Keys to the macrolichens and checklist of the lichens and ...

28a. Thallus in the centre not foliose; only along the margins...................................... 29
28b. Thallus foliose throughout ..................................................................................... 30
29a. Hymenium I+ bright blue ........................................................................... Pannaria
29b. Hymenium I+ dirty blue ...............................................................Psoroma filicicola
30a. Thallus white, grey or brownish grey, lobes up to 5 mm wide, usually matt, often
pruinose; spores brown, 1-septate (Physciaceae)................................................... 31
30b. Thallus yellow-green, grey or brown, lobes from 1 mm to several centimetres
wide, usually ± shiny in younger parts, rarely pruinose; spores colourless, simple
(Parmeliaceae)........................................................................................................ 36
31a. Thallus whitish to bluish grey, K+ yellow............................................................. 32
31b. Thallus grey brown to brown, K-........................................................................... 35
32a. Rhizines nearly absent; medulla UV+ white ..............................................Dirinaria
32b. Rhizines present; medulla UV-.............................................................................. 33
33a. Thallus with marginal cilia or rhizines; upper cortex and hyphae running parallel
to the upper surface (microscope)........................................................Heterodermia
33b. Thallus without marginal rhizines or cilia; upper cortex and hyphae with a cellular
structure (microscope) ........................................................................................... 34
34a. Hypothecium black; lower surface usually black; thallus often UV+ yellow Pyxine
34b. Hypothecium pale; lower surface white to black; thallus UV-......................Physcia
35a. Rhizines absent or sparse..................................................Hyperphyscia adglutinata
35b. Rhizines numerous...............................................................................Phaeophyscia
36a. Cilia with inflated base .......................................................................................... 37
36b. Cilia, if present, without inflated base ................................................................... 38
37a. Upper surface grey, K+ yellow, with atranorin ........................................ Bulbothrix
37b. Upper surface yellowish green, with usnic acid ...........................................Relicina
38a. Thallus erect, ± tufted ............................................................................................ 39
38b. Thallus adnate to loosely overlapping ................................................................... 40
39a. Thallus lobes brown throughout .................................................................. Cetraria
39b. Thallus lobes yellow-green, green to grey-green or whitish.... Flavocetraria nivalis
40a. Pseudocyphellae present on upper surface, punctiform or effigurate.................... 41
40b. Pseudocyphellae absent ......................................................................................... 43
41a. Pseudocyphellae effigurate .........................................................Parmelia erumpens
41b. Pseudocyphellae punctiform.................................................................................. 42
42a. Lobes overlapping, apothecia usually absent................................................ Cetrelia
42b. Lobes not overlapping, apotheciaoften present .................................. Nephromopsis