Physciaceae Physcia caesia Growth type foliose Chemical results: Cortex and medulla K+ yellow On basic, well-lit nutrient-rich rocks, cement and asphalt. Also found on basic-barked trees. The pale bluish-grey thallus has adpressed convex lobes with small pseudocyphellae. Underside white to tan with scattered rhizines. Abundant blue-grey farinose or globular soralia, mainly laminal. The black, pruinose apothecia with prominent margins are rare. Similar: Phaeophyscia orbicularis has greenish soralia. Physcia dubai. Pseudocyphellae and cilia absent, acidic substrates

Physcia caesia
Corfe Mullen and Sturminster Marshall, Dorset. January and March 2014