Taxon Report

Calystegia vanzuukiae Brummitt & Namoff

Van Zuuk's morning-glory

Print Report

Taxon Summary

Calystegia vanzuukiae, commonly known as Van Zuuk's 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 500 to 1180 meters. Calystegia vanzuukiae is ranked 1B.3, Plants Rare, Threatened or Endangered in California and Elsewhere; Not very threatened in California.

Classification


Scientific Name:	Calystegia vanzuukiae Brummitt & Namoff
Common Name:	Van Zuuk's morning-glory
Family:	Convolvulaceae
Element Code:	PDCON040Q0
USDA Plants Symbol:	CAVA
Synonyms/Other Names:

Ecology and Life History


Lifeform:	perennial rhizomatous herb
Blooming Period: May-Aug	May-Aug
Elevation:	500-1180 (1640-3870)
General Habitats:	Chaparral, Cismontane woodland
Microhabitat:	Gabbroic, Serpentine
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	1B.3
Global Rank:	G2
State Rank:	S2
State List:	None
Fed List:	None
Other Status:	BLM_S; SB_UCSC
CRPR Changes:	added to 1B.3 on 2014-07-16

Occurrence Data from the CNDDB


Total Occurrences:	13
Element Occurrence Ranks:
Excellent (A)	3
Good (B)	3
Fair (C)	1
Poor (D)	1
None (X)	0
Unknown (U)	5

Location


California Endemic: True
California Counties and Islands: Name (Code)
El Dorado (ELD), Placer (PLA)
Quads: Name (Quad Code)
Dutch Flat (3912027), Foresthill (3912017), Garden Valley (3812077), Georgetown (3812087), Michigan Bluff (3912016)

Threat List Data from the CNDDB


Threat List Total:	9
EOs with Threat Listed:	Total EOs	% of EOs
	9	69 %
Road/trail construction/maint.	8	61%
Non-native plant impacts	6	46%
ORV activity	4	30%
Recreational use (non-ORV)	2	15%
Dam/Inundation	2	15%
Foot traffic/trampling	2	15%
Logging	2	15%
Mining	1	7%
Other	1	7%

Notes



Known only from the Central Sierra Nevada foothills. Potentially threatened by mining, vehicles, and non-native plants. Probably a stabilized hybrid between C. stebbinsii and C. occidentalis ssp. occidentalis. See Aliso 31(1):15-18 (2013) for original description.
Threats:

Taxonomy:

Selected References

Proposed Addition to CRPR 1B.3, G2Q / S2 (2014)

Citation California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 16 November 2025].