Editing Algae (section)

===Lichens===
{{Main|Lichen}}
[[File:Lichens near Clogher Head (stevefe).jpg|thumb|Rock lichens in Ireland]]
[[Lichen]]s are defined by the [[International Association for Lichenology]] to be "an association of a fungus and a photosynthetic [[symbiont]] resulting in a stable vegetative body having a specific structure".<ref>{{cite book |last1=Brodo |first1=Irwin M. |last2=Sharnoff |first2=Sylvia Duran |last3=Sharnoff |first3=Stephen |last4=Laurie-Bourque |first4=Susan |title=Lichens of North America |date=2001 |publisher=Yale University Press |location=New Haven |isbn=978-0-300-08249-4 |page=8}}</ref> The fungi, or mycobionts, are mainly from the [[Ascomycota]] with a few from the [[Basidiomycota]]. In nature, they do not occur separate from lichens. It is unknown when they began to associate.<ref>{{cite book |last=Pearson |first=Lorentz C. |title=The Diversity and Evolution of Plants |date=1995 |publisher=CRC Press |isbn=978-0-8493-2483-3 |page=221}}</ref> One or more<ref>{{Cite journal |last1=Tuovinen |first1=Veera |last2=Ekman |first2=Stefan |last3=Thor |first3=Göran |last4=Vanderpool |first4=Dan |last5=Spribille |first5=Toby |last6=Johannesson |first6=Hanna |date=2019-01-17 |title=Two Basidiomycete Fungi in the Cortex of Wolf Lichens |url=https://linkinghub.elsevier.com/retrieve/pii/S0960982218316543 |journal=Current Biology |volume=29 |issue=3 |pages=476–483.e5 |doi=10.1016/j.cub.2018.12.022 |pmid=30661799 |bibcode=2019CBio...29E.476T |issn=0960-9822}}</ref> mycobiont associates with the same phycobiont species, from the green algae, except that alternatively, the mycobiont may associate with a species of cyanobacteria (hence "photobiont" is the more accurate term). A photobiont may be associated with many different mycobionts or may live independently; accordingly, lichens are named and classified as fungal species.<ref>Brodo et al. (2001), p. 6: "A species of lichen collected anywhere in its range has the same lichen-forming fungus and, generally, the same photobiont. (A particular photobiont, though, may associate with scores of different lichen fungi)."</ref> The association is termed a morphogenesis because the lichen has a form and capabilities not possessed by the symbiont species alone (they can be experimentally isolated). The photobiont possibly triggers otherwise latent genes in the mycobiont.<ref>Brodo et al. (2001), p. 8.</ref>

[[Trentepohlia (alga)|Trentepohlia]] is an example of a common green alga genus worldwide that can grow on its own or be lichenised. Lichen thus share some of the habitat and often similar appearance with specialized species of algae (''[[aerophyte]]s'') growing on exposed surfaces such as tree trunks and rocks and sometimes discoloring them.