Collema flaccidum (Ach.) Ach.
Lichenogr. Univ.: 647, 1810. Basionym: Lichen flaccidus Ach. - K. Vetensk.-Akad. Nya Handl., 16: 14, 1795.
Synonyms: Collema atroplumbeum Hue; Collema furvum var. flaccidum (Ach.) Spreng.; Collema rupestre (Sw.) Rabenh.; Lathagrium rupestre (Sw.) A. Massal.; Lichen rupestris Sw. nom. illegit.; Parmelia flaccida (Ach.) Ach.; Synechoblastus flaccidus (Ach.) Körb.; Synechoblastus rupestris (Sw.) Trevis.
Distribution: N - VG (Carvalho 1997), Frl (Tretiach & Hafellner 2000, Tretiach & Molaro 2007), Ven (Caniglia & al. 1999, Nascimbene 2008c), TAA (Philippi 1983, Nascimbene 2005b, Nascimbene & al. 2007b, 2022), Lomb (Philippi 1983, Arosio & al. 2003, Valcuvia & al. 2003, De Vita & Valcuvia 2004, Gheza 2019, Gheza & al. 2020, 2023), Piem (Morisi & Sereno 1995, Isocrono & al. 2004, Isocrono & Piervittori 2008), VA (Valcuvia 2000, Valcuvia & al. 2000b, Piervittori & al. 2001, Matteucci & al. 2015c, Ongaro & al. 2022), Emil (Gasparo & Tretiach 1996, Tretiach & al. 2008, Fariselli & al. 2020), Lig (Giordani & Incerti 2008, Giordani & al. 2025). C - Tosc (Benesperi & al. 2007, Benesperi 2011, Brackel 2015), Marc (Nimis & Tretiach 1999), Umb (Ravera 1998, Panfili 2000b, Ravera & al. 2006), Laz (Ravera 2001, Massari & Ravera 2002, Ravera & Genovesi 2008), Abr (Olivieri & Pacioni 1996, Olivieri & al. 1997, 1997b, Loppi & al. 1999, Nimis & Tretiach 1999, Caporale & al. 2008, 2016, Brackel 2015, Corona & al. 2016, Gheza & al. 2021), Mol (Frati & al. 2004, Caporale & al. 2008), Sar (Nöske 2000, Zedda 2002, Rizzi & al. 2011, Cossu 2013, Di Nuzzo & al. 2022). S - Camp (Ricciardi & al. 2000, Nimis & Tretiach 2004, Nascimbene & al. 2010b, Garofalo & al. 2010, Brunialti & al. 2013, Ravera & Brunialti 2013), Pugl (Nimis & Tretiach 1999), Bas (Nimis & Tretiach 1999, Potenza 2006, Potenza & Fascetti 2010), Cal (Puntillo 1996), Si (Czezuga & al. 1994, Grillo 1998, Grillo & Caniglia 2004, Liistro & Cataldo 2011, Ottonello & al. 2011, Campisi & al. 2020).
