Hymenoxys cooperi
Cooper goldflower
(c) Joe Decruyenaere, some rights reserved (CC BY-SA) · licence
Family: Asteraceae · Type: Herb · Native
Hymenoxys cooperi (Cooper goldflower) is a native California herb in the Asteraceae family, recognized by monocarpic habit and narrow leaf lobes.
Cooper goldflower is a California native perennial found in the Sweetwater Mountains and eastern desert mountains in roadsides, open areas, and edges of juniper and pine forest at elevations of 1,000 to 3,500 meters. Flowering from May to September, this plant produces yellow ray flowers with distinctive ray lengths of 10 to 17 millimeters and disk flowers arranged in compact clusters. Growing with reddish-purple stems 20 to 80 centimeters tall that are moderately branched and somewhat hairy, it develops from a simple or weakly branched caudex. Its leaves range 4 to 9 centimeters long, typically divided into 3 to 9 linear lobes, with middle blades featuring 3 to 5 lobes and terminal lobes 1 to 2 millimeters wide. The inflorescence includes 7 to 45 flower heads arranged in panicle-like or flat-topped clusters with disk heads 8 to 10 millimeters wide.
Identification and appearance
Key characters: 2 sympatric species; distinguished by monocarpic habit and narrow leaf lobes
Habitat and range
Habitat: Roadsides, open areas, edges of juniper/pine forest
Elevation: 1000-3500 m
Outside California: Oregon, Idaho, Nevada, Utah, Arizona
Bloom period
Hymenoxys cooperi blooms May-Sep.
How to tell it apart
vs Helenium: Helenium has simple entire or toothed leaves; Hymenoxys has deeply dissected thread-like segments.; vs Hulsea: Hulsea has simple entire to shallowly toothed leaves; Hymenoxys has deeply divided linear segments.; vs Helianthella: Helianthella has broad simple leaves; Hymenoxys has finely dissected thread-like foliage.; vs Arnica: Arnica has paired opposite simple leaves; Hymenoxys has alternate dissected leaves.; vs Eatonella: Eatonella has simple spoon-shaped leaves; Hymenoxys has dissected linear segments.
Frequently asked questions
Is Hymenoxys cooperi native to California?
Yes. Hymenoxys cooperi is native to California (recorded as native).
When does Hymenoxys cooperi bloom?
Hymenoxys cooperi blooms May-Sep.
What plant family does Hymenoxys cooperi belong to?
Hymenoxys cooperi is in the Asteraceae family, genus Hymenoxys.
What habitat does Hymenoxys cooperi grow in?
Hymenoxys cooperi grows in Roadsides, open areas, edges of juniper/pine forest.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
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.