Glossary of Lichenological Terms

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by Pier Luigi Nimis

Like all languages, botanical language has deep roots in the past. Modern authors tend to adopt the same terms they learnt as students from their professors, just as the latter did when they were students. Old-inherited terminology, however, can easily degenerate into jargon. A term like leprose dates back to times when lepra was a common skin disease in Europe. Today, it evokes something only to people which have other things to do than appreciating a leprose thallus. Botanical jargon largely derives from Greek and Latin (e. g. acicular, anisotomic, apothecium, paraplectenchymatous). Coined at a time where most scholars were fluent in these languages, those terms are often mute to modern users. Technical jargon is indispensable in any scientific discipline. We wonder, however, whether at least some of the old-inherited terms could be made more understandable in broader circles. The present glossary includes the most frequent terms which can be encountered in any key to lichens.

Acicular (of spores): needle-like, narrow and long, e. g. those of Arthrorhaphis.

Acuminate (of spores): pointed, with acute ends.

Adglutinate (of paraphyses): not easily detachable from each other, almost glued together.

Adnate (of apothecia): not restricted at the base.

Adpressed (of thallus): closely adhering to the substrate.

Alpine (of distribution): occurring above treeline in the Alps and in the highest peaks of the Central Apennines. More details in the introduction.

Amyloid (of asci, or thallus parts): reacting I+ blue.

Anastomosing (of paraphyses): branched, the branches joining irregularly, forming a net; e. g. those of Micarea.

Angiocarp (of ascocarps): the hymenium is not exposed until the asci are mature. This term was not used in this book. See also hemiangiocarp.

Anisotomic (of thallus parts): dividing in unequal parts, with a division which is thicker or/and longer then the others; e. g. the branching of Alectoria nigricans. See also dichotomic, iso-, isotomic, tetrachtomous, trichotomous.

Anti (general Greek suffix): something against something else.

Anticlinally (of hyphae): the hyphae are arranged perpendicularly to the surface of the thallus.

Anular (Latin: annulus = ring): ring-like, like the structure found in the apical apparatus of some asci.

Apical (Latin: apex: the top of something): located at the top. See also tholus.

Apo- (general Greek suffix): lying above something else.

Apothecia (singular: apothecium): the fruiting bodies of discocarpous Ascomycetes, ascocarps where the hymenium is fully exposed to the air, usually forming a disc, surrounded or not by a margin. Depending on the type of margin, they may be lecanorine or non-lecanorine. Most apothecia have a more or less rounded form, with several exceptions: some (e. g. those of some Pertusaria) are perithecioid, the disc being completely surrounded by the thalline margin, the spores being discharged by a narrow pore, others (e. g. in Graphis, Opegrapha, etc.) are elongated and ramified (lirelliform), etc.

Arachnoid (of thallus): a tissue of lax hyphae, cottony in appearance, like the web of some spiders (Arachnida).

Areolae (singular: areola, Latin: area): portions of crustose thalli divided by cracks. They may be contiguous or dispersed, rounded, angular, or elongate, flat or convex, etc.

Areolate (of thallus, or of cortex): disrupted into areolae. This term is often used also for the schizidia-like structures present on the podetia of some Cladonias (e. g. in Cladonia pyxidata).

Asci (singular: ascus): sac-like structures within which the spores are formed. Important taxonomic characters at supraspecific level are the layers of the ascus wall (see bitunicate, unitunicate), and the structure of the ascus tip, which facilitates the dispersal of spores (see tholus). These features - best observed under the microscope by applying I to a thin section - are rarely used in the dichotomies, being rather difficult to appreciate, but they are often mentioned in the descriptions.

Ascocarp: the fruiting body of any ascomycete, i. e. the structure in which the fungal partner produces the spores. See apothecia and perithecia.

Ascoma (plural: ascomata): see ascocarp.

Ascospores: see spores.

Aspicilioid (of apothecia): lecanorine apothecia half-immersed in the thallus, the thalline margin not prominent, but containing algae in section; e. g. those of Aspicilia calcarea. See also cryptolecanorine.

Axil (of podetia): the point where two branches diverge. In some species of Cladonia the axils are occupied by a hole (perforated axils).

Axis (plural: axils) the term mostly refers to the compact, thread-like medulla of Usnea-species (central axis, or central chord).

Bacilliform (of spores and conidia, from Latin): stick-shaped, narrowly cylindrical, the ends not acute.

Biatorine (of apothecia): apothecia “lacking a true exciple when mature, and which are pale or more or less coloured, soft in consistency, and generally strongly convex” (from Purvis et al. 1992). In other terms, a lecideine apothecium with a non-black margin. This difficult term is not used here, being subsumed under the expression “non-lecanorine”.

Biseriate (of spores): arranged more or less in two rows inside the asci.

Bitunicate (of ascus walls): the ascus wall is composed of two layers (endo- and esoascus), which tend to separate at the time of dispersal of spores: the more rigid outer wall breaks, the inner wall rapidly collapses. See also: fissitunicate, unitunicate.

Blastidia: propagules for the asexual reproduction of the lichen symbiosis, produced by the budding of thalli in a yeast-like manner, with each new blastidium produced from the tip of the previous one; they are easily confused with soredia, more rarely with isidia; in these keys, they are mostly subsumed under “soredia”.

Branches: parts of ramified fruticose lichens with a more or less circular section.

Bullate (of thallus parts): bubble-like, restricted at the base. Used esp. for squamulose lichens, e. g. the squamules of some Toninia, e. g. T. toepfferi.

C'''''' (reagents): bleaching water solution (sodium hypochlorite) or undiluted commercial bleach. This reagent is short-lasting, it should renovated after ca. 10-20 days (more often in summer or in heated spaces). Reactions with C are sometimes ephemeral. Attention! Pure sodium hypochlorite - due to its odour - is becoming rare in supermarkets, being substituted by other products, some of which may give odd reactions.

