An intricately branched, pale green lichen hangs from a branch.
Usnea filipendula – one of about 20,000 described species of lichen

The following outline provides an overview of and topical guide to lichens.

Lichencomposite organism made up of multiple species – a fungal partner, one or more photosynthetic partners, which can be either green algae or cyanobacteria, and, in at least 52 genera of lichens, a yeast.[1] In American English, "lichen" is pronounced the same as the verb "liken" (/ˈlkən/). In British English, both this pronunciation and one rhyming with "kitchen" (/ˈlɪən/) are used.[2]

What type of thing is a lichen?

Further information: Biological classification

A lichen can be described as all of the following:

  • Composite organism – a symbiotic life form composed of multiple partners from different biological domains, families and kingdoms, and from different phyla, classes and divisions within those domains and kingdoms. In the case of lichens, a fungal partner (the mycobiont) combines with one or more photosynthetic partner(s) (the photobiont) as well as (in some cases) a yeast.
  • Eukaryote (domain) – organisms with a cell nucleus within a nuclear envelope; both the mycobiont and any algal partners fall into this domain.[3]
  • Fungi (kingdom) – the fungal partner and any yeast partner fall into this kingdom.[1]
  • For the biological classes and families these fungi belong to, see below.
  • Prokaryote (domain) – organisms without a cell nucleus; any cyanobacterial partner falls into this domain.[3]

Nature of lichens

Section labeled "a" is grey, dotted with hundreds of small white circles. Section labeled "b" has grey strands surrounding numerous green circles. Section labeled "c" has loosely tangled grey strands with much open space between them. Section labeled "d" mirrors section labeled "a". In the section labeled "e", the structure in section "d" descends to two points - again grey with many white circles
Schematic cross section of foliose lichen:
(a) The cortex is the outer layer of tightly woven fungal filaments (hyphae)
(b) This photobiont layer has photosynthesizing green algae
(c) Loosely packed hyphae in the medulla
(d) A tightly woven lower cortex
(e) Anchoring hyphae called rhizines, where the fungus attaches to the substrate

Morphology

  • Apoplast – the symbiotic interface zone between the mycobiont and photobiont, outside the cell membranes or walls of both.[8]
  • Haustorium (pl. haustoria) – a root-like structure which allows the fungal partner to extract nutrients from its photosynthetic partner(s).[9]
  • Ascocarp – the fruiting body of a lichen, which contains the asci.[11]
  • Ascus (pl. asci) – a sexual, fungal spore-bearing structure, typically sac-like in shape.[12]
  • Ascospore – a fungal spore, the product of meiosis, produced in an ascus.[13]
  • Epispore – a transparent bag-like outer covering on some spores,[9] which helps to determine spore shape.[14]
  • Cephalodium (pl. cephalodia) – a gall-like structure that contains cyanobacteria[15]
  • Hypha (pl. hyphae) – a long, branching, thread-like structure composed of one or more fungal cells, which typically makes up a large part of lichens; hyphae are densely compacted in the cortex and more loosely interwoven in the medulla.[16]
  • Pycnidium (pl. pycnidia) – a flask-shaped, asexual fruiting body possessed by some lichens.[17]
  • Conidium (pl. conidia) – an asexual fungal spore produced in pycnidia by some lichens.[18]
  • Rhizine – a root-like structure that anchors a lichen to the substrate on which it grows.[19]
  • Soralium (pl. soralia) – a localized region or structure, typically a crack or pore, containing soredium.[20]
  • Soredium (pl. soredia) – asexual reproductive propagules composed of loose clumps of fungal hyphae and photobiont cells, produced in soralia.[20]
  • Thallus (pl. thalli) – the vegetative body of a lichen, made up of both mycobiont and photobiont components.[21]
  • Cortex – the lichen's outer layer(s), made up of tightly woven fungal filaments.[22]
  • Isidium (pl. isidia) – outgrowths of the thallus which contain photobiont cells and provide means of vegetative reproduction for some lichens.[23]
  • Medulla – a loose layer of interwoven fungal hyphae within the thallus.[24]
  • Podetium (pl. podetia) – an upright secondary thallus, which supports the fruiting bodies of Cladonia species.[25]

Ecology

A leafy, dark bronze lichen with wavy, white-tipped edges on a piece of bark
Lichens with a cyanobacteria as the photosynthetic partner, like this Peltigera collina, can fix nitrogen.[26]

Types of lichens

Lichen lists

Main category: Lists of lichens

Lichen taxonomical classifications

Several small brown balls rest atop black stalks rising from a bit of wood.
Chaenotheca brunneola falls into Coniocybomycetes, a small fungal class which contains only a handful of lichen species.[34]

Lichen systematics – Although they are composite organisms, lichens have traditionally been classified on the basis of their fungal partner. These span eight different biological classes, 39 orders, 117 families, and around 1,000 genera.[34][35]

Classes

Main category: Lichen classes

Lichens fall into eight fungal classes and several subclasses:[38]

  1. Agaricomycetes
    1. Agaricomycetidae
  2. Arthoniomycetes
  3. Coniocybomycetes
  4. Dothideomycetes
    1. Dothideomycetidae
  5. Eurotiomycetes
    1. Chaetothyriomycetidae
  6. Lecanoromycetes
    1. Acarosporomycetidae
    2. Lecanoromycetidae
    3. Ostropomycetidae
  7. Lichinomycetes
  8. Sordariomycetes
    1. Sordariomycetidae