Description: Thallus foliose, homoiomerous, gelatinous when wet, blackish brown to black, 70-170(-200) µm thick when wet, smooth, loosely attached, up to 6 cm in diam. (usually less). Lobes (0.5-)1-2(-3) cm broad, rounded at apex, flattened, contiguous, appressed, with an entire, undulate, not swollen margin, with isidia-like outgrowths that are globular when young, but soon become flattened and squamiform, 0.2-0.5(-0.8) mm wide, diffuse and mostly simple. Lower surface usually paler, with sparse white hapters. Upper and lower cortex absent. Apothecia rare, lecanorine, sessile and constricted at base, up to 2.5(-3) mm across, with a reddish brown, epruinose or white-pruinose, flat to finally convex disc and a thin, entire, smooth, persistent or finally excluded thalline margin. Thalline exciple pseudocorticate; proper exciple subparaplectenchymatous to rarely almost euthyplectenchymatous; epithecium brownish; hymenium colourless, 90-130 µm high, I+ blue; paraphyses simple or sparingly branched, 2(-4) µm thick, with clavate to subglobose tips; hypothecium colourless. Asci 8-spored, cylindrical-clavate, the apex strongly thickened, the apical dome K/I+ pale blue, with a downwardly projecting K/I+ deep blue tubular structure. Ascospores transversely 3-5-septate, hyaline, fusiform-elongate, (20-)25-35(-40) x 6-7 µm. Pycnidia common, usually thicker than thallus. Conidia bacilliform, sometimes slightly thickened at the ends, straight, (3-)4-4.5(-6) x 1-1.5(-2) µm. Photobiont cyanobacterial (Nostoc, the cells in long chains). Spot tests: all negative. Chemistry: without lichen substances.Note: a mainly temperate to southern boreal-montane lichen with a fragmented holarctic range, found on bark, epilithic mosses, base-rich siliceous and slightly calciferous rocks in sheltered, humid situations; more common in the past and now absent from urban areas and from the Po-Plain; mostly Tyrrhenian in Italy, but still locally frequent in humid Alpine and pre-Alpine areas.
Growth form: Foliose, broad lobed
Substrata: bark and rocks
Photobiont: cyanobacteria, filamentous (e.g. Nostoc, Scytonema)
Reproductive strategy: mainly asexual, by isidia, or isidia-like structures (e.g. schizidia)
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)
Commonnes-rarity: (info)
Alpine belt: absent
Subalpine belt: absent
Oromediterranean belt: absent
Montane belt: very rare
Submediterranean belt: extremely rare
Padanian area: absent
Humid submediterranean belt: rather common
Humid mediterranean belt: common
Dry mediterranean belt: extremely rare
Predictive model
Herbarium samples
P.L. Nimis CC BY-SA 4.0
TSB 15001
P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (11346)
2001/12/04
P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (15001)
2008.03.06
P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (15001)
2008.03.06
P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (15001)
2008.03.06
Antonio Valero; Owner: Antonio Valero
Spain
2010
Antonio Valero; Owner: Antonio Valero
Spain
2010
Antonio Valero; Owner: Antonio Valero
Spain
2010
Domenico Puntillo - CC BY-SA 4.0
Italy
exceptionally fruiting species
Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/
Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/
Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/
Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/
Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/
P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (11346)
2001/12/04
Leif Stridvall Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/
Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_C/Collema_flaccidum.htm; Owner: -
France, session AFL 2015 dans le Lot, Autoire
Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_C/Collema_flaccidum.htm; Owner: -
France, session AFL 2015 dans le Lot, Autoire
Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_C/Collema_flaccidum.htm; Owner: -
France, session AFL 2015 dans le Lot, Autoire
Bernard Bouffinier - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Cranou
Bernard Bouffinier - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Cranou
Bernard Bouffinier - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Source de la Bidouze
Bernard Bouffinier - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Source de la Bidouze
Michel David - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Landevennec, Abbaye
Michel David - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Landevennec
Michel David - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Landevennec
Bernard Bouffinier - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Cranou
Bernard Bouffinier - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Cranou
Ulrich Kirschbaum CC BY-SA 4.0 - Source: https://www.thm.de/lse/ulrich-kirschbaum/flechtenbilder
Austria; Alps: Kärnten.
Ulrich Kirschbaum CC BY-SA 4.0 - Source: https://www.thm.de/lse/ulrich-kirschbaum/flechtenbilder
Austria; Alps: Kärnten.
