Taxon Report

Castilleja ambigua Hook. & Arn. var. meadii J.M. Egger & J.A. Ruygt

Mead's owls-clover

Print Report

Taxon Summary

Castilleja ambigua var. meadii, commonly known as Mead's owls-clover, is a annual herb (hemiparasitic) in the Orobanchaceae that is found only in California. It occurs within Meadows and seeps, and Vernal pools, growing at elevations from 450 to 475 meters. Castilleja ambigua var. meadii 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. meadii J.M. Egger & J.A. Ruygt
Common Name:	Mead's owls-clover
Family:	Orobanchaceae
Element Code:	PDSCR0D404
USDA Plants Symbol:	CAAMM
Synonyms/Other Names:

Ecology and Life History


Lifeform:	annual herb (hemiparasitic)
Blooming Period: Apr-May	Apr-May
Elevation:	450-475 (1475-1560)
General Habitats:	Meadows and seeps, Vernal pools
Microhabitat:	Clay, Gravelly, Volcanic
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 2013-01-03

Occurrence Data from the CNDDB


Total Occurrences:	3
Element Occurrence Ranks:
Excellent (A)	0
Good (B)	0
Fair (C)	0
Poor (D)	0
None (X)	0
Unknown (U)	3

Location


California Endemic: True
California Counties and Islands: Name (Code)
Napa (NAP)
Quads: Name (Quad Code)
Capell Valley (3812242), Yountville (3812243)

Threat List Data from the CNDDB


Threat List Total:	1
EOs with Threat Listed:	Total EOs	% of EOs
	1	33 %
Non-native plant impacts	1	33%

Notes



Known only from the Atlas Peak area; needs field surveys. Threatened by non-native plants. Potentially threatened by vineyard development. Not in TJM 2. See Phytoneuron 2012-68:1-12 (2012) for original description.
Threats:

Taxonomy:

Selected References

Proposed Addition to CRPR 1B.1, G4T1 / S1 (2013)

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].