Interesting article by MikeDunne on Idaho wines: SacBee:IdahoWines
The part that really interested me was:
▪ 10. High on a slope at the far reaches of the Idaho Botanical Garden next to the old state penitentiary at Boise sprawled a tall grape vine, its foliage flaming, its grapes small and black. At the base was a sign that called it purpurea, a member of the vitis-vinifera family of grapes, responsible for most of the world’s fine wines. I’d never heard of the grape, and several vintners who I asked about it also didn’t understand it or what it was doing in the garden. No one had a clue about whether it ever played a role in Idaho’s winemaking culture. A couple of them, however, sounded eager to look into the matter, maybe even plant some and see what kind of wine it would yield.
Apparently the grape is grown more for its decorative qualities as the leaves turn in the Fall. Mostly it's talked about on the Gardening Sites.
Probably pretty badly virus infected.