2a Photobiont Nostoc, with rounded cells in chains, embedded in continuous jelly --- 3
2b Photobiont not Nostoc --- 6

3a Thallus with cellular outer layer --- 4
3b Thallus without cellular outer layer --- 5

4a Thallus black, foliose, underside covered by fine hairs --- Leptogium saturninum (Dicks.) Nyl.
4b Thallus grey, variously shaped: underside not hairy --- Leptogium

5a Ascospores septate --- Collema
5b Ascospores simple --- Staurolemma

6a (2) Thallus crustose, composed of adjacent, to ca. 1 mm tall segments --- 7
6b Thallus foliose to fruticose, composed of over 1 mm long lobes --- 8

7a Photobiont with reddish gelatinous sheaths, at least near thallus margin; on siliceous rock --- Pyrenopsis
7b Photobiont with colourless gelatinous sheaths; on limestone --- Psorotichia

8a Thallus composed of ca. 2-5 mm wide, more or less lobed, dark brown to black warts, resembling Toninia but with cyanobacteria as photobiont and with immersed ascocarps; on soil, sometimes in rock fissures --- Gloeoheppia turgida (Ach.) Gyeln.
8b Thallus with cylindrical to flattened lobes; usually growing directly on rock --- 9

9a Thallus fruticose --- 10
9b Thallus foliose, centrally attached and more or less deeply divided into flattened slips --- 12

10a Thallus small, forming to ca. 1 mm tall cushions, with terminal apothecia --- Peccania
10b Thallus lobes several mm long, more or less flattened --- 11

10a Ultimate divisions of thallus terete-coralloid and delicate, blueish grey --- Polychidium
10b Ultimate divisons of thallus often folded or flattened, over 1 mm thick, black --- Lichinella

12a Thallus in section with distinct medulla containing well-recognizable, separate hyphae and no photobiont --- Thyrea
12b Thallus in section without distinct medulla, containing dense photobiont cells and dense, scarcely distinguishable hyphae throughout the thallus --- Anema

25a (1) Thallus fruticose, usually several cm high; segments mainly standing up or hanging freely in the air, without cilia or rhizines; segments when flattened on both sides of similar structure and colour --- 26
25b Thallus foliose or crustose, flat and mainly parallel to the substrate; upper side clearly different from the underside --- 50

26a Thallus composed of erect, hollow, cylindrical or cup-shaped parts (podetia) and squamules: genus Cladonia; a few common species are keyed out here --- 27
26b Thallus lobes all similar, erect or pending, cylindrical or more or less flattened --- 31

27a Podetia wineglass-shaped, with granular surface --- Cladonia pyxidata (L.) Hoffm.
27b Podetia cylindrical, more or less branched --- 28

28a Podetia scarcely branched, with mealy (sorediate) surface --- Cladonia awasthiana Ahti & Upreti
28b Podetia densely branched, with mostly smooth surface --- 29

29a Podetia greenish grey, white-maculate --- Cladonia rangiformis Hoffm.
29b Podetia predominantly brown, sometimes longitudinally split --- 30

30a Podetia completely without mealy (sorediate) areas on the surface --- Cladonia furcata (Huds.) Schrad.
30b Podetia with mealy areas on the surface --- Cladonia scabriuscula (Delise) Nyl.

31a (26) Thallus lobes flattened, solid --- 32
31b Thallus lobes cylindrical, solid or with central cavity --- 36

32a Thallus lobes with greenish grey upper side and pale yellow underside --- Evernia prunastri (L.) Ach.
32b Thallus lobes the same colour on both sides, more or less greenish grey --- 33

33a Thallus greenish to grey, with smooth surface throughout; ascospores pale, uniseptate --- 34
33b Thallus yellow (except in deep shade), with smooth surface; ascospores pale, polarilocular --- Xanthoria

34a Thallus greenish grey, with smooth surface throughout --- Ramalina
34b Thallus pale grey, short-haired, at least at lobe tips --- 35

35a Apothecia with yellow disc; ascospores pale, uniseptate with thick septum; thallus sometimes with yellow spots --- Seirophora
35b Apothecia with black disc; ascospores grey, uniseptate with thin septum; thallus never with yellow spots --- Tornabea scutellifera (With.) J.R.Laundon

