Taxon Report

Oxytheca watsonii T. & G.

Watson's oxytheca

Print Report

Taxon Summary

Oxytheca watsonii, commonly known as Watson's oxytheca, is a annual herb in the Polygonaceae that is found in California and elsewhere. It occurs within Joshua tree "woodland", and Mojavean desert scrub, growing at elevations from 1200 to 2000 meters. Oxytheca watsonii is ranked 2B.2, Plants Rare, Threatened, or Endangered in California, But More Common Elsewhere; Moderately threatened in California.

Classification


Scientific Name:	Oxytheca watsonii T. & G.
Common Name:	Watson's oxytheca
Family:	Polygonaceae
Element Code:	PDPGN0J070
USDA Plants Symbol:	OXWA
Synonyms/Other Names:

Ecology and Life History


Lifeform:	annual herb
Blooming Period: May-Jul	May-Jul
Elevation:	1200-2000 (3935-6560)
General Habitats:	Joshua tree "woodland", Mojavean desert scrub
Microhabitat:	Sandy
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	2B.2
Global Rank:	G2
State Rank:	S1
State List:	None
Fed List:	None
Other Status:
CRPR Changes:	changed from 2.2 to 2B.2 on 2013-06-12

Occurrence Data from the CNDDB


Total Occurrences:	7
Element Occurrence Ranks:
Excellent (A)	0
Good (B)	1
Fair (C)	0
Poor (D)	0
None (X)	0
Unknown (U)	6

Location


California Endemic: False
California Counties and Islands: Name (Code)
Inyo (INY)
Quads: Name (Quad Code)
Darwin (3611735), Emigrant Canyon (3611742), Emigrant Pass (3611732), Harris Hill (3611754), Lee Wash (3611745), Nelson Range (3611756), Santa Rosa Flat (3611746), Talc City Hills (3611736)

Threat List Data from the CNDDB


Threat List Total:	3
EOs with Threat Listed:	Total EOs	% of EOs
	2	29 %
Grazing	1	14%
ORV activity	1	14%
Recreational use (non-ORV)	1	14%

Notes



Known in CA from fewer than five occurrences. See Madroño 29(4):273-274 (1982) for first CA occurrences, and Phytologia 66(4):385-86 (1989) for taxonomic treatment.
Threats:

Taxonomy:

Selected References

Citation California Native Plant Society, Rare Plant Program. 2026. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 4 April 2026].