Letharia vulpina
Photographed in the San Gabriel Mountains, Los Angeles
Conservation status
Secure  (NatureServe)[1]
Scientific classification
Kingdom:	Fungi
Division:	Ascomycota
Family:	Parmeliaceae
Genus:	Letharia
Species:	L. vulpina
Binomial name
Letharia vulpina (L.) Hue (1899)
Synonyms
Lichen vulpinus L. (1753)

Letharia vulpina is a lichen. People call it wolf lichen in English. It is a fruticose lichenized species of fungus in the family Parmeliaceae. It is bright yellow-green in color. Its body has many branches. It grows on the skin of living and dead trees with needles and coness in western Europe, continental Europe, the Pacific Northwest in North America, and the northern Rocky Mountains in North America. The chemical that makes it yellow, vulpinic acid, is poison to animals with fur. People have used it to kill wolves and foxes. Many native North American ethnic groups also use it in dye and paint.

The Swedish scientist Carl Linnaeus wrote the first paper about this fungus in 1753. He put it in his Lichen group, which was the normal way scientists did things at that time.^[2] In 1899, Auguste-Marie Hue moved it to the genus group Letharia.^[3]

The Latin name for this lichen, vulpina comes from the word for "fox." People call it "wolf lichen" because it can be used to kill wolves.

The thallus, or vegetative body, has a fruticose shape — that is, it is shrubby and has many branches close together. It is bright yellow to yellow-green in color. It is usually 2 to 7 cm (0.8 to 3 in) across.^[4] The vegetative reproductive structures soredia and isidia are present on the surface of the thalli, often abundantly.

Like most lichens, L. vulpina does not die in freezing cold. Scientists put some of this lichen in cold storage for 15 hours, and it started making food from sunlight again after only 12 minutes, when its body was still partly frozen. Scientists think this lichen might still make food for itself during the winter.^[5]

Letharia vulpina grows in the Pacific Northwest. People see it the most on branches whose bark has fallen off. It lives in old forests with lots of water, but people see it in the drier parts of those forests.^[4] This lichen can live with some air pollution but not as much as some other lichens.^[4] In the Rocky Mountains, Letharia species are found in ponderosa forests where the grassland meets the forest not too high above sea level and higher above sea level in Douglas fir and lodgepole pine forests.

Some Plateau Indian people used wolf lichen as medicine for swelling, bruises, sores, and boils. They boiled it as a drink to stop bleeding.^[6]

People put the lichen's colorful fruiting bodies in with flowers because they are beautiful.^[4]

Wolf moss can be the yellow dye in Chilkat blankets that the Tlingit people make. The dye also kills pests that can hurt wool clothing.^[7] The wolf moss does not grow in Tongass forest, so the people who live there must have gotten it from other people by trade. The Klamath Indians in California used this lichen to color porcupine quills yellow. Then they used the quills to make baskets.^[8]

People have used L. vulpina to kill wolves and foxes for at least hundreds of years. Christoph Gedner wrote about L. vulpina poison in "Of the use of curiosity," which he wrote before 1759.^[9] According to British lichen scientist Annie Lorrain Smith, people would put lichen and powdered glass inside dead reindeer that the wolves nad foxes would eat.^[10] The lichen does not need the glass to kill animals.^[9] The yellow dye and the poison are the same chemical: vulpinic acid. Mice and rabbits can eat it without being poisoned, but meat-eating animals cannot.^[9]

Letharia columbiana does not have the isidia and soredia that L. vulpina has. Instead, it has apothecia.^[4] It is also less branched than L. vulpina.^[11]

• Media related to Letharia vulpina at Wikimedia Commons