Hypogymnia tubulosa (Schaerer) Havaas forme corticole.

    Thallus foliose, forming irregular rosettes, 5-10 cm across, lobes hollow, swollen and folded, gutter-shaped, 1-3 mm wide, arranged like fingers, apices upturned, soralia developed at margin of lobes apices, at first as brown bugs becoming farinose and capitate, grey-greenish, upper surface pale grey, grey-bluish, grey-greenish, lower surface blackish towards the center, margin brownish. Apothecia very rare, 2-7 mm diam., disc brown reddish. Ascospores colourless, almost globose,  Photobiont: Chlorococcoid.  Cortex : C-, K+ yellow; medulla and  soralia : C-, K-, KC+ yellow > red, Pd-. Species whose most common form occurs on the bark of trunks and large branches of trees, sometimes at the base of heather but also quite common on rocks by the sea see Hypogymnia tubulosa forme saxicole but also on the branches of large trees especially in the canopy, see Hypogymnia tubulosa forme ramicole as well as on worked wood (poles) see Hypogymnia tubulosa forme lignicole. N.B. Hypogymnia physodes looks a lot like it and some unusual specimens are sometimes difficult to separate.