TYVM! Trichostema dichotomum seems a match. What a cute little native, and supposedly a true annual. I will try to flag some plants to gather seeds later.

We did consult with both the concrete company (Knife River) and an independent specialist. The base color that was mixed in at the plant is quite dark already, and we were told the only direction a stain would go was to take it darker, which we didn't want, either. So I think this is the best we can get out of a snafu. We wanted very low maintenance floors, nothing that would require frequent resealing. So I'm just trying now to mitigate the color--which IS less purple since the scrubbing and with the sealer.

Thanks Guys!Tony,it is a Breynia!Now I may be able to find some hints on propagating.It is growing in a very narrow space between the house and a concrete pathway so I don't have room to dig or anything.Wombat,I live in the south west of WA,we get some savage frosts here but my plant is doing well up against the house.It does have flowers but they are of the strictly functional variety,barely noticiable.It is a beautiful plant,changing colour throughout the year.

Looks like a Neomarica to me, maybe N. caerulea. Common name is walking iris.