Ca. (abbreviation): more or less, almost (from the Latin circa).

Canaliculate (of thallus parts): channelled (e. g. the lobes of Flavocetraria cucullata).

Capitate (of soralia): soredia grouped into more or less convex knots, located at the end of lobes or branches (e. g. those of Hypogymnia tubulosa); the term is sometimes used also for paraphyses with distinctly swollen apical cells.

Capitulum: the spore-bearing, enlarged part of the pin-like apothecia of some Caliciales.

Carbonaceous (of parts of the ascocarps): coal-like, black, non-transparent, and friable (section!), such as the apothecial margins of Opegrapha.

Cephalodia (singular: cephalodium, from the Greek Kephalon = head, brain): lichenised structures containing cyanobacteria, found in thalli with a chlorococcoid photobiont. They may appear as warts (e. g. Peltigera aphthosa), or coralloid outgrowths (e. g. Lobaria amplissima) on the upper surface of foliose lichens, or as small warts on the pseudopodetia of fruticose lichens such as Stereocaulon. In some species they are scarcely visible, being immersed in the thallus (e. g. the internal cephalodia of some Solorina-species).

Cerebriform (from the Latin cerebrum= brain): folded, like the human brain.

Chlorococcoid (of photobiont): one-celled green algae, excluding Trentepohlia: the photobiont layer has a bright green colour. See also trentepohliod.

Chord: see axis.

Cilia: human hair-like, stout outgrowths composed by several hyphae, usually arising from the edge of foliose thalli. (e. g. in Parmotrema), not to be confused with hairs.

Clavate (of spores, or of asci): club-like, with one end thicker than the other.

Coccoid (of photobiont cells): more or less spherical.

Concolourous: of the same colour.

Concrescent (e. g. of apothecia, of lobes, etc.): becoming jointed.

Confluent: becoming merged (e. g. of soralia).

Conglutinate (of apothecial parts, esp. paraphyses): not easily detachable, almost glued together.

Conidia (singular: conidium): fragments of fungal hyphae produced in great number within pycnidia. They may serve for vegetative reproduction, but their most probable role is that of acting as male cells for the sexual reproduction of the mycobiont of ascomycetes. Their dubious role is the reason of a confusing terminology: they are often called pycnoconidia, pycnospores, spermatia, spermogonia. They may be one- or more-celled, and of very different forms and sizes. They are important in systematics (see Vobis 1980), but they rarely appear in the dichotomies of these keys, because they are not always easy to observe. In some groups (e. g. Micarea) there are different types of conidia, whose different functions still await elucidation: see macroconidia, microconidia.

Conidiophorous (of cells): fungal cells, usually located inside pycnidia, which in various ways give rise to conidia.

Consoredia: a term used only for some species of Lepraria and Leproloma, which have a thallus consisting of a mass of soredia-like granules. It refers to the case in which the granules are fused into larger clusters.

Constricted (of apothecia): becoming narrow towards the attachment point, e. g. the apothecia of Lecanora epibryon as opposed to those of Micarea adnata.

Constricted (of spores): the width of the spore is shorter at the level of the septum than between septa.

Coralloid (of isidia, or thallus parts): coral-like, densely ramified, sometimes almost shrubby, e. g. the isidia of Lasallia pustulata.

Cortex: the outer layer of thalli, when it consists of densely compacted and ordinately arranged hyphae. Several foliose lichens may have both an upper and a lower cortex. See also paraplectenchymatous, prosoplectenchymatous.

Corticate (of thallus parts): provided with a cortex.

Crenate-crenulate (of thallus and thallus parts): with rounded marginal teeth.

Crustose (of thallus): crust-like, without lower cortex and rhizinae, attached to the substratum by a dense hyphal net, hence gas exchanges only possible through the upper surface. Crustose lichens can be only collected together with their substratum.

Cryptolecanorine (of apothecia): lecanorine apothecia more or less immersed in the thallus, the thalline margin not prominent (see also aspicilioid).

Crystals (of anatomical sections): usually of oxalates. The presence and size of crystals in anatomical sections (esp. of apothecia) is important for identification in some groups (e. g. in some Lecanora). They are best observed in thin sections under polarised light. The pruina as well is mostly composed of small to coarse crystals.

Cups (in Cladonia): cup-like endings of podetia. They generally bear apothecia and pycnidia at the margin; sometimes they are proliferating, either from the margin or from the centre, giving rise to several stocks of superimposed cups (e. g. in Cladonia cervicornis subsp. verticillata).

Cyanobacterial (of photobiont): the photobiont is a Cyanobacterium. In section, it has a characteristic blue-green colour. Cyanobacteria belong to two main different groups: filamentous (thread-like, e. g. Nostoc, Scytonema) and coccaceous (several cells joined into a spherical structure, e. g. Gloeocapsa). Nostoc, however, can occur in the typical form, with a thread-like, moniliform series of globular cells (e. g. in Collema), or in very short-chained forms, sometimes reduced to a series of a few cells only (e. g. in some small Leptogium-species).

Cyphellae (singular: cyphella): like pseudocyphellae, these are structures for facilitating gas-exchange, but have a more complex structure, with a layer of globular, thin-walled cells delimiting a gaping hole. The only Italian lichens with cyphellae (more or less round openings in the lower surface) belong to Sticta, which is not included in these keys.

Diaspore: a rather confusing term of the lichenological jargon, designating anything which can reproduce the lichen, including things like spores (sexual reproduction) and isidia (vegetative reproduction), both protected by the large umbrella of the term “spores”. This term, in our opinion, must be abandoned. See also propagule.

Dichotomous (of thallus parts): branching into equal branches, as in the letter Y (see also: anisotomic, isotomic tetrachtomous'','' trichotomous'').

Diffuse (of soralia): evenly spread through the thallus (e. g. those of Phlyctis argena).

Disc (of apothecia): the exposed upper surface of the hymenium in lichens with apothecia.

