Bare-bottomed Sunburst

Xanthomendoza fulva

Bare-bottomed Sunburst is a bright yellow–orange foliose lichen commonly found on tree bark in the Upper Midwest. Colonies often appear irregular and variable, with portions of the thallus ranging from powdery and granular to more distinctly lobed within the same patch. This variability, combined with its vivid color, frequently leads to confusion with other yellow bark lichens.

For identification details and comparison with other similar species, see the Field Notes section, Xanthomendoza fulva.

Bare-bottomed Sunburst on Bark
A variable expression of a yellow foliose lichen, shifting from granular to lobed growth forms. Camera: Canon EOS 5D Mk IV
Lens: EF100mm f/2.8L Macro IS USM
Settings: ISO 200 • Aperture f/13 • Shutter 2.0 s
E21A8251A-56A-60A • Size: 6720×4480

A bright colony of Bare-bottomed Sunburst spreads across rough bark, showing both powdery sorediate patches and more distinctly lobed margins within the same frame. The white, nearly bare underside—lacking rhizines—is not visible here, but remains the most reliable diagnostic feature separating this species from other sunburst lichens.

Lichen Ember Cluster
A bright scatter of Sunburst lobes burning through a matrix of gray-green foliose neighbors.
Camera: Canon EOS 5D Mk IV
Lens: EF100mm f/2.8L Macro IS USM
Settings: ISO 100 • Aperture f/13 • Shutter 4.0 s
E21A6511 • Size: 6720×4480

The Lichen Ember Cluster image captures a compact, fractured expression of X. parietina, where its yellow-orange lobes erupt in scattered fragments across elm bark. Instead of forming a continuous patch, the colony breaks into glowing clusters, each surrounded by paler foliose neighbors such as Mealy Shadow and Powdery Shield. The result is a mosaic of warm pigments set against cooler grays.

Softfield Scatter
Fine yellow clusters drifting across rough bark, softened by moss and pale foliose neighbors.
Camera: Canon EOS 5D Mk IV
Lens: EF100mm f/2.8L Macro IS USM
Settings: ISO 100 • Aperture f/16 • Shutter 1/2 s
E21A6562-67 • Size: 6720×4480

A diffuse patchwork of Sunburst Lichen spreads in gentle fragments across the bark, its lemon-yellow lobes forming a Softfield Scatter rather than a single mass. Around it, gray-green foliose lichens and tufts of moss weave into the texture, creating a softer, more muted composition than the brighter, consolidated colonies elsewhere on the tree. In this quieter arrangement, the Sunburst appears almost dusted onto the bark—an airy, scattered bloom shaped by moisture flow and uneven light.