Taxon Report

Eschscholzia rhombipetala Greene

diamond-petaled California poppy

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Taxon Summary

Eschscholzia rhombipetala, commonly known as diamond-petaled California poppy, is a annual herb in the Papaveraceae that is found only in California. It occurs within Valley and foothill grassland (alkaline, and clay), growing at elevations from 0 to 975 meters. Eschscholzia rhombipetala is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.


  Classification

Scientific Name:
Eschscholzia rhombipetala Greene
Common Name:
diamond-petaled California poppy
Family: Papaveraceae
Element Code: PDPAP0A0D0
USDA Plants Symbol: ESRH
Synonyms/Other Names:

Ecology and Life History

Lifeform: annual herb
Blooming Period: Mar-Apr Mar-Apr
Elevation: 0-975 (0-3200)
General Habitats: Valley and foothill grassland
Microhabitat:
Microhabitat Details:

Occurrence Data from the CNDDB

Total Occurrences: 12
Element Occurrence Ranks:
   Excellent (A) 1
   Good (B) 3
   Fair (C) 2
   Poor (D) 0
   None (X) 2
   Unknown (U) 4
California Endemic:  True
California Counties and Islands: Name (Code)
Alameda (ALA), Colusa (COL)*, Contra Costa (CCA)*, Kern (KRN), San Joaquin (SJQ), San Luis Obispo (SLO), Stanislaus (STA)*
Quads: Name (Quad Code)
Antioch North (3812117)*, Byron Hot Springs (3712176)*, California Valley (3512031), Clifton Court Forebay (3712175), La Panza (3512032)?*, Las Yeguas Ranch (3511948)*, Lodoga (3912234), Midway (3712165), Patterson (3712142)*, Simmler (3511938), Tracy (3712164), Westley (3712152)

Threat List Data from the CNDDB

Threat List Total: 6
EOs with Threat Listed: Total EOs % of EOs
6 50 %
Agriculture 3 25%
Erosion/runoff 2 16%
Grazing 2 16%
Non-native plant impacts 1 8%
Recreational use (non-ORV) 1 8%
Foot traffic/trampling 1 8%

Notes

Rediscovered on Carrizo Plain by David Keil in 1992. Also found at Lawrence Livermore Laboratory Site 300, ALA Co. in 1997. Historical occurrence for SJQ Co. from literature lacks documentation; occurrence from La Panza, SLO Co. (244C) probably misidentified E. lemmonii ssp. lemmonii. Threatened by agriculture and grazing. See MadroƱo 47(2):138 (2000) for ALA Co. occurrence information and 50(1):1-7 (2003) for population characteristics information.
Threats:
Taxonomy:
Citation California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 30 January 2025].