Discocarpous (of mycobionts): lichenised fungi with apothecia'''.

Dorsiventral (of thallus): with clearly different upper and lower surfaces (e. g. the thallus of Evernia prunastri).

E- (general suffix): without (e. g. epruinose, ecorticate, etc.).

Ecorticate (of thallus): without cortex.

Effigurate (of crustose thalli): with radiating marginal lobes, e. g. Squamarina lentigera; see also placodioid.

e. g. (abbreviation): for example (from the Latin exempli gratia).

Endo- (general Greek suffix): lying inside something else (e. g. endolithic, endoascus).

Endoascus (of asci): see bitunicate'''.

Endolithic (of thallus): completely embedded in the rock, incl. the photobiont layer (e. g. in most species of Bagliettoa, or in Clauzadea immersa). There are at least two types of endolithic lichens: some are typical of dry areas (deserts and semi-deserts, dry valleys in Antarctica, etc.), mostly on siliceous rocks, others - the most widespread in Italy - occur on compact limestone. These two types differ considerably in morphology and ecology (Tretiach 1995). See also endosubstratic, hemiendosubtratic.

Endosubstratic (of thallus): completely embedded in the substratum, incl. the photobiont layer, e. g. the thallus of Bagliettoa parmigera). See also endolithic, hemiendosubtratic.

Ephemeral (of thalli): of short duration.

Epi- (general Greek suffix): lying above something else (e. g. epithecium, epiphytic).

Epicortex (of thallus): a term used only for Parmelia s. latiss., which designates a more or less amorphous layer lying above the upper cortex. Never used in this book.

Epigaeic (of lichens): growing on the ground; see Introduction.

Epihymenium (of apothecia): see epithecium.

Epilithic (of thallus): growing above a rock surface (see also: endolithic).

Epinecral (of thallus): a superficial layer consisting of the residues of dead fungal and algal cells covering the upper surface, with an amorphous appearance in microscopic sections, commonly present in several crustose lichens, both with and without a true cortex.

Epiphytic (of thallus): growing on the bark of higher plants (sometimes used also for lichens growing on the leaflets of bryophytes).

Epipsamma (of apothecia): a term used for the epihymenium, when this is granular, or rich in crystals. Never used in this book.

Epispore: the outer part of the spore wall, when this is thick and often ornamented (e. g. with ridges, warts, etc.). See also perispore.

Epithecium (of apothecia): the uppermost part of the hymenium, formed by the usually pigmented upper cells of paraphyses: it often has a distinct colour, sometimes characteristic reactions useful for identification. It must be observed under thin microscopic sections.

Epruinose (of thallus and apothecia): without pruina.

Eso- (general Greek suffix): lying outside something else (e. g. esoascus).

Esoascus (of asci): see bitunicate'''.

Excipulum (sometimes deformed into “exciple”, of ascocarps): the tissue(s) forming the margin of an apothecium, or the walls of a perithecium. For apothecia, lichenologists often distinguish between an “excipulum proprium” (proper, or true margin, formed only by the fungus) and an “excipulum thallinum” (thalline margin, containing also the photobiont). In this book the term “excipulum” may appear in the descriptions - in which case it is always used for anatomical features of the proper margin. It is not used in the dichotomies, being subsumed under margin for all lichens with non-lecanorine apothecia. See also pyrenium.

Farinose (of soredia, pruina): small and powdery, looking like meal. See also granulose.

Fasciculate (of rhizines, from the Latin fascium = bundle, e. g. Fascist, Fascism): with several, more or less parallel branches originating from the same point.. See also squarrose.

Fibrillae (singular: fibrilla): in Usnea these are short, simple branches perpendicular to the main ones; in foliose lichens this term is used for pale cilia-like structures found on the margin of the lobes (e. g. in Physcia adscendens, Anaptychia ciliaris, etc.).

Filamentous (of thallus, or of cyanobacterial photobionts): thread-like (e. g. the thalli of Alectoria, Bryoria, Ramalina thrausta, Usnea, and those of Nostoc among photobionts).

Fissitunicate (of asci): bitunicate'''.

Foliose (of thallus, from the Latin folia = leaf): leaf-like, flattened, with an upper and lower surface, gas exchange occurring from both faces, usually with rhizinae. Some lichens (e. g. Anaptychia ciliaris and Pseudevernia furfuracea) have a basically foliose, flattened thallus, which, however, tends to develop into three dimensions, and is not attached to the substratum by rhizinae; in these keys, they are treated both among the foliose and the fruticose lichens.

Foveolate (of thallus, from the Latin fovea = depression): with small, shallow depressions.

Fruticose (of thallus): developing in three dimensions, often shrub-like, and round to inflated in section, gas exchange occurring throughout the surface. See also foliose, and squamulose.

Fusiform (of spores): spindle-like, broader in the centre and narrowing towards the ends.

Gelatinous (of thallus - cyanobacterial lichens): becoming jellyish when wet (e. g. Collema). The cyanobacterial cells are surrounded by coats which tend to absorb liquid water, becoming jelly-like when wet. This character is easy to appreciate in some genera (e. g. Collema) in which the photobiont is predominant, less easy in other genera, like Leptogium. See also homeomerous, heteromerous.

Glabrous: without hairs or tomentum.

Glaucescent (of colours): bluish-greenish grey.

Globose: spherical.

Gloeocapsa: a genus of cyanobacteria characterised, together with other similar genera, by more or less spherical masses containing clusters of cells with a distinct, multi-layered, sometimes pigmented gelatinous coat. Most frequent in the Lichinaceae.

Goniocyst: more or less spherical groups of green algal cells surrounded by short hyphae, but without a true cortex (section!), forming a minutely-granulose thallus (e. g. in Micarea).

Granules (of thallus parts): small, coarse, more or less spherical, mostly corticate elements making up most of the thallus.

Granulose (of soredia): coarse, resembling granules, but without cortex. See also farinose.

