1a Thallus foliose
2a Thallus K+ purple
2b Thallus K-
3a Lobes < 0.5 mm wide and < 2 mm long
3b Lobes > 1 mm wide
1b Thallus fruticose
4a Thallus medium to large (generally > 2 cm diameter)
5a Thallus bright yellow to fluorescent green; widespread
5b Thallus orange; immediate coast
4b Thallus minute (generally < 2 cm long), yellow to orange
6a Soredia present
7a Thallus dwarf erect fruticose, generally < 2 mm high; on rock, occasionally trees.
7b Thallus small, prostrate to suberect fruticose, generally > 2 mm high; sheltered crevices in calcareous rock in steppe and dry forests.
6b Soredia lacking
8a On seacoast rocks
8b On other substrates
9a Thallus knobby, short-branched, yellow to orange, typically forming compact globular clusters on twigs; apothecia generally present
9b Thallus of short, branched, erect, orange filaments, the filaments forming a mat generally < 5 mm high; apothecia absent; common on tree trunks in many habitats, generally where moist