Botany, Conservation & Research
November 19, 2022

Rare Lichens in California

By Rikke Reese Næsborg, Ph.D.

California is home to over 2000 species of lichens, but only 15 are considered rare or endangered by the state. This tiny percentage (0.73%) gives the false impression that the remaining 99.27% of California lichens are more common. In reality, we don’t know enough about the vast majority of our lichens to determine whether they are rare, endangered, or common. The California Lichen Society (CALS) works with the California Native Plant Society to add more lichens to the rare and endangered list. Some California lichens are listed on the International Union for Conservation of Nature (IUCN) red list, but being on this red list does not by itself afford protection by state or federal entities. The information below is gleaned from CALS rare lichen sponsorships and IUCN red lists. More information can be found by clicking on the “CALS” and/or “IUCN” links for each species.

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