Rock Greenshield Lichen (Lichens of Chiricahua NM)

Rock Greenshield Lichen

Flavoparmelia baltimorensis

Summary ⁷

Flavoparmelia baltimorensis or Rock greenshield lichen (from Lichens of North America) is a medium to large foliose lichen with a yellow green upper surface when dry; lobes rounded without pseudocyphellae; the upper surface with globose, pustule-like growths resembling isidia. Lower surface is black with a narrow brown zone at the margins.

Description ⁸

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; Sonoran distribution: central Arizona south along the Sierra Madre Occidental, Southern California and Baja California.