Trying to avoid guessing about the saxicolous yellow-green parmelias, for the most part, especially from photos, with no chemistry available. Looks like it's going to be important to check the underside on these.
See Xanthos at http://www.sharnoffphotos.com/lichensH/lichens15_index.html
Descriptions below are from CNALH: lichenportal.org
I tend to assume the common ones on siliceous rock in Colorado foothills are usually X cumberlandia (esp with its abundant apothecia), but here are a few more:
Flavoparmelia caperata
lower surface black in center, brown at edges; sorediate, no isidia; apothecia rare; rarely on rocks
Thallus: adnate to loosely adnate, foliose, 5-20 cm in diam., sometimes forming extensive patches, irregularly lobate lobes: subirregular, elongate, plane to subconvex, separate, 5-13 mm wide, contiguous to somewhat imbricate; apices rotund, crenate, eciliate upper surface: yellow green to pale yellow, occasionally green-gray (in shade), smooth but becoming rugose and folded with age, dull to somewhat shiny; epruinose and emaculate soredia: laminal, granular to wart-like, initially in circular soralia but becoming diffuse and confluent; isidia: absent medulla: white with continuous algal layer lower surface: black centrally, brown and naked peripherally; rhizines: dense to sparse centrally to edge of brown zone, black, simple, sometime brown or white tipped Apothecia: rare, up to 8 mm wide, laminal, sessile; disc: brown; margin: smooth but sorediate sometimes asci: clavate, 8-spored ascospores: simple, ellipsoid, hyaline, 15-24 x 8-13 µm Pycnidia: laminal, immersed conidia: weakly bifusiform, 6 x 1 µm Spot tests: upper cortex K-, C-, KC+ yellow, P-; medulla K-, C-, KC-, P+ red
Substrate and ecology: on broad leafed trees, shrubs and fence posts in open habitats, coastal to montane up to 2000m, rarely on rocks
World distribution: North and South America, Europe, Asia, Africa
Flavoparmelia baltimorensis:
lower surface black or dark, rhizinate; isidioid pustulae; apo rare
Thallus: adnate to loosely adnate, foliose, 6-15 cm in diam., often fusing to cover large areas, irregularly lobate lobes: sublinear to irregular, elongate, plane to subconvex, separate, 3-8 mm wide; apices: subrotund, crenate, eciliate upper surface: yellow-green, smooth but becoming rugose with age, dull to somewhat shiny, epruinose and emaculate pustulae: abundant, laminal crateriform, isidioid, breaking open apically but not sorediate; true isidia and soredia absent medulla: white with continuous algal layer lower surface: black centrally and toward margin, narrow brown zone peripherally, smooth to papillate; rhizines: sparse to moderately abundant, black, simple Apothecia: rare, laminal on thallus, sessile, 1-4 mm wide; disc: brown; margin: pustulate, pruina and soredia absent asci: clavate, 8-spored ascospores: simple, ellipsoid, hyaline, 13-15 x 6-7 µm Spot tests: upper cortex K-, C-, KC+ yellow, P-; medulla K-, C+ red, KC+ red, P+ red Secondary metabolites: upper cortex with usnic acid; medulla with protocetraric acid (major) and gyrophoric acid (minor to accessory). Substrate and ecology: commonly on acidic rock, rarely tree bases World distribution: eastern and SW North America
Xanthoparmelia cumberlandia
lower surface pale brown to brown; no soredia or isidia; apothecia common
Thallus: foliose, adnate, 6-12 cm in diam., irregularly lobate lobes: primarily subirregular, less often sublinear, elongate, plane, 0.1-0.5 mm wide, separate, usually continguous, less often partially imbricate, 1-2 mm wide, sometimes becoming lobulate centrally lobulae: flat, entire, often branched; apices: subrotund, smooth to crenate, eciliate upper surface: yellow-green to sometimes bluish green, smooth, shiny, epruinose and emaculate, without isidia, soralia or pustulae medulla: white, with continuous algal layer lower surface: pale brown or brown, plane, moderately rhizinate; rhizines: pale brown, simple, 0.3-0.8 mm long Apothecia: common, substipitate, 2-10 mm wide, laminal on thallus; disc: cinnamon-brown to dark brown; margin:smooth, pruina absent asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid, 9-10 x 4-5 µm Pycnidia: common, immersed conidia: bifusiform, 5-7 x 0.5 µm Spot tests: upper cortex K+ yellow to orange, C-, KC-, P+ orange; medulla K+ yellow becoming dark red, C-, KC-, P+ orange Secondary metabolites: upper cortex with usnic acid (major); medulla with stictic acid (major) and constictic and norstictic acids (both minor) and connorstictic, cryptostictic and peristictic acids (all trace). Substrate and ecology: usually on acidic rocks but in coastal areas on soil and/or pebbles as well, often in open or partially shaded habitats World distribution: Europe, North and South America