Hairs: short, erect, transparent, hair-like structures, generally present on the upper cortex, and formed by a single hypha (e. g. in Agonimia opuntiella, Phaeophyscia hirsuta). See also cilia, fibrillae, and tomentum.

Halonate (of spores): with a thick, transparent, gelatinous outer coat. See also perispore.

Hamathecium (of ascocarps): a rather difficult, “neutral” term, which was never used in this book, referring to all types of sterile hyphae (paraphyses, paraphysoids, periphyses, etc.) which occur in the hymenium.

Haustorium (plural: haustoria): hyphae of the mycobiont which apparently penetrate inside the cells of the photobiont.

Hemi- (general Greek suffix): almost, partially.

Hemiangiocarp (of ascocarps): the hymenium is initially protected by a covering layer, which disrupts when the asci are ripe. Not used in this book. See also angiocarp.

Hemiendolithic (of thallus): see hemiendosubtratic'''.

Hemiendosubstratic (of thallus): embedded in the substratum, except the photobiont layer (e. g. Caloplaca ochracea as opposed to Bagliettoa-species). This character, being difficult to appreciate, was not used in these keys.

Hetero- (general Greek suffix): looking different from something else.

Heterocyst (of photobionts): a cell of filamentous cyanobacteria which differs from the others in the chain by its paler cytoplasm and its thicker wall, devoted to nitrogen fixation. Never used in these keys.

Heteromerous (of thallus): having the mycobiont and the photobiont separated into well-distinct layers. See also homeomerous, gelatinous when wet.

Homeo- (general Greek suffix): looking similar to something else.

Homeomerous (of thallus): having the mycobiont and the photobiont evenly intermixed throughout the thallus (e. g. in Collema). See also gelatinous when wet, heteromerous.

Hyaline (of spores): transparent, colourless.

Hymenial algae (of lichens with perithecia): green algal cells contained inside the hymenium of some groups of pyrenocarpous lichens (e. g. Endocarpon, Staurothele). They are often visible under a binocular, the sections of perithecia having a bright green core. These algae are often different in shape and size from those of the thallus.

Hymenium (of ascocarps, in section): the layer where asci arise and spores are produced. Its thickness, colour, and the reactions, esp., with I, may be important in some groups. The thickness should be measured starting from the roots of the asci, including the epihymenium. See also thecium.

Hypha (plural: hyphae): one of the filaments constituting the fungal mycelium.

Hypo- (general Greek suffix): lying below something else (e. g. hypothallus, hypothecium). See also sub-.

Hypothallus: marginal part of the thallus of foliose or squamulose lichens, composed only by the fungus, normally with a different colour and texture. In these keys, this term is often merged with prothallus'''.

Hypothecium (of apothecia): in these keys this terms refers indiscriminately for all tissues located below the hymenium. Its thickness, reactions and esp. pigmentation may be important for identification. See also subhymenium.

I (reactions): the typical Lugol’s solution, which can be purchased by specialised furnishers: a solution with 2 g of Iodine stock solution and 20 g distilled water. To prepare the stock solution: (3% IKI) dissolve 1 g iodine crystals and 2 g potassium iodide in 30 ml distilled water.

i. e. (abbreviation): equal to something else (from the Latin id est).

Imbricate (of thallus parts): overlapping, shingle-like, as the tiles of a roof, e. g. the squamules of Mycobilimbia lurida.

Immersed (of ascocarps and pycnidia): embedded in the substratum (e. g. the apothecia of Clauzadea immersa), or in the thallus (e. g. the perithecia of Catapyrenium cinereum).

Inflated (of thallus parts, from the Latin inflatus): swollen.

Inspersed (of the hymenium, in sections): full of oil droplets which render it somehow milky, not transparent in a microscopic section.

Involucrellum (of perithecia): a usually black, lid-like structure originating from the upper part of the perithecium, protecting the ostiole. It can be best observed under a binocular, by vertically sectioning the perithecium. It is mostly limited to the upper part of the perithecium, but sometimes it extends until its base. Its presence may be important for identification (e. g. in Catapyrenium s. lat., Verrucaria).

Isidia (singular: isidium): structures for the vegetative reproduction of the lichen, which derive from swellings of the upper cortex, and contain photobionts. True isidia are always corticate, as opposed to soredia. They may have different forms: erect and more or less round in section (simple or ramified-coralloid), or flattened (spathulate, peltate), etc. See also blastidia, phyllidia, and schizidia.

Isidiate (of thalli): with isidia.

Iso- (general Greek suffix): equal, e. g. isodiametric, isotomic.

Isodiametric (of thallus parts): having more or less the same diameter, mostly rounded in shape.

Isotomic (of thallus parts): dividing in regular dichotomies into equal branches. See also anisotomic, dichotomic, tetrachtomous'','' trichotomous.

K (reactions): a ca. 10% water solution of potassium hydroxide (KOH). It can be substituted with household lye (sodium hydroxide, NaOH).

KC (reactions): the test is performed by wetting the tested area first with K, then with C. These reactions are often ephemeral. In most cases, the KC test enhances the results obtained with C only.

Labriform (of soralia, from the Latin labrum = lip): soredia originating from the lower face of lobes which tend to bent upwards, the soralia assuming a lip-like form (e. g. Hypogymnia physodes, Phaeophyscia chloantha).

Laciniae (singular: lacinia, from Latin): flattened parts of ramified fruticose lichens (e. g. Ramalina fraxinea). Sometimes called lobes.

Laminal (from Latin: lamina, something thing and flattened): located on the upper surface of the thallus, e. g. the soralia of Parmelia sulcata.

Lax (of medulla): loose, not compact.

Lecanorine (of apothecia): with a thalline margin containing photobionts. In most cases, the colour of the margin is very different from that of the disc. In some genera, however the colour is similar (e. g. in several species of Caloplaca), and one has to look for photobionts in microscopic sections. See also aspicilioid, biatorine, lecideine, zeorine.

