Taxon Report

Rhinotropis acanthoclada (A. Gray) J. R. Abbott

thorny milkwort

Print Report

Taxon Summary

Rhinotropis acanthoclada, commonly known as thorny milkwort, is a perennial shrub in the Polygalaceae that is found in California and elsewhere. It occurs within Chenopod scrub, Joshua tree "woodland", and Pinyon and juniper woodland, growing at elevations from 760 to 2285 meters. Rhinotropis acanthoclada is ranked 2B.3, Plants Rare, Threatened, or Endangered in California, But More Common Elsewhere; Not very threatened in California.

Classification


Scientific Name:	Rhinotropis acanthoclada (A. Gray) J. R. Abbott
Common Name:	thorny milkwort
Family:	Polygalaceae
Element Code:	PDPGL02020
USDA Plants Symbol:	POAC2
Synonyms/Other Names:	Polygala acanthoclada Gray

Ecology and Life History


Lifeform:	perennial shrub
Blooming Period: May-Aug	May-Aug
Elevation:	760-2285 (2495-7495)
General Habitats:	Chenopod scrub, Joshua tree "woodland", Pinyon and juniper woodland
Microhabitat:
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	2B.3
Global Rank:	G4
State Rank:	S2S3
State List:	None
Fed List:	None
Other Status:
CRPR Changes:	changed from 2.3 to 2B.3 on 2013-06-12

Occurrence Data from the CNDDB


Total Occurrences:	27
Element Occurrence Ranks:
Excellent (A)	0
Good (B)	4
Fair (C)	0
Poor (D)	0
None (X)	0
Unknown (U)	23

Location


California Endemic: False
California Counties and Islands: Name (Code)
Riverside (RIV), San Bernardino (SBD)
Quads: Name (Quad Code)
Castle Peaks (3511532), Crescent Peak (3511542), Ivanpah (3511533), Melville Lake (3411645), Mescal Range (3511545), Mineral Hill (3511544), Old Woman Springs (3411646), Pinto Valley (3511523), Porcupine Wash (3311577)

Threat List Data from the CNDDB


Threat List Total:	3
EOs with Threat Listed:	Total EOs	% of EOs
	3	11 %
ORV activity	3	11%
Development	2	7%
Mining	2	7%

Notes



See Proceedings of the American Academy of Arts and Sciences 11:73 (1876) for original description.
Threats:

Taxonomy:

Selected References

Proposed Non-Substantive Name Changes: Multiple taxa in various plant families from the Jepson eFlora revision 11 (2023)

Journal of the Botanical Research Institute of Texas 5: 125 – 137. (2011)

Citation California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 10 November 2025].