Felix Schumm - CC BY-SA 4.0
[VZ1257], Hungaria. Montes Matra, regio montis Agasvár, in vallerivuli Csörgö, 480 m. Ad saxa andesitica. Leg. G. Kiszely, T. Pócs et A.Vezda, 5.06.1974. - EX A. VEZDA: LICHENES SELECTI EXSICCATI NR.1257
Felix Schumm - CC BY-SA 4.0
[VZ1257], Hungaria. Montes Matra, regio montis Agasvár, in vallerivuli Csörgö, 480 m. Ad saxa andesitica. Leg. G. Kiszely, T. Pócs et A.Vezda, 5.06.1974. - EX A. VEZDA: LICHENES SELECTI EXSICCATI NR.1257
Felix Schumm - CC BY-SA 4.0
[VZR470], Germania. Bavaria, Berchtesgadener Land, Königsee, St.Bartholomä, 610 m. Ad corticem arboris (Tilia platyphyllos). Leg. &det. R. Türk & H. Wunder, 11.04.1989 - EX A. VEZDA: LICHENES RARIORES EXSICCATI NR. 470.
Felix Schumm - CC BY-SA 4.0
[VZR470], Germania. Bavaria, Berchtesgadener Land, Königsee, St.Bartholomä, 610 m. Ad corticem arboris (Tilia platyphyllos). Leg. &det. R. Türk & H. Wunder, 11.04.1989 - EX A. VEZDA: LICHENESRARIORES EXSICCATI NR. 470.
Wolfgang von Brackel - CC BY-4.0
Germany, Bavaria, Elmaubachtal
Wolfgang von Brackel - CC BY-4.0
Germany, Bavaria, Elmaubachtal
Collezione lichenologica Abramo Massalongo del Museo di Storia Naturale G. Ligabue di Venezia - Autori: Seggi, Linda; Trabucco, Raffaella Proprietà: Fondazione Musei Civici di Venezia - CC BY-NC
Italy, Veneto, in nem. Montello
As Letagrium rupestre
CC BY 4.0 - Source: Košuthová A, Jonsson F, Nordin U, Wedin M (2025) Phylogeny of the European Collema species (Peltigerales, Lecanoromycetes). MycoKeys 115: 209-220. https://doi.org/10.3897/mycokeys.115.144718
UPS-L872188
Manuel Gil
Spain, Canary Islands, Tenerife
on soil
Manuel Gil
Spain, Canary Islands, Tenerife
on soil
Manuel Gil
Spain, Canary Islands, Tenerife
on soil
Manuel Gil
Spain, Canary Islands, Tenerife
on soil
Manuel Gil
Spain, Canary Islands, Tenerife
on soil
Manuel Gil
Spain, Canary Islands, Tenerife
on soil
Triin Aimla; Owner: University of Tartu
Degelius G. 1954. The lichen genus Collema in Europe: Morphology, Taxonomy, Ecology. Symbolae Bot. Upsal. 13, 2: 1-499.
Growth form: Foliose, broad lobed
Substrata: bark and rocks
Photobiont: cyanobacteria, filamentous (e.g. Nostoc, Scytonema)
Reproductive strategy: mainly asexual, by isidia, or isidia-like structures (e.g. schizidia)
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)
Commonnes-rarity: (info)
Alpine belt: absent
Subalpine belt: absent
Oromediterranean belt: absent
Montane belt: very rare
Submediterranean belt: extremely rare
Padanian area: absent
Humid submediterranean belt: rather common
Humid mediterranean belt: common
Dry mediterranean belt: extremely rare
Predictive model
| Herbarium samples |
INDEX FUNGORUM
GBIF
DOLICHENS
P.L. Nimis CC BY-SA 4.0
TSB 15001
P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (11346)
2001/12/04
P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (15001)
2008.03.06
P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (15001)
2008.03.06
P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (15001)
2008.03.06
Antonio Valero; Owner: Antonio Valero
Spain
2010
Antonio Valero; Owner: Antonio Valero
Spain
2010
Antonio Valero; Owner: Antonio Valero
Spain
2010
Domenico Puntillo - CC BY-SA 4.0
Italy
exceptionally fruiting species
Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/
Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/
Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/
Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/
Leif Stridvall
Courtesy: Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/
P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (11346)
2001/12/04
Leif Stridvall Anita Stridvall -Source: http://www.stridvall.se/lichens/gallery/
Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_C/Collema_flaccidum.htm; Owner: -
France, session AFL 2015 dans le Lot, Autoire
Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_C/Collema_flaccidum.htm; Owner: -
France, session AFL 2015 dans le Lot, Autoire
Courtesy Danièle et Olivier Gonnet - Source: https://www.afl-lichenologie.fr/Photos_AFL/Photos_AFL_C/Collema_flaccidum.htm; Owner: -
France, session AFL 2015 dans le Lot, Autoire
Bernard Bouffinier - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Cranou
Bernard Bouffinier - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Cranou
Bernard Bouffinier - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Source de la Bidouze
Bernard Bouffinier - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Source de la Bidouze
Michel David - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Landevennec, Abbaye
Michel David - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Landevennec
Michel David - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Landevennec
Bernard Bouffinier - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Cranou
Bernard Bouffinier - Source: https://italic.units.it/index.php?procedure=images2&taxon=1129
France, Cranou
Ulrich Kirschbaum CC BY-SA 4.0 - Source: https://www.thm.de/lse/ulrich-kirschbaum/flechtenbilder
Austria; Alps: Kärnten.
