Taxon Report

Mentzelia hirsutissima Wats.

hairy stickleaf

Print Report


Taxon Summary

Mentzelia hirsutissima, commonly known as hairy stickleaf, is a annual herb in the Loasaceae that is found in California and elsewhere. It occurs within Sonoran desert scrub, growing at elevations from 0 to 700 meters. Mentzelia hirsutissima is ranked 2B.3, Plants Rare, Threatened, or Endangered in California, But More Common Elsewhere; Not very threatened in California.

  Classification
Scientific Name:
 Mentzelia hirsutissima Wats.
Common Name:
 hairy stickleaf
Family: Loasaceae
Element Code: PDLOA030K0
USDA Plants Symbol: MEHI3
Synonyms/Other Names:
  • Mentzelia hirsutissima Wats. var. stenophylla (Urb. & Gilg.) Jtn.

Ecology and Life History
Lifeform: annual herb
Blooming Period: Mar-May Mar-May
Elevation: 0-700 (0-2295)
General Habitats: Sonoran desert scrub
Microhabitat:
Microhabitat Details:

Conservation Status
CA Rare Plant Rank: 2B.3
Global Rank: G4?
State Rank:
 S3
State List: None
Fed List: None
Other Status: SB_CalBG/RSABG; SB_USDA
CRPR Changes:
  • changed from 2.3 to 2B.3 on 2013-06-12

Occurrence Data from the CNDDB
Total Occurrences: 28
Element Occurrence Ranks:
   Excellent (A) 1
   Good (B) 2
   Fair (C) 0
   Poor (D) 1
   None (X) 0
   Unknown (U) 24

Location
California Endemic:  False
California Counties and Islands: Name (Code)
Imperial (IMP), San Diego (SDG)
Quads: Name (Quad Code)
Agua Caliente Springs (3211683), Arroyo Tapiado (3211682), Borrego Mountain SE (3311611), Borrego Palm Canyon (3311634), Borrego Sink (3311623), Carrizo Mtn. (3211671), Coyote Wells (3211568), Earthquake Valley (3311614), Heber (3211565), In-ko-pah Gorge (3211661), Jacumba (3211662), Mount Signal (3211566), Painted Gorge (3211578), Sombrero Peak (3211673), Sweeney Pass (3211672)

Threat List Data from the CNDDB

Threat List Total: 6
EOs with Threat Listed: Total EOs % of EOs
5 18 %
ORV activity 4 14%
Foot traffic/trampling 2 7%
Non-native plant impacts 2 7%
Grazing 1 3%
Mining 1 3%
Vandalism/dumping/litter 1 3%

Notes
Possibly threatened by vehicles and foot traffic. See Proc. Am. Acad. 12: 252 (1877) for original description and Annals of the Missouri Botanical Garden 21: 201-202 (1934) for species account.
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 19 November 2025].