Lomatium observatorium
Mount hamilton lomatium, Mount Hamilton Lomatium
(c) Ken-ichi Ueda, some rights reserved (CC BY) · licence
Family: Apiaceae · Type: Herb · Native
Conservation status: CNPS 1B.2
Lomatium observatorium (Mount hamilton lomatium) is a native California herb in the Apiaceae family, recognized by no sympatric species.
Mount hamilton lomatium is a rare (CNPS 1B.2) California native perennial found in the southeastern San Francisco Bay Area's Mount Hamilton Range in volcanic soil and rocky openings of pine and oak woodland at elevations of 1,280 to 1,330 meters. Flowering from March to May, this plant produces small white to yellow flowers in delicate umbels with 1 to 3 rays. Growing with slender stems 10 to 30 centimeters tall and lacking a prominent above-ground stem, it develops a substantial taproot up to 15 centimeters long. Its leaves are complex and finely divided, with ternate-pinnate blades 4 to 12 centimeters long, featuring narrow lance-linear segments 1 to 8 millimeters long with ciliate margins. The fruit is a small, glabrous ovate structure approximately 7 to 10 millimeters long with narrow wings.
Identification and appearance
Key characters: Geographically isolated; no sympatric species
Habitat and range
Habitat: Volcanic soil, rocky openings in pine/oak woodland
Elevation: 1280-1330 m
California counties: Santa Clara, Stanislaus
Bloom period
Lomatium observatorium blooms Mar-May.
Conservation status
CNPS 1B.2
How to tell it apart
vs Tauschia: Lomatium fruits have prominent marginal wings; Tauschia fruits lack wings or have only slight ribs.; vs Sanicula: Lomatium has typical umbrella-shaped flower clusters; Sanicula has dense ball-like flower heads with hooked bristles.; vs Cymopterus: Lomatium grows upright with a stem; Cymopterus is stemless and grows flat to the ground.; vs Conium: Lomatium grows in dry natural habitats; Conium has purple-spotted stems and grows in moist disturbed areas.; vs Daucus: Lomatium fruits are flat with thin wings; Daucus fruits are cylindrical with spiny bristles.
Frequently asked questions
Is Lomatium observatorium native to California?
Yes. Lomatium observatorium is native to California (recorded as native).
When does Lomatium observatorium bloom?
Lomatium observatorium blooms Mar-May.
Where in California does Lomatium observatorium grow?
Lomatium observatorium occurs in Santa Clara, Stanislaus, at elevations of 1280-1330 m.
What plant family does Lomatium observatorium belong to?
Lomatium observatorium is in the Apiaceae family, genus Lomatium.
Is Lomatium observatorium rare or endangered?
Lomatium observatorium carries California Rare Plant Rank 1B.2, state rank S1.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.