Rare Plant Ranking
Over 50 years of reviewing and ranking California’s native plants
Since 1974, the CNPS Rare Plant Inventory (RPI) has been a widely-recognized resource that directly guides rare plant conservation planning in California. The heart of the RPI is our ongoing assessment of the current conservation status of our state’s rare, threatened, and endangered plants.
The RPI is where conservationists, consultants, planners, researchers, and resource managers go on a daily basis to help educate landowners and public policy makers about the importance of rare plant stewardship and conservation. Individuals preparing environmental documents for California Environmental Quality Act (CEQA) and/or National Environmental Quality Act (NEPA) review often use the RPI to determine the potential for resource conflicts and to develop project-specific lists of rare plants that have the potential to occur on project sites prior to conducting on-site surveys. Conservationists and resource managers use the same information to review environmental documents and prepare public testimony to influence decision-makers.
The following individuals and companies are professional subscribers of the RPI. Professional subscribers directly contribute to the status review process for updates and changes to California Rare Plant Ranks, updates to rare plant information and data, and updates and advancements to the RPI database and web application. For more information about professional RPI subscriptions and what they support see here.
Support the CNPS Rare Plant Inventory by becoming a professional subscriber today!
About the Rare Plant Inventory
Rare Plant Status Review
CNPS leads the effort to review and rank the rarity of California’s native plants. This iterative and scientifically vetted process is made possible through a community of scientists and volunteers working throughout the state and nation while working closely with the California Natural Diversity Database (CNDDB) of the California Department of Fish and Wildlife. The resulting data builds a foundation for the ongoing stewardship, appreciation, and conservation of California’s rare and endangered plants.
CNPS solicits information about proposed changes to the RPI via the Rare Plant Status Review Process. The CNPS Rare Plant Program encourages anyone who has knowledge about native plants, particularly rare plants, to contribute their comments/data as a Rare Plant Status Reviewer.
If you feel you might qualify as a reviewer, but are not able to fill out and/or submit this form, please contact the CNPS Rare Plant Program at rareplants@cnps.org for more information on how to become involved.
The plant status review groups are email groups divided into seven regions throughout the state following the Jepson eFlora geographic subdivisions. Status review proposals are sent to each regional email group that the plant under review is known to geographically occur in.
Formal nominations for California Rare Plant Rank additions, changes, deletions, or Threat Rank and taxonomic name changes in the RPI can be made using the Status Update Proposal Form.
California Rare Plant Ranks
California Rare Plant Ranks (CRPRs) are a ranking system developed by CNPS to define and categorize rarity in the California flora. The six CRPRs range from presumed extinct species (CRPR 1A) to limited distribution/watchlist species (CRPR 4). Visit the RPI Glossary to learn the criteria and see definitions of each rank.
Lichens of Conservation Concern
In collaboration with the California Lichen Society’s (CALS) Conservation Committee, the CNPS Rare Plant Program began including Lichens of Conservation Concern in the CNPS Inventory in 2014.
As with vascular and non-vascular plants in the Inventory, the CNPS Rare Plant Program updates and maintains information on rare lichens through contributions from botanists along with the review of data submitted to the CNDDB. Unlike plants, however, additions and status changes to lichens in the Inventory can be based on the CALS Conservation Committee’s sponsorship process, the Rare Plant Status Review Process, or a combination of both. For additional information about Lichens of Conservation Concern, please view their sponsorships available on the CALS website, as well as the data provided on them in the Inventory.
Previous Editions
1st Edition (1974)
2nd Edition (1980)
Supplement 1 (1981)
Supplement 2 (1982)
3rd Edition (1984)
4th Edition (1988)
5th Edition (1994)
6th Edition (2001)
CNPS staff walk you through using the RPI.
