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Physconia grisea  (Lam.) Poelt

Synonyms:

Family: PHYSCIACEAE

Habitat: Ubiquitous

Description

    Thallus foliose, more or less rosette-shaped, 5-8 cm diam., tightly appressed to the substratum, composed of lobes, 1-2 mm wide, radiating and partly overlapping, upper surface markedly spotted pruinose, whitish, conspicuous towards the margins, spots possibly contiguous in the center, overall aspect pale greyish, pale grey-brownish when dry, bronze to brown-greenish when moist, markedly green when rainy or rehydrated, covered notably towards the center with granular isidia and sorelia, grey-greeenish, lower surface whitish, darker in the center, simple rhizines, whitish to pale ochre. Apothecia very rare, more or less sessile, 1-3 mm diam., disc brown-red, pruinose, thalline exciple sorediate. Ascospores brown, thick walls, minutely dotted, 22-34 x 12-17 µm. Pycnidia frequent. Cortex: K-; medulla (white): K-. On nutrient-enriched bark of deciduous tree trunks in parklands or isolate, also on rocks and walls provided that the substratum is neutral or alkaline. Not to be confused with Physconia perisidiosa a of which the rhizines are bottle-brush-shaped and with  Physconia enteroxantha which has a yellow medulla.







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Physconia grisea Han sur Lesse 2
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Physconia grisea Plovan 1
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Physconia grisea Plovan 2
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Physconia grisea Plovan 3
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Physconia grisea Plovan 4
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Physconia grisea Humide Pont l'Evêque 1
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Physconia grisea Humide Pont l'Evêque 2
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Physconia grisea Humide Face inférieure Pont l'Evêque 3
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Physconia grisea Humide Face inférieure Pont l'Evêque 4
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Physconia grisea Humide Pont l'Evêque 5
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Physconia grisea Photobionte Pont l'Evêque 6
Philippe CLOWEZ



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