FTTS F04 Paul’s Lichen Lecture 11/8/04 Page 1 of 2What are lichens?SymbiosisIntimate biological union of two different organisms– Mycorrhizae—over 90% of plants have fungi growing on their roots– Lichens—Relationship between algae & fungus that forms a “new” organism that bears noresemblance to either “parent.”Symbiotic relationships form a continuumSymbiotic relationships in lichensOne alga species + one fungus– Either green algae or cyanobacteriaTwo algal species + one fungus– both green algae and cyanobacteria, or two different green algae may be possibleLichen-forming fungiBasidiomycetesAscomycetes– Over 200 genera, ~15,000 speciesMajor Categories of Ascomycetous LichensCrustoseFolioseFruticoseGeneral anatomy of a lichenFTTS F04 Paul’s Lichen Lecture 11/8/04 Page 2 of 2Crustose lichensCrust-like, flat, more or less prostrate,Anchored to the substrate over all or most of their underside.More or less firmly attached to the sustrate by their bodies but not by rhizines; Always lacking a lower cortexFoliose lichensFlat, more or less prostrate,Anchored to the substrate over much or all of their underside.– More or less loosely attached to the substrate, usually by rhizines;Have a lower cortex.Colour varies– pale grey, yellowish green, dark green, light brown, dark brown, orange, red to almost black, depending on species.Generalized foliose lichenFoliose lichensIntroduction to Lichen Morphology andBiodiverisityAfter McCune’s key in Macrolichens ofthe PNW.Unstratified gelatinous lichensStratified lichensHave distinct algal layer– Can see medulla and green layer with hand lens– Rip lichen and view with hand lensFruticose lichensComposed of an upright or hanging axisAnchored at the base to the substrateMore or less round in cross-section,Often found hanging from tree branches.Lichen structuresSoredia– Asexual reproductive structure that are algal cells coated with myceliumCephalodia– Cyanobacteria-containing structures in lichens where the primary photobiont is green
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