Taxon Report

Sidalcea hickmanii Greene ssp. napensis S.R. Hill

Napa checkerbloom

Print Report


© Jake Ruygt

Taxon Summary

Sidalcea hickmanii ssp. napensis, commonly known as Napa checkerbloom, is a perennial herb in the Malvaceae that is found only in California. It occurs within Chaparral, growing at elevations from 415 to 610 meters. Sidalcea hickmanii ssp. napensis is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.

  Classification
Scientific Name:
 Sidalcea hickmanii Greene ssp. napensis S.R. Hill
Common Name:
 Napa checkerbloom
Family: Malvaceae
Element Code: PDMAL110A6
USDA Plants Symbol:
Synonyms/Other Names:

Ecology and Life History
Lifeform: perennial herb
Blooming Period: Apr-Jun Apr-Jun
Elevation: 415-610 (1360-2000)
General Habitats: Chaparral
Microhabitat:
Microhabitat Details: rhyolitic

Conservation Status
CA Rare Plant Rank: 1B.1
Global Rank: G2T1
State Rank:
 S1
State List: None
Fed List: None
Other Status: SB_CalBG/RSABG
CRPR Changes:
  • added to 1B.1 on 2009-04-02

Occurrence Data from the CNDDB
Total Occurrences: 2
Element Occurrence Ranks:
   Excellent (A) 0
   Good (B) 0
   Fair (C) 0
   Poor (D) 0
   None (X) 0
   Unknown (U) 2

Location
California Endemic:  True
California Counties and Islands: Name (Code)
Napa (NAP), Sonoma (SON)
Quads: Name (Quad Code)
Calistoga (3812255), Mt. George (3812232)

Threat List Data from the CNDDB

Threat List Total: 1
EOs with Threat Listed: Total EOs % of EOs
1 50 %
Agriculture 1 50%

Notes
Known from only 2 occurrences. Threatened by agriculture. See J. Bot. Res. Inst. Texas 2(2): 783-791 (2008) for original description.
Threats:
Taxonomy:

Selected References

CRPR List Addition on 2009-04-02
Citation California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 25 November 2025].