Orders

A thick branch covered with a white crust, marked by black spots and thin black lines.
Lecidella elaeochroma is a member of Lecanorales, the fungal order which contains the greatest number of lichen species.[38]

Main category: Lichen orders

They are split across nearly 40 orders. Those which cannot be assigned to a particular order are assigned instead to "incertae sedis" within the appropriate class. These orders were listed in Lücking, Hodkinson and Leavitt's 2016 treatise on the classification of lichenized fungi, except where otherwise noted,[38] with orders updated in 2021.[34]

  1. Acarosporales
  2. Agaricales
  3. Arthoniales
  4. Atheliales
  5. Baeomycetales
  6. Caliciales
  7. Candelariales
  8. Cantharellales
  9. Capnodiales
  10. Chaetothyriales
  11. Collemopsidiales
  12. Coniocybales
  13. Corticiales
  14. Eremithallales
  15. Lecanorales
  16. Lecideales
  17. Lepidostromatales
  18. Leprocaulales
  19. Lichinales
  20. Monoblastiales
  21. Odontotrematales
  22. Ostropales
  23. Peltigerales
  24. Pertusariales
  25. Phaeomoniellales
  26. Pleosporales
  27. Pyrenulales
  28. Rhizocarpales
  29. Sarrameanales
  30. Schaereriales[39][40]
  31. Strigulales
  32. Teloschistales
  33. Thelenellales[39][40]
  34. Thelocarpales
  35. Trypetheliales
  36. Umbilicariales
  37. Verrucariales
  38. Vezdaeales
  39. Xylariales

Families

Main category: Lichen families

They fall into 117 families. Those which cannot be assigned to a particular family are assigned instead to "incertae sedis" within the appropriate order. These were listed in Lücking, Hodkinson and Leavitt's 2016 treatise on the classification of lichenized fungi, except where otherwise noted;[35] families were updated in 2021.[34]

  1. Acarosporaceae
  2. Agyriaceae
  3. Andreiomycetaceae
  4. Aphanopsidaceae
  5. Arctomiaceae
  6. Arthoniaceae
  7. Arthrorhaphidaceae
  8. Atheliaceae
  9. Baeomycetaceae
  10. Biatorellaceae
  11. Brigantiaeaceae
  12. Caliciaceae
  13. Cameroniaceae
  14. Candelariaceae
  15. Carbonicolaceae
  16. Catillariaceae
  17. Celotheliaceae
  18. Chrysotrichaceae
  19. Cladoniaceae
  20. Clavulinaceae
  21. Coccocarpiaceae
  22. Coccotremataceae
  23. Coenogoniaceae
  24. Collemataceae
  25. Coniocybaceae
  26. Corticiaceae
  27. Cystocoleaceae
  28. Dacampiaceae
  29. Dactylosporaceae
  30. Elixiaceae
  31. Fuscideaceae[41]
  32. Gloeoheppiaceae
  33. Gomphillaceae
  34. Graphidaceae
  35. Gyalectaceae
  36. Gypsoplacaceae
  37. Haematommataceae
  38. Harpidiaceae[42]
  39. Helocarpaceae
  40. Hygrophoraceae
  41. Hymeneliaceae
  42. Icmadophilaceae
  43. Koerberiaceae
  44. Lecanographaceae
  45. Lecanoraceae
  46. Lecideaceae
  47. Lepidostromataceae
  48. Leprocaulaceae
  49. Letrouitiaceae
  50. Lichinaceae
  51. Lopadiaceae
  52. Lyrommataceae
  53. Malmideaceae
  54. Massalongiaceae
  55. Megalariaceae
  56. Megalosporaceae
  57. Megasporaceae
  58. Melaspileaceae
  59. Microtheliopsidaceae
  60. Monoblastiaceae
  61. Mycoporaceae
  62. Nephromataceae
  63. Ochrolechiaceae
  64. Opegraphaceae
  65. Ophioparmaceae
  66. Pachyascaceae
  67. Pannariaceae
  68. Parmeliaceae
  69. Peltigeraceae
  70. Peltulaceae
  71. Pertusariaceae
  72. Phaneromycetaceae[41][43]
  73. Phlyctidaceae
  74. Physciaceae
  75. Pilocarpaceae
  76. Placynthiaceae
  77. Protothelenellaceae
  78. Psilolechiaceae
  79. Psoraceae
  80. Pycnoraceae
  81. Pyrenotrichaceae
  82. Pyrenulaceae
  83. Ramalinaceae
  84. Ramboldiaceae
  85. Redonographaceae[41]
  86. Requienellaceae
  87. Rhizocarpaceae
  88. Roccellaceae
  89. Roccellographaceae
  90. Ropalosporaceae
  91. Sagiolechiaceae
  92. Sarrameanaceae
  93. Schaereriaceae
  94. Scoliciosporaceae
  95. Sphaerophoraceae
  96. Sporastatiaceae
  97. Stereocaulaceae
  98. Stictidaceae
  99. Strangosporaceae
  100. Strigulaceae
  101. Teloschistaceae
  102. Tenuitholiascaceae[44][45]
  103. Tephromelataceae
  104. Thelenellaceae
  105. Thelocarpaceae
  106. Thrombiaceae
  107. Trapeliaceae
  108. Trichosphaeriaceae[42]
  109. Trichotheliaceae[41]
  110. Trypetheliaceae
  111. Umbilicariaceae
  112. Vahliellaceae
  113. Varicellariaceae
  114. Verrucariaceae
  115. Vezdaeaceae
  116. Xanthopyreniaceae
  117. Xylographaceae

