Tiburon Jewelflower

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(Streptanthus Niger)

Classification: Family- Brassicaceae
Genus- Streptanthus
Species- S. Niger

Geographic Distribution:

Region: Tiburon Peninsula Northern California

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The Tiburon Jewelflower is endemic to the Tiburon Peninsula in Northern California and specifically to Marin County. It occurs at elevations around 100 meters on Serpentine grasslands.

Human Use:

Humans have no use for this particular species but humans use members of S. Niger family the brassicaceae primarily for food. The Tiburon Jewelflower is threatened by human activity though as its home is susceptible to foot traffic and non native grasses.

Family Members:
The Brassicaceae family are angiosperms that are commonly referred to as the mustards and the crucifers. They are called the crucifers because the four petals of their flowers often appear in a cross shaped fashion. The flowers are also very uniform throughout this family and tend to have four sepals, four petals, four stamen, and two carpels. This family includes many plants that are common in human diets such as broccoli, cabbage, and turnips.

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(Brassica Oleracea)

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(Brassica Oleracea Capitata)

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(Brassica rapa var. rapa)


The Tiburon Jewelflower is an interesting species because it is highly endangered. It is narrowly endemic to the Tiburon Peninsula and only two known populations exist, both in Marin County, California and within a two mile distance of each other. As its habitat becomes more threatened the Tiburon Jewelflower will likely continue to disappear.


The Tiburon Jewelflower only grows on grasslands above shallow serpentine soils and often on slopes. Serpentine soils offer harsh conditions with little nutrients and few plants can sustain themselves in this type of environment. These soils derive from rocks that are solidified magma and while most plants would not find this a suitable environment to live in, the Tiburon Jewelflower needs it to survive.