RHH's photos with the keyword: elk thistle

I believe this is Elk Thistle, a plant native to Yellowstone National Park and photographed in the Fountain Paint Pots area of the park. Its root is edible and an explorer who was separated from his party and lost for over a month in the park in 1870 subsisted on the raw root of the plant the whole time since itt was the only edible plant he knew.