On watch list in NV. Formerly included plants from the Klamath Ranges, which are now recognized as P. eddyense. Possibly related to both P. eximium and P. elegans. See A Manual of the Flowering Plants of California, p. 783 (1925) by W.L. Jepson for original description, and Madroño 60(3):243-248 (2013) for revised circumscription.