36a Thallus lobes with central cavity, rod-shaped, few cm long and over 1 mm wide --- 37
36b Thallus lobes compact, tread-like --- 38

37a On soil; thallus pale grey, richly branched, not sorediate; presence in Iran needs confirmation, probably mistake for Cladonia rangiformis --- Cladonia rangiferina (L.) F.H.Wigg.
37b On tree bark or rock; thallus greenish grey, scarcely branched --- Ramalina

38a Thallus with elastic, stretchable, central string --- 39
38b Thallus without central string --- 40

39a Thallus draped over branches, thicker parts saucisson-like with inflated segments separated by constrictions --- Usnea articulata (L.) Hoffm.
39b Thallus erect or hanging from branches or along trunks, when hanging without inflated segments --- Usnea

40a Thallus brown --- Bryoria fuscescens (Gyeln.) Brodo & D.Hawksw.
40b Thallus pale to greenish grey --- 41

41a Thallus pale grey, K+ yellow, branchlets with straight tips --- Bryoria capillaris (Ach.) Brodo & D.Hawksw.
41b Thallus greenish grey, K-, branchlets with hooked tips --- Ramalina thrausta (Ach.) Nyl.

50a (25) Thallus foliose, lower side free from substrate over most of its surface and attached by rhizines or small patches of the lower side --- 51
50b Thallus crustose or squamulose, attached to the substrate with the whole lower surface or with raised, free margins --- 100

51a Rhizines or cilia (marginal rhizines) present --- 52
51b Rhizines and cilia absent --- 81

52a Cilia present --- 53
52b Cilia absent --- 57

53a On soil; thallus lobes incurved when dry and showing pale yellow underside --- Cladonia foliacea (Huds.) Willd.
53b On tree bark or rock; thallus lobes not incurved when dry, lower side not visible from above --- 54

54a Thallus yellow, small; lobes to ca. 1 mm wide and 2 mm long --- Candelaria concolor (Dicks.) Stein
54b Thallus pale to greenish grey --- 55

55a Thallus upper surface with short hairs, at least at the lobe tips --- Anaptychia
55b Thallus upper side without hairs --- 56

56a Thallus deeply divided, lobes ca. 1 mm wide, linear; cilia prominent at lobe tips, to ca. 1 mm long --- Physcia
56b Thallus shallowly divided, lobes ca. 1 cm wide; cilia prominent at lobe tips, to ca. 1 mm long --- Parmotrema perlatum (Eschw.) M. Choisy
56c Thallus deeply divided, lobes irregular; cilia mainly marginal, tiny, ca. 0.1 mm long --- Myelochroa

57a Thallus lower side veined or with reticulate grooves; upper side often tomentose; rhizines often short and weakly conglutinated --- 58
57b Thallus lower side not veined; upper side always smooth; rhizines always strongly conglutinated --- 59

58a Thallus upper side reticulate-ridged --- Lobaria
58b Thallus upper side flat --- Peltigera

59a Thallus umbilicate; rhizines without attachment function --- 60
59b Thallus not umbilicate, attached by rhizines --- 61

60a Perithecia present --- Dermatocarpon vellereum Zschacke
60b Perithecia absent --- Umbilicaria

61a Pseudocyphellae present on upper side: white, rounded or elongate spots --- 62
61b Pseudocyphellae absent --- 64

62a Pseudocyphellae elongate, in reticulate pattern; medulla K+ yellow turning red --- Parmelia
62b Pseudocyphellae round, dot-like --- 63

63a Thallus applanate, with rhizines to near the lobe tips; medulla C+ red in some species --- Punctelia
63b Thallus with ascending, wide marginal lobes without rhizines below; medulla C- --- Cetrelia

64a Ascocarps perithecia; thallus of crustose aspect, composed of few mm wide, rounded sectors --- Neocatapyrenium
64b Ascocarps apothecia; thallus of leafy aspect, in larger, usually several cm wide, deeply lobes patches --- 65

