Fig. 13.14Squamulose lichens, commonly found on peaty soils. The squamules of Cladoniaspp (a) are small, green,
scale-like structures, about 1–2 mm diameter, like flakes of skin (hence the name squamulose). These lichens are very
variable because they can grow in different forms, including goblet-shaped and candle-shaped structures (b) with
squamules at their base.(a) (b)Fig. 13.15Crustose lichens, which usually grow on bare rock surfaces, often produce a patchwork of colonies with
apothecia. (a) A rock surface, about 15×10 cm, colonized predominantly by a green-coloured lichen, Rhizocarpon
geographicum(the “map lichen”). (b) A gray, crustose lichen that has covered a rock surface and produced conspicu-
ous red-brown apothecia, up to 5 mm diameter.
(a) (b)Fig. 13.16Cross-section of Xanthoria
parietina, showing the zonation of tissues.