Thallus: loosely attached, 6-20 cm broad, forming wavy, wide-spreading patches; lobes: broad and rotund, 0.5-1 (-2) cm wide; margins wavy, crisped, raised; upper surface: greenish mineral gray (glaucous gray, sometimes tinged brown), pseudocyphellate with small pores (up to 0.5 mm wide); soredia: farinose, primarily along margins of lobes; without isidia; lower surface: black, often with brown, rhizine-free zone towards the margin, somewhat wrinkled; rhizines: scattered, simple, black; Apothecia: rare, 1-7 mm in diam.; hymenium: 60-110 micro meter tall; ascospores: ellipsoid, 12-15 x 7-10 micro meter; Pycnidia: unknown; Spot tests: upper cortex K+ yellow, C-, KC- and P+ yellow; medulla K-, C+ red, KC+ red, P-, UV+ white; Secondary metabolites: upper cortex with atranorin and chloroatranorin; medulla with olivetoric acid.; Substrate and ecology: amongst mosses on broad-leaved trees, or less frequently rocks, in well-lit, but moist or boggy, sheltered, often long-established, woodlands and Salix; World distribution: temperate and montane forests of the Northern Hemisphere, particularly in eastern North America, western Europe and eastern Asia; Sonoran distribution: only reported for southern California [Hasse (1913), as Parmelia olivetorum determined by Nylander].; Notes: The species may be extinct now as it was not found by Ross (1982) and was not recognized by Culberson and Culberson (1968) as occurring in southern California. The spot test reactions given by Hasse do, however, fit the species. 

Canada

Origin: Unknown/Undetermined

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

United States

Origin: Unknown/Undetermined

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

In Great Britain and/or Ireland:
Lichen / pathogen
perithecium of Clypeococcum cladonema infects and damages perforated thallus of Cetrelia olivetorum

Lichen / parasite
pycnidium of Lichenoconium coelomycetous anamorph of Lichenoconium xanthoriae parasitises blackened apothecium of Cetrelia olivetorum

Canada

Rounded National Status Rank: NNR - Unranked

United States

Rounded National Status Rank: NNR - Unranked

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: "Cetrelia olivetorum is found on tree trunks and rocks in the open woods from the Upper Great Lakes and New England southward in the mountains and foothills to Georgia and Alabama" (Flenniken 1999).