Lecideine (of apothecia): having a margin exclusively consisting of dark-coloured fungal hyphae. In these keys, this term is subsumed under the expression non-lecanorine. See also biatorine, excipulum, lecanorine, zeorine.

Leprose (of thallus, from Latin Lepra: a skin disease): a powdery mass of hydrophobic, soredia-like granules. Some experience is needed to distinguish truly leprose thalli from crustose thalli with abundant, diffuse soredia.

Lichenised (of mycobionts): always growing in symbiosis with a photobiont. In certain groups, e. g. Arthonia, some species are clearly lichenised, others are clearly non-lichenised (no true lichens), still others are of uncertain attribution.

Lignicolous: growing on wood.

Linear (of pseudocyphellae, from Latin: linea): when well-developed, narrow and elongated.

Lirelliform (of apothecia): a non-lecanorine apothecium with a long, narrow, elongated form (e. g. of Graphis, Opegrapha).

Lobes (of thalli): flattened, elongated, lichenised structures developed at the margin of the thalli (e. g. in Squamarina lentigera), or around the apothecia (e. g. in Physconia venusta). Their width should be measured in the central part. See also effigurate, placodiomorph.

Lobulate: with small lobes.

Lugol (of reactions): see I.

Macroconidia (singular: macroconidium): the larger conidium of a species that has more than one type of conidium (e. g. in some species of Micarea, or Porina).

Maculiform (of soralia, from the Latin macula: spot, patch): laminal soralia grouped into more or less round patches. See also punctiform.

Maezedium: a mass of spores liberated continuously by the asci of Caliciales. It appears as a powdery mass covering the apothecium. See also capitulum.

Margin (of apothecia, Latin margo: margin): apothecia have two main types of margin: a) a proper margin consisting of fungal hyphae only; usually, the proper margin is similar in colour to the disc, different from the thallus. b) a thalline margin, which includes photobionts; usually similar in colour to the thallus, different from the disc (with several exceptions., e. g. in Caloplaca). In these keys, unless otherwise specified, the term “margin” always refers to the thalline margin for lecanorine apothecia, to the proper margin for non-lecanorine apothecia.

Marginal (of soralia): soredia limited to the marginal parts of thallus parts (usually lobes of foliose lichens).

Mediterranean (of distribution): occurring in the belt dominated by evergreen broad-leaved trees, mainly Quercus ilex.

Medulla: the “central” part of the thallus, located under the photobiont layer. It is composed exclusively by loosely arranged fungal hyphae, the spaces between them facilitating gas exchange for the photosynthetic partner. It can be compact, loose or almost hollow, pigmented or not, and it often contains lichens substances which are absent in the cortex (hence, it can have peculiar reactions, or a characteristic colour under a UV-lamp).

Micareoid (of photobionts): green algae with a diameter of 4-7 mm, thin-walled, often occurring in pairs (e. g. those of Micarea).

Micro- (general Greek suffix): very small.

Microconidia (singular: microconidium): the smaller conidium of a species that has more than one type of conidium (e. g. in some species of Micarea).

Moniliform (of hyphae): arranged in a thread consisting in a series of globose cells, looking like a rosary, or the chains of Nostoc.

Montane (of distribution): In Italy the region dominated by beech (Fagus sylvatica).

Morphic (-morphous, a Greek suffix): the form of something.

Muriform (of spores): looking like a brick-wall, many-celled, with many longitudinal septa and crosswalls. See also submuriform.

Mycelium: the tissue composed by the fungal partner of the lichen, consisting of hyphae.

Myco- (general Greek suffix): related to a fungus (Latin: fungus).

Mycobiont: the fungal symbiotic partner in a lichen, to which the scientific name of the lichen refers.

N (reactions): concentrated nitric acid (HNO3). Warning: this is a strong acid, and can easily damage microscopic gears.

Non-lecanorine (of apothecia): without a thalline margin. See also apothecium, biatorine, lecanorine, margin, zeorine.

Nostoc: a genus of cyanobacteria with more or less long chains of rounded cells. In some genera (e. g. some Leptogium species) the chains are very short, consisting of a few cells only.

Ocular chamber (of asci): the ascus is bitunicate, the two layers separate at the tip leaving an empty space (see tholus), this space is concave with respect to the inner part of the ascus.

Orbicular (of thallus): more or less circular in shape.

Ornamented (of spores): spore wall not smooth. Ornamentation is important in some groups, e. g. in Buellia.

Oro- (Greek suffix): having to do with mountains.

Oromediterranean (of distribution): occurring above treeline in the highest mountains of the Mediterranean, excluding the Alps and the Central Apennines. More details in the Introduction.

Ostiole (from the Latin ostium: door): pore-like opening situated at the top of a perithecium or of pycnidia, through which the propagules escape.

Oval (of spores): egg-like, the convex part lying more or less in the centre, symmetrical with respect to the two axes.

Ovoid (of spores): see oval.

P (reagents): A saturated solution of para-phenylendiamine in ethilic alcoholi (of short duration!). It is also possible to prepare P in water solution: e. g. 1 g of para-phenylendiamine, 10 g of Natrium sulphate in 100 ml water. This substance, although still utilised e. g. for hair dying, might be carcinogenic. It should be used with great care (especially avoid to breath it when using the microscope!). Teachers should not endorse its use by students, unless if coupled with a lesson on the use of potentially dangerous substances, and with the corresponding measures.

Para- (general Greek suffix): located near, beside something else.

Paraphyses (singular: paraphysis): sterile hyphae in the hymenium, forming a palisade within which the asci are interspersed. They may be simple or ramified, in some case they are anastomosing; the upper cells, sometimes inflated and most often pigmented, form the epihymenium. The true paraphyses always start from the base of the hymenium. See also paraphysoids and periphyses.

Paraphysoids: structures resembling paraphyses, but originating from the hymenial tissue between the asci as pre-ascal elements stretching with the growth of the hymenium. They are usually thin, abundantly branched and anastomosing, e. g. in Arthonia. In this book, this term is sometimes used in the descriptions, being substituted by the term paraphyses in the dichotomies.