Genera

Main category: Lichen genera

Extant lichens are found in more than 1000 genera. These were listed in Lücking, Hodkinson and Leavitt's 2016 treatise on the classification of lichenized fungi, except where otherwise noted.[35]

  1. Absconditella
  2. Acantholichen
  3. Acanthothecis
  4. Acanthotrema
  5. Acarospora
  6. Acarosporina
  7. Aciculopsora
  8. Acolium
  9. Acrocordia
  10. Acroscyphus
  11. Actinoplaca
  12. Adelolecia
  13. Aderkomyces
  14. Aggregatorygma
  15. Agonimia
  16. Ahtiana
  17. Ainoa
  18. Albemarlea[46]
  19. Alectoria
  20. Allantoparmelia
  21. Allocalicium
  22. Allocetraria
  23. Allographa[47]
  24. Allophoron[42]
  25. Alyxoria
  26. Amandinea
  27. Amazonomyces
  28. Amazonotrema
  29. Ameliella
  30. Amphorothecium
  31. Ampliotrema
  32. Amundsenia
  33. Amygdalaria
  34. Amylora
  35. Anamylopsora
  36. Anaptychia
  37. Ancistrosporella
  38. Andina[48]
  39. Andreiomyces
  40. Anema
  41. Angiactis
  42. Anisomeridium
  43. Anomalographis
  44. Anomomorpha
  45. Antennulariella
  46. Anthracocarpon
  47. Anthracothecium
  48. Anzia
  49. Anzina
  50. Apatoplaca
  51. Aphanopsis
  52. Aplanocalenia
  53. Aptrootia
  54. Aquacidia[49]
  55. Architrypethelium
  56. Arctocetraria
  57. Arctomia
  58. Arctoparmelia
  59. Argopsis
  60. Aridoplaca[50]
  61. Arrhenia
  62. Arthonia (list)
  63. Arthopyrenia
  64. Arthotheliopsis
  65. Arthothelium
  66. Arthrorhaphis
  67. Arthrosporum
  68. Asahinea
  69. Aspicilia
  70. Aspiciliopsis
  71. Aspidothelium
  72. Aspilidea
  73. Asteristion
  74. Asteroporum
  75. Asterothyrium
  76. Astrochapsa
  77. Astrothelium
  78. Athallia
  79. Athelopsis
  80. Atla
  81. Atrophysma[51]
  82. Aulaxina
  83. Auriculora
  84. Australiaena
  85. Australidea[52]
  86. Austrella
  87. Austrographa
  88. Austrolecia
  89. Austromelanelixia[53][54]
  90. Austroparmelina
  91. Austropeltum
  92. Austroplaca
  93. Austroroccella
  94. Austrotrema
  95. Awasthia
  96. Awasthiella
  97. Bacidia
  98. Bacidina
  99. Bacidiopsora
  100. Bactrospora
  101. Baculifera
  102. Badimia
  103. Badimiella
  104. Baeomyces
  105. Baflavia
  106. Bagliettoa
  107. Bahianora
  108. Baidera[55]
  109. Bapalmuia
  110. Bartlettiella
  111. Barubria
  112. Bathelium
  113. Bellemerea
  114. Biatora
  115. Biatorella
  116. Biatoridium
  117. Bibbya[56]
  118. Bilimbia
  119. Blastenia
  120. Blastodesmia
  121. Blennothallia
  122. Bogoriella
  123. Boreoplaca
  124. Borinquenotrema
  125. Botryolepraria
  126. Bouvetiella
  127. Brasilicia
  128. Brianaria
  129. Brigantiaea
  130. Brodoa
  131. Brownliella
  132. Bryobilimbia
  133. Bryocaulon
  134. Bryodina
  135. Bryogomphus
  136. Bryonora
  137. Bryoplaca
  138. Bryoria
  139. Bryostigma
  140. Buellia (list)
  141. Buelliastrum
  142. Bulbothrix
  143. Bunodophoron
  144. Burrowsia[57]
  145. Byssolecania
  146. Byssoloma
  147. Byssotrema
  148. Caeruleum
  149. Calathaspis
  150. Calenia
  151. Caleniopsis
  152. Calicium
  153. Callome
  154. Calogaya
  155. Calopadia
  156. Calopadiopsis
  157. Caloplaca (list)
  158. Calotrichopsis
  159. Calvitimela
  160. Calycidium
  161. Cameronia
  162. Candelaria
  163. Candelariella
  164. Candelina
  165. Canoparmelia
  166. Caprettia
  167. Carassea
  168. Carbacanthographis
  169. Carbonicola
  170. Catapyrenium
  171. Catarrhospora
  172. Catarraphia
  173. Catenarina
  174. Catillaria
  175. Catillochroma
  176. Catinaria
  177. Catolechia
  178. Cecidonia
  179. Celothelium
  180. Cenozosia
  181. Cephalophysis
  182. Cerothallia
  183. Cetradonia
  184. Cetraria
  185. Cetrariella
  186. Cetrelia
  187. Cetreliopsis
  188. Chaenotheca
  189. Chapsa
  190. Charcotiana
  191. Cheiromycina
  192. Chiodecton
  193. Chrismofulvea
  194. Chromatochlamys
  195. Chroodiscus
  196. Chrysothrix
  197. Cinnabaria[58]
  198. Ciposia
  199. Circinaria
  200. Cladia
  201. Cladidium
  202. Claurouxia
  203. Cladonia (list)
  204. Clandestinotrema
  205. Clathroporina
  206. Clauzadea
