Montana Field Guide

Thallus foliose, umbilicate, roundish to somewhat lobed, mostly less than 6 cm in diameter, margins often turned under; upper surface gray to brown gray; lower surface pale gray, brown, or black, with pale to dark rhizines and somewhat platey; isidia lacking; soredia present, powdery, diffuse, near the margins; and apothecia rare (McCune and Geiser 2009).

This is the only sorediate species of Umbilicaria in North America. The soredia develop from disintegration of the upper cortex close to the margins. The soredia are often sparse and inconspicuous. A good search image is a pale brownish gray thallus (more like a Dermatocarpon than an Umbilicaria in color) and sheltered habitats, similar to U. americana and U. vellea, rather than the exposed habitats of many Umbilicaria species (McCune and Geiser 2009).

On rock outcrops and siliceous rock where partially shaded. May be associated with seeps.

Reproduces primarily asexually by soredia, but can reproduce sexually by spores from the apothecium.

None identified.