How the CNPS Rare Plants List Affects CEQA Environmental Review

Many projects requiring CEQA review involve CNPS listed plants, which may have left you asking: What is CNPS, anyway? A consortium of scientists, botanists, and enthusiasts, the California Native Plants Society (CNPS) has a mission to accurately review and categorize the rarity of native plants in California.  The resulting list of sensitive plant species produced by CNPS can be above and beyond the federal and state lists of threatened and endangered species. CNPS rankings can therefore be used as a criterion for environmental review in the CEQA process.


CNPS-ranked plants come into play during the California Environmental Quality Act (CEQA) environmental review process of a proposed project.  If a property has suitable habitat, CEQA may require analysis for all CNPS Rank 1B, Rank 2, Rank 3 and Rank 4 plants that could potentially occur in the vicinity.  Surveys should be completed to California Department of Fish and Wildlife  and CNPS protocols and during the plant species’ blooming period to stand up to rigorous environmental review.  Leaving out CNPS species now can mean more work later!   But even worse, if the blooming season is missed, a project could be held up for an entire year until a survey can be completed the next blooming season.

Background of CNPS

CNPS formed in 1965 as an organization with an avid interest in native plants.  Over time, its goals have evolved from promoting native plant appreciation to encouraging research, education, and conservation of sensitive native plants.  The CNPS mission is to “develop current, accurate information on the distribution, ecology, and conservation of California’s rare and endangered plants” (CNPS 2012).  This information is then used to establish new and continually improving science-based conservation approaches within California.

How the CNPS Ranking System Works

CNPS places sensitive native plants into categories or ranks reflecting degrees of concern.  The most common rankings break down as follows:

  • Rank 1B:  Plants rare, threatened, or endangered in California and elsewhere.
  • Rank 2:  Plant rare, threatened, or endangered in California, but are more common elsewhere.
  • Rank 3:  Plants about which we need more information – a review list.
  • Rank 4:  Plants that have a limited distribution – a watch list.

Some additional background is important to understand the full implications of these rankings.  First, Rank 1B plants are considered most rare by CNPS and the closest to possible extinction.  Rank 2 clearly reflects plants that may be abundant elsewhere, but are rare, threatened, or endangered in California.  However, Rank 1, 2, and 3 plants are all considered rare in California; “rare” means that this species has been analyzed by a CNPS Rare Plant Biologist and then approved by a consensus of industry professionals.  Rank 4 plants – the watch list plants- may be considered to be rare species if they occur in less than two California counties or if they are of  local concern.  Plants with these rankings may not be considered rare by federal or state government standards.  Therefore not all CNPS-ranked plants are listed as threatened or endangered on a federal or state level. 

An Example of the Difference Between CNPS and Federal Listing

Congdon’s tarplant (Centromadia parryi ssp. congdonii) provides a good example.  As a Rank 1B plant, this species is considered rare in California.  This annual herb blooms between May and November, and is typically found in grasslands.  CNPS believes Congdon’s tarplant is severely threatened by development and, to a lesser extent, by grazing and invasion of non-native plants.   Despite the concern and ranking by CNPS, it is not listed as a federally or state threatened or endangered species.