Lung Lichen

You may think there’s no old growth forest or wilderness on PEI, but that’s not true. We have amazing ancient and wild spaces if you know where to look and can recognize the signs. Lung Lichen (Lobaria pulmonaria) is one of those signs.

A lichen is a unique creature: usually, it’s a combination of a fungus and an alga or cyanobacterium functioning as one organism. But Lung Lichen is one PEI’s few tripartite lichens: it includes a fungus, a green alga, and a cyanobacterium. 

Cyanobacteria – also known as blue-green algae – have a bad reputation because some are toxic. In lichens, cyanobacteria play the important role of fixing nitrogen, changing it from an inert gas into forms the lichen (as well as other fungi and plants) can use. Because of this, when Lung Lichens fall to the forest floor or are spread by animals, they enrich the soil and make essential nitrogen available to other living things. 

The cyanobacteria in Lung Lichen aren’t toxic, but they are very sensitive to air pollution, making this lichen a good indicator of air quality. Lung Lichen also grows just a few millimetres per year, and so large patches are indicative of older, undisturbed forests. 

Lung Lichen is leafy and bright green when wet (main photo) and more olive or brown when dry. If you look closely – and if the lichen is at least 20 years old – you may see its apothecia: brownish disks at the margins that produce fungal spores (inset photo). If the spores meet up with the right algae and cyanobacteria they’ll grow into new lichens, but that’s a risky reproductive investment that requires a lot of factors to come together in the right place at the right time. To hedge its bets, Lung Lichen can also reproduce vegetatively from bits that break off and are dispersed by wind, water, or animals.

Lung Lichen is food for snails, slugs, mice, voles, squirrels, and – elsewhere in its range – deer, moose, and caribou. Humans have traditionally used it to treat respiratory issues (it’s been found to contain soothing mucilage as well as antibiotic, anti-inflammatory, and antioxidant compounds) and it can be boiled to create an orange-brown dye. 

Lung Lichen is a great indicator of clean air and older forests on PEI Untamed!