Taxon Report

Calystegia collina (E.Greene) Brummitt ssp. tridactylosa (Eastw.) Brummitt

three-fingered morning-glory

Print Report

Taxon Summary

Calystegia collina ssp. tridactylosa, commonly known as three-fingered morning-glory, is a perennial rhizomatous herb in the Convolvulaceae that is found only in California. It occurs within Chaparral, and Cismontane woodland, growing at elevations from 0 to 600 meters. Calystegia collina ssp. tridactylosa is ranked 1B.2, Plants Rare, Threatened or Endangered in California and Elsewhere; Moderately threatened in California.

Classification


Scientific Name:	Calystegia collina (E.Greene) Brummitt ssp. tridactylosa (Eastw.) Brummitt
Common Name:	three-fingered morning-glory
Family:	Convolvulaceae
Element Code:	PDCON04036
USDA Plants Symbol:	CACOT
Synonyms/Other Names:

Ecology and Life History


Lifeform:	perennial rhizomatous herb
Blooming Period: Apr-Jun	Apr-Jun
Elevation:	0-600 (0-1970)
General Habitats:	Chaparral, Cismontane woodland
Microhabitat:	Gravelly, Openings, Rocky, Serpentine
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	1B.2
Global Rank:	G4T1T2
State Rank:	S1S2
State List:	None
Fed List:	None
Other Status:	BLM_S
CRPR Changes:	added to 1B.2 on 2006-11-17

Occurrence Data from the CNDDB


Total Occurrences:	11
Element Occurrence Ranks:
Excellent (A)	2
Good (B)	0
Fair (C)	1
Poor (D)	0
None (X)	0
Unknown (U)	8

Location


California Endemic: True
California Counties and Islands: Name (Code)
Colusa (COL), Lake (LAK), Mendocino (MEN)
Quads: Name (Quad Code)
Brushy Mtn. (3912352), Covelo West (3912373), Dos Rios (3912363), Hull Mountain (3912258), Jamison Ridge (3912362), Leesville (3912224), Plaskett Ridge (3912268), The Geysers (3812277), Wilbur Springs (3912214)

Threat List Data from the CNDDB


Threat List Total:	2
EOs with Threat Listed:	Total EOs	% of EOs
	2	18 %
Development	2	18%
Road/trail construction/maint.	1	9%

Notes



Potentially threatened by geothermal energy development. May intergrade with Calystegia occidentalis ssp. occidentalis and Calystegia malacophylla ssp. malacophylla. See Proceedings of the California Academy of Sciences, series 4, 20: 151 (1931) for original description and Annals of the Missouri Botanical Garden 52(2): 214-216 (1965) for revised nomenclature.
Threats:

Taxonomy:

Selected References

Proposed Addition to CRPR 1B.2, G4T1 / S1.2 (2006)

Citation California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 7 December 2025].