  207. Clauzadeana
  208. Clauzadella
  209. Clavascidium
  210. Cliostomum
  211. Clypeopyrenis
  212. Coccocarpia
  213. Coccotrema
  214. Coelopogon
  215. Coenogonium
  216. Collema
  217. Collemopsidium
  218. Combea
  219. Compositrema
  220. Compsocladium
  221. Coniangium
  222. Coniarthonia
  223. Coniocarpon
  224. Conotremopsis
  225. Constrictolumina
  226. Coppinsia
  227. Coppinsidea[59]
  228. Cora
  229. Corella
  230. Coronoplectrum
  231. Cornicularia
  232. Corticorygma
  233. Corynecystis
  234. Coscinocladium
  235. Cratiria
  236. Creographa
  237. Crespoa
  238. Cresponea
  239. Cresporhaphis[42]
  240. Crocellina
  241. Crocodia
  242. Crocynia
  243. Cruentotrema
  244. Crustospathula
  245. Crutarndina
  246. Cryptodictyon
  247. Cryptodiscus
  248. Crypthonia
  249. Cryptophaea
  250. Cryptothecia
  251. Cryptothele
  252. Culbersonia
  253. Cyanoporina
  254. Cyphelium
  255. Cyphellostereum
  256. Cyphobasidium
  257. Cystocoleus
  258. Dacampia
  259. Dactylina
  260. Davidgallowaya
  261. Degelia
  262. Dendriscosticta
  263. Dendrographa
  264. Dermatiscum
  265. Dermatocarpon
  266. Dermiscellum
  267. Diaphorographis
  268. Dibaeis
  269. Dichosporidium
  270. Dictyocatenulata
  271. Dictyographa
  272. Dictyomeridium
  273. Dictyonema
  274. Digitothyrea
  275. Dijigiella[60][61]
  276. Dimelaena
  277. Dimidiographa
  278. Diorygma
  279. Diploicia
  280. Diploschistella
  281. Diploschistes
  282. Diplotomma
  283. Dirinaria
  284. Dirina
  285. Dirinastrum
  286. Diromma
  287. Distopyrenis
  288. Distothelia
  289. Dolichocarpus
  290. Dolichousnea[62][54]
  291. Ducatina[63][64]
  292. Dufourea
  293. Dyplolabia
  294. Echidnocymbium
  295. Echinoplaca
  296. Edrudia
  297. Edwardiella
  298. Eiglera
  299. Eilifdahlia
  300. Elixia
  301. Elixjohnia[65][61]
  302. Emmanuelia[66]
  303. Emodomelanelia
  304. Encephalographa
  305. Enchylium
  306. Endocarpon
  307. Endocena
  308. Endohyalina
  309. Enterodictyon
  310. Enterographa
  311. Epilichen
  312. Enigmotrema
  313. Eopyrenula
  314. Ephebe
  315. Eremastrella
  316. Eremithallus
  317. Eremothecella
  318. Erinacellus
  319. Erioderma
  320. Ertzia
  321. Erythrodecton
  322. Eschatogonia
  323. Esslingeriana
  324. Eugeniella
  325. Eumitria[62][54]
  326. Euopsis
  327. Evernia
  328. Everniopsis
  329. Farnoldia
  330. Fauriea
  331. Feigeana
  332. Felipes
  333. Fellhanera
  334. Fellhaneropsis
  335. Ferraroa
  336. Fibrillithecis
  337. Filsoniana
  338. Finkia
  339. Fissurina
  340. Flabelloporina[67]
  341. Flakea
  342. Flavobathelium
  343. Flavocetraria
  344. Flavoparmelia
  345. Flavoplaca
  346. Flavopunctelia
  347. Flegographa
  348. Fluctua
  349. Follmannia
  350. Follmanniella
  351. Fominiella[68]
  352. Fouragea
  353. Franwilsia
  354. Frigidopyrenia
  355. Frutidella
  356. Fulgidea
  357. Fulvophyton
  358. Fuscidea
  359. Fuscoderma
  360. Fuscopannaria
  361. Gabura[42]
  362. Gassicurtia
  363. Geisleria
  364. Gibbosporina
  365. Gintarasia
  366. Gintarasiella[69]
  367. Glaucotrema
  368. Gloeheppia
  369. Glomerilla
  370. Glomerulophoron
  371. Glyphis
  372. Glypholecia
  373. Glyphopeltis
  374. Glyphopsis
  375. Glysoplaca
  376. Gomphillus
  377. Gondwania
  378. Gorgadesia
  379. Gossypiothallon
  380. Gowardia
  381. Granulopyrenis
  382. Graphidastra
  383. Graphis
  384. Gregorella
  385. Gudelia
  386. Gyalecta
  387. Gyalectaria
  388. Gyalectidium
  389. Gyalidea
  390. Gyalideopsis
  391. Gyalolechia
  392. Gymnoderma
  393. Gymnographa
  394. Gymnographopsis
  395. Gyrocollema
  396. Gyrographa
  397. Gyronactis
  398. Gyrotrema
  399. Haematomma
  400. Halecania
  401. Halegrapha
  402. Halographis
  403. Haloplaca
  404. Hanstrassia[70]
  405. Haplodina
  406. Haploloma
  407. Harpidium
  408. Harusavskia[71]
  409. Heiomasia
  410. Helicobolomyces[72][73]
  411. Helminthocarpon
  412. Helocarpon
  413. Hemithecium
  414. Henrica
  415. Heppia
  416. Heppsora
  417. Herpothallon
  418. Hertella
