Outline of lichens

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?

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]
  • Lichen morphology – a lichen's external appearance and structures are very different than those of its individual partners.[10]
  • 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

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

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

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]

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]

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. Porinaceae
  78. Protothelenellaceae
  79. Psilolechiaceae
  80. Psoraceae
  81. Pycnoraceae
  82. Pyrenotrichaceae
  83. Pyrenulaceae
  84. Ramalinaceae
  85. Ramboldiaceae
  86. Redonographaceae[41]
  87. Requienellaceae
  88. Rhizocarpaceae
  89. Roccellaceae
  90. Roccellographaceae
  91. Ropalosporaceae
  92. Sagiolechiaceae
  93. Sarrameanaceae
  94. Schaereriaceae
  95. Scoliciosporaceae
  96. Sphaerophoraceae
  97. Sporastatiaceae
  98. Stereocaulaceae
  99. Stictidaceae
  100. Strangosporaceae
  101. Strigulaceae
  102. Teloschistaceae
  103. Tenuitholiascaceae[44][45]
  104. Tephromelataceae
  105. Thelenellaceae
  106. Thelocarpaceae
  107. Thrombiaceae
  108. Trapeliaceae
  109. Trichosphaeriaceae[42]
  110. Trypetheliaceae
  111. Umbilicariaceae
  112. Vahliellaceae
  113. Varicellariaceae
  114. Verrucariaceae
  115. Vezdaeaceae
  116. Xanthopyreniaceae
  117. Xylographaceae

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

Species

In 2009, taxonomists estimated that the total number of lichen species (including those yet undiscovered) might be as high as 28,000.[100] By 2016, 19,387 species of lichens had been described and widely accepted.[101]

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.[102]

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.[111]

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.[117]

Africa

Antarctica

Asia

Australia

Europe

North America

Oceania

Pacific

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.[118]

Lichen metabolites

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.[120]

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.[121]

Study of lichens

Lichenology – the study of lichens.[122]

Threats

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[131]

Lichen organizations

  • Herzogia – peer-reviewed journal published by BLAM.
  • 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