Taxon Report

Phacelia cookei Const. & Heckard

Cooke's phacelia

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Taxon Summary

Phacelia cookei, commonly known as Cooke's phacelia, is a annual herb in the Hydrophyllaceae that is found only in California. It occurs within Great Basin scrub, and Lower montane coniferous forest, growing at elevations from 1095 to 1700 meters. Phacelia cookei is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.

Classification


Scientific Name:	Phacelia cookei Const. & Heckard
Common Name:	Cooke's phacelia
Family:	Hydrophyllaceae
Element Code:	PDHYD0C0Y0
USDA Plants Symbol:	PHCO20
Synonyms/Other Names:

Ecology and Life History


Lifeform:	annual herb
Blooming Period: Jun-Jul	Jun-Jul
Elevation:	1095-1700 (3595-5580)
General Habitats:	Great Basin scrub, Lower montane coniferous forest
Microhabitat:	Sandy, Volcanic
Microhabitat Details:

Conservation Status


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

Occurrence Data from the CNDDB


Total Occurrences:	6
Element Occurrence Ranks:
Excellent (A)	1
Good (B)	0
Fair (C)	0
Poor (D)	0
None (X)	0
Unknown (U)	5

Location


California Endemic: True
California Counties and Islands: Name (Code)
Siskiyou (SIS)
Quads: Name (Quad Code)
Juniper Flat (4112253), The Whaleback (4112252)

Threat List Data from the CNDDB


Threat List Total:	4
EOs with Threat Listed:	Total EOs	% of EOs
	5	83 %
Other	4	66%
Road/trail construction/maint.	1	16%
Biocides	1	16%
Non-native plant impacts	1	16%

Notes



Known from fewer than five occurrences. Threatened by non-native plants, and possibly by fire suppression. See Brittonia 22(1):25-30 (1970) for original description.
Threats:

Taxonomy:

Selected References

Phacelia cookei account for potential Species of Conservation Concern evaluation (2021)

Citation California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 7 November 2025].