Can you show us one growing? Are there lots of them? It almost looks like a diseased white poplar sucker.

Or a weird variety of coleus…

The leaf arrangement looks alternate to me.

I've seen lambsquarters with purple spots on the leaves similar to that.

Floral, you your eyes may be better than mine, but I see paired leaves and squarish stems.

@djacob could you please show us more pictures here?

Will take more tomorrow if I can find more. No white poplar around here. It does remind me of coleus, but don’t think it is as they are annuals here.

debra

Here are a couple more pics:

unfortunately, no really large plants

Growing in cracks

I know this is blurry, but I am trying to show side shot

Better leaf shot, looks like little hairs on leaf

debra

I looked online at lambsquarters with purple spots and it seems that’s what it is. The spots are a Virus called quinoa……..? Do you agree?

debra

The new pix confirm Chenopodium. A bit of research shows the spots are from a leaf hopper, Paraphlepsius strobi. https://www.invasive.org/browse/hostthumb.cfm?host=5294&Res=3

Quinoa is a species of Chenopodium, C. quinoa, not a virus.

Actually, quinoa has a reputation as being a "universal plant virus host", whatever that may be. Perhaps that's where the confusion originates.

I was addressing this : ‘The spots are a Virus called quinoa’.

And I just remarked on it as a possible explanation for the OP's reference to a "quinoa virus"