Taxon Report

Ceanothus decornutus V.T. Parker

Nicasio ceanothus

Print Report


© 2014 Vernon Smith

Taxon Summary

Ceanothus decornutus, commonly known as Nicasio ceanothus, is a perennial shrub in the Rhamnaceae that is found only in California. It occurs within Chaparral, growing at elevations from 235 to 290 meters. Ceanothus decornutus is ranked 1B.2, Plants Rare, Threatened or Endangered in California and Elsewhere; Moderately threatened in California.

  Classification
Scientific Name:
 Ceanothus decornutus V.T. Parker
Common Name:
 Nicasio ceanothus
Family: Rhamnaceae
Element Code: PDRHA04440
USDA Plants Symbol:
Synonyms/Other Names:

Ecology and Life History
Lifeform: perennial shrub
Blooming Period: Mar-May Mar-May
Elevation: 235-290 (770-950)
General Habitats: Chaparral
Microhabitat: Clay (sometimes), Rocky, Serpentine
Microhabitat Details:

Conservation Status
CA Rare Plant Rank: 1B.2
Global Rank: G1
State Rank:
 S1
State List: None
Fed List: None
Other Status: SB_CalBG/RSABG
CRPR Changes:
  • added to 1B.2 on 2016-06-16

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

Location
California Endemic:  True
California Counties and Islands: Name (Code)
Marin (MRN)
Quads: Name (Quad Code)
San Geronimo (3812216)

Threat List Data from the CNDDB

Threat List Total: 2
EOs with Threat Listed: Total EOs % of EOs
1 50 %
Non-native plant impacts 1 50%
Other 1 50%

Notes
Discovered in the 1980’s by Wilma Follette. Similar to C. jepsonii; primarily differs from it in having 5-merous flowers that are white, light blue, or pink. See Madroño 61(4):399-406 (2014) for original description.
Threats:
Potentially threatened by non-native plants. Possibly threatened by insect herbivory.
Taxonomy:

Selected References

Proposed Addition to CRPR 1B.2, G1 / S1 (2016)
Citation California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 27 January 2025].