North America Native Plant

Egg Milkvetch

Botanical name: Astragalus oophorus var. lonchocalyx

USDA symbol: ASOOL

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Egg Milkvetch: A Rare Native Gem for Specialized Gardens Meet the egg milkvetch (Astragalus oophorus var. lonchocalyx), a perennial native plant that’s as rare as it sounds intriguing. This little-known variety belongs to the vast Astragalus genus, which includes hundreds of species across North America. While you won’t find this ...

Rare plant alert!

Region: Conservation status by state

Status: S4T2: Status is uncertain but is somewhere between the following rankings: Subspecies or variety is imperiled: Extremely rare due to factor(s) making it especially vulnerable to extinction. Typically 6 to 20 occurrences or few remaining individuals (1,000 to 3,000) ⚘ 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 ⚘

Egg Milkvetch: A Rare Native Gem for Specialized Gardens

Meet the egg milkvetch (Astragalus oophorus var. lonchocalyx), a perennial native plant that’s as rare as it sounds intriguing. This little-known variety belongs to the vast Astragalus genus, which includes hundreds of species across North America. While you won’t find this particular plant at your local garden center, it represents an important piece of our native botanical heritage.

Where Does Egg Milkvetch Call Home?

This native beauty has a pretty exclusive address – you’ll only find it naturally growing in Nevada and Utah. It’s what we call an endemic species, meaning it evolved in this specific region and doesn’t occur anywhere else in the world. Talk about being a true local!

Should You Grow Egg Milkvetch?

Here’s where things get a bit complicated. Astragalus oophorus var. lonchocalyx carries a Global Conservation Status of S4T2, which indicates it’s quite rare in the wild. This means while it’s not immediately threatened with extinction, it’s uncommon enough that we need to be thoughtful about how we interact with it.

If you’re considering growing this plant, please keep these important points in mind:

  • Only source seeds or plants from reputable native plant societies or conservation organizations
  • Never collect from wild populations
  • Consider growing it as part of conservation efforts rather than typical landscaping
  • Connect with local botanical gardens or native plant groups who might have propagation programs

What Makes This Plant Special?

As a member of the legume family, egg milkvetch likely shares some wonderful traits with its relatives. Most Astragalus species are nitrogen-fixers, meaning they actually improve soil health by partnering with beneficial bacteria to convert atmospheric nitrogen into forms plants can use. It’s like having a tiny soil improvement factory right in your garden!

Growing Conditions and Care

While specific growing information for this variety is limited due to its rarity, we can make educated guesses based on its Nevada and Utah origins:

  • Climate: Likely adapted to arid and semi-arid conditions
  • Soil: Probably prefers well-draining, possibly alkaline soils
  • Water: Once established, likely drought-tolerant
  • Hardiness: Based on its range, probably hardy in USDA zones 4-8

Wildlife and Pollinator Benefits

While we don’t have specific data on this variety’s wildlife benefits, Astragalus species are generally valuable to native ecosystems. They often support specialized native bees and other pollinators, and their seeds may provide food for birds and small mammals.

The Bottom Line

Egg milkvetch is definitely not your typical garden center find, and that’s probably for the best. Its rarity makes it more suitable for serious native plant enthusiasts, conservation gardens, or research settings rather than general landscaping. If you’re passionate about preserving native biodiversity and have connections to conservation organizations, this could be a meaningful plant to grow.

For most gardeners interested in supporting native ecosystems in Nevada and Utah, consider exploring more common Astragalus species or other native legumes that can provide similar ecological benefits without the conservation concerns. Your local native plant society can point you toward beautiful, locally appropriate alternatives that will thrive in your garden while supporting wildlife.

Remember, sometimes the best way to appreciate rare plants is to learn about them, support conservation efforts, and choose more common native alternatives for our home landscapes. Every native plant we grow – rare or common – is a step toward supporting our local ecosystems!

Egg 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 oophorus S. Watson - egg milkvetch

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