California Native Plant Society

The California Rare Plant Ranking System

California Rare Plant Ranks (formerly known as CNPS Lists)

CNPS initially created five California Rare Plant Ranks (CRPR) in an effort to categorize degrees of concern; however, in order to better define and categorize rarity in California's flora, the CNPS Rare Plant Program and Rare Plant Program Committee have developed the new California Rare Plant Ranks (CRPR) 2A and CRPR 2B (see this page for more information). These new categories, in addition to the initial categories, are described as follows:

Astragalus pycnostachyus var. lanosissimus (photo by Nick Jensen 2006)
Astragalus pycnostachyus var. lanosissimus (Rediscovered in 1997- now CRPR 1B.1), photo by Nick Jensen 2006
Mimulus pictus (photo by Lara Hartley 2006)
Mimulus pictus (CRPR 1B.2), photo by Lara Hartley 2006

California Rare Plant Rank 1A: Plants Presumed Extirpated in California and Either Rare or Extinct Elsewhere

The plants with a California Rare Plant Rank of 1A are presumed extirpated because they have not been seen or collected in the wild in California for many years. This rank includes plants that are both presumed extinct as well as those plants which are presumed extirpated in California. A plant is extinct if it no longer occurs anywhere. A plant that is extirpated from California has been eliminated from California, but may still occur elsewhere in its range.

All of the plants constituting California Rare Plant Rank 1A meet the definitions of Secs. 2062 and 2067 (California Endangered Species Act) of the California Department of Fish and Game Code, and are eligible for state listing. Should these taxa be rediscovered, it is mandatory that they be fully considered during preparation of environmental documents relating to the California Environmental Quality Act (CEQA).

California Rare Plant Rank 1B: Plants Rare, Threatened, or Endangered in California and Elsewhere

Plants with a California Rare Plant Rank of 1B are rare throughout their range with the majority of them endemic to California. Most of the plants that are ranked 1B have declined significantly over the last century. California Rare Plant Rank 1B plants constitute the majority of taxa in the CNPS Inventory, with more than 1,000 plants assigned to this category of rarity.

All of the plants constituting California Rare Plant Rank 1B meet the definitions of Secs. 2062 and 2067 (California Endangered Species Act) of the California Department of Fish and Game Code, and are eligible for state listing. It is mandatory that they be fully considered during preparation of environmental documents relating to CEQA.

California Rare Plant Rank 2A: Plants Presumed Extirpated in California, But More Common Elsewhere

Penstemon janishiae (photo by Cheryl Beyer)
Penstemon janishiae (CRPR 2.2), photo by Cheryl Beyer

The plant taxa of California Rare Plant Rank 2A are presumed extirpated because they have not been observed or documented in California for many years. This list includes only those plant taxa that are presumed extirpated in California, but more common elsewhere in their range.

All of the plants on List 2A meet the definitions of Secs. 2062 and 2067 (California Endangered Species Act) of the California Department of Fish and Game Code, and are eligible for state listing. Should these taxa be rediscovered, it is mandatory that they be fully considered during preparation of environmental documents relating to the California Environmental Quality Act (CEQA).


California Rare Plant Rank 2B: Plants Rare, Threatened, or Endangered in California, But More Common Elsewhere

Except for being common beyond the boundaries of California, plants with a California Rare Plant Rank of 2B would have been ranked 1B. From the federal perspective, plants common in other states or countries are not eligible for consideration under the provisions of the Endangered Species Act.

With California Rare Plant Rank 2B, we recognize the importance of protecting the geographic range of widespread species. In this way we protect the diversity of our own state's flora and help maintain evolutionary processes and genetic diversity within species. All of the plants constituting California Rare Plant Rank B2 meet the definitions of Secs. 2062 and 2067 (California Endangered Species Act) of the California Department of Fish and Game Code, and are eligible for state listing. It is mandatory that they be fully considered during preparation of environmental documents relating to CEQA.