  419. Herteliana
  420. Hertelidea
  421. Heterocarpon
  422. Heterocyphelium
  423. Heterodermia
  424. Heteromyces
  425. Heteroplacidium
  426. Himantormia
  427. Hippocrepidea
  428. Homothecium
  429. Hormosphaeria
  430. Hosseusia
  431. Hosseusiella[74]
  432. Huea
  433. Hueidea
  434. Huneckia
  435. Hydropunctaria
  436. Hymenelia
  437. Hyperphyscia
  438. Hypocenomyce
  439. Hypoflavia
  440. Hypogymnia
  441. Hypotrachyna
  442. Icmadophila
  443. Igneoplaca
  444. Ikaeria[75]
  445. Immersaria
  446. Imshaugia
  447. Ingaderia
  448. Ingvariella
  449. Inoderma
  450. Involucropyrenium
  451. Ionaspis
  452. Ioplaca
  453. Isalonactis
  454. Jamesiella
  455. Japewia
  456. Japewiella
  457. Jarmania
  458. Jasonhuria
  459. Jenmania
  460. Joergensenia
  461. Josefpoeltia
  462. Julella[42]
  463. Kaernefeltia
  464. Kaernefia
  465. Kalbiana
  466. Kalbionora[76][77]
  467. Kalbographa
  468. Kashiwadia
  469. Kantvilasia
  470. Klauskalbia[78]
  471. Knightiella[42]
  472. Koerberia
  473. Koerberiella
  474. Krogia
  475. Kroswia
  476. Kuettlingeria
  477. Kurokawia[79]
  478. Labyrintha
  479. Lambiella
  480. Lasallia
  481. Lasioloma
  482. Lathagrium
  483. Lazarenkoella
  484. Lecanactis
  485. Lecania
  486. Lecanographa
  487. Lecanora (list)
  488. Lecidea (list)
  489. Lecidella
  490. Lecidoma
  491. Lecidopyrenopsis
  492. Leciophysma
  493. Leifidium
  494. Leightoniella
  495. Leimonis
  496. Leioderma
  497. Leiorreuma
  498. Lemmopsis
  499. Lempholemma
  500. Lendemeriella
  501. Lepidocollema
  502. Lepidostroma
  503. Lepra
  504. Leprantha
  505. Lepraria
  506. Leprocaulon
  507. Leprocollema
  508. Leproplaca
  509. Leptochidium
  510. Leptogidium
  511. Leptogium
  512. Leptorhaphis
  513. Leptotrema
  514. Letharia
  515. Lethariella
  516. Letrouitia
  517. Leucodecton
  518. Leucodermia
  519. Lichenomphalia
  520. Lichina
  521. Lichinella
  522. Lichinodium
  523. Lignoscripta
  524. Lithoglypha
  525. Lithographa
  526. Lithogyalideopsis
  527. Lithothelium
  528. Llimonaea
  529. Lobaria
  530. Lobariella
  531. Lobarina
  532. Lobothallia
  533. Loekoesia
  534. Loflammia
  535. Loflammiopsis
  536. Logilvia
  537. Lopacidia
  538. Lopadium
  539. Lopezaria
  540. Loxospora
  541. Loxosporopsis
  542. Lueckingia
  543. Lyromma
  544. Magmopsis
  545. Malcolmiella
  546. Malmidea
  547. Malmographina
  548. Mangoldia
  549. Marcelaria
  550. Marchandiomphalina
  551. Marchantiana
  552. Marfloraea
  553. Maronea
  554. Maronella
  555. Maronina[62][80]
  556. Masonhalea
  557. Massalongia
  558. Mastodia
  559. Mawsonia
  560. Mazaediothecium
  561. Mazosia
  562. Megalaria
  563. Megaloblastenia
  564. Megalospora
  565. Megalotremis
  566. Megaspora
  567. Melanelia
  568. Melanelixia
  569. Melanohalea
  570. Melanolecia
  571. Melanophloea
  572. Melanotopelia
  573. Melanotrema
  574. Melarthonis
  575. Melaspilea
  576. Menegazzia (list)
  577. Meridianelia
  578. Metamelanea
  579. Metus
  580. Micarea
  581. Microtheliopsis
  582. Milospium
  583. Miltidea
  584. Minksia
  585. Miriquidica
  586. Mischoblastia
  587. Mobergia
  588. Monerolechia
  589. Monoblastia
  590. Montanelia
  591. Moriola
  592. Multiclavula
  593. Multisporidea[81]
  594. Mycobilimbia
  595. Mycoblastus
  596. Mycoporum
  597. Myelochroa
  598. Myeloconis
  599. Myelorrhiza
  600. Myriolecis
  601. Myrionora
  602. Myriospora
  603. Myriostigma
  604. Myochroidea
  605. Nadvornikia
  606. Nebularia
  607. Neobrownliella[82]
  608. Neocatapyrenium
  609. Neophyllis
  610. Neopsoromopsis
  611. Neosergipea
  612. Nephroma
  613. Nephromopsis
  614. Nevesia
  615. Niebla
  616. Nigrovothelium
  617. Nipponoparmelia
  618. Nitidochapsa
  619. Nodobryoria
  620. Normandina
  621. Notocladonia
  622. Notolecidea
  623. Notoparmelia
  624. Novomicrothelia
  625. Nyungwea
  626. Obscuroplaca[83]
  627. Ocellomma
  628. Ocellularia (list)
  629. Ochrolechia
  630. Oevstedalia
  631. Olegblumia
  632. Oletheriostrigula
