The underleaves are prominent, wider than the stem but about or less than half the size of the leaves, 2–3 clefted, and with ciliate margins (even more finely divided into slender projections).

[1][2][3][4] In the past, this plant has been reported from Russia and Japan, but recent literature calls it an endemic of the west coast of North America, ranging from southeastern Alaska to northern California.

It is typically epiphytic on bark at the base of standing mature to old-growth trees (Abies concolor, A. magnifica, and Pseudotsuga menziesii) or recently fallen logs; rarely on other organic substrates such as decaying logs and stumps, or humus covering boulders.

At the southern end of its range (Oregon and California) this species is distinctly restricted to middle elevation forests.

The survival of Ptilidium californicum in the southern end of its range (i.e., northern California) depends upon the protection of the known sites as dispersal sources.