California Rare Plant Rank 3: Plants About Which More Information is Needed - A Review List

Salvia dorrii var. incana (photo by Steve Matson 2006)
Salvia dorrii var. incana (CRPR 3), photo by Steve Matson 2006

The plants that comprise California Rare Plant Rank 3 are united by one common theme - we lack the necessary information to assign them to one of the other ranks or to reject them. Nearly all of the plants constituting California Rare Plant Rank 3 are taxonomically problematic. For each California Rare Plant Rank 3 plant we have provided the known information and indicated in the "Notes" section of the CNPS Inventory record where assistance is needed. Data regarding distribution, endangerment, ecology, and taxonomic validity are welcomed and can be submitted by emailing the Rare Plant Botanist at asims cnps.org or (916) 324-3816.

Some of the plants constituting California Rare Plant Rank 3 meet the definitions of Secs. 2062 and 2067 (California Endangered Species Act) of the California Department of Fish and Game Code, and are eligible for state listing. We strongly recommend that California Rare Plant Rank 3 plants be evaluated for consideration during preparation of environmental documents relating to CEQA.

California Rare Plant Rank 4: Plants of Limited Distribution - A Watch List

Phacelia exilis (photo by Lara Hartley 2005)
Phacelia exilis (CRPR 4.3), photo by Lara Hartley 2005

The plants in this category are of limited distribution or infrequent throughout a broader area in California. While we cannot call these plants "rare" from a statewide perspective, they are uncommon enough that their status should be monitored regularly. Should the degree of endangerment or rarity of a California Rare Plant Rank 4 plant change, we will transfer it to a more appropriate rank.

Some of the plants constituting California Rare Plant Rank 4 meet the definitions of Secs. 2062 and 2067 (California Endangered Species Act) of the California Department of Fish and Game Code, and few, if any, are eligible for state listing. Nevertheless, many of them are significant locally, and we strongly recommend that California Rare Plant Rank 4 plants be evaluated for consideration during preparation of environmental documents relating to CEQA. This may be particularly appropriate for:

  • The type locality of a California Rare Plant Rank 4 plant,
  • Populations at the periphery of a species' range,
  • Areas where the taxon is especially uncommon,
  • Areas where the taxon has sustained heavy losses, or
  • Populations exhibiting unusual morphology or occurring on unusual substrates.

Threat Ranks

The CNPS Threat Rank is an extension added onto the California Rare Plant Rank and designates the level of threats by a 1 to 3 ranking with 1 being the most threatened and 3 being the least threatened. A Threat Rank is present for all California Rare Plant Rank 1B's, 2B's, 4's, and the majority of California Rare Plant Rank 3's. California Rare Plant Rank 4 plants are seldom assigned a Threat Rank of 0.1, as they generally have large enough populations to not have significant threats to their continued existence in California; however, certain conditions exist to make the plant a species of concern and hence be assigned a California Rare Plant Rank. In addition, all California Rare Plant Rank 1A and 2A (presumed extirpated in California), and some California Rare Plant Rank 3 (need more information) plants, which lack threat information, do not have a Threat Rank extension.

Threat Ranks

  • 0.1-Seriously threatened in California (over 80% of occurrences threatened / high degree and immediacy of threat)
  • 0.2-Moderately threatened in California (20-80% occurrences threatened / moderate degree and immediacy of threat)
  • 0.3-Not very threatened in California (<20% of occurrences threatened / low degree and immediacy of threat or no current threats known)

Notes:

  1. The above Threat Rank guidelines only represent a starting point in the assessment of threat level. Other factors, such as habitat vulnerability and specificity, distribution, and condition of occurrences, are also considered in setting the Threat Rank.
  2. Many of the Threat Ranks have not been reassessed since the time they were first designated after implementation of the Rare Plant Status Review Process, and therefore may not represent the current level of threats associated with a given taxon.
  3. The Threat Ranks do not designate a change of environmental protections. For instance a CRPR 1B.3 plant has the same environmental protections as a CRPR 1B.1 plant, and it is mandatory that both be fully considered during preparation of environmental documents relating to CEQA.

 

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