Lobaria pulmonaria is a large epiphytic lichen consisting of an ascomycete fungus and a green algal partner living together in a symbiotic relationship with a cyanobacterium—a symbiosis involving members of three kingdoms of organisms.

It is a foliose lichen and its leaf-like thallus is green, leathery and lobed with a pattern of ridges and depressions on the upper surface.

The cortex, the outer protective layer on the thallus surface, is roughly comparable to the epidermis of a green plant.

[10] In sexual reproduction, the species produces small reddish-brown discs known as apothecia containing asci, from which spores are forcibly released into the air (like ballistospores).

[15] It has a wide distribution in Europe, Asia, North America and Africa, preferring damp habitats with high rainfall, especially coastal areas.

[21] Various environmental factors are thought to affect the distribution of L. pulmonaria, such as temperature, moisture (average humidity, rapidity and frequency of wet-dry cycles), sunlight exposure, and levels of air pollution.

[23] Due to declining population, L. pulmonaria is considered to be rare or threatened in many parts of the world, especially in lowland areas of Europe.

[40] In India it is used as a traditional medicine to treat hemorrhages and eczema,[5] and it is used as a remedy for coughing up blood by the Hesquiaht in British Columbia, Canada.

[41] An ethnophytotherapeutical survey of the high Molise region in central-southern Italy revealed that L. pulmonaria is used as an antiseptic, and is rubbed on wounds.

[44] Furthermore, methanol extracts also have potent antioxidative activity and reducing power, probably due to the presence of phenolic compounds.

[45] Lobaria pulmonaria has also been used to produce an orange dye for wool, in the tanning of leather, in the manufacture of perfumes and as an ingredient in brewing.