Ulrich Kirschbaum CC BY-SA 4.0 - Source: https://www.thm.de/lse/ulrich-kirschbaum/flechtenbilder
Austria; Alps: Kärnten.
Felix Schumm - CC BY-SA 4.0
[VZ1257], Hungaria. Montes Matra, regio montis Agasvár, in vallerivuli Csörgö, 480 m. Ad saxa andesitica. Leg. G. Kiszely, T. Pócs et A.Vezda, 5.06.1974. - EX A. VEZDA: LICHENES SELECTI EXSICCATI NR.1257
Felix Schumm - CC BY-SA 4.0
[VZ1257], Hungaria. Montes Matra, regio montis Agasvár, in vallerivuli Csörgö, 480 m. Ad saxa andesitica. Leg. G. Kiszely, T. Pócs et A.Vezda, 5.06.1974. - EX A. VEZDA: LICHENES SELECTI EXSICCATI NR.1257
Felix Schumm - CC BY-SA 4.0
[VZR470], Germania. Bavaria, Berchtesgadener Land, Königsee, St.Bartholomä, 610 m. Ad corticem arboris (Tilia platyphyllos). Leg. &det. R. Türk & H. Wunder, 11.04.1989 - EX A. VEZDA: LICHENES RARIORES EXSICCATI NR. 470.
Felix Schumm - CC BY-SA 4.0
[VZR470], Germania. Bavaria, Berchtesgadener Land, Königsee, St.Bartholomä, 610 m. Ad corticem arboris (Tilia platyphyllos). Leg. &det. R. Türk & H. Wunder, 11.04.1989 - EX A. VEZDA: LICHENESRARIORES EXSICCATI NR. 470.
Wolfgang von Brackel - CC BY-4.0
Germany, Bavaria, Elmaubachtal
Wolfgang von Brackel - CC BY-4.0
Germany, Bavaria, Elmaubachtal
Collezione lichenologica Abramo Massalongo del Museo di Storia Naturale G. Ligabue di Venezia - Autori: Seggi, Linda; Trabucco, Raffaella Proprietà: Fondazione Musei Civici di Venezia - CC BY-NC
Italy, Veneto, in nem. Montello
As Letagrium rupestre
CC BY 4.0 - Source: Košuthová A, Jonsson F, Nordin U, Wedin M (2025) Phylogeny of the European Collema species (Peltigerales, Lecanoromycetes). MycoKeys 115: 209-220. https://doi.org/10.3897/mycokeys.115.144718
UPS-L872188
Manuel Gil
Spain, Canary Islands, Tenerife
on soil
Manuel Gil
Spain, Canary Islands, Tenerife
on soil
Manuel Gil
Spain, Canary Islands, Tenerife
on soil
Manuel Gil
Spain, Canary Islands, Tenerife
on soil
Manuel Gil
Spain, Canary Islands, Tenerife
on soil
Manuel Gil
Spain, Canary Islands, Tenerife
on soil
Triin Aimla; Owner: University of Tartu
