Previously on List 4.3; rarer than previously thought. Many occurrences historical; need field surveys. Potentially threatened by trail maintenance and logging. See Species Plantarum 1:397 (1753) for original description and A Manual of the Botany of the Northern United States, p. 273 (1848) for taxonomic treatment.
California Native Plant Society (CNPS).
Inventory of Rare and Endangered Plants (online edition, v8-01a).
California Native Plant Society. Sacramento, CA. Accessed on
.