  633. Omphalodium
  634. Omphalora
  635. Opegrapha
  636. Opeltia[84]
  637. Ophioparma
  638. Orceolina
  639. Orcularia
  640. Orientophila
  641. Oropogon
  642. Orphniospora
  643. Oxnerella
  644. Pachnolepia
  645. Pachyascus
  646. Pachypeltis
  647. Pachyphysis
  648. Palicella
  649. Pallidogramme
  650. Pannaria
  651. Pannoparmelia
  652. Parabagliettoa
  653. Paracollema
  654. Paragyalideopsis[85][86]
  655. Paraingaderia
  656. Parainoa
  657. Paraporpidia
  658. Paraschismatomma
  659. Parasiphula
  660. Paratopeliopsis
  661. Paratricharia
  662. Parmelia
  663. Parmeliella
  664. Parmelina
  665. Parmelinella
  666. Parmeliopsis
  667. Parmostictina
  668. Parmotrema (list)
  669. Parmotremopsis
  670. Parvoplaca
  671. Paulia
  672. Peccania
  673. Pectenia
  674. Peltigera
  675. Peltula
  676. Peltularia
  677. Pentagenella
  678. Pertusaria (list)
  679. Petractis
  680. Phaeographis
  681. Phaeographopsis
  682. Phaeophyscia
  683. Phaeorrhiza
  684. Phloeopeccania
  685. Phlyctis
  686. Phoebus
  687. Phylliscidium
  688. Phyllisciella
  689. Phylliscidiopsis
  690. Phylliscum
  691. Phyllobaeis
  692. Phyllobathelium
  693. Phylloblastia
  694. Phyllocratera
  695. Phyllogyalidea
  696. Phyllopsora
  697. Physcia
  698. Physcidia
  699. Physciella
  700. Physconia
  701. Physma
  702. Piccolia
  703. Pilophorus
  704. Placidiopsis
  705. Placidium
  706. Placocarpus
  707. Placolecis
  708. Placomaronea
  709. Placopsis
  710. Placopyrenium
  711. Placothelium
  712. Placynthiella
  713. Placynthiopsis
  714. Placynthium
  715. Platismatia
  716. Platygramme
  717. Platythecium
  718. Plectocarpon
  719. Pleopsidium
  720. Pleurosticta
  721. Pliariona
  722. Podostictina
  723. Podotara
  724. Poeltiaria
  725. Poeltidea
  726. Poeltinula
  727. Polistroma
  728. Polyblastia
  729. Polyblastidium
  730. Polycauliona
  731. Polychidium
  732. Polymeridium
  733. Polypyrenula
  734. Polysporina
  735. Porina
  736. Porocyphus
  737. Porpidia
  738. Porpidinia[42]
  739. Protoblastenia
  740. Protomicarea
  741. Protopannaria
  742. Protoparmelia
  743. Protoparmeliopsis
  744. Protoroccella[42]
  745. Protothelenella
  746. Protousnea
  747. Psammina
  748. Psathyrophlyctis
  749. Pseudarctomia
  750. Pseudephebe
  751. Pseudevernia
  752. Pseudobaeomyces
  753. Pseudocalopadia
  754. Pseudochapsa
  755. Pseudocyphellaria
  756. Pseudohepatica
  757. Pseudoheppia
  758. Pseudolecanactis
  759. Pseudoleptogium
  760. Pseudopannaria
  761. Pseudoparmelia
  762. Pseudopaulia
  763. Pseudopeltula
  764. Pseudopyrenula
  765. Pseudoramonia
  766. Pseudosagedia
  767. Pseudoschismatomma
  768. Pseudothelomma
  769. Pseudotopeliopsis
  770. Psilolechia
  771. Psiloparmelia
  772. Psora
  773. Psorinia
  774. Psoroglaena
  775. Psoroma
  776. Psoromella
  777. Psoromidium[42]
  778. Psoronactis
  779. Psorotheciopsis
  780. Psorotichia
  781. Psorula
  782. Pterygiopsis
  783. Ptychographa
  784. Pulvinodecton
  785. Pulvinora[87]
  786. Punctelia
  787. Punctonora
  788. Puttea
  789. Pycnora
  790. Pycnothelia
  791. Pycnotrema
  792. Pyrenocarpon
  793. Pyrenocollema
  794. Pyrenodesmia
  795. Pyrenopsis
  796. Pyrenothrix
  797. Pyrenowilmsia
  798. Pyrenula (list)
  799. Pyrgillus
  800. Pyrrhospora
  801. Pyxine
  802. Racodium
  803. Racoleus
  804. Raesaeneniana
  805. Ramalea
  806. Ramalina
  807. Ramalodium
  808. Ramboldia
  809. Ramonia
  810. Redingeria
  811. Redonia
  812. Redonographa
  813. Rehmanniella[88]
  814. Reichlingia
  815. Reimnitzia
  816. Relicina
  817. Remototrachyna
  818. Requienella
  819. Rhabdodiscus
  820. Rhabdopsora
  821. Rhaphidicyrtis
  822. Rhexophiale
  823. Rhizocarpon
  824. Rhizolecia
  825. Rhizoplaca
  826. Ricasolia
  827. Rimularia
  828. Rinodina (list)
  829. Rinodinella
  830. Robergea
  831. Rocella
  832. Roccellographa
  833. Roccellina
  834. Roccellinastrum
  835. Rockefellera[89]
  836. Rolfidium
  837. Rolueckia
  838. Romjularia
  839. Ropalospora
  840. Rostania
