Taxon Report

Cordylanthus nidularius J.T. Howell

Mt. Diablo bird's-beak

Print Report

Taxon Summary

Cordylanthus nidularius, commonly known as Mt. Diablo bird's-beak, is a annual herb (hemiparasitic) in the Orobanchaceae that is found only in California. It occurs within Chaparral, growing at elevations from 600 to 800 meters. Cordylanthus nidularius is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.

Classification


Scientific Name:	Cordylanthus nidularius J.T. Howell
Common Name:	Mt. Diablo bird's-beak
Family:	Orobanchaceae
Element Code:	PDSCR0J0F0
USDA Plants Symbol:	CONI2
Synonyms/Other Names:

Ecology and Life History


Lifeform:	annual herb (hemiparasitic)
Blooming Period: Jun-Aug	Jun-Aug
Elevation:	600-800 (1970-2625)
General Habitats:	Chaparral
Microhabitat:
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	1B.1
Global Rank:	G1
State Rank:	S1
State List:	CR
Fed List:	None
Other Status:	SB_UCBG
CRPR Changes:

Occurrence Data from the CNDDB


Total Occurrences:	2
Element Occurrence Ranks:
Excellent (A)	0
Good (B)	1
Fair (C)	0
Poor (D)	0
None (X)	0
Unknown (U)	1

Location


California Endemic: True
California Counties and Islands: Name (Code)
Contra Costa (CCA)
Quads: Name (Quad Code)
Clayton (3712188)

Threat List Data from the CNDDB


Threat List Total:	3
EOs with Threat Listed:	Total EOs	% of EOs
	1	50 %
Feral pigs	1	50%
Foot traffic/trampling	1	50%
Road/trail construction/maint.	1	50%

Notes



Known from only one occurrence on Mt. Diablo. Threatened by trail construction and recreation, and possibly by fire suppression. See Leaflets of Western Botany 3(9):207 (1943) for original description, and Systematic Botany Monographs 10:48-50 (1986) for taxonomic treatment.
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 5 November 2025].