GREGORY G. DIMIJIAN, M.D. / SCIENCE PHOTO LIBRARY GREGORY G. DIMIJIAN, M.D. / SCIENCE PHOTO LIBRARY
Wolf lichen, (Letharia vulpina), covering trunk of a white fir, (Abies concolor), in the Sierra Nevada mountains of Sequoia National Park, California. The lichen produces a toxin, vulpinic acid. Wolf lichen also occurs in northern Europe, where it was once used to poison foxes and wolves.
Model release not required. Property release not required.