Streptanthus glandulosus subsp. niger
Tiburon jewelflower, Tiburon Jewelflower
(c) Ken-ichi Ueda, some rights reserved (CC BY), uploaded by Ken-ichi Ueda · licence
Family: Brassicaceae · Type: Annual · Native
Conservation status: CNPS 1B.1 · Endangered
Streptanthus glandulosus subsp. niger (Tiburon jewelflower) is a native California annual in the Brassicaceae family, recognized by dark purple-black sepals distinctive.
Tiburon jewelflower is a rare (CNPS 1B.1) California native annual found in northern Central Coast regions on the Tiburon Peninsula in Marin County, specifically growing on serpentine outcrops in grassland at elevations below 150 meters. Flowering from May to July, this plant produces dark purple flowers approximately 10 to 12 millimeters long with striking dark purple-black sepals. Growing with erect glabrous stems 20 to 110 centimeters tall, it develops an elegant upright structure with wavy flowering axes. Its cauline leaves are glabrous, with upper leaves remaining entire and unserrated, creating a clean, simple foliage profile. The plant produces elongated fruits 3.5 to 6.7 centimeters long that spread at an ascending angle, adding architectural interest to its slender form.
Identification and appearance
Key characters: Geographically isolated with 0 sympatric species; dark purple-black sepals distinctive
Habitat and range
Habitat: Serpentine outcrops in grassland
Elevation: < 150 m
California counties: Marin, San Luis Obispo
Bloom period
Streptanthus glandulosus subsp. niger blooms May-Jul.
Conservation status
CNPS 1B.1 · Endangered
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 glandulosus subsp. niger native to California?
Yes. Streptanthus glandulosus subsp. niger is native to California (recorded as native).
When does Streptanthus glandulosus subsp. niger bloom?
Streptanthus glandulosus subsp. niger blooms May-Jul.
Where in California does Streptanthus glandulosus subsp. niger grow?
Streptanthus glandulosus subsp. niger occurs in Marin, San Luis Obispo, at elevations of < 150 m.
What plant family does Streptanthus glandulosus subsp. niger belong to?
Streptanthus glandulosus subsp. niger is in the Brassicaceae family, genus Streptanthus.
Is Streptanthus glandulosus subsp. niger rare or endangered?
Streptanthus glandulosus subsp. niger carries California Rare Plant Rank 1B.1, state rank S1.
Related species
Other California species in the same genus, family, or bioregion.
- Streptanthus glandulosus subsp. pulchellus — Mount tamalpais bristly jewelflower
- Streptanthus glandulosus subsp. raichei — Raiche's jewelflower
- Streptanthus glandulosus subsp. secundus — One-sided jewelflower
- Streptanthus glandulosus subsp. sonomensis — Uncommon jewelflower
- Streptanthus gracilis — Alpine jewelflower
- Streptanthus hesperidis — Green jewelflower
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
Last updated 2026-10-06
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.