North America Native Plant

Washington Twinpod

Botanical name: Physaria alpestris

USDA symbol: PHAL6

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Washington Twinpod: A Rare Alpine Treasure for Specialized Gardens If you’re drawn to rare native plants and have a passion for alpine gardening, Washington twinpod (Physaria alpestris) might catch your eye. But before you start planning where to plant this little beauty, there are some important things every gardener should ...

Rare plant alert!

Region: Conservation status by state

Status: S3?: Status is uncertain but is somewhere between the following rankings: Inexact rank: ⚘ 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 ⚘

Washington Twinpod: A Rare Alpine Treasure for Specialized Gardens

If you’re drawn to rare native plants and have a passion for alpine gardening, Washington twinpod (Physaria alpestris) might catch your eye. But before you start planning where to plant this little beauty, there are some important things every gardener should know about this uncommon Pacific Northwest native.

What Makes Washington Twinpod Special

Washington twinpod is a perennial forb—essentially a non-woody herbaceous plant that comes back year after year. Like other members of the mustard family, it produces cheerful yellow flowers that add a bright splash of color to the landscape. Its low-growing habit makes it an interesting ground cover option for the right garden setting.

Where Does It Come From?

This plant is a true Washington state endemic, meaning it naturally occurs only within the borders of the Evergreen State. Its extremely limited geographic distribution makes it quite special—and quite rare. You won’t find Washington twinpod growing wild anywhere else in the world.

The Rarity Factor: What Gardeners Need to Know

Here’s where things get important: Washington twinpod has a Global Conservation Status of S3?, which indicates some level of conservation concern. This rarity status means that if you’re interested in growing this plant, you absolutely must source it responsibly. Never collect plants or seeds from wild populations, as this could harm already vulnerable native colonies.

Instead, look for reputable native plant nurseries that propagate their stock rather than wild-collecting. You might also check with local native plant societies or botanical gardens that maintain conservation collections.

Garden Design and Landscaping Role

Washington twinpod is best suited for specialized native gardens, particularly:

  • Rock gardens that mimic alpine conditions
  • Native plant collections focused on regional endemics
  • Conservation gardens that showcase rare species
  • Educational landscapes that highlight local biodiversity

This isn’t a plant for every garden or every gardener. Its specialized needs and conservation status make it more appropriate for dedicated native plant enthusiasts who understand the responsibility that comes with growing rare species.

Growing Conditions and Care

While specific growing information for Washington twinpod is limited due to its rarity, we can make educated assumptions based on its alpine nature and family characteristics. Like many mountain plants, it likely prefers:

  • Excellent drainage—probably requiring rocky or gravelly soils
  • Full sun to partial shade
  • Cool, moist conditions similar to its native alpine habitat
  • Minimal fertilization (mountain plants typically prefer lean soils)

Given its Washington state distribution, it’s likely hardy in USDA zones 4-7, though local microclimates and elevation will play a significant role in its success.

Benefits to Pollinators and Wildlife

As a member of the mustard family, Washington twinpod likely provides nectar and pollen for native bees and other small pollinators. However, due to its rarity, specific wildlife relationships haven’t been extensively studied or documented.

Should You Plant Washington Twinpod?

The answer depends on your gardening goals and commitment level. If you’re passionate about native plant conservation, have experience with challenging alpine plants, and can source the plant responsibly, Washington twinpod could be a meaningful addition to a specialized collection.

However, for most gardeners, there are more readily available native alternatives that can provide similar aesthetic benefits without the conservation concerns. Consider other Washington natives like kinnikinnick, Oregon sunshine, or native sedums for reliable ground cover options.

The Bottom Line

Washington twinpod represents the fascinating but fragile world of endemic plants. While it offers unique appeal for serious native plant gardeners, its rarity demands respect and responsible stewardship. If you choose to grow this special plant, you’re not just adding to your garden—you’re participating in conservation efforts for Washington’s unique botanical heritage.

Remember: rare plants require rare dedication. Make sure you’re ready for the commitment before bringing this alpine treasure into your garden.

Washington Twinpod

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

Physaria (Nutt. ex Torr. & A. Gray) A. Gray - twinpod

Species

Physaria alpestris Suksd. - Washington twinpod

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