  841. Rubrotricha
  842. Rufoplaca
  843. Rusavskia
  844. Sagedia
  845. Sagema
  846. Sagenidiopsis
  847. Sagiolechia
  848. Sanguinotrema
  849. Santessonia
  850. Sarcographa
  851. Sarcographina
  852. Sarcogyne
  853. Sarcosagium
  854. Sarea
  855. Sarrameana
  856. Savoronala
  857. Schadonia
  858. Schaereria
  859. Schismatomma
  860. Schistophoron
  861. Schizodiscus
  862. Schizopelte
  863. Schizotrema
  864. Schizoxylon
  865. Sclerococcum
  866. Sclerophora
  867. Sclerophyton
  868. Scleropyrenium
  869. Scoliciosporum
  870. Sculptolumina
  871. Scutaria
  872. Scytinium
  873. Sedelnikovaea
  874. Segestria
  875. Seirophora
  876. Semigyalecta
  877. Semiomphalina
  878. Septotrapelia
  879. Servitia
  880. Shackletonia
  881. Sigridea
  882. Simonyella
  883. Sipmaniella
  884. Siphula
  885. Siphulastrum
  886. Siphulella
  887. Sipmania
  888. Sirenophila
  889. Snippocia[90][73]
  890. Solenopsora
  891. Solitaria
  892. Solorina
  893. Solorinaria
  894. Sparria
  895. Speerschneidera
  896. Sphaerophorus
  897. Sphaerophoropsis
  898. Spheconisca
  899. Sphinctrinopsis
  900. Spilonema
  901. Sporastatia
  902. Sporodictyon
  903. Sporodophoron
  904. Sporopodiopsis
  905. Sporopodium
  906. Sporostigma
  907. Sprucidea[91][80]
  908. Squamarina
  909. Squamella
  910. Squamulea
  911. Staurospora[92][93]
  912. Staurolemma
  913. Staurothele
  914. Stegobolus
  915. Steinera
  916. Steineropsis
  917. Steinia
  918. Stellarangia
  919. Stenhammarella
  920. Stephanocyclos
  921. Stereocaulon
  922. Sticta
  923. Stictis
  924. Stigmatochroma
  925. Stigmidium
  926. Strangospora
  927. Streimannia
  928. Streimanniella
  929. Stirtonia
  930. Stirtoniella
  931. Strigula
  932. Stromatella
  933. Sulcaria
  934. Sulcopyrenula
  935. Sulzbacheromyces
  936. Synalissa
  937. Synarthonia
  938. Synarthothelium
  939. Syncesia
  940. Szczawinskia
  941. Tania
  942. Tapellaria
  943. Tapellariopsis
  944. Tarasginia
  945. Tarbertia
  946. Tasmidella
  947. Tassiloa
  948. Tayloriellina
  949. Teloschistes
  950. Teloschistopsis
  951. Tenuitholiascus[94][45]
  952. Tephromela
  953. Tetramelas
  954. Teuvoa
  955. Texosporium
  956. Thallinocarpon
  957. Thalloloma
  958. Thamnochrolechia
  959. Thamnolecania
  960. Thamnolia
  961. Thecaria
  962. Thecographa
  963. Thelenella
  964. Thelenidia
  965. Thelidiopsis
  966. Thelignya
  967. Thelliana
  968. Thelocarpon
  969. Thelomma
  970. Thelopsis
  971. Thelotrema
  972. Thermutis
  973. Thermutopsis
  974. Tholurna
  975. Thrombium
  976. Thyrea
  977. Thysanothecium
  978. Tibellia
  979. Timdalia
  980. Tingiopsidium
  981. Toensbergia
  982. Toninia
  983. Toniniopsis
  984. Topelia
  985. Topeliopsis
  986. Tornabea
  987. Trapelia
  988. Trapeliopsis
  989. Traponora
  990. Tremolecia
  991. Tremotylium[42]
  992. Tricharia
  993. Trichothelium
  994. Trimmatothele
  995. Trimmatothelopsis
  996. Trinathotrema
  997. Trizodia
  998. Trypetheliopsis
  999. Trypethelium
  1000. Tuckermanella
  1001. Tuckermanopsis
  1002. Tylophorella
  1003. Tylophoron
  1004. Tylophoropsis
  1005. Tylothallia
  1006. Umbilicaria
  1007. Upretia[95]
  1008. Usnea
  1009. Usnocetraria
  1010. Usnochroma
  1011. Vahliella
  1012. Vainionora
  1013. Varicellaria
  1014. Variospora
  1015. Verrucaria (list)
  1016. Verruculopsis
  1017. Verseghya[96]
  1018. Vezdaea
  1019. Vigneronia
  1020. Villophora
  1021. Violella
  1022. Viridothelium
  1023. Vulpicida
  1024. Wadeana
  1025. Wahlenbergiella
  1026. Watsoniomyces[97]
  1027. Wawea
  1028. Waynea
  1029. Wetmoreana
  1030. Willeya
  1031. Wirthiotrema
  1032. Xalocoa
  1033. Xanthocarpia
  1034. Xanthomendoza
  1035. Xanthoparmelia (list)
  1036. Xanthopeltis
  1037. Xanthopsorella
  1038. Xanthoria
  1039. Xenolecia
  1040. Xenus
  1041. Xyleborus
  1042. Xylographa
  1043. Xyloschistes
  1044. Xylopsora
  1045. Yarrumia
  1046. Yoshimuria
  1047. Yoshimuriella
  1048. Zahlbrucknerella
  1049. Zeroviella
  1050. Zwackhia

