Taxon Report

Chorizanthe valida Wats.

Sonoma spineflower

Print Report

Taxon Summary

Chorizanthe valida, commonly known as Sonoma spineflower, is a annual herb in the Polygonaceae that is found only in California. It occurs within Coastal prairie, growing at elevations from 10 to 305 meters. Chorizanthe valida is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.

Classification


Scientific Name:	Chorizanthe valida Wats.
Common Name:	Sonoma spineflower
Family:	Polygonaceae
Element Code:	PDPGN040V0
USDA Plants Symbol:	CHVA
Synonyms/Other Names:

Ecology and Life History


Lifeform:	annual herb
Blooming Period: Jun-Aug	Jun-Aug
Elevation:	10-305 (35-1000)
General Habitats:	Coastal prairie
Microhabitat:
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	1B.1
Global Rank:	G1
State Rank:	S1
State List:	CE
Fed List:	FE
Other Status:	SB_CalBG/RSABG
CRPR Changes:

Occurrence Data from the CNDDB


Total Occurrences:	6
Element Occurrence Ranks:
Excellent (A)	0
Good (B)	3
Fair (C)	0
Poor (D)	0
None (X)	3
Unknown (U)	0

Location


California Endemic: True
California Counties and Islands: Name (Code)
Marin (MRN), Sonoma (SON)*
Quads: Name (Quad Code)
Arched Rock (3812342), Drakes Bay (3812218), Fort Ross (3812352), Petaluma (3812226)?, Petaluma River (3812225), Plantation (3812353), Sebastopol (3812247)*

Threat List Data from the CNDDB


Threat List Total:	4
EOs with Threat Listed:	Total EOs	% of EOs
	3	50 %
Grazing	3	50%
Other	2	33%
Road/trail construction/maint.	1	16%
Non-native plant impacts	1	16%

Notes



Thought extinct for 77 years; only known extant occurrence was rediscovered in 1980 at Pt. Reyes NS. Experimental introduction work ongoing as of 2000. Closely related to C. pungens. See Proceedings of the American Academy of Arts and Sciences 12:271 (1877) for original description, Phytologia 66(2):132-134 (1989) for taxonomic treatment, Fremontia 18(1):17-18 (1990) for species account, and Madroño 39(4):271-280 (1992) and 40(4):285-288 (1993) for discussion of grazing effects.
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 29 October 2025].