Taxon Report

Thelypodium stenopetalum Wats.

slender-petaled thelypodium

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Taxon Summary

Thelypodium stenopetalum, commonly known as slender-petaled thelypodium, is a perennial herb in the Brassicaceae that is found only in California. It occurs within Meadows and seeps (mesic, and alkaline), growing at elevations from 1600 to 2500 meters. Thelypodium stenopetalum is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.


  Classification

Scientific Name:
Thelypodium stenopetalum Wats.
Common Name:
slender-petaled thelypodium
Family: Brassicaceae
Element Code: PDBRA2N0F0
USDA Plants Symbol: THST
Synonyms/Other Names:

Ecology and Life History

Lifeform: perennial herb
Blooming Period: May-Sep May-Sep
Elevation: 1600-2500 (5250-8205)
General Habitats: Meadows and seeps
Microhabitat:
Microhabitat Details:

Occurrence Data from the CNDDB

Total Occurrences: 11
Element Occurrence Ranks:
   Excellent (A) 0
   Good (B) 4
   Fair (C) 1
   Poor (D) 1
   None (X) 4
   Unknown (U) 1
California Endemic:  True
California Counties and Islands: Name (Code)
San Bernardino (SBD)
Quads: Name (Quad Code)
Big Bear City (3411637), Big Bear Lake (3411628), Fawnskin (3411638), Moonridge (3411627)

Threat List Data from the CNDDB

Threat List Total: 14
EOs with Threat Listed: Total EOs % of EOs
11 100 %
Development 9 81%
Altered flood/tidal/hydrologic regime 8 72%
ORV activity 6 54%
Grazing 5 45%
Non-native plant impacts 5 45%
Wood cutting or brush clearing 5 45%
Foot traffic/trampling 4 36%
Other 3 27%
Recreational use (non-ORV) 2 18%
Road/trail construction/maint. 2 18%
Vandalism/dumping/litter 1 9%
Erosion/runoff 1 9%
Mining 1 9%
Non-native animal impacts 1 9%

Notes

Known from approximately ten occurrences. Seriously threatened by foot traffic, grazing, hydrological alterations, mining, vehicles, and urbanization. Protected in part at Baldwin Lake ER (DFG). See Proceedings of the American Academy of Arts and Sciences 22:468 (1887) for original description, Contributions from the Gray Herbarium 204:114-115 (1973) for taxonomic treatment, and Fremontia 13(1):22-23 (1985) for species account.
Threats:
Taxonomy:
Citation California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 14 March 2025].