Romneya trichocalyx
Hairy matilija poppy, Hairy Matilija Poppy
Photo by Chez Brungraber
Family: Papaveraceae · Type: Shrub · Native
Romneya trichocalyx (Hairy matilija poppy) is a native California shrub in the Papaveraceae family, recognized by (R. coulteri). Key difference is fruit size and seed texture/color.
Hairy matilija poppy is a California native shrub found in western Southern California, Transverse Ranges, and Peninsular Ranges in dry washes and canyons at elevations below 1,500 meters. Flowering from April to June, this plant produces large, striking white flowers with delicate crinkled petals and bright yellow centers. Growing up to 2 to 3 meters tall with multiple woody stems emerging from underground rhizomes, it forms expansive, dense clusters in rugged terrain. Its leaves are deeply lobed, gray-green in color, with a rough, slightly hairy texture that adds visual complexity to the plant's structure. The fruit develops into large capsules approximately 2.5 to 3.5 centimeters long, containing smooth, light brown seeds.
Identification and appearance
Key characters: 1 sympatric species (R. coulteri). Key difference is fruit size and seed texture/color.
Habitat and range
Habitat: dry washes, canyons
Elevation: < 1500 m
California counties: San Diego, Los Angeles, Ventura, Orange, Riverside, Mendocino, Santa Barbara, Alameda, Imperial, Contra Costa
Outside California: northern Baja California
Bloom period
Romneya trichocalyx blooms Apr-Jun.
How to tell it apart
vs Argemone: Shrub with deeply lobed leaves, not prickly-spiny herbaceous plant.; vs Rosa: Six white petals (not five), leaves deeply divided into narrow segments.; vs Cistus: Six white petals around golden center, not five petals with simple leaves.; vs Artemisia: Spectacular large white flowers 4+ inches across, not tiny in dense clusters.; vs Papaver: Large woody shrub with 6 petals, not herbaceous annual with 4 petals.
Frequently asked questions
Is Romneya trichocalyx native to California?
Yes. Romneya trichocalyx is native to California (recorded as native).
When does Romneya trichocalyx bloom?
Romneya trichocalyx blooms Apr-Jun.
Where in California does Romneya trichocalyx grow?
Romneya trichocalyx occurs in San Diego, Los Angeles, Ventura, Orange, Riverside, Mendocino, Santa Barbara, Alameda and other counties, at elevations of < 1500 m.
What plant family does Romneya trichocalyx belong to?
Romneya trichocalyx is in the Papaveraceae family, genus Romneya.
What habitat does Romneya trichocalyx grow in?
Romneya trichocalyx grows in dry washes, canyons.
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.