Taxon Report

Sidotheca emarginata (H.M. Hall) Reveal

white-margined oxytheca

Print Report

Taxon Summary

Sidotheca emarginata, commonly known as white-margined oxytheca, is a annual herb in the Polygonaceae that is found only in California. It occurs within Chaparral, Lower montane coniferous forest, and Pinyon and juniper woodland, growing at elevations from 1200 to 2500 meters. Sidotheca emarginata is ranked 1B.3, Plants Rare, Threatened or Endangered in California and Elsewhere; Not very threatened in California.

Classification


Scientific Name:	Sidotheca emarginata (H.M. Hall) Reveal
Common Name:	white-margined oxytheca
Family:	Polygonaceae
Element Code:	PDPGN0J030
USDA Plants Symbol:
Synonyms/Other Names:	Oxytheca emarginata Hall

Ecology and Life History


Lifeform:	annual herb
Blooming Period: (Feb)Apr-Jul(Aug)	(Feb)Apr-Jul(Aug)
Elevation:	1200-2500 (3935-8205)
General Habitats:	Chaparral, Lower montane coniferous forest, Pinyon and juniper woodland
Microhabitat:
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	1B.3
Global Rank:	G3
State Rank:	S3
State List:	None
Fed List:	None
Other Status:	SB_CalBG/RSABG; SB_USDA; USFS_S
CRPR Changes:

Occurrence Data from the CNDDB


Total Occurrences:	21
Element Occurrence Ranks:
Excellent (A)	0
Good (B)	1
Fair (C)	0
Poor (D)	0
None (X)	0
Unknown (U)	20

Location


California Endemic: True
California Counties and Islands: Name (Code)
Riverside (RIV)
Quads: Name (Quad Code)
Anza (3311656), Butterfly Peak (3311655), Idyllwild (3311666), Palm View Peak (3311665), San Jacinto Peak (3311676), Toro Peak (3311654)

Threat List Data from the CNDDB


Threat List Total:	1
EOs with Threat Listed:	Total EOs	% of EOs
	1	5 %
Foot traffic/trampling	1	4%

Notes



Threatened by development, grazing, recreational activities, and trampling. See University of California Publications in Botany 1: 75 (1902) for original description, Harvard Papers in Botany 9(1): 211 (2004) for revised nomenclature, and Phytologia 66(4): 388 (1989) 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 26 October 2025].