North America Native Plant

Idaho Milkvetch

Botanical name: Astragalus conjunctus var. rickardii

USDA symbol: ASCOR2

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Idaho Milkvetch: A Rare Pacific Northwest Native Worth Protecting Meet Idaho milkvetch (Astragalus conjunctus var. rickardii), a special little perennial that’s quietly making its home in the Pacific Northwest. While you might not have heard of this particular plant before, it’s actually a fascinating member of the pea family that ...

Rare plant alert!

Region: Conservation status by state

Status: S4T3: Status is uncertain but is somewhere between the following rankings: 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. ⚘ Apparently Secure: Uncommon but not rare, and usually widespread. Possibly cause for longterm concern. Typically more than 100 occurrences in the state or more than 10,000 individuals ⚘

Idaho Milkvetch: A Rare Pacific Northwest Native Worth Protecting

Meet Idaho milkvetch (Astragalus conjunctus var. rickardii), a special little perennial that’s quietly making its home in the Pacific Northwest. While you might not have heard of this particular plant before, it’s actually a fascinating member of the pea family that deserves a spot in the conversation about native gardening—though with some important caveats we’ll discuss.

Where You’ll Find Idaho Milkvetch

This native beauty calls Oregon and Washington home, making it a true Pacific Northwest original. It’s perfectly adapted to life in the lower 48 states, having evolved alongside the region’s unique climate and ecosystems over thousands of years.

A Plant That Needs Our Help

Here’s where things get interesting (and important): Idaho milkvetch has a Global Conservation Status of S4T3. While that might sound like alphabet soup, it’s actually telling us something crucial. The T3 part means this particular variety is considered vulnerable to extirpation—in other words, it could disappear from parts of its range if we’re not careful.

This rarity status means that if you’re interested in growing Idaho milkvetch, you’ll want to be extra thoughtful about where you source your plants. Only purchase from reputable native plant nurseries that propagate their stock responsibly, rather than wild-collecting.

Why Grow Idaho Milkvetch?

You might be wondering why you’d want to grow a plant that comes with conservation considerations. Here are a few compelling reasons:

  • You’ll be supporting biodiversity by providing habitat for native wildlife
  • As a perennial, it’s a long-term investment in your garden’s ecosystem
  • It’s perfectly adapted to Pacific Northwest conditions, meaning less work for you once established
  • You’ll be participating in conservation efforts by maintaining genetic diversity

The Growing Challenge

We’ll be honest with you: growing Idaho milkvetch isn’t like picking up petunias at the garden center. Because it’s a specialized native with a limited range, detailed cultivation information is scarce. Most Astragalus species (commonly called milkvetches) prefer well-drained soils and can be somewhat finicky about their growing conditions.

If you’re determined to grow this rare beauty, your best bet is to:

  • Contact local native plant societies in Oregon or Washington for specific growing advice
  • Connect with botanical gardens or universities studying Pacific Northwest natives
  • Work with specialized native plant nurseries that may have experience with this variety

Supporting Conservation Through Gardening

Sometimes the best way to appreciate a rare plant like Idaho milkvetch is to support its conservation indirectly. Consider planting other native Astragalus species or Pacific Northwest natives that are more readily available and easier to grow. This approach still supports local ecosystems while leaving the rarest plants to conservation professionals.

If you do decide to grow Idaho milkvetch, remember that you’re becoming a steward of a vulnerable variety. Keep records of your plants, share seeds or divisions responsibly, and consider connecting with conservation organizations working to protect Pacific Northwest flora.

The Bottom Line

Idaho milkvetch represents something special in the plant world—a reminder that even in our well-explored landscapes, there are still treasures worth protecting. While it may not be the easiest addition to your garden, it offers the unique opportunity to participate in conservation right in your own backyard. Just remember to source responsibly and embrace the learning curve that comes with growing something truly special.

Idaho 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 conjunctus S. Watson - Idaho milkvetch

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