Collema

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Genus of lichens

title: "Collema" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["peltigerales", "lichen-genera", "peltigerales-genera", "taxa-described-in-1780"] description: "Genus of lichens" topic_path: "general/peltigerales" source: "https://en.wikipedia.org/wiki/Collema" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Genus of lichens ::

| image = Collema flaccidum (Ach.) Ach 316011.jpg | image_caption = Collema flaccidum | taxon = Collema | authority = Weber ex F.H.Wigg. (1780) | type_species = Collema lactuca | type_species_authority = (Weber) Weber ex F.H.Wigg. (1780) | synonyms_ref = | synonyms = {{Collapsible list|bullets=on |Chiastosporum Dughi (1956) |Collema P.Browne (1756) |Collema sect. Collemodiopsis Vain. (1890) |Collema sect. Eucollema Tuck. (1872) |Collema subgen. Lathagrium Ach. (1810) |Collematomyces E.A.Thomas ex Cif. & Tomas. (1953) |Collemis Clem. (1931) |Collemodiopsis (Vain.) B.de Lesd. (1910) |Dicollema Clem. (1909) |Eucollema (Tuck.) Horw. (1912) |Kolman Adans. (1763) |Synechoblastus Trevis. (1853) |Tichodea Körb. (1848) | subdivision_ranks = Species | subdivision =

Collema (jelly lichen) is a genus of lichens in the family Collemataceae. The photobiont is the cyanobacterium genus Nostoc. Species in this genus typically grow on nutrient-rich bark or somewhat siliceous or calcareous rocks in humid environments.

Description

Collema lichens are characterized by their medium to large size, with a diameter of 3 to. They have a leaf-like, membranous structure that does not swell noticeably when wet. The upper surface of the thallus is dark olive-green to brown-black and is not hairy. The are 2 to 15 mm broad, rounded, and usually flat or partially raised, with smooth or surfaces adorned with elongated ridges or folds.

Both upper and lower are absent in Collema, and the photobiont Nostoc forms chains of cells throughout the thallus without creating a separate . Isidia can be present or absent, while soredia are not found in this genus. The reproductive structures, known as apothecia, have a pale brown to red-brown that can be flat or convex. The is whole and sometimes displays isidia.

The consists of cells that can be either uniformly sized or elongated. The is indistinct and can be colourless or pigmented, while the hymenium is colorless and turns blue when treated with iodine. A more or less colourless is also present. The comprises paraphyses that separate in a solution of potassium hydroxide and may be unbranched or branched, often connecting near their tips, which can be club-shaped or round and exhibit a yellowish to reddish-brown hue.

The asci are club-shaped (clavate) with a strongly thickened apex, and both the and the downwardly projecting annulus and apical cap react blue to iodine. Each ascus produces eight spores that are narrowly ellipsoidal to spindle-shaped or nearly cylindrical with transverse septa. , or , are immersed within the thallus and can be located on the margins or lamina with a pale ostiole. The are rod-shaped with a slightly enlarged apex. No lichen products have been detected in Collema using thin-layer chromatography.

Species

, Species Fungorum (in the Catalogue of Life) accepts 24 species of Collema. ::figure[src="https://upload.wikimedia.org/wikipedia/commons/6/65/Collema_subconveniens_1272916.jpg" caption="''Collema subconveniens''"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/d/d7/Collema_subflaccidum_Degel_408008.jpg" caption="''Collema subflaccidum''"] ::

References

References

  1. Dobson, F.S. (2000) Lichens, an illustrated guide to the British and Irish species. 4th edition. Richmond publishing Co., Slough, England.
  2. (2020). "Peltigerales: Collemataceae, including the genera ''Blennothallia'', ''Callome'', ''Collema'', ''Enchylium'', ''Epiphloea'', ''Lathagrium'', ''Leptogium'', ''Pseudoleptogium'', ''Rostania'' and ''Scytinium''". Revisions of British and Irish Lichens.
  3. "''Collema''".
  4. (1954). "The lichen genus ''Collema'' in Europe".
  5. (1974). "The lichen genus ''Collema'' with special reference to the extra-European species".
  6. (2003). "Two new taxa of the lichen genus ''Collema'' from China". Mycosystema.
  7. (1858). "Lichenes collecti in Mexico a Fr. Müller". Flora (Regensburg).
  8. (1863). "Lichenographia Novogranatensis prodromus". Acta Societatis Scientiarum Fennicae.
  9. (1867). "Synopsis lichenum Novae Caledoniae". Bulletin de la Société Linnéenne de Normandie.
  10. "Synonymy: ''Collema'' Weber ex F.H. Wigg., Prim. fl. holsat. (Kiliae): 89 (1780)". [[Species Fungorum]].
  11. (2009). "Contributions to an epiphytic lichen flora of northwest North America: I. Eight new species from British Columbia inland rain forests". The Bryologist.
  12. (1864). "Observations on North American and other lichens". Proceedings of the American Academy of Arts and Sciences.

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peltigeraleslichen-generapeltigerales-generataxa-described-in-1780