Taxon Report

Hesperolinon didymocarpum H.K. Sharsm.

Lake County western flax

Print Report

Taxon Summary

Hesperolinon didymocarpum, commonly known as Lake County western flax, is a annual herb in the Linaceae that is found only in California. It occurs within Chaparral, Cismontane woodland, and Valley and foothill grassland, growing at elevations from 330 to 365 meters. Hesperolinon didymocarpum is ranked 1B.2, Plants Rare, Threatened or Endangered in California and Elsewhere; Moderately threatened in California.

Classification


Scientific Name:	Hesperolinon didymocarpum H.K. Sharsm.
Common Name:	Lake County western flax
Family:	Linaceae
Element Code:	PDLIN01070
USDA Plants Symbol:	HEDI3
Synonyms/Other Names:

Ecology and Life History


Lifeform:	annual herb
Blooming Period: May-Jul	May-Jul
Elevation:	330-365 (1085-1200)
General Habitats:	Chaparral, Cismontane woodland, Valley and foothill grassland
Microhabitat:	Serpentine
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	1B.2
Global Rank:	G1
State Rank:	S1
State List:	CE
Fed List:	None
Other Status:	BLM_S; SB_UCSC
CRPR Changes:

Occurrence Data from the CNDDB


Total Occurrences:	6
Element Occurrence Ranks:
Excellent (A)	0
Good (B)	2
Fair (C)	2
Poor (D)	0
None (X)	0
Unknown (U)	2

Location


California Endemic: True
California Counties and Islands: Name (Code)
Lake (LAK)
Quads: Name (Quad Code)
Middletown (3812275)

Threat List Data from the CNDDB


Threat List Total:	5
EOs with Threat Listed:	Total EOs	% of EOs
	4	67 %
Grazing	3	50%
Other	1	16%
Recreational use (non-ORV)	1	16%
Dam/Inundation	1	16%
Erosion/runoff	1	16%

Notes



Known from fewer than ten occurrences in the Big Cyn. area near Middletown. Potentially threatened by grazing, agriculture, and urbanization. See University of California Publications in Botany 32:235-314 (1961) for original description.
Threats:

Taxonomy:

Selected References

Citation California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 3 November 2025].