Taxon Report

Lomatium observatorium Constance & Ertter

Mt. Hamilton lomatium

Print Report

Taxon Summary

Lomatium observatorium, commonly known as Mt. Hamilton lomatium, is a perennial herb in the Apiaceae that is found only in California. It occurs within Cismontane woodland, growing at elevations from 1219 to 1330 meters. Lomatium observatorium is ranked 1B.2, Plants Rare, Threatened or Endangered in California and Elsewhere; Moderately threatened in California.

Classification


Scientific Name:	Lomatium observatorium Constance & Ertter
Common Name:	Mt. Hamilton lomatium
Family:	Apiaceae
Element Code:	PDAPI1B2J0
USDA Plants Symbol:	LOOB3
Synonyms/Other Names:

Ecology and Life History


Lifeform:	perennial herb
Blooming Period: Mar-May	Mar-May
Elevation:	1219-1330 (4000-4365)
General Habitats:	Cismontane woodland
Microhabitat:
Microhabitat Details:

Conservation Status


CA Rare Plant Rank:	1B.2
Global Rank:	G1
State Rank:	S1
State List:	None
Fed List:	None
Other Status:	BLM_S; SB_CalBG/RSABG; SB_UCSC
CRPR Changes:

Occurrence Data from the CNDDB


Total Occurrences:	4
Element Occurrence Ranks:
Excellent (A)	0
Good (B)	0
Fair (C)	0
Poor (D)	0
None (X)	0
Unknown (U)	4

Location


California Endemic: True
California Counties and Islands: Name (Code)
Santa Clara (SCL), Stanislaus (STA)
Quads: Name (Quad Code)
Isabel Valley (3712135), Lick Observatory (3712136), Mt. Boardman (3712144)

Threat List Data from the CNDDB


Threat List Total:	3
EOs with Threat Listed:	Total EOs	% of EOs
	2	50 %
Foot traffic/trampling	1	25%
Other	1	25%
Road/trail construction/maint.	1	25%

Notes



Possibly threatened by fire suppression and non-native plants. Not in TJM (1993). See Madroño 43(4):515 (1996) 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 30 January 2025].