Biogeography of Rare Lichens from the Coast of Oregon

Along the Oregon coast there are pockets of exceptionally high diversity of rare lichen species. These include a number of extreme disjunct populations, with affinities to the flora of the southern hemi­ sphere, tropical and subtropical areas, California, northeast Asia, maritime Arctic, eastern North America, and Europe. Only two of these rare species are endemic to the Pacific Northwest. Concentrations of rare lichens tend to occur on peninsulas, headlands, bald mountaintops near the coast, and the extensive dune sheet between Heceta Head and Cape Arago. Many of these species are known in North America only from the immediate coast. The geographic distribution of these populations of rare species and their biogeographic affmities are described. Fourteen species are new records for Oregon. Acarospora subrufula is newly reported for North America. Hypogymnia pulverata is a new record for western North America.