear in this dry summer area only in frequently irrigated beds and in other sunny places that apparently stay moist enough for them such as among rocks - I have never seen any in the woods or any other locations much shaded by other shrubs and trees.

Well that's encouraging. It is growing out in a field that doesn't get watered. I'll keep an eye out once it flowers. Thanks Embo.

Most of the infamous weedy ornamental plants of the eastern states (burning bush, Callery pear, empress tree, Japanese barberry, Japanese honeysuckle, silk tree etc.) don't go wild much if at all here - apparently because we don't get buckets of rain in the summer. A notable exception I am aware of is the occasional significant Norway maple infestations that have been seen in or near Seattle. But that is a European tree, rather than an east Asian one - the majority of kinds of wild plant species in local developed areas are Eurasian in origin.