North America Native Plant

Lyall’s Milkvetch

Botanical name: Astragalus lyallii

USDA symbol: ASLY

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Lyall’s Milkvetch: A Pacific Northwest Native Worth Knowing If you’re passionate about native gardening in the Pacific Northwest, you’ve probably encountered plenty of showy natives like Oregon grape and Pacific bleeding heart. But have you met Lyall’s milkvetch? This understated perennial might not win any flashiness contests, but it’s got ...

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 ⚘

Lyall’s Milkvetch: A Pacific Northwest Native Worth Knowing

If you’re passionate about native gardening in the Pacific Northwest, you’ve probably encountered plenty of showy natives like Oregon grape and Pacific bleeding heart. But have you met Lyall’s milkvetch? This understated perennial might not win any flashiness contests, but it’s got charm, resilience, and an important story to tell about our region’s botanical heritage.

What Exactly Is Lyall’s Milkvetch?

Lyall’s milkvetch (Astragalus lyallii) is a perennial member of the legume family that’s as Pacific Northwest as it gets. This native wildflower is found exclusively in Washington state, making it a true regional specialty. Like other milkvetches, it produces small, pea-like flowers and has compound leaves that give it a delicate, almost fern-like appearance.

The plant produces clusters of purple to pink flowers in spring and early summer, followed by small pods typical of legumes. Its silvery-green foliage adds a soft texture to the garden even when it’s not in bloom.

Where Does It Call Home?

This little native is quite the Washington state patriot – it’s endemic to the region, primarily calling the Puget Sound area and surrounding regions home. You won’t find wild populations of Lyall’s milkvetch anywhere else in the world, which makes it pretty special from a conservation standpoint.

A Conservation-Minded Choice

Here’s where things get important: Lyall’s milkvetch appears to have a conservation status that suggests it may be uncommon or potentially at risk. This means if you’re considering adding it to your garden, you’ll want to be extra thoughtful about sourcing. Always purchase from reputable native plant nurseries that propagate their own stock rather than wild-collecting. Better yet, if you can find seeds from ethical sources, growing your own is a wonderful way to contribute to conservation efforts.

Why Grow Lyall’s Milkvetch?

You might wonder why you’d choose this relatively modest plant over showier natives. Here are some compelling reasons:

  • Support local biodiversity: By growing this Washington endemic, you’re helping preserve regional plant diversity
  • Pollinator magnet: Those small flowers are perfect for native bees and other pollinators
  • Low maintenance: Once established, it’s quite drought tolerant
  • Soil improvement: As a legume, it fixes nitrogen in the soil
  • Unique story: It’s a conversation starter about regional conservation

Perfect Garden Spots

Lyall’s milkvetch isn’t your typical border plant, but it shines in the right settings:

  • Rock gardens: Its drought tolerance and compact nature make it ideal for rocky, well-draining spots
  • Native plant gardens: A must-have for serious Pacific Northwest native collections
  • Naturalized areas: Great for areas you want to look wild and natural
  • Xeriscaping: Perfect for low-water garden designs

Growing Conditions and Care

The good news is that Lyall’s milkvetch isn’t particularly fussy once you understand its preferences:

Light: Full sun to partial shade, though it tends to prefer good light

Soil: Well-draining soil is crucial – this plant doesn’t appreciate wet feet. Sandy or gravelly soils work well

Water: Moderate water during establishment, then quite drought tolerant

Climate: Hardy in USDA zones 6-9, perfect for most of the Pacific Northwest

Planting and Care Tips

Getting Lyall’s milkvetch established requires a bit of patience, but it’s worth it:

  • Timing: Plant in fall or early spring when temperatures are moderate
  • Soil prep: Ensure excellent drainage – consider adding gravel or sand to heavy soils
  • Watering: Water regularly the first year, then reduce significantly
  • Fertilizing: Generally unnecessary – too much fertility can actually harm legumes
  • Maintenance: Very low maintenance once established

The Bottom Line

Lyall’s milkvetch might not be the star of your garden show, but it’s the kind of thoughtful plant choice that reflects a deeper understanding of place and conservation. If you can source it responsibly, it’s a wonderful addition to native gardens, rock gardens, or any space where you want to celebrate the unique flora of the Pacific Northwest.

Remember, growing rare natives like this is both a privilege and a responsibility. By choosing plants like Lyall’s milkvetch, you’re not just gardening – you’re participating in conservation, one garden at a time.

Lyall’s 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 lyallii A. Gray - Lyall's milkvetch

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