California Native Plant Society

The California Rare Plant Ranking System

CNPS announces new and revised California Rare Plant Ranks: 2A and 2B!

Poliomintha incana
Poliomintha incana (Photo by Al Schneider) With the advent of the new California Rare Plant Ranks, Poliomintha incana was recently changed from CRPR 1A to 2A. It is presumed extirpated in California, where only known from a single historical collection from 1938 at Cushenbury Springs, San Bernardino County. Poliomintha incana was possibly extirpated in California from mining activities. Like all CRPR 2A plants, it is common outside of the state and still has the potential to be rediscovered in California.

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. CRPR 2B contains all of the plants formerly included on CRPR 2, and are defined as plants that are rare in California, but are more common outside of the state's boundaries. CRPR 2A includes a small number of plants formerly included on CRPR 1A, which are presumed extirpated in California, but more common elsewhere. These new ranks help further clarify that CRPR '2' plants are more common outside of California, while emphasizing that CRPR '1' plants are rare throughout their entire range. Furthermore, with the addition of CRPR 2A, the definition of 1A has been revised to include only those plants that are presumed to be wholly extinct or that have been extirpated in California and are rare elsewhere.

At the same time, the newly named CRPR 2B (formerly CRPR 2) further delineates its parallels with CRPR 1B; emphasizing the importance of protecting plants that are rare in California, regardless of how common they may be elsewhere. California state laws, namely the California Environmental Quality Act (CEQA), clearly indicate that the evaluation of a plant or animal's rarity is restricted to its range and abundance within the borders of California. As a result, CRPR 2B plants are afforded the same consideration in the evaluation of a project's environmental impacts as CRPR 1B plants. From a practical perspective, it is imperative that we protect the diversity of our own state's flora and help maintain genetic diversity and evolutionary processes regardless of jurisdictional boundaries.

In order to help remember and understand the new CRPR 2A and renamed CRPR 2B, one can think of the designations in the following manner; where '1' and '2' are qualifiers of the geographic extent of rarity, and 'A' and 'B' are qualifiers of extirpation and/or rarity:

  • 1 = Rare in California and elsewhere
  • 2 = Rare in California, but not elsewhere
  • A = Presumed extirpated or extinct
  • B = Rare, threatened, or endangered
Poliomintha incana Pyrola Pyrola
Pyrola chlorantha - Photos by Diana D. Jolles (left, center) and Thomas Stoughton (right)
Pyrola chlorantha
is common to the Circumboreal Region and presumed extirpated in California. It was recently changed from CRPR 1A to the new CRPR 2A in the CNPS Inventory. In California it is only known from a single historical collection near Downieville, Sierra County. Field work is needed in attempts to potentially rediscover this presumed extirpated species in California."


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