Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Life habit: lichenized Thallus: foliose to subfruticose or caespitose, separate, loosely imbricate, lobate, lobes: linear, frequently subdichotomously branched; apices: usually subtruncate, eciliate upper surface: light gray to gray, smooth, plane to rugulose, shiny or dull, maculate or not, usually epruinose; with or without isidia or soredia; pseudocyphellae absent upper cortex: with a pored epicortex, palisade paraplectenchymatous medulla: white, loosely packed, cell walls containing Cetraria-type lichenan photobiont: primary one a Trebouxia, secondary photobiont absent lower surface: tan to black, sometimes mottled white, naked, channeled revealing part of the medulla between inrolled cortices on either side, erhizinate, attached by basal holdfasts; cyphellae, pseudocyphellae and tomentum absent Ascomata: apothecial, laminal, orbicular, cup-shaped, subpedicellate or pedicellate; margin: prominent, with thalloid rim; disc: imperforate, brown to dark brown; exciple: gray or hyaline; epithecium: brown or brownish yellow; hypothecium: hyaline asci: lecanoral, wall layers apex thickened, apex I+ blue, with wide, axial body divergent towards apex, c. 8-spored ascospores: simple, ellipsoid; 7-10 x 4-6 µm; walls: thin, hyaline, I- Conidiomata: pycnidial, laminal or marginal, immersed or emergent to sessile conidia: bifusiform, 5.5-7 x c. 1 µm Secondary metabolites: upper cortex with atranorin and chloroatranorin; medulla with some combination of orcinol depsides, depsidones, or ß-orcinol depsidones Geography: temperate Europe to north Africa and Pakistan, NE and SW North America extending to Central America Substrate: mostly bark, particularly common on conifers. Notes: Although the name implies a relationship to the common fruticose genus Evernia, the similarity is not very great. In general habit they are perhaps closest. But Evernia is only weakly dorsiventral, has a lax medulla and has a different cortical and medullary chemistry. In the southern part of the Sonoran region, it is more likely to be confused with Everniastrum, that has a similar subfruticose to caespitose growth form. However, the latter genus differs in having marginal cilia (and occasionally short rhizines), a paraplectenchymatous upper cortex, has substantially larger spores and isolichenan in the medullary cell walls.