Paraplectenchymatous (of sections): a fungal tissue (section!) consisting of more or less isodiametric, rounded to angular cells. See also: plectenchyma, prosoplectenchymatous.

Parasitic: this term is used here in a very broad, often incorrect sense: it refers both to truly parasitic fungi growing on lichens, and to the so-called “parasymbiontic” lichens, i. e. those which regularly start their life-cycle on other lichens, without being true parasites; in fact, having a photobiont layer, they are autotrophic. Their “parasitism” probably consisting in “stealing” photobionts from the host lichen. More research is necessary to clarify the complex relations between “parasymbiontic” lichens and their hosts.

Parasymbiontic: see parasitic.

Parathecium (of apothecia): proper margin, formed only by fungal hyphae. Not used in this book, because not necessary.

Peltate: plate-like, with a single attachment point from the centre of the lower surface (e. g. the isidia of Peltigera lepidophora).

Peri - (Greek suffix): lying around something else.

Periclinal (of hyphae): parallel to something else (e. g. the apothecial margin).

Periphyses (singular: periphysis): hyphae resembling paraphyses, produced near the ostioles of perithecia. They are mostly short and thin, hair-like.

Periphysoids: this term is used by some authors for paraphyses-like structures of pyrenocarpous lichens, developing from the upper part of the pyrenium, near the ostiole, and growing downwards. In these keys the term was not used consistently.

Perispore (of spores): a colourless gelatinous layer around a spore, visible in microscopic sections. See also epispore, halonate.

Perithecia (singular: perithecium): globose to flask-like ascomata where the hymenium is enclosed within a “box” opening through a narrow apical pore at the summit, called ostiole. See also: involucrellum, pyrenocarpous.

Perithecioid (of apothecia): opening through a pore, hence disc not evident and the whole structure resembling a perithecium (e. g. Pertusaria pertusa). In a few cases, it might be difficult to distinguish between a true perithecium and a perithecioid apothecium (e. g. in Belonia russula).

Photo - (Greek suffix): related to light.

Photobiont (from the Greek photos = light and bios = life): the photosynthetic partner of a lichen. In our keys three main types of photobionts are used for identification: cyanobacterial, chlorococcoid, and trentepohlioid.

Phyllos (Greek suffix): similar to a leaf.

Phyllidia (singular: phyllidium, from the Greek phyllos = leaf): flattened structures resembling small lobes, formed by abstriction of a leaf-like part of the thallus, and serving for the vegetative reproduction of the lichen; they are sometimes difficult to distinguish from flattened isidia; this term is used very seldom in these keys.

Phyllocladia (singular: phyllocladium, from the Greek cladon = branch): minute, granular, verrucose to coralloid, peltate to digitate parts of the thallus of Stereocaulon, bearing the photobiont.

Pigmented (mostly of spores): coloured, not transparent in section (e. g. the spores of Buellia and Rinodina).

Placodioid (of crustose thalli): orbicular, with radiating marginal lobes. A difficult, not indispensable term of the lichenological jargon. See also effigurate.

Placodiomorph (of crustose thalli): see placodioid'''.

Plectenchyma (of thallus sections): a general term for all false tissues formed by the mycobiont only. See also paraplectenchymatous, prosoplectenchymatous.

Pluricellular (of spores): many-celled.

Podetia (singular: podetium): lichenised, fruticose structures of Cladonia and a few related genera, ontogenetically developing from a vertical extension of the lower apothecial tissues. Most of the Cladonia have two types of thallus: a primary, crustose to squamulose thallus, and the "podetia". A beginner might wonder whether the thalli of e. g. Dactylina ramulosa or Thamnolia vermicularis are "podetia" or not. As far as possible, we have tried to use this term only within Cladonia. See also primary, pseudopodetia.

Polar-diblastic (of spores): two-celled, the cells being connected by a narrow canal (most Teloschistaceae), whose length may be important for identification.

Poly - (general Greek suffix):

Polymorphic: of different forms.

Polysporous (of asci): with many (more than 8) spores.

Primary (of thallus parts): some fruticose lichens (especially Cladonia) have two types of thallus: the primary one, crustose or squamulose, gives origin to fruticose structures (podetia and pseudopodetia). In this book the term “primary squamules” exclusively refers to those of Cladonia, while the term “primary thallus” also refers to other genera in which podetia or pseudopodetia originate from a crust-like thallus (e. g. Baeomyces, Stereocaulon). The term “primary” has to do with the ontogeny of of thallus parts, non-primary structures (like podetia) developing from the generative tissue of the apothecia, a character which is of no use for identification.

Proliferating (of podetia): formed in the centre (e. g. in Cladonia cervicornis subsp. verticillata) or along the margins (e. g. sometimes in Cladonia pyxidata) of cups, giving rise to one or several stocks of podetia.

Propagule: any structure serving to reproduce the lichen. Mostly used for those related to vegetative reproduction (soredia, isidia, thalloconidia, etc.). See also diaspore.

Proper (of apothecial margin): see margin'''.

Prosoplectenchymatous (of thallus sections): fungal tissue consisting of coalesced, more or less elongated hyphal cells; see also paraplectenchymatous.

Prothallus: marginal part of the thallus of crustose lichens, composed only by the fungus, normally with a different colour and texture. In some cases (e. g. Placynthium nigrum) it is rather thick and felt-like, in other cases (e. g. Rhizocarpon species growing on quartz) it appears in the form of thin, branched bundles of hyphae exploring the substratum. See also hypothallus'''.

Pruina: powdery, frost-like deposits of crystals (often calcium oxalates), present on the cortex, or on the ascocarps; they may be very small and powdery, or aggregated into larger clumps; they are usually white, rarely of other colours (e. g. yellow in some Caliciales).

Pruinose: covered by pruina.

Pseudo - (general Latin suffix): resembling something without being it (e. g. pseudopodetia).

Pseudocyphellae (singular: pseudocyphella): small interruptions of the cortex where the medulla is exposed to facilitate gas exchange. They may be linear-elongate (e. g. in Parmelia sulcata), reticulate (e. g. in Parmotrema reticulatum), punctiform (e. g. in Punctelia subrudecta). This character is important, esp. for foliose lichens, but is often difficult to appreciate for beginners (cracks in the cortex are often mistaken for pseudocyphellae).

Pseudopodetia (singular: pseudopodetium): in the dictionary of Fungi by Hawksworth et al. (1995) this term is defined as follows “a lichenised, podetium-like structure of vegetative origin, ascogonia arising on this not on the pre-formed granular or squamulose thallus initials”. The difference between podetia and pseudopodetia has to do with their ontogeny (see primary), and lies outside the scope of identification keys. In the dichotomies, pseudopodetia are mostly subsumed under podetia.

Pubescent (of thallus parts): covered by thin, short hairs.

Pustula (plural: pustulae): bubble-like swellings present on the thalli of some species (e. g. Collema nigrescens, Lasallia).

Pustulate (of thallus): covered by pustulae.

Pycnidia (singular: pycnidium): flask-like structures, resembling perithecia, in which conidia are produced. They are mostly, but not always, dark-coloured, immersed in the thallus, appearing as small dots. Sometimes, however, they become prominent (e. g. in some Micarea species), and may have very different colours (from white to yellow-orange).

Pycnidiospores: see conidia. This term was never used in these keys.

Pyrenium (of perithecia): the wall of perithecia. A term which was never used in these keys. See also excipulum.

Pyrenocarpous (of mycobionts): lichenised fungi with perithecia.

Pyrenolichen: a lichen with perithecia.

Pyriform (of spores, perithecia, from the Latin Pyrus: the pear tree and its fruits): pear-shaped.

Reniform (of spores): kidney-like, curved.

Reticulate: net-like and interconnected (e. g. like the pseudocyphellae of Parmotrema reticulatum).

Revolute (of thallus parts): bent downward.

Rhiz - (general suffix, from Greek): a root, or something anchoring somewhat else into the ground.

Rhizines: bundles of hyphae mostly originating from the lower cortex, which anchor foliose or squamulose lichens to the substratum. Their shape and length may be important in some genera (e. g. Peltigera). See also rhizohyphae.

Rhizinomorphs: rhizine-like structures, usually found on the lower surface of umbilicate thalli belonging to Umbilicaria and Dermatocarpon, which do not function as attachment organs.

Rhizohyphae: individual hyphae, pigmented or colourless, which anchor the squamules of some lichens (e. g. Catapyrenium s. lat.) to the substratum. They should not be confused with rhizines, which originate from a lower cortex, and are stouter, being composed of thick bundles of hyphae.

Rimose (of thallus): irregularly and minutely cracked, without distinct areolae. A rather odd term, seldom used in these keys.

Rosette-shaped (of thallus): rounded in shape, symmetrical, mostly with radiating marginal lobes (e. g. Squamarina lentigera).

s. lat. (of taxa): in the broad sense (from the Latin sensu lato).

s. str. (of taxa): in the strict sense (from the Latin sensu stricto).

Saddle-shaped (of apothecia): used only for some Peltigera-species, those whose apothecia are elongated and curved, like the saddle of a horse (e. g. P. polydactyla), as opposed to those with flattened, horizontal apothecia (e. g. P. horizontalis).

Scabrose (of thallus surface): having a minutely roughened surface, generally caused by an accumulation of dead cortical material (e. g. Peltigera scabrosa).

Schizo (Greek suffix): abruplty separating from something else.

Schizidia (singular: schizidium): structures for the vegetative reproduction of the lichen, deriving from the scale-like flaking of the upper cortex into flattened to convex areolae which are detached from the thallus. They have the same function as isidia and phyllidia, but they are corticate only above (e. g. Cladonia pyxidata, Fulgensia subbracteata).

Scytonema'''''' (of photobionts): a genus of filamentous cyanobacteria with “false” branching, by breaking through its gelatinous sheath.

Secundary (of thallus): see primary.

Semi- (suffix): half, almost.

Semi-immersed (of apothecia): half immersed in the thallus.

Septa (of spores, singular: septum): cross-walls separating the individual cells of more than 1-celled spores; their thickness is an important character in some groups (e. g. in Caloplaca).

Sessile (of apothecia): not immersed, sitting on the surface, but without a stalk of any kind. See also stipitate.

Soralia (singular: soralium): well-delimited parts of thallus where soredia are produced breaking the upper cortex. They may be of different forms: punctiform, maculiform, labriform, linear, capitate, helmet-shaped, etc.

Soredia (singular: soredium): bundles of hyphae entwining a few photobiont cells, which serve to the vegetative reproduction of the lichen. They mostly originate from the medulla, and appear as powdery or granular masses. See also blastidia, soralia.

Spathulate (of thallus parts, from the Latin spatula): flattened, in the form of a spatula, or of a spoon.

Spermatia: see conidia.

Spermogonia (singular: spermogonium): see conidia.

Spores: this term is the origin of much confusion in Mycology; in these keys it is exclusively used for the sexual propagules of the mycobionts, which, produced inside the asci. Spore characters (size, shape, number of cells, pigmentation, etc.) are important for identification.

Squamulose (of thallus): composed by small, scale-like lobes lifting from the surface. Among the traditionally recognised growth-forms, this is the most ambiguous. Typically squamulose is the primary thallus of most Cladonia-species, which consists of small, leaf-like units attached to the substratum only laterally, without rhizines.. However, the term squamulose is often used also for small-fruticose thalli (e. g. Toninia opuntioides). In our opinion, squamulose thalli should have both an upper and lower surface for gas exchange, but should be attached to the substratum only laterally or centrally. In this book, we still stick to the old-fashioned definition of the term.

