Streptanthus polygaloides subsp. alternans

Tuolumne jewelflower

Streptanthus polygaloides — parent species of Streptanthus polygaloides subsp. alternans

Photo: parent species Streptanthus polygaloides · (c) Ken-ichi Ueda, some rights reserved (CC BY) · licence

Family: Brassicaceae · Type: Annual · Native

Streptanthus polygaloides subsp. alternans (Tuolumne jewelflower) is a native California annual in the Brassicaceae family, recognized by Serpentine SN foothill/montane jewelflower; sepals yellow in bud but turning uniformly PURPLE in flower; adaxial stamen filaments fused.

Tuolumne jewelflower is a California native annual found in the Sierra Nevada foothills in gravelly serpentine slopes and roadcuts at elevations of 260 to 780 meters. Flowering from May to June, this plant produces flowers that transform from yellow buds to striking purple blooms with distinctive petal characteristics. Growing with delicate stems reaching upward, the plant develops intricate floral structures with unique adaptations. Its petals feature adaxial claws that widen toward the tip, creating an unusual flower shape with glabrous sepals. The plant's specialized form reflects its adaptation to serpentine chaparral environments, showcasing remarkable morphological details.

Identification and appearance

Key characters: Serpentine SN foothill/montane jewelflower; sepals yellow in bud but turning uniformly PURPLE in flower; adaxial stamen filaments fused

Habitat and range

Habitat: Gravelly serpentine slopes and roadcuts, serpentine chaparral

Elevation: 260-780 m

Bloom period

Streptanthus polygaloides subsp. alternans blooms May-Jun.

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. alternans native to California?

Yes. Streptanthus polygaloides subsp. alternans is native to California (recorded as native).

When does Streptanthus polygaloides subsp. alternans bloom?

Streptanthus polygaloides subsp. alternans blooms May-Jun.

What plant family does Streptanthus polygaloides subsp. alternans belong to?

Streptanthus polygaloides subsp. alternans is in the Brassicaceae family, genus Streptanthus.

What habitat does Streptanthus polygaloides subsp. alternans grow in?

Streptanthus polygaloides subsp. alternans grows in Gravelly serpentine slopes and roadcuts, serpentine chaparral.

Related species

Other California species in the same genus, family, or bioregion.

All Streptanthus species · All Brassicaceae

Sources: Jepson eFlora · CalPhotos

Last updated 2026-09-30

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.