65a Thallus upper cortex K+ yellow, KC- (containing atranorin); thallus pale grey --- 66
65b Thallus upper cortex K-, KC+ yellow (containing usnic acid); thallus yellowish- to greenish grey --- 67
65c Thallus upper cortex K+ dark redviolet, KC- (containing parietin); thallus yellow to orange; ascospores polarilocular --- Xanthoria parietina (L.) Th.Fr.
65d Thallus upper cortex K-, KC- (without atranorin, usnic acid or parietin); thallus pale grey, brownish to olive-green --- 68

66a Medulla C+ red --- Parmelina
66b Medulla C- --- Physcia

67a Thallus sorediate; on bark, occasionally over moss on rock --- Flavoparmelia caperata (L.) Hale
67b Thallus not sorediate; not on bark, on rock or soil --- Xanthoparmelia

68a Thallus olive-brown to brown; ascospores colourless, not septate --- 69
68b Thallus dark grey; ascospores grey, uniseptate --- Phaeophyscia
68c Thallus pale grey to white; ascospores grey, uniseptate; rhizines often with perpendicular, dense branchlets --- Physconia

69a On rock; thallus closely attached --- Neofuscelia
69b On tree bark, occasionally on rock; thallus loosely attached --- 70

70a Thallus large, often several dm wide; apothecia large and numerous, often over 1 mm wide --- Pleurosticta acetabulum (Neck.) Elix & Lumbsch
70b Thallus small, usually few cm wide; apothecia rarely over 5 mm wide --- Melanelia

81a (51) Thallus umbilicate, on rocks --- 82
81b Thallus not umbilicate, on soil or bark --- 84

82a Thallus with perithecia --- Dermatocarpon miniatum (L.) W.Mann
82b Thallus without perithecia --- 83

83a Apothecia immersed in thallus; ascospores many per ascus --- Glypholecia scabra (Pers.) Müll.Arg.
83b Apothecia finally sessile on thallus with lecanorine margin; ascospores 8/ascus --- Rhizoplaca

84a Thallus yellow to orange, with parietin, K+ dark redviolet --- Xanthoria
84b Thallus grey, K- or + pale yellow --- 85

85a On soil or moss over limestone; apothecia on the bottom of depressions in the thallus --- Solorina saccata (L.) Ach.
85b On tree bark --- 86

86a Thallus lobes erect, greenish grey --- Evernia prunastri (L.) Ach.
86b Thallus lobes closely attached, seemingly crustose, pale grey --- Hyperphyscia adglutinata (Floerke) Mayrh. & Poelt

100a (50) Thallus lobed at the margins or consisting completely of squamules --- 101
100b Thallus with entire margins and continuous or more ore less fissured and divided into areoles --- 150

101a Thallus yellow to orange, K + dark redviolet or pale reddish --- 102
101b Thallus grey to brown --- 106

102a Thallus K+ dark redviolet --- 103
102b Thallus K- or weakly K+ reddish --- 104

103a On rock or bark, rarely on moss; ascospores polarilocular --- Caloplaca
103b Among moss on soil over rock; ascospores not septate --- Fulgensia

104a On bark or soil --- 105
104b On rock of steep cliffs --- Pleopsidium

105a On bark; thallus lobes free from substrate --- Candelaria concolor (Dicks.) Stein
105b On mossy soil; thallus underside completely attached to substrate --- Candelariella placodizans (Nyl.) H.Magn.

106a (101) Thallus squamules attached to substrate only by their oldest parts, underside free and often visible from above; squamules elongate --- Cladonia
106b Thallus squamules attached to substrate by more or less bundled hyphae usually covering the whole underside, which is not visible from above; squamules rounded or elongate --- 107

107a Thallus producing perithecia, in most species frequently --- 108
107b Thallus producing apothecia, in many species infrequently --- 109

108a Hymenium without algal cells; ascospores not septate, colourless --- Placidium
108b Hymenium with ca. 5 mu wide algal cells; ascospores muriform, finally brown --- Endocarpon

109a Photobiont cyanobacteria --- 110
109b Photobiont green algae --- 111

110a Asci with 8 spores; growing on soil --- Heppia
110b Asci with many spores; usually growing on rock --- Peltula