Xanthoparmelia lineola:
lower surface pale to med brown, rhizinate; no soredia or isidia; apo common
Thallus: foliose, adnate, 4-20 cm in diam., irregularly lobate lobes: subirregular, elongate, plane to subconvex, separate and contiguous, 0.8-3 mm wide, not lobulate; apices: subrotund, smooth to crenate, eciliate upper surface: yellow to yellow-green, smooth but becoming strongly rugose with age, dull to slightly shiny, epruinose and emaculate, without soralia, isidia, or pustulae medulla: white, with continuous algal layer lower surface: pale to medium brown, plane, moderately rhizinate; rhizines: brown, simple, 0.2-0.4 mm long Apothecia: common, substipitate, 2-5 mm wide, laminal on thallus; disc: cinnamon-brown to dark brown; margin: smooth, pruina absent asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid, 9-12 x 6-7 µm Pycnidia: common, immersed conidia: bifusiform, 6-7 x 1 µm Spot tests: upper cortex K-, C-, KC-, P-; medulla K+ yellow becoming dark red, C-, KC-, P+ red Secondary metabolites: upper cortex with usnic acid (major); medulla with salazinic acid (major) and consalazinic acid (minor) and often with norstictic and protocetraric acids (both trace). Substrate and ecology: on acidic rocks, often in open or partially shaded habitats World distribution: Australasia, southern Africa and North and South America
Xanthoparmelia conspersa: (X plittii is similar)
lower surface black; apo rare; densely isidiate
Thallus: foliose, adnate to loosely adnate, 4-12 cm in diam., irregularly lobate lobes: subirregular, elongate, plane to subconvex, often black rimmed, separate, contiguous to somewhat imbricate, (0.5-)1-3 mm wide, rarely lobulate; apices: subrotund to subtruncate, smooth to crenate, eciliate upper surface: yellow-green, smooth, shiny, epruinose and emaculate, moderately to densely isidiate isidia: initially globose, soon becoming cylindrical, simple to coralloid branched, 0.06-0.2 mm in diam., 0.1-1 mm tall; tips: syncorticate, dull brown to black; soralia and pustulae absent medulla: white, with continuous algal layer lower surface: black, plane, moderately to densely rhizinate; rhizines: black, simple to furcate, 0.2-0.6 mm long Apothecia: rare, substipitate, 2-8 mm wide, laminal on thallus; disc: cinnamon-brown to dark brown, epruinose; margin isidiate asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid, 9-10 x 5-6 µm Pycnidia: rare, immersed conidia: bifusiform, 6-7 x 1 µm Spot tests: upper cortex K-, C-, KC-, P-; medulla K+ yellow to orange, C-, KC-, P+ orange Secondary metabolites: upper cortex with usnic acid (major); medulla with stictic acid (major), constictic, cryptostictic and norstictic acids (all minor), connorstictic acid (trace), and sometimes hyposalazinic acid (trace). Substrate and ecology: on acidic rocks, rarely on wood, often in open, arid habitats but also in more shaded, forested habitats World distribution: Europe, Africa, North and South America
Xanthoparmelia novomexicana
lower surface pale to med brown, rhizinate; upper becoming rugose but no soredia or isidia; apo common
Thallus: foliose, moderately to loosely adnate, (2-)4-20 cm in diam., irregularly lobate lobes: subirregular to sublinear, elongate, plane to subconvex, separate and contiguous, 0.8-3 mm wide, not lobulate; apices: subrotund to subtruncate, smooth to crenate, eciliate upper surface: yellow to yellow-green, smooth but becoming strongly rugose with age, dull to slightly shiny, epruinose and emaculate, without soralia, isidia, or pustulae medulla: white, with continuous algal layer lower surface: pale to medium brown, plane, moderately rhizinate; rhizines: pale brown, simple, 0.1-0.3 mm long Apothecia: common, substipitate, 2-5 mm wide, laminal on thallus; disc: cinnamon-brown to dark brown; margin: smooth, pruina absent asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid, 10-11 x 4-5 µm Pycnidia: common, immersed conidia: bifusiform, 5-6 x 1 µm Spot tests: upper cortex K-, C-, KC-, P-; medulla K-, C-, KC-, P+ red Secondary metabolites: upper cortex with usnic acid (major); medulla with fumarprotocetraric acid (major), protocetraric acid (minor), confumarprotocetraric acid (minor), ±caperatic acid (major), ±norcaperatic acid (minor). Substrate and ecology: on acidic rocks, often in open or partially shaded habitats World distribution: montane areas of western North America extending south to Veracruz
