Taxon Report

Trifolium buckwestiorum Isely

Santa Cruz clover

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Taxon Summary

Trifolium buckwestiorum, commonly known as Santa Cruz clover, is a annual herb in the Fabaceae that is found only in California. It occurs within Broadleafed upland forest, Cismontane woodland, and Coastal prairie, growing at elevations from 35 to 610 meters. Trifolium buckwestiorum is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.

  Classification
Scientific Name:
 Trifolium buckwestiorum Isely
Common Name:
 Santa Cruz clover
Family: Fabaceae
Element Code: PDFAB402W0
USDA Plants Symbol: TRBU3
Synonyms/Other Names:

Ecology and Life History
Lifeform: annual herb
Blooming Period: Apr-Oct Apr-Oct
Elevation: 35-610 (115-2000)
General Habitats: Broadleafed upland forest, Cismontane woodland, Coastal prairie
Microhabitat: Gravelly
Microhabitat Details: margins

Conservation Status
CA Rare Plant Rank: 1B.1
Global Rank: G2
State Rank:
 S2
State List: None
Fed List: None
Other Status: BLM_S; SB_SBBG; SB_UCSC; SB_USDA
CRPR Changes:

Occurrence Data from the CNDDB
Total Occurrences: 64
Element Occurrence Ranks:
   Excellent (A) 6
   Good (B) 13
   Fair (C) 5
   Poor (D) 1
   None (X) 1
   Unknown (U) 38

Location
California Endemic:  True
California Counties and Islands: Name (Code)
Mendocino (MEN), Monterey (MNT), San Mateo (SMT), Santa Clara (SCL), Santa Cruz (SCR), Sonoma (SON)
Quads: Name (Quad Code)
Ano Nuevo (3712213), Big Foot Mtn. (3812372), Castle Rock Ridge (3712221), Cazadero (3812351), Comptche (3912335), Davenport (3712212), Elk (3912326), Eureka Hill (3812385), Felton (3712211), Fort Ross (3812352), Gube Mountain (3812373), Laughlin Range (3912333), Loma Prieta (3712117), Marina (3612167), McGuire Ridge (3812374), Mindego Hill (3712232), Mt. Sizer (3712125), Ornbaun Valley (3812383), Philo (3912314), Salinas (3612166), Santa Rosa (3812246), Seaside (3612157), Soquel (3612188), Spreckels (3612156), Two Rock (3812237), Zeni Ridge (3812384)

Threat List Data from the CNDDB

Threat List Total: 11
EOs with Threat Listed: Total EOs % of EOs
17 27 %
Non-native plant impacts 9 14%
Other 5 7%
Road/trail construction/maint. 5 7%
Logging 2 3%
Development 2 3%
Feral pigs 2 3%
Foot traffic/trampling 1 1%
Disease 1 1%
Erosion/runoff 1 1%
Recreational use (non-ORV) 1 1%
ORV activity 1 1%

Notes
Threatened by land clearing and non-native plants. Possibly threatened by road maintenance. See Madroño 39(2):90 (1992) for original description.
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 29 January 2025].