Crusty pink and green lichens on an oak tree. Lichens on oak trees are a sign of clean air, they are a symbiotic relationship between fungi & algae.

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Size: 5472px × 3648px
Location: Yorkshire, England.
Photo credit: © Ros Crosland / Alamy / Afripics
License: Royalty Free
Model Released: No

Keywords: air, algae, association, bark, clean, crusted, crustose, crusty, cyanobacteria, fungi, lichen, lichens, oak, pink, sign, symbiosis, symbiotic, tree, trees, trunk