Species

Main category: Lichen species

In 2009, taxonomists estimated that the total number of lichen species (including those yet undiscovered) might be as high as 28,000.[98] By 2016, 19,387 species of lichens had been described and widely accepted.[99]

Lichens, by growth form

Stick covered with flat, yellowy-green, wavy-edged lichen speckled with raised orange spots
Xanthoria parietina has the leafy-looking growth of a foliose lichen.[100]

Lichen growth forms – These vary depending on the species:

Lichens, by substrate

Photo of stony ground with one large rock covered in a multitude of lichens of different sizes, shapes and colours
Saxicolous lichens are those which grow on stone.[109]

Lichens can be classified by the substrate on which they grow:

Lichens, by region

Photo of sandy ground with patches of flat brown and bright orange ball-shaped lichens
Namibia's vast deserts, which hold many species of lichen, remain largely unsurveyed.[115]

Main category: Lichens by continent

Africa

Main category: Lichens of Africa

Antarctica

Main category: Lichens of the Antarctic

Asia

Main category: Lichens of Asia

Australia

Main category: Lichens of Australia

Europe

Main category: Lichens of Europe

North America

Main category: Lichens of North America

Oceania

Main category: Lichens of Oceania

Pacific

Main category: Lichens of the Pacific

South America

Main category: Lichens of South America

Photobiont

Picture through microscope of four algal cells: round with clear edges and bright green centres
The photobiont in most lichens is a green alga, particularly those from the genus Trebouxia.[6]

Photobiont – the photosynthetic partner in a lichen.[116]

Lichen metabolites

Further information: Secondary metabolite

Main category: Lichen products

Lichen product – organic products, known as secondary metabolites, produced by lichens; these provide a variety of protections for the lichen – from microbes, viruses, herbivores, radiation, oxidants and more.[118]

Four photos showing a leafy dark green lichen; the top two are virtually identical, though one photo is labeled C (calcium hypochlorite or sodium hypochlorite) and K (potassium hydroxide) and the other labeled C and KC (K followed immediately by C). The bottom two show a colour change; where the medulla has been exposed, its colour changes to pinkish-red when exposed to C and KC.
Chemical spot tests on the foliose lichen Punctelia borreri showing thallus (top) and medulla (bottom). The pinkish-red colour change of the medulla in the C and KC tests indicate the presence of gyrophoric acid, a chemical feature that helps to distinguish this lichen from similar species in the same genus.[119]

Study of lichens

Main category: Lichenologists

Lichenology – the study of lichens.[120]

Threats

Main category: Lichenicolous fungi

  • List of lichenicolous fungi
  • Lichens and air pollution – many lichens are sensitive to various forms of air pollution.[127]
  • Lichens and climate change – the inability of algae to quickly evolve means that climate change may adversely impact lichens.[128]

Lichens in culture

Two black loaves sit on a plate with knife and fork beside them.
Two baked loaves of Bryoria fremontii, an important traditional food for some First Nations people[129]

Lichen organizations

  • Australasian Lichenology – official publication of the Australasian Lichen Society.
  • Herzogia – peer-reviewed journal published by BLAM.
  • Buxbaumiella – peer-reviewed journal published by BLWG.
  • Lindbergia – peer-reviewed journal co-published by the Dutch Bryological and Lichenological Society and the Nordic Bryological Society.

Independent lichenological journals

See also

Citations

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References