Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.
Thallus: fruticose, pendulous, up to 20 cm long branching: pendulous, sparingly branched, growing from a narrow holdfast branches: solid, flat throughout the branches, 1-3(-10) mm wide surface: yellowish green, smooth or longitudinal ridged, dull, without soredia pseudocyphellae: common, ellipsoid to short linear, not forming continuously narrow lines cortex: thin; chondroid strands: common, discontinuous, smooth Apothecia: common, stipitate disc: concave, without white margin; margin: concolorous with the thallus, entire or reticulate ridged, pseudocyphellate asci: elongate-clavate, 8-spored ascospores: hyaline, 1-septate, ellipsoid, 14-16 x 4.8-5.6 µm Pycnidia: not observed Spot tests: cortex K-, C-, KC+ yellow, P-; medulla K-, C-, KC- P+ yellow Secondary metabolites: cortex with usnic acid (major); medulla with psoromic acid (major). Substrate and ecology: on bark World distribution: endemic to Mexico Sonoran distribution: scattered in Chihuahua and Sinaloa. Notes: Ramalina psoromica might be confused with R. usnea, that differs in having linear and continuous pseudocyphellae, cracked chondroid strands, narrowly fusiform ascospores and in lacking psoromic acid.