Physcia adscendens
Also called ‘Hooded Rosette Lichen’, it is a grey-green foliose lichen with tiny helmet-like protrusions. It is a good nitrogen indicator. Thallus 2cm in diameter.
Found on tree bark, rocks, stonework and concrete. Common and widespread throughout.
Photograph of Rosette Lichen (Physcia adscendens), taken February 2012 on old Willow, local field, Staffordshire. © Pete Hillman 2012. Camera used Panasonic Lumix DMC-FZ38.