''Collema'' (jelly lichen) is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...

s in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Collemataceae The Collemataceae are a family of mostly lichen-forming fungi in the order Peltigerales. The family contains twelve genera and about 325 species. The family has a widespread distribution. Taxonomy The family was circumscribed by Jonathan Carl Z ...

. The

photobiont A lichen ( , ) is a hybrid colony of algae or cyanobacteria living symbiotically among filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualistic relationship.

is the

cyanobacterium Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteria' ...

genus ''

Nostoc ''Nostoc'', also known as star jelly, troll's butter, spit of moon, fallen star, witch's butter (not to be confused with the fungi commonly known as witches' butter), and witch's jelly, is the most common genus of cyanobacteria found in a variety ...

''.Dobson, F.S. (2000) Lichens, an illustrated guide to the British and Irish species. 4th edition. Richmond publishing Co., Slough, England. 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 . They have a leaf-like, membranous structure that does not swell noticeably when wet. The upper surface of the

thallus Thallus (: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. A thallus usually names the entir ...

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 ''

'' forms chains of cells throughout the thallus without creating a separate .

Isidia An isidium (plural: isidia) is a tiny, wart- or finger-like outgrowth on the thallus surface of certain lichen species. It is one of two principal types of vegetative reproduction, vegetative reproductive structures in lichens, the other being ...

can be present or absent, while

soredia Soredia are common reproduction, reproductive structures of lichens. Lichens asexual reproduction, reproduce asexually by employing simple fragmentation and production of soredia and isidia. Soredia are powdery propagules composed of fungus, fung ...

are not found in this genus. The reproductive structures, known as

apothecia An ascocarp, or ascoma (: ascomata), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. As ...

, 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 The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in oth ...

is colorless and turns blue when treated with

iodine Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vi ...

. A more or less colourless is also present. The comprises paraphyses that separate in a solution of

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utili ...

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

ellipsoid An ellipsoid is a surface that can be obtained from a sphere by deforming it by means of directional Scaling (geometry), scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a Surface (mathemat ...

al to spindle-shaped or nearly cylindrical with transverse

septa SEPTA, the Southeastern Pennsylvania Transportation Authority, is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly four million people througho ...

. , or , are immersed within the thallus and can be located on the margins or lamina with a pale

ostiole An ''ostiole'' is a small hole or opening through which algae or fungi release their mature spores. The word is a diminutive of wikt:ostium, "ostium", "opening". The term is also used in higher plants, for example to denote the opening of the ...

. The are rod-shaped with a slightly enlarged apex. No

lichen product Lichen products, also known as lichen substances, are organic compounds produced by a lichen. Specifically, they are secondary metabolites. Lichen products are represented in several different chemical classes, including terpenoids, orcinol deri ...

s have been detected in ''Collema'' using

thin-layer chromatography Thin-layer chromatography (TLC) is a chromatography technique that separates components in non-volatile mixtures. It is performed on a TLC plate made up of a non-reactive solid coated with a thin layer of adsorbent material. This is called the sta ...

Species

Species Fungorum ''Index Fungorum'' is an international project to index all formal names (Binomial nomenclature, scientific names) in the fungus Kingdom (biology), kingdom. As of 2015, the project is based at the Royal Botanic Gardens, Kew, one of three partn ...

(in the

Catalogue of Life The Catalogue of Life (CoL) is an online database that provides an index of known species of animals, plants, fungi, and microorganisms. It was created in 2001 as a partnership between the global Species 2000 and the American Integrated Taxono ...

) accepts 24 species of ''Collema''. Collema subconveniens 1272916

*'' Collema actinoptychum'' *'' Collema coniophilum'' – Canada *''

Collema flaccidum ''Collema flaccidum'' is a species of lichen belonging to the family Collemataceae The Collemataceae are a family of mostly lichen-forming fungi in the order Peltigerales. The family contains twelve genera and about 325 species. The family has ...

'' *'' Collema furfuraceum'' *'' Collema glaucophthalmum'' *'' Collema glebulentum'' *'' Collema implicatum'' *'' Collema insulare'' *'' Collema japonicum'' *'' Collema laeve'' *'' Collema leptaleum'' *'' Collema leucocarpum'' *'' Collema marginale'' *'' Collema nigrescens'' *'' Collema pulcellum'' *'' Collema pustulatum'' *'' Collema rugosum'' *'' Collema ryssoleum'' *'' Collema sichuanense'' – China *'' Collema subconveniens'' *'' Collema subflaccidum'' *'' Collema subnigrescens'' *'' Collema substipitatum''

References

{{Authority control Peltigerales Lichen genera Peltigerales genera Taxa described in 1780