111a Growing directly on rock --- 112
111b Growing on bark, mosses or soil --- 119

112a Ascospores grey, uniseptate --- Dimelaena oreina (Ach.) Norman
112b Ascospores colourless --- 113

113a Apothecia immersed in the thallus --- 114
113b Apothecia sessile on the thallus --- 115

114a Ascospores not septate, many per ascus --- Acarospora bullata Anzi
114b Ascospores septate or not, 8/ascus --- Lobothallia

115a Apothecia with lecideine margin; disc usually black, often with whitish pruina --- 116
115b Apothecia with lecanorine margin; disc usually shades of brown or yellow --- 118

116a Ascospores not septate; apothecia dark brown to black, not pruinose --- 117
116b Ascospores septate; apothecia black, often with whitish pruina --- Toninia

117a Apothecia black; on siliceous stone --- Psorula rufonigra (Tuck.) G.Schneider
117b Ascospores brown; on calcareous stone --- Mycobilimbia lurida (Ach.) Hafellner & Türk

118a Ascospores septate --- Solenopsora
118b Ascospores not septate --- Lecanora

119a (111) On soil or among mosses on soil or rock --- 120
119b On bark (thallus free from substrate but very closely attached) --- Hyperphyscia

120a Apothecia with lecanorine margin and yellow to brown disc, often present --- 121
120b Apothecia with lecideine margin and black or white-pruinose disc, often absent --- 122

121a On humous soil or on moss over humous soil or bark; thallus brownish --- Psoroma hypnorum (Vahl) Gray
121b On mineral soil or on moss over rock; thallus greenish to yellowish grey --- Squamarina

122a Thallus composed of rounded and more or less flattened parts, shades of brown to grey but often white-pruinose --- 123
122b Thallus deeply lobed, white --- Buellia zoharyi Galun

123a Ascospores not septate --- Psora
123b Ascospores septate --- Toninia

150a (100) Ascocarps absent, pycnidia, soredia or isidia present (species which regularly produce ascocarps are NOT included here, even though many specimens may be without) --- 151
150b Ascocarps present --- 160

151a Thallus yellow to green --- 152
151b Thallus pale grey --- 153

152a Thallus consisting of dense, ca. 50 mu thick soredia --- Candelariella xanthostigma (Ach.) Lettau
152b Thallus consisting of scattered, ca. 200 mu thick granules --- Chrysothrix candelaris (L.) J.R.Laundon

153a Thallus without conidia, producing soredia --- Lepraria
153b Thallus producing conidia; soredia absent --- 154

154a Pycnidia present, in ca. 0.5 mm wide, white warts --- Opegrapha vermicellifera (Kunze) J.R.Laundon
154b Thalloconidia present, produced in ca. 1 mm wide, blackish, rounded spots --- Milospium graphideorum (Nyl.) D.Hawksw.

160a (150) Ascocarps with persistently dot-like opening (perithecia, or apothecia with dot-like disc) --- 161
160b Ascocarps with wider opening, disc-like (apothecia) or elongate (lirellae), sometimes punctiform in young stages --- 180

161a Growing on bark --- 162
161b Growing on rock --- 165

162a Ascospores grey, 4-celled --- Pyrenula
162b Ascospores colourless, variously septate --- 163

163a Ascospores not septate --- 164
163b Ascospores one-septate --- Acrocordia gemmata (Ach.) A.Massal.

164a Ascospores thick-walled and usually over 50 mu long; ascocarps apothecia, without exciple --- Pertusaria
164b Ascospores thin-walled, under 30 mu long; ascocarps perithecia, with more or less carbonized exciple --- Thrombium

165a Ascospores colourless, not septate --- 166
165b Ascospores grey, muriform --- 170

166a Thallus flat and less than 1 mm thick, sometimes fissured and areolate --- 167
166b Thallus either over 1 mm thick or composed of scattered, rounded segments --- 168

167a Paraphyses persistent --- Thrombium
167b Paraphyses soon disappearing, absent when spores are present --- Verrucaria

168a Thallus continuous or areolate, over 1 mm thick; on limestone --- 169
168b Thallus of scattered, rounded segments; usually on soil --- Placidium

