North America Native Plant

Shieldplant

Botanical name: Streptanthus tortuosus var. optatus

USDA symbol: STTOO3

Life cycle: biennial

Habit: subshrub

Native status: Native to the lower 48 states  

Shieldplant: A Rare California Native Worth Discovering Meet the shieldplant (Streptanthus tortuosus var. optatus), a fascinating little wildflower that’s as unique as its twisted name suggests. This California native belongs to the mustard family and represents one of nature’s more understated gems – the kind of plant that rewards the ...

Rare plant alert!

Region: Conservation status by state

Status: S5T3?: Status is uncertain but is somewhere between the following rankings: Inexact rank: ⚘ Subspecies or variety is vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals. ⚘ Secure: At very low or no risk of extinction in the jurisdiction due to a very extensive range, abundant populations or occurrences, with little to no concern from declines or threats. ⚘

Shieldplant: A Rare California Native Worth Discovering

Meet the shieldplant (Streptanthus tortuosus var. optatus), a fascinating little wildflower that’s as unique as its twisted name suggests. This California native belongs to the mustard family and represents one of nature’s more understated gems – the kind of plant that rewards the observant gardener with quiet beauty rather than showy displays.

What Makes Shieldplant Special?

Shieldplant is what botanists call a forb – essentially a non-woody flowering plant that can live for one year (annual), two years (biennial), or multiple years (perennial). Think of it as the Swiss Army knife of plant life cycles! This flexibility allows it to adapt to varying conditions and opportunities in its native California landscape.

As a true California native, this plant has evolved specifically for the Golden State’s unique climate and soil conditions. It’s perfectly adapted to thrive where many other plants might struggle, making it a valuable addition to native plant gardens.

Where Does Shieldplant Call Home?

You’ll find shieldplant growing naturally throughout California, where it has made itself at home in the state’s diverse ecosystems. This plant represents thousands of years of evolution fine-tuned to California’s Mediterranean climate, seasonal rainfall patterns, and native soil types.

A Word of Caution: Rarity Matters

Here’s something important to know: shieldplant carries a Global Conservation Status of S5T3?, which indicates some level of conservation concern, though the exact status remains undefined. This means that while it’s not necessarily endangered, it’s not exactly common either. If you’re interested in growing this plant, it’s crucial to source seeds or plants only from reputable native plant nurseries that collect sustainably and legally.

Why Consider Growing Shieldplant?

There are several compelling reasons to include this native in your garden:

  • True California heritage: Support your local ecosystem with a plant that belongs
  • Low-maintenance appeal: Native plants typically require less water and care once established
  • Wildlife connections: Native plants support local wildlife in ways non-natives simply can’t match
  • Conservation contribution: Growing rare natives helps preserve genetic diversity

Growing Shieldplant Successfully

While specific growing information for this variety is limited, we can draw from its natural habitat and family characteristics. As a California native from the mustard family, shieldplant likely prefers:

  • Well-draining soil: Most California natives despise soggy conditions
  • Full to partial sun: Typical for mustard family plants
  • Minimal summer water: Once established, follow California’s natural dry summer pattern
  • Fall or early spring planting: Align with natural rainfall patterns

The Responsible Gardener’s Approach

If shieldplant captures your interest, remember that responsible gardening means responsible sourcing. Never collect plants or seeds from wild populations. Instead:

  • Contact California native plant societies for reputable sources
  • Check with local botanical gardens or universities
  • Connect with certified native plant nurseries
  • Consider participating in seed collection events organized by conservation groups

The Bottom Line

Shieldplant might not be the flashiest choice for your garden, but it offers something increasingly precious: authenticity. In a world where gardens often feature plants from every continent except our own, growing a true California native like shieldplant connects your garden to the land’s natural heritage.

While this isn’t a plant for every gardener or every garden, those interested in native plants, conservation, or creating habitat for local wildlife will find shieldplant a worthy addition. Just remember: with rarity comes responsibility. Source ethically, grow thoughtfully, and help ensure that future generations can enjoy this quiet California treasure.

Shieldplant

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Dilleniidae

Order

Capparales

Family

Brassicaceae Burnett - Mustard family

Genus

Streptanthus Nutt. - twistflower

Species

Streptanthus tortuosus Kellogg - shieldplant

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA