Placidium
Family: Verrucariaceae
Placidium image
Othmar Breuss
  • Greater Sonoran Desert
  • Resources
Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Life habit: lichenized Thallus: squamulose squamules: almost leafy, appressed or with margins free from the substrate upper surface: various shades of brown, smooth, dull or shiny upper cortex: paraplectenchymatous, 30-130 µm thick, composed of large (6-20 µm), angular, strongly conglutinated cells with the separating hyphal walls ± thickened above, often overlain by an epinecral layer medulla: white, composed of irregularly interwoven filamentous hyphae (prosoplectenchymatous), or with ± numerous globular cells photobiont: primary one a Myrmecia, secondary photobiont absent; algal layer: horizontally continuous, sharply delimited from the upper cortex; algal cells: 7-18 µm in diam. lower cortex: paraplectenchymatous or composed of more densely aggregated globular cells or lacking lower surface: pale to black, usually attached by a weft of hyaline or brownish rhizohyphae, with additional true rhizines in a few species Ascomata: perithecial, laminal, immersed, broadly pyriform or subglobose, without involucrellum; exciple: hyaline or yellowish or brown; interascal filaments: absent; hymenial gel: amyloid, I+ reddish or blue, always blue after pretreatment with K; ostiolar filaments: present asci: ± cylindrical, thin-walled (I-), without a tholus, 8-spored ascospores: uniseriate at least when young, ellipsoid to subglobose, obtuse at the poles, aseptate; wall: hyaline, smooth, without thickenings, halo or sculpturing Conidiomata: pycnidial, Dermatocarpon-type (Harada 1993), multilocular conidia: oblong-ellipsoid or bacilliform Secondary metabolites: none detected Geography: world-wide, but mainly in temperate regions Substrate: soil, moss, detritus, rock or bark.
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Placidium acarosporoides
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Placidium adami-borosi
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Placidium aegyptiacum
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Placidium analogicum
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Placidium andicola
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Placidium arboreum
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Placidium boccanum
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Placidium californicum
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Placidium cartilagineum
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Placidium chilense
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Placidium cinerascens
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Placidium corticola
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Placidium crassum
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Placidium custnani
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Placidium deosaiense
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Placidium elisavetae
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Placidium fingens
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Placidium imbecillum
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Placidium imitans
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Placidium insulare
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Placidium iranicum
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Placidium kaernefeltii
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Placidium krylovianum
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Placidium lachneoides
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Placidium lachneum
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Placidium lesdainii
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Placidium marcomanici
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Placidium michelii
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Placidium monstrosum
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Placidium norvegicum
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Placidium pilosellum
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Placidium podolepis
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Placidium pseudorufescens
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Placidium psorinum
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Placidium pusillum
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Placidium pyrenaicum
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Placidium rhizinosum
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Placidium ruiz-lealii
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Placidium semaforonense
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Placidium squamulosum
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Placidium steineri
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Placidium subrufescens
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Placidium tenellum
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Placidium tuckermanii
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Placidium tumidulum
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Placidium velebiticum
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Placidium verruculosum
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Placidium yoshimurae
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