Rim Lichens

(Lecanora spp.)

Rim Lichen (Lecanora sp.)
Photo by Luciearl

Lecanora is a genus of crust-forming (crusticose) lichens known by the common name Rim Lichens. It has a worldwide distribution, occurring on every continent including Antarctica. There are about 500 species of Lecanora worldwide, 171 species in North America, and at least 97 species in Minnesota. The genus Squamarina also has the common name Rim Lichens.

Some species grow on rock, other species grow on trees. The photosynthetic partner (the photobiont) is green algae.

The genus name Lecanora is from the Greek lekanon (a small bowl) and ora (form, beauty).


Lecanora is a large crusticose lichen. It is attached to a substrate, usually a rock or a tree, rarely immersed in the substrate. When wet it can usually be removed intact with a knife.

The vegetative body (thallus) is granular, like grains of sugar. This is best seen with magnification with a x10 lens. It is sharply divided into islands separated by cracks (areolate). It may be crusticose in the center but lobed and pleated on the edges, or it may be shield-like.

The reproductive structure (apothecium) is disk-like and variously colored. It usually has a rim of dead algal cells the same color as the thallus. It is usually conspicuous, but in some species it is reduced or absent. The sac-like cell (ascus) contains 8 ascospores. It is colorless and is not divided by walls.


Distribution Map



4, 24, 26, 29, 30, 77.

  Kingdom Fungi (fungi)  
  Subkingdom Dikarya  
  Phylum Ascomycota (sac fungi)  
  Subphylum Pezizomycotina  
  Class Lecanoromycetes (common lichens)  
  Subclass Lecanoromycetidae  






Lecanora (rim lichens)  

Subordinate Taxa



Beaded Rim-lichen (Lecanora cinereofusca)

Black-eyed Rim Lichen (Lecanora circumborealis)

Brown-eyed Rim Lichen (Lecanora allophana)

Bumpy Rim Lichen (Lecanora hybocarpa)

Common Rim Lichen (Lecanora pulicaris)

Frosted Rim-lichen (Lecanora caesiorubella)

Fused Rim Lichen (Lecanora symmicta)

Granite-speck Rim Lichen (Lecanora polytropa)

Hagen’s Rim Lichen (Lecanora hagenii)

Imshaug’s Rim Lichen (Lecanora imshaugii)

Mapledust Lichen (Lecanora thysanophora)

Mealy Rim-lichen (Lecanora strobilina)

Mortar Rim Lichen (Lecanora dispersa)

Perplexed Rim Lichen (Lecanora perplexa)

rim lichen (Lecanora albella)

rim lichen (Lecanora albella var. albella)

rim lichen (Lecanora albella var. rubescens)

rim lichen (Lecanora albescens)

rim lichen (Lecanora allophana f. sorediata)

rim lichen (Lecanora appalachensis)

rim lichen (Lecanora argentata)

rim lichen (Lecanora argentea)

rim lichen (Lecanora atra)

rim lichen (Lecanora cadubriae)

rim lichen (Lecanora caesiorubella subsp. caesiorubella)

rim lichen (Lecanora caesiorubella subsp. lathamii)

rim lichen (Lecanora caesiorubella subsp. saximontana)

rim lichen (Lecanora carpinea)

rim lichen (Lecanora cateilea)

rim lichen (Lecanora cervina)

rim lichen (Lecanora chlarona)

rim lichen (Lecanora chlarotera)

rim lichen (Lecanora chloropolia)

rim lichen (Lecanora chrysoleuca)

rim lichen (Lecanora cinerea)

rim lichen (Lecanora coilocarpa)

rim lichen (Lecanora confusa)

rim lichen (Lecanora conizaea)

rim lichen (Lecanora crenulata)

rim lichen (Lecanora densa)

rim lichen (Lecanora epanora)

rim lichen (Lecanora erysibe)

rim lichen (Lecanora expallens)

rim lichen (Lecanora flotoviana)

rim lichen (Lecanora flotowiana)

rim lichen (Lecanora frustulosa)

rim lichen (Lecanora fugiens)

rim lichen (Lecanora fuliginosa)

rim lichen (Lecanora fuscata)