169a Thallus completely areolate, areoles with black rims --- Placopyrenium bucekii (Nadv. & Servit) Breuss
169b Thallus fissured to areolate, uniformly coloured --- Placocarpus schaereri (Fr.) Breuss

170a Paraphyses persistent; no algal cells in hymenium --- Diploschistes actinostomus (Pers.) Zahlbr.
170b Paraphyses disappearing in sporulating ascocarps; algal cells in hymenium --- Staurothele

180a (160) Ascocarps elongate and growing at the ends (lirellae) --- 181
180b Ascocarps rounded and growing in all directions (apothecia) --- 190

181a Paraphyses straight and unbranched; hymenium I-negative --- 182
181b Paraphyses branched and anastomosing; hymenium I+ orange-red or blue --- 184

182a Ascospores persistently colourless; apothecium labia thick and carbonized --- 183
182b Ascospores grey when ripe; apothecium labia thin --- Phaeographis dendritica (Ach.) Müll.Arg.

183a Ascospores transversely septate --- Graphis scripta (L.) Ach.
183b Ascospores muriform --- Graphina analoga (Nyl.) Zahlbr.

184a Ascocarp labia thick and carbonized --- 185
185b Ascocarp labia thin or absent, not carbonized --- 186

185a Ascospores bicellular; lichenized thallus indistinct or absent --- Melaspilea
185b Ascospores pluricellular; lichenized thallus distinct --- Opegrapha

186a Asci only slightly thickened at apex, about 5 times as long as wide --- Enterographa
186b Asci with strongly swollen apex, 2-3 times as long as wide --- Arthonia

190a (180) Ascospores grey to brown when ripe --- 191
190b Ascospores persistently colourless or somewhat brown when decaying --- 200

191a Ascospores bicellular --- 192
191b Ascospores pluricellular --- 195

192a Ascospores in a powdery layer on top of the apothecia, staining the finger when touched --- Pyrgidium montellicum (Beltr.) Tibell
192b Ascospores ripening inside the hymenium, apothecia not staining --- 193

193a Ascospores with unequally thickened walls and septa when ripe --- Rinodina
193b Ascospores with thin walls when ripe --- 194

193a Apothecium margin lecideine --- Buellia
193b Apothecium margin lecanorine --- Rinodinella

195a Paraphyses branched and anastomosing; ascospores with halo --- Rhizocarpon
195b Paraphyses unbranched, straight; ascospores without halo --- 196

196a Apothecia sessile; margin lecideine, soon disappearing --- Diplotomma
196b Apothecia immersed in thallus, which sometimes forms a distinct, lecanorine margin around it --- Diploschistes

200a (190) Ascospores not septate --- 201
200b Ascospores septate --- 230

201a Thallus yellow --- 202
201b Thallus grey to brown --- 203

202a Ascospores 8/ascus; apothecia sessile, with lecanorine margin --- Candelariella
202b Ascospores many/ascus; apothecia immersed, without distinct margin --- Acarospora

203a Ascospores 8/ascus --- 204
203b Ascospores more than 16/ascus --- 225

204a Apothecia immersed in the thallus, without distinct margin --- 205
204b Apothecia sessile, with distinct margin at least when young --- 209

205a Asci with distinct I+ blue staining in the tholus --- 206
205b Asci without I+ blue staining in the tholus --- 208

206a Tholus with I+ blue tube (asci of Porpidia-type) --- 207
206b Tholus with I+ blue cap, without tubular structure --- Eiglera flavida (Hepp) Hafellner

207a Ascospores I-negative, without halo; ascocarps separated from surrounding thallus by a split --- Immersaria
207b Ascospores I+ pale blue, with halo; epithecium brown --- Bellemerea cupreoatra (Nyl.) Clauz. & Roux

208a Epithecium olive-green to -brown --- Aspicilia
208b Epithecium brown --- Hymenelia

209a (204) Ascospores over 40 mu long --- 210
209b Ascospores under 30 mu long --- 211

210a Ascospores up to ca. 60 mu long, with thin (c. 1 mu) wall --- Megaspora
210b Ascospores often much larger, with thick (c. 5 mu) wall --- Pertusaria

