Lasallia papulosa (Ach.) Llano
Lasallia pustulata (L.) Mérat ssp. papulosa (Ach.) W.A. Weber
Umbilicaria papulosa (Ach.) Nyl.
Umbilicaria pustulata (L.) Hoffm. var. papulosa (Ach.) Tuck.
Common Toadskin Lichen, Blistered Naval Lichen
Toadskin lichen is aptly named. It is found on boulders and cliff faces: sandstones, granites, rhyolites, other acid rocks; and very dry surfaces. It is found throughout much of North America.
Identification: This is an umbilicate lichen, attached to a rock at a single point. Each lichen is up to 3½" (9 cm) in diameter, with pustules (bumps) that appear to radiate from the center. The upper surface is gray, flecked with black apothecia; or may be brown with rust-colored bumps. A technical description is available at the Consortium of North American Lichen Herbaria.
Lasallia papulosa on Stephen Sharnoff Photography
Lasallia papulosa on lichenportal.org
Lasallia papulosa on Wikispecies
Lasallia papulosa description by Thomas H. Kent, last updated 12 Oct 2018.