Taxon Report

Alopecurus aequalis Sobol. var. sonomensis Rubtzoff

Sonoma alopecurus

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Taxon Summary

Alopecurus aequalis var. sonomensis, commonly known as Sonoma alopecurus, is a perennial herb in the Poaceae that is found only in California. It occurs within Marshes and swamps (freshwater), and Riparian scrub, growing at elevations from 5 to 365 meters. Alopecurus aequalis var. sonomensis is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.

Classification


Scientific Name:	Alopecurus aequalis Sobol. var. sonomensis Rubtzoff
Common Name:	Sonoma alopecurus
Family:	Poaceae
Element Code:	PMPOA07012
USDA Plants Symbol:	ALAES
Synonyms/Other Names:

Ecology and Life History


Lifeform:	perennial herb
Blooming Period: May-Jul	May-Jul
Elevation:	5-365 (15-1200)
General Habitats:	Marshes and swamps, Riparian scrub
Microhabitat:
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	1B.1
Global Rank:	G5T1
State Rank:	S1
State List:	None
Fed List:	FE
Other Status:	SB_CalBG/RSABG
CRPR Changes:

Occurrence Data from the CNDDB


Total Occurrences:	21
Element Occurrence Ranks:
Excellent (A)	0
Good (B)	3
Fair (C)	2
Poor (D)	3
None (X)	6
Unknown (U)	7

Location


California Endemic: True
California Counties and Islands: Name (Code)
Marin (MRN), Sonoma (SON)
Quads: Name (Quad Code)
Bolinas (3712286), Camp Meeker (3812248), Drakes Bay (3812218), Duncans Mills (3812341), Inverness (3812217), Kenwood (3812245), Sebastopol (3812247), Two Rock (3812237)

Threat List Data from the CNDDB


Threat List Total:	6
EOs with Threat Listed:	Total EOs	% of EOs
	13	62 %
Grazing	10	47%
Other	5	23%
Foot traffic/trampling	3	14%
Non-native plant impacts	3	14%
Development	2	9%
Altered flood/tidal/hydrologic regime	1	4%

Notes



Two occurrences introduced in 1987 (485C, 485D), but both appear to have failed as of 1993. Historical localities need field surveys. See A. aequalis in The Jepson Manual.
Threats:
Threatened by cattle trampling, wetland habitat loss, and non-native plants.
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 6 November 2025].