Since its inception in 1968, the CNPS Rare Plant Program has been a trusted resource for scientific accuracy and integrity. CNPS rare plant data are widely accepted as the standard for information on the rarity and endangerment status of the California flora. Today, we’re using these data to fight extinction, engage citizen scientists, and inform land use decisions statewide. Support CNPS plant science today!
Areas of Focus
Get details on the CNPS ranking categories and how plants are assigned each rank.
These species are critical to the preservation of regional genetic diversity. Here’s what you should know.
Using the RPI's advanced search allows you to unlock even more capabilities! List/Rank, Location, Biology, and more.
Over one-third of California’s flora is considered rare. Learn expert tips to search the RPI to prepare a list of rare plant species for a project.
It sounds mysterious and magical, like an ancient tome you would check out of the library. Where does it come from?