top of page

Physcia tribacia (Ach.) Nyl.

Family :


Nylander, Flora 57: 307: 1874 

Basionym: Lecanora tribacia Acharius, Lich. Univ.: 415. 1810

ID :


Thallus :

Foliose, orbicular to irregular, up to 3 cm diam.

Lobes :

Up to 1 mm wide, sometimes scale-like; margin: mostly crenulate when soralia not present, eciliate

Upper Side:

Whitish gray to dark gray or cream-colored (with darker margins), shiny and epruinose or rarely weakly pruinose, sorediate

Isidia :

In marginal or terminal soralia that develop from the lower surface of the lobe tips, eroding the tip and sometimes also the lower surface

Lower Side :

White to brownish gray, often weakly rose colored

Medulla :

Upper cortex: paraplectenchymatous with rounded cells, medulla: white, lower cortex: paraplectenchymatous with rounded cells

Uncommon, up to 2 mm diam.; margins: partly sorediate; disc: dark brown to black, without pruina

Apothecia :

Brown, 1-septate, intermediate between Physcia- and Pachysporaria-types, (16-) 17.5-21.5 (-22.5) x (7.5-) 8.5-10.5 (-12) µm Pycnidia: usually numerous conidia: subcylindrical, 4-6 x 1 µm

Ascospores :

Cortex K+ yellow, C-, KC-, P+ yellow; medulla K-, C-, KC-, P- Secondary metabolite: upper cortex with atranorin

Chemistry :

bottom of page