Beard lichen
Usnea spp.
Family · Parmeliaceae · Harmless
The grey-green beards hanging from branches in mountain woods. Not a plant and not a parasite: it is a lichen, and its presence says something very specific about the air there.
Uplands · Oak woods · Pine woods
Also known asold man's beard, usnea
How to tell it
Hanging, branched, grey-green filaments. The confirming test: pull a filament slowly and you see a white elastic cord inside, which no similar lichen has.
What it is confused with
No dangerous lookalikes known in the Iberian Peninsula.
What it is for
Its most valuable use is as an indicator: usnea is extremely sensitive to sulphur dioxide and disappears with air pollution. If it is there, the air in that valley is clean.
Where it occurs
Each square is an area with recorded observations of this plant. The lighter background is the set of areas where any of the entries has been observed, and serves as a reference. Note what this is not: it is not where the plant lives, it is where people record it, so trails and towns always look fuller than the mountains. Data from GBIF.
Sources
Community
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