Anaptychia ciliaris

Anaptychia ciliaris, commonly known as the great ciliated lichen or eagle's claws, is a species of fruticose lichen in the family Physciaceae. It is predominantly found in Northern Europe, with its range extending to European Russia, the Caucasus, Central and Southern Europe, the Canary Islands, and parts of Asia. First mentioned in botanical literature by the Italian botanist Fabio Colonna in 1606, the species was formally described by Carl Linnaeus in 1753, who highlighted its unique physical characteristics such as its grey colour, its unusual leafy form with linear fringe-like segments, and the presence of hair-like structures (cilia). This lichen is adaptable in its choice of substrates, mostly growing on tree barks and less commonly on rocks.

Throughout history, the lichen has been used in early scientific investigations about lichen structure and development. Early botanists like Joseph Pitton de Tournefort and Johann Hedwig made observations about the lichen's structure. More recent studies have investigated its potential biological activities, including antibacterial, insecticidal, and antioxidant properties. A. ciliaris has been used in research to monitor atmospheric pollution, including detecting air pollution following the Chernobyl disaster. Beyond its scientific importance, the lichen has had various practical applications. For example, in the 17th century, it was one of several lichen ingredients in "Cyprus Powder", used as a personal grooming and cosmetic product.

Anaptychia ciliaris is readily recognizable by its fruticose (bushy) thallus that varies in colour from greyish-white to brownish-grey, to greenish when wet, and its large and distinctive cilia. The lichen can form extensive colonies made of neighbouring lichens each attached to the substrate at a single point, all with narrow lobes, known as laciniae, growing outwards. These laciniae, which are covered in fine hairs, split repeatedly into equal branches. Circular reproductive structures (apothecia) with brown discs occur on the thallus surface. The internal anatomy of A. ciliaris makes it sensitive to air pollutants, leading to observable changes in its form when exposed to these conditions. Two species of green algae in the genus Trebouxia have been shown to serve as the photobionts (photosynthetic partners) of this lichen.