Chorizanthe robusta var. robusta
Robust spineflower
Photo: parent species Chorizanthe robusta · (c) Adam J. Searcy, some rights reserved (CC BY) · licence
Family: Polygonaceae · Type: Herb · Native
Conservation status: CNPS 1B.1 · Endangered
Chorizanthe robusta var. robusta (Robust spineflower) is a native California herb in the Polygonaceae family, recognized by coastal location and robust size.
Robust spineflower is a rare (CNPS 1B.1) California native perennial found in north and central Coast Ranges of Santa Cruz and Monterey counties, and historically in southwestern San Francisco Bay area, inhabiting sandy or gravelly terrain at elevations of 10 to 300 meters. Flowering from May to September, this plant produces white flowers in delicate involucres 2.5 to 4 millimeters wide with distinctive white-margined lobes. Growing with spreading or decumbent stems 10 to 20 centimeters long, it forms low, intricate ground-hugging patches. Its leaves are slender, with blades 1.5 to 5 centimeters long and remarkably narrow, measuring just 0.3 to 0.7 centimeters wide. This uncommon spineflower thrives in sparse, open coastal habitats, adapting to challenging sandy environments with its compact growth form.
Identification and appearance
Key characters: Geographically isolated; diagnostic coastal location and robust size
Habitat and range
Habitat: Sand or gravel
Elevation: 10-300 m
California counties: Santa Cruz, Marin, San Mateo, Monterey, Alameda
Bloom period
Chorizanthe robusta var. robusta blooms May-Sep.
Conservation status
CNPS 1B.1 · Endangered
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 robusta var. robusta native to California?
Yes. Chorizanthe robusta var. robusta is native to California (recorded as native).
When does Chorizanthe robusta var. robusta bloom?
Chorizanthe robusta var. robusta blooms May-Sep.
Where in California does Chorizanthe robusta var. robusta grow?
Chorizanthe robusta var. robusta occurs in Santa Cruz, Marin, San Mateo, Monterey, Alameda, at elevations of 10-300 m.
What plant family does Chorizanthe robusta var. robusta belong to?
Chorizanthe robusta var. robusta is in the Polygonaceae family, genus Chorizanthe.
Is Chorizanthe robusta var. robusta rare or endangered?
Chorizanthe robusta var. robusta carries California Rare Plant Rank 1B.1, 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.