Madder, woad and weld were such commonly grown dye plants that they've self seeded themselves in some areas and quite happily become native.
Woad stinks like rotting cabbage when it's being turned into dye. It's actually a pretty good herbal plant too, traditionally a wound plant, it's antibacterial and seems to have some anti fungus properties too. Skin infections and the like, but supposedly good for sore throats too....I'm not advising anyone use it internally, I know that it's seems fine on the skin. I used it, it healed a horrible wet seeping scrape, and I have over sensitive skin and react badly to a lot of things.
Weld self seeds and grows on everything from sandy dunes to building sites. It doesn't like to be shaded by other plants when it's in it's first year, but leave it alone someplace open and gravelly and it'll be everywhere there in a year or two.
Again, used for skin irritations, cuts, scrapes, etc., inflammation, etc.,
Madder....well there's the lady's bedstraw which gives colour from it's roots, and I've mentioned it before, but it's a decent-ish rennet replacer. If you don't want to kill a calf, (I'm told a hen can do it too, just it's a matter of scale) then folks looked for a plant alternative. Nettles do it, but the cheese ends up a weird yellowy green sort of unappetising colour, but lady's bedstraw gives that lovely colour that we now fake to make coloured red cheddar
Pretty sure they didn't use madder for that though.
Madder was pretty much a dried import from Roman times through to somewhere in the Dark Ages, when we think the Anglo Saxons started growing it again.
I have tried growing it here; no joy, it just does not thrive in our cold and wet.
