Arabis oregana
Oregon rockcress, Oregon rockcress, Oregon rockcress
(c) Dee Shea Himes, some rights reserved (CC BY), uploaded by Dee Shea Himes · licence
Family: Brassicaceae · Type: Herb · Native
Conservation status: CNPS 4.3
Arabis oregana (Oregon rockcress) is a native California herb in the Brassicaceae family, recognized by purple flowers, hairy habit, and erect fruits.
Oregon rockcress is a California native perennial ranked 4.3 by CNPS, found in the Klamath Ranges and northern Coast Ranges in rocky hillsides and chaparral at elevations of 500 to 1,400 meters. Flowering from April to May, this plant produces purple or pink flowers 12 to 15 millimeters long with petals 4 to 5 millimeters wide. Growing with slender stems 20 to 50 centimeters tall, it has a branched or simple stem covered with a mixture of simple and forked hairs. Its basal leaves are 1.5 to 8 centimeters long, obovate to oblanceolate, with entire or wavy margins and hairy surfaces. The fruit is an erect to ascending silique 4.5 to 5 centimeters long and 1.5 to 2 millimeters wide.
Identification and appearance
Key characters: 4 sympatric species; key features are purple flowers, hairy habit, and erect fruits
Habitat and range
Habitat: Rocky hillsides, steep banks, chaparral
Elevation: 500-1400 m
California counties: Siskiyou, Napa, Lake, Trinity, Placer
Outside California: southern Oregon
Bloom period
Arabis oregana blooms Apr-May.
Conservation status
CNPS 4.3
How to tell it apart
vs Boechera: Arabis pods are narrower (under 2mm vs 2mm+) and consistently straight; Boechera pods are often curved.; vs Matthiola: Arabis has stalked star-shaped hairs and erect narrow pods; Matthiola has soft unbranched hairs and stouter pods.; vs Raphanus: Arabis has tiny star-shaped hairs and thin erect pods; Raphanus has larger flowers and thick beaded pods.; vs Pelargonium: Arabis has four petals and narrow upright pods; Pelargonium has five petals and beak-like fruits.; vs Phlox: Arabis has four separate petals and seed pods; Phlox has fused tubular flowers and capsules.
Frequently asked questions
Is Arabis oregana native to California?
Yes. Arabis oregana is native to California (recorded as native).
When does Arabis oregana bloom?
Arabis oregana blooms Apr-May.
Where in California does Arabis oregana grow?
Arabis oregana occurs in Siskiyou, Napa, Lake, Trinity, Placer, at elevations of 500-1400 m.
What plant family does Arabis oregana belong to?
Arabis oregana is in the Brassicaceae family, genus Arabis.
Is Arabis oregana rare or endangered?
Arabis oregana carries California Rare Plant Rank 4.3, state rank S3.
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.