Streptanthus polygaloides subsp. purpureus
Purple milkwort jewelflower
Photo: parent species Streptanthus polygaloides · (c) Ken-ichi Ueda, some rights reserved (CC BY) · licence
Family: Brassicaceae · Type: Annual · Native
Streptanthus polygaloides subsp. purpureus (Purple milkwort jewelflower) is a native California annual in the Brassicaceae family, recognized by distinctive deep purple sepals with pale margins.
Purple milkwort jewelflower is a California native annual found in serpentine barrens and grasslands within ponderosa pine forests of the California Floristic Province at elevations of 760 to 1,460 meters. Flowering from May to July, this plant produces deep purple flowers with pale-margined sepals and distinctive petal claws that widen toward the tip. Growing with delicate stems characteristic of the jewelflower genus, it forms a slender annual herb reaching 10 to 30 centimeters tall. Its leaves are arranged alternately along the stem, with lower leaves typically broader and more rounded than the upper, lance-shaped foliage. The flowers feature uniquely structured stamens, with adaxial filaments fused from base to tip, creating an intricate botanical display against the serpentine landscape.
Identification and appearance
Key characters: 22 sympatric species; distinctive deep purple sepals with pale margins
Habitat and range
Habitat: Serpentine barrens and grassland, in ponderosa pine forest
Elevation: 762-1460 m
Bloom period
Streptanthus polygaloides subsp. purpureus blooms May-Jul.
How to tell it apart
vs Caulanthus: Seed pods are flattened like sword blades versus cylindrical tubes in Caulanthus.; vs Boechera: Robust plants often over 2.5 feet with large flowers (sepals 4-8mm) versus more delicate habit.; vs Claytonia: Mustard family with 4 petals and 6 stamens versus Claytonia with 5 petals.; vs Silene: Mustard family with seed pods versus Silene with inflated capsules and opposite leaves.; vs Lonicera: Herbaceous mustard with alternate leaves versus woody vine with opposite leaves.
Frequently asked questions
Is Streptanthus polygaloides subsp. purpureus native to California?
Yes. Streptanthus polygaloides subsp. purpureus is native to California (recorded as native).
When does Streptanthus polygaloides subsp. purpureus bloom?
Streptanthus polygaloides subsp. purpureus blooms May-Jul.
What plant family does Streptanthus polygaloides subsp. purpureus belong to?
Streptanthus polygaloides subsp. purpureus is in the Brassicaceae family, genus Streptanthus.
What habitat does Streptanthus polygaloides subsp. purpureus grow in?
Streptanthus polygaloides subsp. purpureus grows in Serpentine barrens and grassland, in ponderosa pine forest.
Related species
Other California species in the same genus, family, or bioregion.
- Streptanthus polygaloides subsp. undulatus — Pine flat jewelflower
- Streptanthus sp. — Jewelflower
- Streptanthus tortuosus — Mountain jewelflower
- Streptanthus tortuosus subsp. truei — True's mountain jewelflower
- Streptanthus tortuosus var. foliosus — Wawona jewelflower
- Streptanthus tortuosus var. oblongus — Klamath mountains jewelflower
Sources: Jepson eFlora · CalPhotos
Last updated 2026-09-15
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.