CNPS Inventory
of Rare Plants

• 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

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.

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.

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.