Taxon Report

Castilleja ambigua Hook. & Arn. var. heckardii J. M. Egger & Excoffier

Heckard's owl's-clover

Print Report

Taxon Summary

Castilleja ambigua var. heckardii, commonly known as Heckard's owl's-clover, is a annual herb in the Orobanchaceae that is found only in California. It occurs within Coastal prairie, growing at elevations from 50 to 180 meters. Castilleja ambigua var. heckardii is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.

Classification


Scientific Name:	Castilleja ambigua Hook. & Arn. var. heckardii J. M. Egger & Excoffier
Common Name:	Heckard's owl's-clover
Family:	Orobanchaceae
Element Code:	PDSCR0D405
USDA Plants Symbol:
Synonyms/Other Names:

Ecology and Life History


Lifeform:	annual herb
Blooming Period: May-Jul	May-Jul
Elevation:	50-180 (165-590)
General Habitats:	Coastal prairie
Microhabitat:	Openings, Sandy, Vernally Mesic
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	1B.1
Global Rank:	G5T1
State Rank:	S1
State List:	None
Fed List:	None
Other Status:
CRPR Changes:	added to 1B.1 on 2022-04-07

Occurrence Data from the CNDDB


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

Location


California Endemic: False
California Counties and Islands: Name (Code)
San Luis Obispo (SLO)
Quads: Name (Quad Code)
Burro Mountain (3512173), Piedras Blancas (3512163)

Threat List Data from the CNDDB


Threat List Total:	0
EOs with Threat Listed:	Total EOs	% of EOs
	0	%

Notes




Threats:
Potentially threatened by inappropriate grazing and non-native plants.
Taxonomy:
Previously identified as C. ambigua ssp. ambigua and ssp. insalutata.

Selected References

Proposed Addition to CRPR 1B.1, G5T1 / S1 (2022)

Phytoneuron 15: 1–17 (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 14 November 2025].