CNPS Inventory
of Rare Plants

Lilium pardalinum ssp. pitkinense, 1b.1. Photo: Amy Patten.

Since 1974, the CNPS Inventory of Rare and Endangered Plants of California has been a widely-recognized resource that directly guides rare plant education, protection, conservation planning, and land acquisition and management in California. The heart of the CNPS Inventory is our assessment of the current conservation status of our state’s rare, threatened, and endangered plants. Beginning with six print editions from 1974 to 2001, the Inventory is now a fully integrated web application that enables species maintenance functions to be performed in the same web-based program, ensuring the immediate release of the most up-to-date rare plant information to help inform conservation priorities.

The Inventory 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 Inventory 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 development of the current Inventory could not have been possible without the help from our sponsors listed at the bottom of this page in addition to major contributions from the State of California, the Center for Plant Conservation, the California Plant Rescue initiative, and the Pacific Southwest Region of the US Forest Service.

Inventory Details

California Rare Plant Ranks

  • California Rare Plant Rank 1A: Plants presumed extirpated in California and either rare or extinct elsewhere
  • California Rare Plant Rank 1B: Plants rare, threatened, or endangered in California and elsewhere
  • California Rare Plant Rank 2A: Plants presumed extirpated in California but common elsewhere
  • California Rare Plant Rank 2B: Plants rare, threatened, or endangered in California but common elsewhere
  • California Rare Plant Rank 3: Plants about which more information is needed, a review list
  • California Rare Plant Rank 4: Plants of limited distribution, a watch list

Full California Rare Plant Rank definitions

Considered but Rejected and Postponed taxa

A category of Considered but Rejected (CBR) exists for plants that either previously had a California Rare Plant Rank (CRPR), or that were considered for addition to the Inventory but were rejected for one or more reasons. Any plant that is deleted from a CRPR category in the Inventory is not fully removed and is instead changed to the CBR category. Rejected plants are searchable by selecting the “Considered But Rejected” button in the California Rare Plant Rank section of simple and advanced search. A brief description of the reason why the plant was rejected is included for each CBR entry.

A category of Postponed (PPD) exists for approximately 300 plants that were considered as possible new additions during the development of the CNPS Inventory 6th edition as part of our ongoing data review process, but were “postponed” due to significant taxonomic uncertainty and/or lack of information regarding distribution, abundance, rarity and/or endangerment.

If you have information that any of these taxa deserve inclusion in the CNPS Inventory, please let us know by contacting us at rareplants@cnps.org.

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.

Taxa not included in the Inventory

CNPS has tracked plants that are rare from a statewide perspective since the late 1960s with more than 2,400 taxa currently ranked as rare or uncommon statewide. However, if a species is not included in the CNPS Inventory, it does not necessarily mean that the species is not rare.

A number of attention-worthy plants may not be included in the Inventory for a number of reasons, including:

  • Locally rare but not statewide — Many plants that are not rare from a statewide perspective may nonetheless be rare from a regional perspective (see Locally Rare Plants discussion).
  • Changes over time — Species that were once considered to be too common or that were not thought to occur in California (‘Considered but Rejected’ taxa), may have become rare or have subsequently been found in California. Updates are ongoing.
  • Missing data — Species that are on the list of postponed taxa may in fact be rare and would especially benefit from collection of information so that an accurate assessment of their rarity can be made. See below for a list of Postponed Taxa.
  • Not yet surfaced — There are also taxa that have not yet been brought to the attention of CNPS as rare or that are in the CNPS backlog of rare taxa scheduled to undergo review for inclusion in the Inventory. If you know of a plant that should be considered for inclusion, please submit a status review request to us at rareplants@cnps.org.

Interpreting CNPS Lists to California Rare Plant Ranks

In 2010, the name of “CNPS List” was changed to “California Rare Plant Rank” (CRPR) to reduce confusion over the fact that the CNPS and the California Natural Diversity Database (CNDDB) assign ranks using the collaborative CNPS Status Review Process, and are not solely a CNPS assignment. 

In 2013, CNPS implemented a new CRPR 2A category (extirpated in California, but common elsewhere) and added a “B” to CRPR 2 (seen as 2B) that were developed by the Rare Plant Program Committee. 

The first two print editions of the Inventory defined conservation ranks differently than today and are summarized below.

1st Edition:

  • Very Rare and Rare and Endangered Plants (pp. 12-32), mostly represents what is currently considered CRPR 1A and 1B.
  • Appendix I, Rare and Not Endangered Plants (Including Some of Uncertain Status) (pp. 33-40), mostly represents what is currently considered CRPR 2B.
  • Appendix II, Plants Not Rare But Mostly of Limited Distribution (pp. 41-42), mostly represents what is currently considered CRPR 4.

2nd Edition:

  • List 1- Plants Presumed Extinct, represents what is currently considered CRPR 1A.
  • List 2- Plants Rare and Endangered, represents what is currently considered CRPR 1B.
  • List 3- Plants Rare, But Not Endangered, represents what is currently considered CRPR 4.
  • List 4- Plants Rare in California, Common Elsewhere, represents what is currently considered CRPR 2B.

3rd to 6th Editions:

  • Lists correspond to current CRPRs.

Highlights of changes from previous online version

  • Mobile friendly – Take the Online Inventory with you!
  • Full data search bar is now included at the top menu on every page for quick access to make new searches.
  • Easier to access links and a new Download Report function for every plant’s details.
  • Intuitive search display: add or remove columns by button clicking, quick click column sorting, and easy drag and drop column re-ordering. 
  • New “Other Status” section includes information on seeds that have been banked as part of the California Plant Rescue initiative. 
  • Maps are back and selecting quads on a map in Advanced Search has never been easier!
  • Regular imports of rare plant quads and counties from the California Natural Diversity Database (CNDDB), including updated quads and counties for all CRPR 3 and 4 plants.
  • New Help page describes how to search and view data.
  • Fully updated Glossary – all data fields are now fully described.
  • Completely new Status Review Documents page! Download PDF copies of CNPS status reviews published since 2003.
  • Three plant photos instead of one.
Caulanthus californicus

Online Inventory

Access the online database.

Visit RPI

Previous Editions

Inventory cover, 1st Edition
1st Edition (1974)

Inventory cover, 2nd Edition
2nd Edition (1980)
Supplement 1 (1981)
Supplement 2 (1982)

Inventory cover, 3rd Edition
3rd Edition (1984)

Inventory cover, 4th Edition
4th Edition (1988)


5th Edition (1994)


6th Edition (2001)

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Support the Inventory!

The 9th Online edition would not have been possible without generous supporters. CNPS offers our sincere appreciation for these financial contributions, as well as the combined efforts of many others who’ve helped make this resource possible. To support ongoing enhancements to the Inventory, please contact Christine Pieper, Director of Development, or use the donate button below.

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