Thallus
Foliose, 3–20 cm in diameter, ascending lobes (4–15 mm wide), lobe margins sometimes with very short black cilia (less than 2 mm)
Color
Blue-gray to greenish-grey upper surface, black underside
Reproduction
Apothecia: rare, with brownish disc and sorediate margin
Soralia: whitish to greenish, present at the lobe margin, more or less globose (in the shape of pearls)
Isidia: —
Risk of confusion
Hypogymnia physodes / H. tubulosa, smaller and with a swollen appearance
Sensitivity to air pollution
Sensitive to pollution