Français English

Placynthium nigrum (Huds.) Gray

Synonyms:

Family: PLACYNTHIACEAE

Habitat: Ubiquitous

Description

    Thallus crustose, thick, felt-like, wide spreading, up to 12 cm across, squamules granular or digitate, 1-2 mm, sometimes aggregated and areoles or small cushions forming when dry, blackish, brown-black, black-bluish, prothallus felted or fimbriate, carpet-fringe-like,  conspicuous, typically dark blue, blue green, sometimes when fresh with a white margin. Apothecia leceidine, most often scarce and sometimes absent, 0.5-1 mm, concave at first then cup-shaped and finaly flat or convex, glossy, disc black, exciple black, persistent (except when fully mature, black and markedly convex). Ascospores colourless, narrowly ellipsoid, 1-3-septate, 9-22 x 3-6 µm. Photobiont: Cyanobacteria. Chemical spot tests negative. Not especially maritime, calcicolous, rather common on maritime works, on concrete and cement walls or on calcareous rocks, common on kersantite. Very rare on slightly acid rocks, rather frequent on ground and on compacted soils of calcareous dunes, always near stones and rocks.  N.B. Many different taxa of this highly variable species have been described including some coastal. Unfortunately, the current related knowledge is very limited and they are not be presented here. Another close species (or form according to some authors), Placynthium tremniacum, grows in dryer habitats and differs by its lack of prothallus and shorter, 1-septate ascospores.







Placynthium nigrum Sur kersantite HĂ´pital-Camfrout 1
Alain GERAULT



Placynthium nigrum Kerziguenou 3
Michel DAVID



Placynthium nigrum Sur rocher calcaire Pointe de l'Armorique 2
Alain GERAULT



Placynthium nigrum La Palue (sur sol caillouteux)
Bernard BOUFFINIER



Placynthium nigrum Sur rocher calcaire Pointe de l'Armorique 1
Bernard BOUFFINIER



Placynthium nigrum Kerloc'h
Bernard BOUFFINIER



Placynthium nigrum Sur calcaire L'Aber 1
Michel DAVID



Placynthium nigrum Sur ciment Morgat 1
Michel DAVID



Placynthium nigrum Sur ciment Morgat 2
Michel DAVID



Placynthium nigrum Coupe apothécie avec asque
Jacques HAINE



Placynthium nigrum Spores
Jacques HAINE



Placynthium nigrum Sur béton Crozon 1
Bernard BOUFFINIER



Placynthium nigrum Kerziguenou 1
Michel DAVID



Placynthium nigrum Sur béton Crozon 3
Bernard BOUFFINIER



Placynthium nigrum Lostmarc'h 1
Bernard BOUFFINIER



Placynthium nigrum Kerziguenou 2
Michel DAVID



Placynthium nigrum Kerziguenou 4
Michel DAVID



Placynthium nigrum Coupe apothécie KOH Belgique Ardennes S1
Jacques HAINE



Placynthium nigrum Asques Bleu Coton Belgique Ardennes S2
Jacques HAINE



Placynthium nigrum Spores Bleu Coton Belgique Ardennes S3
Jacques HAINE



Return
Content : Alain Gérault - Website development : Sylvain Ard - Hosting : Online.net