Thallus: foliose, up to 2 cm in diam., mostly irregular with confluent thalli
lobes: up to 2 mm broad, usually around 1 mm, about the same in length but sometimes much longer, ciliate;
cilia: marginal, pale to black, always black in the outer part upper
surface: gray to dark gray; lobe tips mostly much darker, sometimes with a white pruina, sorediate
soredia: in helmet-shaped soralia, usually abundant, starting as holes just beneth the lobe tips
upper cortex: paraplectenchymatous
medulla: white
lower cortex: prosoplechymatous
lower surface: white to grayish;
rhizines: white to black
Apothecia: not seen in Sonoran material; elsewhere up to 2 mm diam., stipItate;
disc: sometimes thinly pruinose ascospores: brown, 1-septate, Physcia-type, 10-23 x 7-10 µm Pycnidia: sparse,
immersed conidia: subcylindrical, 4-6 x 1 µm
Spot tests: upper cortex K+ yellow, C-, KC-, P+ yellow; medulla K-, C-, KC-, P-
Secondary metabolite: atranorin in upper cortex. Substrate and
ecology: growing on trees and branches in fairly open situations, probably introduced by man
World distribution: widely distributed in temperate and boreal areas in all continents but more common at
higher latitude up to 65ºN and 60ºS Sonoran distribution: relatively frequent in upper montane forests of Arizona and coastal southern California and Baja California.
Notes: The species is easy to recognize by the cilia on the lobe margin and the helmet shaped soralia. In the Sonoran Region P. adscendens might be difficult to separate from some phenotypes of Heterodermia erinacea, and it is then necessary to study the upper cortex, which is prosoplectenchymatous in the latter. Physcia adscendens differs from P. tenellula in several aspects. The latter is much smaller and has a different type of soralia and hairs on the upper surface. [lichenportal]

Thallus: orbicular to irregular, to 5 cm diam.
lobes: up to 2 mm broad, flat to convex, eciliate
upper surface: whitish gray to dark gray, rarely brownish gray, usually distinctly white-maculate, sometimes weakly white-pruinose; without soredia or isidia
medulla: white lower
cortex: prosoplectenchymatous with the lowermost part gradually forming rounded, isodiametric cells lower
surface: white to dark lead colored
Apothecia: usually abundant, up to 2 mm diam.; disc: often white-pruinose ascospores: brown, 1-septate, vary from Physcia- to Pachysporaria-type, (19-) 21-25 (-28) x 9-11 (-13) µm
Pycnidia: common, immersed
conidia: subcylindrical, 4-6 x 1 µm
Spot tests: cortex and medulla K+ yellow, C-, KC-, P+ yellow Secondary
metabolites: upper cortex with atranorin; medulla with atranorin, zeorin and rarely other triterpenes.
Substrate and ecology: growing on
trees in fairly open situations World distribution: widely distributed within arctic, boreal and temperate areas of North American and Eurasia, also known from South America
Sonoran distribution: widely distributed from sea level to upper elevation montane sites from Arizona, southern California, Baja California, Baja California Sur, Chihuahua, Sonora and Sinaloa.
Notes: Some material seen from the Sonoran Region is a somewhat different from "typical" P. aipolia, but the difference is not so obvious that a new species is described. The whole pattern of variation in North America has to be studied further. [lichenportal]

Thallus: foliose, often circular in outline, pale greenish gray, adnate on substrate; lobes 0.6-1.5 mm wide; vegetative diaspores laminal, round soralia containing greenish or whitish granular soredia. Photobiont trebouxoid alga. Lower surface corticate, white with simple, white rhizines. Ascomata lecanorine apothecia, rare.
Chemistry: Cortex and medulla K+ yellow; secondary metabolites atronorin and unknown terpenes.
Substrate and Habitat: Mostly on bark of hardwood trees in hardwood and mixed forests.
Distribution: Eastern North America; in North Carolina common throughout.

