Hypogymnia physodes

Thallus foliose 6-10 cm diameter, appressed, lobes hollow inside, ascending at the tips, grey-green, glossy. Soralia labriform. Lower surface black, without rhizines, brown at the margin of the lobes.
Reproduction: mainly by soreida, apothecia very rare.
Photobiont: Chlorococcoid.
Spot test: cortex K+ yellow, C-, KC-, P+ pale yellow, UV-; medulla and soralia K-, C-, KC+. orange-red, P+ orange-red.
Chemistry: upper cortex with atranorin and chloroatranorin; medulla with physodic acid (major), 2'-O-methylphysodic acid (minor or accessory), 3-hydroxyphysodic acid (major), physodalic acid (major), and protocetraric acid (minor).

Habitat: mainly on acid barks; also on bryophytes, plant debris, soil or siliceous rocks; hygrophilic.
Distribution: Holartic, cold and temperate regions.

Position in classification:

Parmeliaceae, Lecanorales, Lecanoromycetidae, Lecanoromycetes, Pezizomycotina, Ascomycota, Fungi.

Locality data:
Location: Vall de la Pena, Paratge Natural d'Interès Nacional de Poblet, Vimbodí i Poblet (Conca de Barberà)
Ecology: On Pinus nigra subsp. salzmannii.
Altitude: 810 m.
Climate: Continental Mediterranean (Tmm=11,7ºC,  600mm).
Common name: monk's-hood lichen.
Etymology of names: Hypogymnia, derived from the Greek ὑπο- (hupó, meaning "under or bellow") and γυμνός (gumnós, "naked"), refers to the bare lower surface of the thallus without rhizines; physodes from the Greek φῡσώδης (phūsṓdēs, “bladder-like”) it may refer to refers to the swollen and fistulous lobes.

Ethnolichenology: Hypogymnia physodes is often used as bioindicator of air pollution. Mixed with Evernia prunastri and Pseudevernia furfuracea as “Lichen Quercinus virides”, a popular drug in the 15^th century in Europe (SENFT, E., 1911. The so-called "Lichen Quercinus virides". Pharm. Post. 43: 1017-1019).