Taxon Report

Leptosyne hamiltonii Elmer

Mt. Hamilton coreopsis

Print Report

Taxon Summary

Leptosyne hamiltonii, commonly known as Mt. Hamilton coreopsis, is a annual herb in the Asteraceae that is found only in California. It occurs within Cismontane woodland, growing at elevations from 550 to 1300 meters. Leptosyne hamiltonii is ranked 1B.2, Plants Rare, Threatened or Endangered in California and Elsewhere; Moderately threatened in California.

Classification


Scientific Name:	Leptosyne hamiltonii Elmer
Common Name:	Mt. Hamilton coreopsis
Family:	Asteraceae
Element Code:	PDAST2L0C0
USDA Plants Symbol:
Synonyms/Other Names:	Coreopsis hamiltonii

Ecology and Life History


Lifeform:	annual herb
Blooming Period: Mar-May	Mar-May
Elevation:	550-1300 (1805-4265)
General Habitats:	Cismontane woodland
Microhabitat:
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	1B.2
Global Rank:	G2
State Rank:	S2
State List:	None
Fed List:	None
Other Status:	BLM_S; SB_UCBG
CRPR Changes:

Occurrence Data from the CNDDB


Total Occurrences:	21
Element Occurrence Ranks:
Excellent (A)	12
Good (B)	6
Fair (C)	0
Poor (D)	0
None (X)	0
Unknown (U)	3

Location


California Endemic: True
California Counties and Islands: Name (Code)
Alameda (ALA), Santa Clara (SCL), Stanislaus (STA)
Quads: Name (Quad Code)
Cedar Mtn. (3712155), Isabel Valley (3712135), Lick Observatory (3712136), Lone Tree Creek (3712154), Mississippi Creek (3712124), Mt. Stakes (3712134), Solyo (3712153)

Threat List Data from the CNDDB


Threat List Total:	5
EOs with Threat Listed:	Total EOs	% of EOs
	5	24 %
Grazing	3	14%
Non-native plant impacts	1	4%
Vandalism/dumping/litter	1	4%
Erosion/runoff	1	4%
Feral pigs	1	4%

Notes



Known only from the Mt. Hamilton Range. See Botanical Gazette 41:323-324 (1906) for original description, and Madroño 4(7):214-215 (1938) for revised nomenclature.
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 20 November 2025].