Squarrose (of rhizinae): densely ramified, brush-like, with short, stiff perpendicular branches, having the appearance of a bottlebrush (e. g. in Peltigera canina).

Stigonema'''''' (of photobionts): a genus of filamentous cyanobacteria having “true branching”, resulting from perpendicular divisions of cells within the filament, found only in few cyanobacterial lichens (e. g. in Ephebe).

Stipitate (of apothecia): brought on a peduncle (e. g. the apothecia of Baeomyces).

Sub- (general Latin suffix): partially, incompletely, approaching (e. g. submuriform), or “lying under something else” (e. g. subhymenium).

Subalpine (of distribution): occurring in the belt dominated by Larix, Pinus cembra and Rhododendron, near treeline in the Alps. More details in the introduction.

Subhymenium (of apothecia): in the strict sense, this is the part of the apothecium (visible in microscopic sections) which corresponds to the generative tissue below the hymenium. In these keys, it is most often used as a synonym of hypothecium.

Submediterranean (of distribution): occurring in the belt dominated by deciduous broad-leaved trees, mainly Quercus, Carpinus and Ostrya, excluding the beech belt. See also montane. More details in the introduction.

Submuriform (of spores): weakly muriform, with only a few longitudinal septa.

Sulcate (of thallus parts): furrowed, e. g. the surface of Parmelia sulcata.

Taxon (plural: taxa, a Greek term): any unit in a classification scheme (family, genus, species, subspecies, etc.).

Terete (of thallus, or thallus parts): round in cross-section (e. g. the branches of many Usnea-species).

Terricolous (of lichens): see Introduction.

Tetrachotomous (of thallus parts, from the Greek tetra = 4): 4-branched (e. g. in some species of Cladonia). (see also: anisotomic, dichotomic, isotomic'', ''trichotomous).

Thalline (of apothecial margins): the margin of lecanorine apothecia, produced by the thallus and hence containing the photobionts. Usually, the thalline margin has the same colour of the thallus, and differs in colour from the disc (e. g. in Lecanora chlarotera). Sometimes, however, especially when the thallus is similar in colour to the disc (e. g. in some species of Candelariella and Caloplaca), a section is needed to reveal the photobiont in the margin.

Thalloconidia (singular: thalloconidium): small propagules serving to the vegetative reproduction of the mycobiont, consisting of clumps of hyphae, which are produced on the thallus, or even on the prothallus. They may be confused with soredia, which, however, contain some cells of the photobiont, while the thalloconidia are formed only by the mycobiont. Rare, and limited to genera such as Umbilicaria (from the lower cortex), and Protoparmelia (e. g. P. leproloma, from the margin of areolae).

Thallus (plural: thalli): the “body” of the lichen, formed by the mycobiont and the photobiont. See also hypothallus, prothallus.

Thecium (of ascocarps, a Greek term for something like a “layer”): a synonym of hymenium. The parts lying above and under the hymenium are often called epihymenium and subhymenium. The term thecium was never used in this book, but we consistently call its upper and lower parts epithecium and hypothecium.

Tholus (of asci): the apex of bitunicate asci, when the two walls become distant from each other, giving the impression of an apical thickening. Its features, best observed after application of I, are important for distinguishing among supraspecific ranks.

Tomentose (of thallus, from Latin): having a cover of soft, matted hairs, best seen under a binocular microscope or a strong lens (e. g. the lobes of Peltigera rufescens).

Torulose (of branches): cylindrical, but with regular swellings at intervals.

Torus (of spores): a thickening occurring near the septum of pluricellular spores, e. g. in most species of Rinodina.

Trentepohlial (of photobiont): a green alga related to Trentepohlia. The algal layer has a characteristic orange to greenish orange colour, due to the presence of pigments which enhance photosynthesis in condition of weak light. Most common in tropical lichens, Trentepohlia occurs in ca. 9% of Italian lichens, esp. those which live in shaded-humid situations.

Trichotomous (of thallus parts): 3-branched, e. g. the thallus of Cladonia portentosa.

Truncate (of thallus parts): ending abruptly, e. g. the lobes of Parmelia sulcata.

Umbilicate (of foliose thalli): attached by a single, more or less central point (e. g. Dermatocarpon, Rhizoplaca, Umbilicaria).

Umbonate (of apothecia): provided with a column of sterile hyphae which protrude from the hymenium in the form of a small, central wart (e. g. in Lecidea umbonata).

Uni - (Latin suffix): referring to one single object.

Uniseriate (of spores): in a single row within the ascus.

Unitunicate (of ascus walls): the wall is composed of one layer only (a primitive character). See also: bitunicate.

Urceolate (of apothecia): deeply concave, pitcher-like in form (e. g. in Diploschistes diacapsis). When young, urceolate apothecia may be confused with perithecia (see also perithecioid).

UV: the colour of thallus or (mostly) of the medulla, as it appears under a UV lamp (in darkness). Protect your eyes with adequate spectacles, and be sure that the material on which you place your sample is not in itself reactive to UV (in principle, avoid white paper). Several UV-lamps permit the observation both under short- and long-wave radiation. Short-wave is the best for lichens.

Vegetative (of reproduction): non-sexual. In lichens vegetative reproduction can involve both partners of the symbiosis (e. g. with soredia, isidia, blastidia), or the mycobiont only (e. g. with thalloconidia). See also conidia.

Veins (of thallus): vein-like thickenings or flattened structures differing in colour or shape from the rest of the lower surface of some foliose lichens, esp. in Peltigera. They are mostly very evident, and should not be confused with small foldings of the lower surface.

Verrucose (of thallus): wart-like.

Zeorine (of apothecia): A lecanorine apothecium with a proper margin completely surrounded by a layer of photobionts reaching the lower part of the hymenium. This difficult term was never used in this book.

Zonate (of thallus): with concentric areas of different colour (e. g. in some forms of Pertusaria amara).