rim lichen (Lecanora fuscescens)

rim lichen (Lecanora galactinula)

rim lichen (Lecanora glabrata)

rim lichen (Lecanora hypoptoides)

rim lichen (Lecanora intricata)

rim lichen (Lecanora invadens)

rim lichen (Lecanora lacustris)

rim lichen (Lecanora laxa)

rim lichen (Lecanora marginata)

rim lichen (Lecanora meridionalis)

rim lichen (Lecanora minutella)

rim lichen (Lecanora mutabilis)

rim lichen (Lecanora nothocaesiella)

rim lichen (Lecanora opiniconensis)

rim lichen (Lecanora pallescens)

rim lichen (Lecanora pallida)

rim lichen (Lecanora pallida var. rubescens)

rim lichen (Lecanora peltata)

rim lichen (Lecanora piniperda)

rim lichen (Lecanora pseudistera)

rim lichen (Lecanora pseudochlarotera)

rim lichen (Lecanora rubina)

rim lichen (Lecanora rugosella)

rim lichen (Lecanora saligna)

rim lichen (Lecanora sambuci)

rim lichen (Lecanora sambuci subsp. minnesotensis)

rim lichen (Lecanora semipallida)

rim lichen (Lecanora sordida)

rim lichen (Lecanora subepulotica)

rim lichen (Lecanora subfusca)

rim lichen (Lecanora subimmergens)

rim lichen (Lecanora subintricata)

rim lichen (Lecanora subrugosa)

rim lichen (Lecanora symmictera)

rim lichen (Lecanora torrida)

rim lichen (Lecanora tristiuscula)

rim lichen (Lecanora valesiaca)

rim lichen (Lecanora varia)

rim lichen (Lecanora verrucosa)

rim lichen (Lecanora wetmorei)

Shameless Rim Lichen (Lecanora impudens)

Smoky Rim Lichen (Lecanora cenisia)

Stonewall Rim Lichen (Lecanora muralis)

Sunken Rim-lichen (Lecanora oreinoides)

Varying Rim Lichen (Lecanora argopholis)

White Rim Lichen (Lecanora rupicola)

Wisconsin Rim Lichen (Lecanora wisconsinensis)

Wood-spot Rim Lichen (Lecanora albellula)


Lecanora albella (rim lichen)

Lecanora albella var. albella (rim lichen)

Lecanora albella var. rubescens (rim lichen)

Lecanora albellula (Wood-spot Rim Lichen)

Lecanora albescens (rim lichen)

Lecanora allophana (Brown-eyed Rim Lichen)

Lecanora allophana f. sorediata (rim lichen)

Lecanora appalachensis (rim lichen)

Lecanora argentata (rim lichen)

Lecanora argentea (rim lichen)

Lecanora argopholis (Varying Rim Lichen)

Lecanora atra (rim lichen)

Lecanora cadubriae (rim lichen)

Lecanora caesiorubella (Frosted Rim-lichen)

Lecanora caesiorubella subsp. caesiorubella (rim lichen)

Lecanora caesiorubella subsp. lathamii (rim lichen)

Lecanora caesiorubella subsp. saximontana (rim lichen)

Lecanora carpinea (rim lichen)

Lecanora cateilea (rim lichen)

Lecanora cenisia (Smoky Rim Lichen)

Lecanora cervina (rim lichen)

Lecanora chlarona (rim lichen)

Lecanora chlarotera (rim lichen)

Lecanora chloropolia (rim lichen)

Lecanora chrysoleuca (rim lichen)

Lecanora cinerea (rim lichen)

Lecanora cinereofusca (Beaded Rim-lichen)

Lecanora circumborealis (Black-eyed Rim Lichen)

Lecanora coilocarpa (rim lichen)

Lecanora confusa (rim lichen)

Lecanora conizaea (rim lichen)

Lecanora crenulata (rim lichen)

Lecanora densa (rim lichen)

Lecanora dispersa (Mortar Rim Lichen)

Lecanora epanora (rim lichen)

Lecanora erysibe (rim lichen)

Lecanora expallens (rim lichen)

Lecanora flotoviana (rim lichen)

Lecanora flotowiana (rim lichen)

