Taxon Report

Isocoma arguta Greene

Carquinez goldenbush

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Taxon Summary

Isocoma arguta, commonly known as Carquinez goldenbush, is a perennial shrub in the Asteraceae that is found only in California. It occurs within Valley and foothill grassland, growing at elevations from 1 to 20 meters. Isocoma arguta is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.


  Classification

Scientific Name:
Isocoma arguta Greene
Common Name:
Carquinez goldenbush
Family: Asteraceae
Element Code: PDAST57050
USDA Plants Symbol: ISAR2
Synonyms/Other Names:

Ecology and Life History

Lifeform: perennial shrub
Blooming Period: Aug-Dec Aug-Dec
Elevation: 1-20 (5-65)
General Habitats: Valley and foothill grassland
Microhabitat:
Microhabitat Details:

Occurrence Data from the CNDDB

Total Occurrences: 14
Element Occurrence Ranks:
   Excellent (A) 0
   Good (B) 4
   Fair (C) 3
   Poor (D) 0
   None (X) 0
   Unknown (U) 7
California Endemic:  True
California Counties and Islands: Name (Code)
Contra Costa (CCA), Solano (SOL)
Quads: Name (Quad Code)
Benicia (3812212), Birds Landing (3812127), Briones Valley (3712282), Cordelia (3812222), Denverton (3812128), Dozier (3812137), Elmira (3812138), Mare Island (3812213), Vine Hill (3812211), Walnut Creek (3712281)

Threat List Data from the CNDDB

Threat List Total: 7
EOs with Threat Listed: Total EOs % of EOs
8 57 %
Grazing 3 21%
Road/trail construction/maint. 3 21%
Other 1 7%
Recreational use (non-ORV) 1 7%
Agriculture 1 7%
Biocides 1 7%
Development 1 7%

Notes

Threatened by grazing and trampling at Jepson Prairie Preserve. Treatened by development and agriculture elsewhere. See Manual of the Botany of the Region of San Francisco Bay, p. 175 (1894) by E. Greene for original description, and Phytologia 70(2):69-114 (1991) for taxonomic treatment.
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 8 March 2025].