Hypogymnia physodes Dark Crottle

A very common foliose lichen with a grey-green, lobed thallus. The lobes are flattened and somewhat appressed, rather than tubular like those of Hypogymnis tubulosa, but often turn upwards. They usually have clusters of powdery soredia on their underside and black dots (pycnidia) usually eveident near the tips of the lobes. It grows on trees, wooden posts and benches, moss, heather, rock and other substrates. It is resistent to sulphur dioxide pollution and likes acidic substrates, but it is more sensitive to nitrogen pollution. As air quality has improved, particularly in terms of sulphur pollution, it seems to be becoming less common.

Listed by Alan Orange in Flora of Glamorgan (Wade et al, 1994)