“List 3” Plants on the Rare Plant Inventory

By Dr. Douglas Stone

The CNPS Rare Plant Inventory (RPI) began in 1974 (almost 50 years ago!) and has been updated more or less continuously ever since. The original database was a set of index cards kept in an old shoebox, but don’t worry—we’re not that analog anymore! The RPI went through six print editions (1974– 2001) before going online.

List 3 (“Plants About Which We Need More Information”) did not appear until the third print edition (Smith & York 1984). At that time, there were 114 plant taxa added to this list, with a note that “[d]ata regarding distribution, endangerment, taxonomic validity, etc. will be gratefully received.”  Since then, some plant taxa have been removed from List 3, and others have been added.  Fast forward to 2022, and there are currently 72 species or infraspecies remaining on California Rare Plant Rank (CRPR) 3.  You can generate a list of these CRPR 3 plants using the “Advanced Search” utility in the RPI, then filtering on “3 Needs Review,” then clicking the “View all 72 Plants” button.

Of the 72 plant taxa currently on CRPR 3, the following 15 have remained there since the 3rd print edition of the RPI (Smith & York 1984). These plants were originally placed on List 3 due to distributional or taxonomic uncertainty, and their status has not changed in close to 40 years:

  • Agrostis hendersonii (Henderson’s bentgrass)
  • Erythranthe acutidens (Kings River monkeyflower)
  • Eschscholzia procera (Kernville poppy)
  • Fritillaria eastwoodiae (Butte County fritillary)
  • Galium oreganum (Oregon bedstraw)
  • Gentiana affinis var. parvidentata (small-toothed prairie gentian)
  • Lewisia cotyledon var. howellii (Howell’s lewisia)
  • Lupinus albifrons var. abramsii (Abrams’ lupine)
  • Lupinus arboreus var. eximius (San Mateo tree lupine)
  • Phacelia amabilis (Saline Valley phacelia)
  • Polystichum lonchitis (holly fern)
  • Ribes amarum var. hoffmannii (bitter gooseberry)
  • Salvia dorrii var. incana (fleshy sage)
  • Tiarella trifoliata var. trifoliata (trifoliate laceflower)
  • Vaccinium coccineum (Siskiyou Mtns. huckleberry)

Why have these plants been allowed to languish on List 3 for such a long time?  This happened due to a combination of previously limited funding and staffing for the RPI, and a policy of waiting for others to contribute the needed information.

In recent years, RPI staffing has grown and we now have the scientific capacity to address the CRPR 3 problem.  There has also been a notable shift in policy, so RPI staff are now more actively engaged in investigating our CRPR 3 plants. In cases of distributional uncertainty (33 taxa), we should be able to complete a status review based on information already at hand. This would allow us to move these plants to other status categories (i.e., CRPR 1A, 1B, 2A, 2B, or 4) or remove them from the RPI (“Considered But Rejected” or CBR).  Of course, we can always reevaluate these plants in future if new or better data become available.

Taxonomic problems (39 taxa) are more difficult to address, because they require gathering new data and publishing the results in a peer-reviewed, scientific journal. RPI staff have begun conducting original research on the genetics of CRPR 3 plants in collaboration with Profs. Travis Columbus and Naomi Fraga of the California Botanic Garden in Claremont.  CNPS members can help in this effort by conducting field work and collecting plant samples for DNA analysis.  For more information, please contact Dr. Doug Stone (dstone@cnps.org). I hope this exploration of List 3 plants in the RPI was useful for you. Please reach out if you have any feedback.



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