California Rare Plant Ranks

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While not a government agency, the California Native Plant Society (CNPS) is a statewide resource conservation organization that has developed an inventory of California's special-status plant species that is highly regarded by the agencies and biologists. This inventory is a summary of information on the distribution, rarity, and endangerment of California's vascular plants. Rare or potentially rare plant species are ranked using the following system (CRPR):

• 1A: Plants Presumed Extirpated in California and Either Rare or Extinct Elsewhere.

• 1B: Plants Rare, Threatened, or Endangered in California and Elsewhere.

• 2A: Plants Presumed Extirpated in California, But Common Elsewhere.

• 2B: Plants Rare, Threatened, or Endangered in California, But More Common Elsewhere.

• 3: Plants About Which More Information is Needed - A Review List.

• 4: Plants of Limited Distribution - A Watch List.

After each rarity ranking, there is also a threat ranking:

• 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 (less than 20% of occurrences threatened / low degree and immediacy of threat or no current threats known).

Endangered Braunton’s Milkvetch (Astragalus brauntonii) on a residential property burned in the Palisades Fire. Photo by Marcus C. England of England|Ecology.