Chorizanthe aphanantha
Irish hills spineflower, Irish Hills spineflower
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Family: Polygonaceae · Type: Perennial · Native
Conservation status: CNPS 1B.1
Chorizanthe aphanantha (Irish hills spineflower) is a native California perennial in the Polygonaceae family, recognized by endemic to serpentine chaparral in San Luis Obispo County.
Irish hills spineflower is a rare (CNPS 1B.1) California native perennial found in San Luis Obispo County in serpentine chaparral at elevations of 100 to 370 meters. Flowering from April to June, this plant produces white flowers with rose-pink to purple anthers in small, tightly clustered inflorescences. Growing as a tufted or mat-forming plant with prostrate to ascending branches reaching up to 26 centimeters in diameter, it has delicate, minutely hairy stems. Its basal leaves are distinctive, with spoon-shaped to widely ovate blades 4 to 8 millimeters long and 0.6 to 5 millimeters wide, typically glabrous or slightly strigose. The plant's involucre is three-angled with six ribs, featuring needle-like bracts and hooked awns that add to its intricate architectural structure.
Identification and appearance
Key characters: Geographically isolated; endemic to serpentine chaparral in San Luis Obispo County
Habitat and range
Habitat: Serpentine chaparral
Elevation: 100-370 m
California counties: San Luis Obispo
Bloom period
Chorizanthe aphanantha blooms Apr-Jun.
Conservation status
CNPS 1B.1
How to tell it apart
vs Eriogonum: Chorizanthe has 1 flower per involucre; Eriogonum has multiple flowers per involucre.; vs Eremothera: Chorizanthe has 6-parted flowers in spiny cups; Eremothera has 4-petaled evening-primrose flowers.; vs Calyptridium: Chorizanthe has flowers in awned involucres; Calyptridium has naked flowers with papery sepals.; vs Lastarriaea: Chorizanthe has thin papery flowers; Lastarriaea has distinctly thick, leathery-textured flowers.; vs Navarretia: Chorizanthe is in Polygonaceae with 6-parted flowers; Navarretia is in Polemoniaceae with 5-lobed tubular flowers.
Frequently asked questions
Is Chorizanthe aphanantha native to California?
Yes. Chorizanthe aphanantha is native to California (recorded as native).
When does Chorizanthe aphanantha bloom?
Chorizanthe aphanantha blooms Apr-Jun.
Where in California does Chorizanthe aphanantha grow?
Chorizanthe aphanantha occurs in San Luis Obispo, at elevations of 100-370 m.
What plant family does Chorizanthe aphanantha belong to?
Chorizanthe aphanantha is in the Polygonaceae family, genus Chorizanthe.
Is Chorizanthe aphanantha rare or endangered?
Chorizanthe aphanantha carries California Rare Plant Rank 1B.1, state rank S1.
Related species
Other California species in the same genus, family, or bioregion.
- Chorizanthe biloba — Two lobed spineflower
- Chorizanthe biloba var. biloba — Two-lobe spineflower
- Chorizanthe biloba var. immemora — Hernandez spineflower
- Chorizanthe blakleyi — Blakley's spineflower
- Chorizanthe brevicornu — Brittle spine flower
- Chorizanthe brevicornu var. brevicornu — Brittle spineflower
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
Last updated 2026-09-30
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.