Lichens are lichenized fungi. 140 species (as of 2008) have been discovered on Ruhnu, the actual number is estimated at up to 170 species. Lichens are most widely-spread on the forested half of the island and on the east coast; on the grassland side of the island there are very few suitable habitats for lichens.

One special feature of Ruhnu is that lichens that should normally grow on trees in dry boreal forests manage to successfully grow on the sands of Limo – for instance tube lichen (Hypogymnia physodes), intense light and dark lichen (Pseudevernia furfuracea) and ring lichen (Evernia divaricata; III conservation class; threatened species). On the dunes of Limo Beach, a total of about 40 different types of foliose lichen have been found, most of which are cup lichen (Cladonia), reindeer lichen (Cladina), felt lichen (Peltigera) and mealy lichen (Stereocaulon); there is also a multitude of crustose lichen. Species characteristic to dunes covered in vegetation are Florke’s cup lichen (Cladonia floerkeana) and cup lichen (C. phyllophora).

Lichen flora in the marsh forests of Ruhnu is also interesting – for instance, needle lichen (Chaenotheca furfuracea), rim lichen (Lecanora chlarotera), old wood rimmed lichen (Lecanactis abietina), lecidella lichen (Lecidella elaeochroma) and several species of cartilage lichen (Ramalina) can be found there. Some of the lichen species found on Ruhnu are rather rare on the mainland, for instance soot lichen (Cyphelium tigillare), rim lichen Lecanora helicopis, Gennar’s rinodina lichen (Rinodina gennarii), pore lichen Pertusaria pertusa and barnacle lichen (Thelotrema lepadinum; III conservation class; near threatened species).

Created in 2014