North America Native Plant

Bitterroot Milkvetch

Botanical name: Astragalus scaphoides

USDA symbol: ASSC4

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Bitterroot Milkvetch: A Rare Native Gem Worth Protecting Meet Bitterroot milkvetch (Astragalus scaphoides), a charming perennial wildflower that’s both a gardener’s delight and a conservation priority. This lesser-known native beauty deserves a spot in your garden—but only if you source it responsibly. Where Does Bitterroot Milkvetch Call Home? This delightful ...

Rare plant alert!

Region: Conservation status by state

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

Bitterroot Milkvetch: A Rare Native Gem Worth Protecting

Meet Bitterroot milkvetch (Astragalus scaphoides), a charming perennial wildflower that’s both a gardener’s delight and a conservation priority. This lesser-known native beauty deserves a spot in your garden—but only if you source it responsibly.

Where Does Bitterroot Milkvetch Call Home?

This delightful native plant is naturally found in the northwestern United States, specifically thriving in Idaho and Montana. As a true native of the lower 48 states, it has spent centuries adapting to the unique conditions of this region, making it perfectly suited to local climates and ecosystems.

Why You Should Care About This Little Legume

Important Conservation Note: Bitterroot milkvetch has a Global Conservation Status of S3, meaning it’s considered vulnerable. This rarity makes it especially precious—and means you should only plant it using responsibly sourced seeds or plants from reputable native plant nurseries, never collected from wild populations.

Despite its vulnerable status (or perhaps because of it), this perennial offers several compelling reasons to include it in your native garden:

  • Supports local pollinators with its attractive white to cream-colored pea-like flowers
  • Helps preserve regional biodiversity
  • Adds authentic local character to native plant gardens
  • Requires minimal care once established

What Does Bitterroot Milkvetch Look Like?

This perennial charmer produces delicate compound leaves made up of small leaflets, giving it a feathery, soft appearance. The real show-stoppers are its small but lovely pea-like flowers, which bloom in shades of white to cream. As a member of the legume family, it shares the characteristic flower shape with its more familiar cousins like beans and peas.

Perfect Garden Situations

Bitterroot milkvetch shines brightest in:

  • Native plant gardens focused on regional species
  • Xerophytic (dry) landscapes
  • Restoration projects
  • Naturalized areas where it can spread gradually
  • Rock gardens with well-draining soil

Growing Conditions That Make It Happy

Like many plants from the mountain West, Bitterroot milkvetch appreciates:

  • Sunlight: Full sun exposure
  • Soil: Well-drained, lean soils (avoid rich, fertile conditions)
  • Water: Drought tolerant once established; prefers dry conditions
  • Climate: Hardy in USDA zones 3-6

Planting and Care Tips

The good news? Once you’ve sourced your Bitterroot milkvetch ethically, it’s refreshingly low-maintenance:

  • Plant in spring after the last frost
  • Choose a sunny spot with excellent drainage
  • Avoid fertilizing—this plant prefers lean, poor soils
  • Water sparingly; overwatering is more harmful than drought
  • Allow it to self-seed in appropriate areas to support local populations

A Win for Pollinators

Those charming little flowers aren’t just pretty—they’re pollinator magnets. Native bees and other small pollinators rely on plants like Bitterroot milkvetch for nectar and pollen. By growing this species, you’re supporting the intricate web of relationships that keep our ecosystems healthy.

The Bottom Line

Bitterroot milkvetch offers native plant enthusiasts a chance to grow something truly special while contributing to conservation efforts. Its vulnerable status means every responsibly grown plant matters. If you’re passionate about preserving regional biodiversity and can source this beauty ethically, it’s a wonderful addition to dry, sunny gardens in appropriate climate zones.

Remember: always purchase from reputable native plant nurseries and never collect from wild populations. This small act of responsibility helps ensure that future generations can enjoy Bitterroot milkvetch both in gardens and in its natural habitat.

Bitterroot Milkvetch

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Rosidae

Order

Fabales

Family

Fabaceae Lindl. - Pea family

Genus

Astragalus L. - milkvetch

Species

Astragalus scaphoides (M.E. Jones) Rydb. - Bitterroot milkvetch

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