Clean air

Bristly beard lichen (Usnea hirta)

Bristly beard lichen (Usnea hirta) is one of the lichens that does not tolerate polluted air. This beard lichen is one of the more common beard lichen species in Europe. Its thallus is like a small (up to 5 cm long), greenish-grey tuft of beard that hangs from tree trunks to branches. It can be most commonly found on the trunks of pines. In dry weather, the lichen is hard and rough, but becomes very soft when it rains. The thick filaments of the lichen thallus are covered by approximately 1 cm long, tiny hair-like formations or fibrils. When the lichen filaments are separated, a white core created by the fungus’ hyphae is visible.