This species is extremely similar to and perhaps conspecific with C. stellaris so that the description of that species may be consulted for the morphology. Slight trends suggested by Ahti are that the youngest branches are frequently very thick and obtuse and the outer medulla thicker than in C. stellaris. Many authors place this as the psoromic acid strain of C. stellaris.

Reactions: K—, KC+ yellow, P+ yellow.

Contents: l-usnic acid, pcrlatolic acid, and psoromic acid.

This species grows on soil and among mosses, sometimes over thin soil on rocks. It is probably circumpolar through approximately the same range as C.stellaris but is comparatively rarely collected. As comparison of the maps shows, there are large areas from which C. stellaris has been collected but from which this species has not. Obviously more study of this species is ncccssary.