Horkelia tenuiloba
Thin-lobed horkelia, Thin-Lobed Horkelia
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Family: Rosaceae · Type: Herb · Native
Conservation status: CNPS 1B.2
Horkelia tenuiloba (Thin-lobed horkelia) is a native California herb in the Rosaceae family, recognized by . Key feature: thin leaf lobes, coastal sandy habitat.
Thin-lobed horkelia is a rare (CNPS 1B.2) California native perennial found in central and northern Coast Ranges, northwestern San Francisco Bay area in sandy soils and open chaparral at elevations of 50 to 500 meters. Flowering from April to July, this plant produces white to cream-colored flowers in small, dense clusters with delicate petals approximately 4 millimeters long. Growing loosely matted with stems less than 40 centimeters tall and spreading hairs, it forms a low, green ground-hugging structure. Its compound leaves feature 8 to 15 leaflets on each side, deeply divided into 3 to 8 narrow linear to oblanceolate lobes, creating a fine, intricate foliage texture. The plant's small fruits are approximately 1.5 millimeters long, nestled among its finely structured leaves.
Identification and appearance
Key characters: 0 sympatric species - geographically isolated. Key feature: thin leaf lobes, coastal sandy habitat
Habitat and range
Habitat: Sandy soils, open chaparral
Elevation: 50-500 m
California counties: Marin, Sonoma, Mendocino, Monterey, San Luis Obispo, Colusa
Bloom period
Horkelia tenuiloba blooms Apr-Jul.
Conservation status
CNPS 1B.2
How to tell it apart
vs Drymocallis: Horkelia has exactly 10 stamens and white-pink flowers; Drymocallis has 20+ stamens and yellow-white flowers.; vs Erodium: Horkelia has pinnate leaves and rose-family flowers; Erodium has lobed/divided leaves and long-beaked fruits.; vs Phacelia: Horkelia has rose-family flowers with separate petals; Phacelia has bell-shaped fused corollas with protruding stamens.; vs Potentilla: Horkelia has exactly 10 stamens and flattened filaments; Potentilla has 20+ stamens and thread-like filaments.; vs Ivesia: Horkelia has flat leaves with 2-15 separated leaflets; Ivesia has cylindrical bottlebrush leaves with overlapping leaflets.
Frequently asked questions
Is Horkelia tenuiloba native to California?
Yes. Horkelia tenuiloba is native to California (recorded as native).
When does Horkelia tenuiloba bloom?
Horkelia tenuiloba blooms Apr-Jul.
Where in California does Horkelia tenuiloba grow?
Horkelia tenuiloba occurs in Marin, Sonoma, Mendocino, Monterey, San Luis Obispo, Colusa, at elevations of 50-500 m.
What plant family does Horkelia tenuiloba belong to?
Horkelia tenuiloba is in the Rosaceae family, genus Horkelia.
Is Horkelia tenuiloba rare or endangered?
Horkelia tenuiloba carries California Rare Plant Rank 1B.2, state rank S2.
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.