Taxon Details

Oxytheca watsonii

Watson's oxytheca

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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:
Name Status:	JEF, FNA, POWO, IPNI, Tropicos

Conservation Status

CA Rare Plant Rank:	2B.2
Fed List:	None
State List:	None
Global Rank:	G2
State Rank:	S1
Other Status:
CRPR Changes:
Add Date:	1980-01-01
Date Edited:	2025-10-29

Ecology and Life History

Lifeform: annual herb

Blooming Period: May-Jul

Elevation:
1200 - 2000 meters
3935 - 6560 feet

General Habitats:

Joshua tree "woodland"
Mojavean desert scrub

Microhabitat Details:

Microhabitat:

Sandy

Notes

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:

Threat List Data from the CNDDB

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

Occurrence Data from the CNDDB

Element Occurrence Ranks:
Total Occurrences:					7
A	B	C	D	X	U
0	1	0	0	0	6

Occurrence Status:
Historical >20 Years	4
Recent <=20 Years	3

Presence:
Presumed Extant	7
Possibly Extirpated	0
Presumed Extirpated	0

Location

California Endemic:

California Island:

States: Name (Code)
California (CA), Nevada (NV)

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)

Notes:

Definitions of codes following a county and/or quad:
*		Presumed extirpated
(?)		Occurrence confirmed, but possibly extirpated
Quad and county data is imported from the CNDDB. Species may be present in other areas where conditions are favorable. These data should NOT be substituted for pre-project review or for on-site surveys.

Regional Map

Map

Presumed Extant

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CNPS Rare Plant Inventory