Thallus: foliose, pale gray, spotted with white maculae; lobes thin, appressed to somewhat ascending, 0.3-1.0(-2.0) mm wide, margins and tips finely divided and dissolving into granular soredia; lower surface white with pale rhizines. Ascomata lecanorine apothecia, absent to abundant, < 1 mm diam.; disk dark brown, often pruinose.
Chemistry: Cortex K+ yellow, medulla K-; atranorin.
Substrate and Habitat: On exposed bark in forest canopies as well as in human altered habitats.
Distribution: Eastern North America; in North Carolina throughout.0
Notes: A very common lichen, Physcia millegrana has been described as the most pollution-tolerant macrolichen in eastern North America (McCune 2000), found dominant in urban settings (e.g., Perlmutter 2010). [lichenportal]

Thallus: to 4 cm across, pale gray, strongly white spotted throughout; lobes narrow, to 0.5 mm across, convex, very irregularly branched, often crowded and appearing verrucose in the center; underside pale; lower cortex prosoplectenchymatous; upper cortex and medulla KOH+ yellow, containing atranorin, zeorin and unknown terpenes.
Apothecia: to 2 mm across; margin not or only slightly raised above disk, smooth, not crenate; disk weakly white pruinose or not pruinose; cortex of apothecia] margin thin, even, of 4-5 rows of "cells"; ascospores Physcia-type, 15-17 x 6-7.5 um. Physcla pumilior has been confused with P. aipolia but is smaller in al respects and the epithet denrives from this fact. Physcia pumilior can be recognized in the fìeld by its narrow, irregular lobes and virtuall epruinose apothecia. Physcia aipolia has flatter, broader, more regularly dichotomous, often more confluent lobes, apothecia with often crenate margin raised above the disk, apothecial cortex many cells thick and often very irregular, apothecial disk strongly pruinose, and larger ascospores.
Distribution: Physcia pumilior is known to me from Alabaman, Arkansas, Florida, Louisiana, Missouri, Oklahoma and South Carolina. There is only a single collection from Florida but probabl will prove common in northern tier of counties. There are two collections from Lousiana and Mississipi morphologicalìy referable to P. aipolia which differ in ascospore type and terpenoid pattern. Otherwise the species is known north of the Mason-Dixon Line. Physcia aipolia var. alnophila (Vainio) Lynge is similar in having narrowo rather irregular lobes but has large spores as in the type variety. Its distribution is apparently also more northern than the type variety and unlikely to appear in the Coastal Plain. I have seen a collection of var. alnophila from Isle Royala, Michigan. I assume the southern specimens cited by aipolia f. anqustata (Ny].) Vainìo are P. pumilior and the northern ones var. alnophila. [somefloridalichens]

Thallus: orbicular or irregular, up to 4 cm diam., sometimes confluent with other thalli, loosely adnate
lobes: radiating, truncate with open sinuses, up to 1 mm wide but mostly c. 0.5 mm, eciliate
upper surface: whitish gray to cream-colored (margin often paler), mostly without pruina and maculation; soredia and isidia absent
upper cortex: paraplectenchymatous
medulla: white
lower cortex: prosoplectenchymatous, cells sometimes short and thick-walled
lower surface: white to brownish, with few pale rhizines
Apothecia: usually abundant, variable in size, up to 1.5 mm diam., but usually less than 1 mm; margins: thick; disc: often pruinose
ascospores: brown, 1-septate, Physcia- or Pachysporaria-type, (14-) 17.5-22.5 (-28) x (6.5-) 8-10 (-12) µm
Pycnidia: ± abundant
conidia: subcylindrical, 4-6 x 1 µm
Spot tests: cortex K+ yellow, C-, KC-, P+ yellow; medulla K-, C-, KC-, P-
Secondary metabolite: upper cortex with atranorin.
Substrate and ecology: growing on trees in open situations
World distribution: widely distributed species within the arctic, boreal and temperate vegetation zones
Sonoran distribution: a relatively frequent species on trees from low to upper montane localities of Arizona, southern California, Baja California, Baja California Sur, and Sonora.
Notes: The abundant apothecia, the K– medulla and corticolous habitat are the main characters of P. stellaris. There is a slight difference in morphology and appearance within the range of its distribution (Moberg 1986: 860) and the Sonoran Desert material is closer to the southern type as would be expected. The closely related species P. convexella differs in lobe shape and substrate preference. [lichenportal]