North America Native Plant

Wind River Rockcress

Botanical name: Arabis williamsii var. williamsii

USDA symbol: ARWIW

Life cycle: biennial

Habit: forb

Native status: Native to the lower 48 states  

Synonyms: Boechera williamsii (Rollins) Dorn (BOWI)  âš˜  Boechera williamsii (Rollins) Dorn var. williamsii (BOWIW)   

Wind River Rockcress: A Rare Wyoming Native Worth Knowing If you’ve never heard of Wind River rockcress (Arabis williamsii var. williamsii), you’re not alone. This little-known native plant is one of Wyoming’s botanical treasures, though it remains shrouded in mystery for most gardeners and even many botanists. What is Wind ...

Rare plant alert!

Region: Conservation status by state

Status: S3QT3Q: Status is uncertain but is somewhere between the following rankings: Uncertain taxonomy: ⚘ 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 ⚘ 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. ⚘

Wind River Rockcress: A Rare Wyoming Native Worth Knowing

If you’ve never heard of Wind River rockcress (Arabis williamsii var. williamsii), you’re not alone. This little-known native plant is one of Wyoming’s botanical treasures, though it remains shrouded in mystery for most gardeners and even many botanists.

What is Wind River Rockcress?

Wind River rockcress is a biennial plant, meaning it completes its life cycle over two years. In botanical circles, you might also see it listed under its synonym Boechera williamsii, as plant classifications have shifted over time. This native species calls the lower 48 states home, though its distribution appears to be quite limited.

Where Does It Grow?

Currently, Wind River rockcress is documented as growing in Wyoming. This restricted range immediately tells us something important about this plant—it’s likely adapted to very specific conditions found in the region’s unique landscapes.

The Rarity Factor

Here’s where things get interesting (and a bit concerning). Wind River rockcress has a Global Conservation Status of S3QT3Q, though the specific meaning of this classification isn’t clearly defined in available resources. What we do know is that any plant with such a restricted range and limited documentation deserves our respect and caution.

If you’re considering adding this plant to your garden, it’s crucial to source any plant material responsibly. Never collect from wild populations, and only purchase from reputable native plant nurseries that can verify their stock comes from ethical propagation practices.

Growing Wind River Rockcress: The Challenge

Here’s the honest truth—we don’t have reliable information about how to successfully cultivate Wind River rockcress. Details about its preferred growing conditions, care requirements, and garden performance remain largely unknown. This lack of cultivation information, combined with its apparent rarity, makes it a challenging choice for home gardeners.

As a biennial, we know it would theoretically complete its growth cycle over two seasons, but without specific guidance on soil preferences, water needs, sun exposure, or hardiness zones, attempting to grow this plant would be largely experimental.

Should You Plant It?

While Wind River rockcress is undoubtedly a fascinating native plant, the combination of limited availability, unclear conservation status, and lack of cultivation information makes it difficult to recommend for most garden situations.

Instead, consider these well-documented native alternatives that can provide similar ecological benefits:

  • Other native rockcress species with known cultivation requirements
  • Native Wyoming wildflowers suited to your specific garden conditions
  • Locally-adapted native plants available through regional native plant societies

The Bottom Line

Wind River rockcress represents the fascinating complexity of our native flora—species that evolved in specific places under particular conditions, creating unique botanical treasures. While we may not be able to easily welcome this plant into our gardens right now, we can appreciate its role in Wyoming’s natural heritage.

If you’re passionate about native plants and particularly interested in rare species, consider supporting botanical research and conservation efforts that work to better understand and protect plants like Wind River rockcress. Sometimes the best way to honor a native plant is to ensure it thrives in its natural habitat while we learn more about its needs and ecological role.

Wind River Rockcress

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

Arabis L. - rockcress

Species

Arabis williamsii Rollins - Wind River rockcress

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