211a Apothecia with lecanorine margin --- 212
211b Apothecia with lecideine or biatorine margin --- 214

212a Hypothecium pale brown; hymenium pale violet; tholus with pointed axial mass (asci of Bacidia-type) --- Tephromela
212b Hypothecium and hymenium colourless; tholus with rounded axial mass (asci of Lecanora-type) --- 213

213a Apothecia with cupular exciple; conidiophores pleurogenous --- Protoparmelia
213b Apothecia without cupular exciple; conidiophores acrogenous --- Lecanora

214a Ascocarps single or occasionally few together; thallus mostly crustose --- 215
214b Ascocarps in groups of several hemisperical merocarps; thallus subsquamulose --- Anamylopsora pulcherrima (Vain.) Timdal

215a On limestone --- 216
215b On siliceous stone or bark --- 217

216a Apothecia black; tholus with I+ blue tubular structure (asci of Porpidia-type) --- Farnoldia jurana (Schaerer) Hertel
216b Apothecia orange to red; asci nor of Porpidia-type --- Protoblastenia

217a Ascocarps darkbrown to black --- 218
217b Ascocarps pink to brown --- Trapelia

218a Tholus with I+ blue cap over a rounded axial mass (asci of Lecanora-type) --- Lecanora marginata (Schaer.) Hertel & Rambold
218b Tholus with I+ blue cap over a pointed axial mass (asci of Bacidia-type) --- Lecidella
218c Tholus with thin, I+ blue cap restricted to its apical part (asci of Lecidea-type) --- Lecidea
218d Tholus with I+ blue tubular structure (asci of Porpidia-type) --- Porpidia

225a (203) Apothecia immersed in the thallus or substrate --- 226
225b Apothecia sessile on the thallus --- 217

226a Thallus above the substrate, areolate --- Acarospora
226b Thallus indistinct, in bark --- Piccolia ochrophora (Nyl.) Hafellner

227a Apothecia with carbonized exciple and carbonized ridges on the disc --- Polysporina
227b Apothecia not carbonized, with smooth disc --- Sarcogyne

230a (200) Ascospores with transverse septa only --- 231
230b Ascospores with transverse and longitudinal septa; ascocarps flat and without differentiated margin --- Arthothelium

231a Ascospores polarilocular, with single, thick septum and thin walls; apothecia and thallus often orange, K+ dark redviolet --- Caloplaca
231b Ascospores with thin septa and walls --- 232

232a Ascospores with one septum --- 233
232b Ascospores with two or more septa --- 237

233a Apothecia without margin, flat or semiglobose --- 234
233b Apothecia with distinct margin, flat or slightly concave or convex --- 235

234a Apothecia flat; photobiont usually Trentepohlia; ascospores often with one enlarged end cell --- Arthonia
234b Apothecia semiglobose; photobiont not Trentepohlia; ascospores with equal end cells --- Micarea

235a Apothecia with lecanorine margin --- Lecania
235b Apothecia with biatorine margin --- Fellhanera bouteillei (Desm.) Vezda
235c Apothecia with lecideine margin --- 236

236a Thallus smooth --- Catillaria
236b Thallus composed of wart-like or somewhat flattened segments --- Toninia

237a (232) Apothecia with lecanorine margin --- 238
237b Apothecia with biatorine to lecideine margin --- 239

238a Apothecia with red disc; spores over 4 cells long, straight --- Haematomma
238b Apothecia with brown disc; spores 4-celled, curved --- Lecania koerberiana J.Lahm

239a Ascospores 4-celled, straight --- Schismatomma decolorans (Turner & Borrer ex Sm.) Clauzade & Vezda
239b Ascospores over 4-celled --- 240

240a Paraphyses loose, branched towards the apex, with swollen tips with brown caps --- Bactrospora
240b Paraphyses conglutinated by hymenial gelatine, without brown-capped, swollen tips --- 241

241a Ascus tholus with I+ blue cap over a pointed axial mass (asci of Bacidia-type) --- Bacidia
241b Ascus tholus with I+ blue cap over a rounded axial mass (asci of Lecanora-type) --- Scoliciosporum