Lecanora frustulosa (rim lichen)

Lecanora fugiens (rim lichen)

Lecanora fuliginosa (rim lichen)

Lecanora fuscata (rim lichen)

Lecanora fuscescens (rim lichen)

Lecanora galactinula (rim lichen)

Lecanora glabrata (rim lichen)

Lecanora hagenii (Hagen’s Rim Lichen)

Lecanora hybocarpa (Bumpy Rim Lichen)

Lecanora hypoptoides (rim lichen)

Lecanora impudens (Shameless Rim Lichen)

Lecanora imshaugii (Imshaug’s Rim Lichen)

Lecanora intricata (rim lichen)

Lecanora invadens (rim lichen)

Lecanora lacustris (rim lichen)

Lecanora laxa (rim lichen)

Lecanora marginata (rim lichen)

Lecanora meridionalis (rim lichen)

Lecanora minutella (rim lichen)

Lecanora muralis (Stonewall Rim Lichen)

Lecanora mutabilis (rim lichen)

Lecanora nothocaesiella (rim lichen)

Lecanora opiniconensis (rim lichen)

Lecanora oreinoides (Sunken Rim-lichen)

Lecanora pallescens (rim lichen)

Lecanora pallida (rim lichen)

Lecanora pallida var. rubescens (rim lichen)

Lecanora peltata (rim lichen)

Lecanora perplexa (Perplexed Rim Lichen)

Lecanora piniperda (rim lichen)

Lecanora polytropa (Granite-speck Rim Lichen)

Lecanora pseudistera (rim lichen)

Lecanora pseudochlarotera (rim lichen)

Lecanora pulicaris (Common Rim Lichen)

Lecanora rubina (rim lichen)

Lecanora rugosella (rim lichen)

Lecanora rupicola (White Rim Lichen)

Lecanora saligna (rim lichen)

Lecanora sambuci (rim lichen)

Lecanora sambuci subsp. minnesotensis (rim lichen)

Lecanora semipallida (rim lichen)

Lecanora sordida (rim lichen)

Lecanora strobilina (Mealy Rim-lichen)

Lecanora subepulotica (rim lichen)

Lecanora subfusca (rim lichen)

Lecanora subimmergens (rim lichen)

Lecanora subintricata (rim lichen)

Lecanora subrugosa (rim lichen)

Lecanora symmicta (Fused Rim Lichen)

Lecanora symmictera (rim lichen)

Lecanora thysanophora (Mapledust Lichen)

Lecanora torrida (rim lichen)

Lecanora tristiuscula (rim lichen)

Lecanora valesiaca (rim lichen)

Lecanora varia (rim lichen)

Lecanora verrucosa (rim lichen)

Lecanora wetmorei (rim lichen)

Lecanora wisconsinensis (Wisconsin Rim Lichen)






Common Names


Rim Lichens











An open, disk-shaped or cup-shaped, reproductive structure, with spore sacs on the upper surface, that produces spores for the fungal partner of a lichen. Plural: apothecia.



Crusty; referring to lichens in such close contact with the rock surface (substrate) that it appears sprayed on like paint.



The photosynthetic partner of a lichen; either green algae or cyanobacteria.



In lichens: The vegetative body of a lichen composed of both the alga and the fungus. In liverworts: a flat, relatively undifferentiated plant body. Plural: thalli.


Heterogenous Genus

As originally defined in 1926, Lecanora was an artificial assemblage of species. Over the years several genera have been split off. However, Lecanora remains a heterogeneous genus, and further splitting is both necessary and inevitable.


Species Identification

It is relatively easy to identify a rim lichen in the genus Lecanora. However, identification to the species is problematic. Many of the North American species look alike and can be identified only with chemical testing.

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Lichen found on large boulder near pond. Covered most of the rock.

    Rim Lichen (Lecanora sp.)   Rim Lichen (Lecanora sp.)  
MinnesotaSeasons.com Photos








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Location: Lake Shore

Lichen found on large boulder near pond. Covered most of the rock.

Rim Lichen (Lecanora sp.)

MinnesotaSeasons.com Sightings






Created: 11/28/2021

Last Updated:

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