Lobaria pulmonaria · The Lungwort Lichen
A symbiosis older
than the forests themselves
Lichens are not a single organism. They are an alliance: a fungus and an alga, sometimes joined by cyanobacteria, living as one. Lobaria is among the most extraordinary of them.
What is a lichen, exactly?
A lichen is not a plant, not a fungus, not an alga. It is a composite organism. The fungal partner (mycobiont) provides structure and protection, while the photosynthetic partner (photobiont) produces sugars from sunlight.
This partnership, called mutualistic symbiosis, has existed for over 400 million years. Lichens were among the first organisms to colonize bare rock after the last ice age, breaking down stone into soil, making life possible for everything that followed.
Today, lichens cover roughly 7% of the Earth's land surface, from Arctic tundra to tropical rainforest canopies.
Lobaria pulmonaria, a forest indicator
Named for its resemblance to lung tissue, Lobaria pulmonaria is one of the largest and most ecologically important foliose lichens in temperate forests. It is a three-partner symbiosis: a fungus, a green alga, and cyanobacteria, all living as one.
Its presence is a reliable indicator of old-growth forest quality. Because it is extremely sensitive to air pollution and requires centuries of undisturbed habitat, ecologists use it as a bioindicator for forest continuity and air quality.
In traditional medicine across Europe and Asia, it was used to treat lung ailments, a case of doctrine of signatures, where its lung-like form was taken as a sign of its purpose.
Slow growth, long memory
A single Lobaria thallus may be decades or even centuries old. Growing only 3–5 mm per year, these organisms are living archives of ecological stability. When a forest is disturbed by logging, pollution, or climate shifts, Lobaria is among the first to disappear.
Its recovery, once lost, takes generations. This makes it both a symbol of fragility and of resilience: where Lobaria thrives, the forest is truly old and truly healthy.
Conservation of these lichens is inseparable from the conservation of the ancient forests they call home.