Field Key to Common Umbilicate Lichens

1a Perithecia present, embedded within thallus and evident as openings dotting upper surface (genus Dermatocarpon)……………………………. 2

1b Perithecia absent; apothecia, if present, saucer-shaped and superficial on the thallus………….. 3

2a Lobes distinct, often widely separated from one another; surface bluish green and dull; typically found on limestone…………. Dermatocarpon muhlenbergii

2b Lobes massed and overlapping; surface bright green and shiny; on wet acidic rocks…………………………….. Dermatocarpon luridum

3a Thallus pustulate above, pitted below.. Lasallia papulosa

3b Thallus smooth above and below… Umbilicaria mammulata