Letharia vulpina ("wolf lichen") on incense cedar bark, western slope of the Sierra Nevada, California. Letharia columbiana, in the previous portrait, is its sister species.
This was the most widely used dye lichen for indigenous peoples in western North America, used from the Rockies to the Pacific coast, from California to Alaska. Some groups also made paint from it.
This lichen is sufficiently poisonous that the Achomawi in Northern California used it to make poison arrowheads, but the Okanagan-Colville made a weak tea of it to treat internal problems, and it was a Blackfoot remedy for stomach disorders.