Split-peg Lichen

The primary thallus typically forms a low mat about 2–6(9) mm deep, made up of small to medium squamules about 1–3(6) by (0.5)1–1.5 mm. The upper surface is pale green to olive or tan, smooth to slightly roughened, sometimes lightly pruinose near the edges. The podetia are mostly 1–3 cm tall, simple to branched, and often have sides that are fissured and split; they usually bear terminal, convex to almost spherical, brown to dark-brown apothecia.

In the western North American material treated as C. cariosa in a strict sense, all specimens contained atranorin. Five chemotypes were detected: atranorin alone (most frequent), or atranorin with fumarprotocetraric acid, homosekikaic acid, norstictic acid, or porphyrilic acid. Rangiformic acid has been reported as an additional substance in some chemotypes, although the authors note that their newly sequenced specimens were not screened for fatty acids such as rangiformic acid because of the type of TLC plates used. Cladonia peziziformis is somewhat similar in appearance, but can be distinguished by differences in chemistry, the paler brown colour of its apothecia, and its greener podetia. Squamulose Cladonia colonies that lack podetia are often difficult to identify, because many diagnostic characters are on the podetia; when podetia are absent, chemical tests may be inconclusive and DNA sequencing may be needed. Within the C. …

Cladonia cariosa is a widespread lichen with a cosmopolitan distribution. It grows directly on soil in calcium-rich and calcium-poor sites, and also in sun-exposed sandy soil. It is widely distributed in northern North America. In western North America it has been collected on soil in a range of settings, including roadcuts (both open and partially shaded), shale-derived soils, and sagebrush grassland soils. In Nepal, the lichen has been reported at 3,100 m elevation in a compilation of published records. Lichenozyma pisutiana is a yeast in the class Cystobasidiomycetes that has been found associating with Cladonia cariosa.