Parmelia imbricaria

Parmelia imbricaria is a foliose (leaf-like) lichen that typically grows 5–10 cm (2–4 in) in diameter, though specimens can reach up to 15 cm (6 in) across. It grows flat against its substrate, ranging from loosely to closely attached. The lichen is characterised by its small lobes that measure 1–2 mm wide, which start out concave when young and become flat to slightly convex as they mature. These primary lobes branch irregularly and develop even smaller secondary lobes (0.2–0.5 mm wide) that strongly overlap each other like shingles, giving the species its name. The upper surface appears pale bluish-grey, turning dark brown in exposed areas. It can be dull or slightly shiny, with or without a powdery coating (pruina). White linear markings called pseudocyphellae appear primarily along the lobe margins, sometimes forming a subtle net-like pattern across the upper surface. The lower surface is black, smooth and shiny, with numerous root-like (rhizines) that help anchor the lichen. …