Common Orange Lichen
Xanthoria parietina is a foliose, or leafy, lichen. It has wide distribution, and many common names such as common orange lichen, yellow scale, maritime sunburst lichen and shore lichen. It can be found near the shore on rocks or walls, and also on inland rocks, walls, or tree bark.
The vegetative body of the lichen, the thallus, is foliose, and typically less than 8 centimetres wide. The lobes of the thallus are 1–4 mm in diameter, and flattened down. The upper surface is some shade of yellow, orange, or greenish yellow, while the lower surface is white, with a cortex, and with sparse pale rhizines or hapters. The vegetative reproductive structures soredia and isidia are absent in this species, however, apothecia are usually present.
The Common Orange Lichen prefers growing on bark and wood; it is found more rarely on rock. Nutrient enrichment by bird droppings enhances the ability of X. parietinato grow on rock.
Source: en.wikipedia.org/wiki/Xanthoria_parietina - 10.11.2008