North America Native Plant

Western Milkvetch

Botanical name: Astragalus robbinsii var. occidentalis

USDA symbol: ASROO

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Synonyms: Astragalus occidentalis (S. Watson) M.E. Jones (ASOC3)   

Western Milkvetch: A Rare Nevada Native Worth Protecting If you’re passionate about native plants and conservation gardening, you might have stumbled across the intriguing western milkvetch (Astragalus robbinsii var. occidentalis). This perennial wildflower represents something special in the world of native gardening – a plant that connects us directly to ...

Rare plant alert!

Region: Conservation status by state

Status: S5T2T3: 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) ⚘ 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. ⚘ Secure: At very low or no risk of extinction in the jurisdiction due to a very extensive range, abundant populations or occurrences, with little to no concern from declines or threats. ⚘

Western Milkvetch: A Rare Nevada Native Worth Protecting

If you’re passionate about native plants and conservation gardening, you might have stumbled across the intriguing western milkvetch (Astragalus robbinsii var. occidentalis). This perennial wildflower represents something special in the world of native gardening – a plant that connects us directly to the unique ecosystems of the American West.

What Makes Western Milkvetch Special?

Western milkvetch belongs to the legume family, and like its relatives, it has the remarkable ability to fix nitrogen in the soil. This perennial plant is native to the lower 48 states, though its current distribution is quite limited. You might also see it listed under its synonym, Astragalus occidentalis, in older botanical references.

Where Does It Grow?

Currently, western milkvetch is found growing wild in Nevada, where it has adapted to the region’s unique climate and soil conditions. This limited geographic distribution makes it a true regional treasure.

A Word of Caution: Rarity Matters

Before we dive into growing tips, there’s something important you should know. Western milkvetch has a Global Conservation Status of S5T2T3, which indicates it’s considered rare or uncommon. This means if you’re interested in growing this plant, you should only obtain seeds or plants from responsible, ethical sources that don’t harvest from wild populations.

Supporting conservation-minded nurseries and seed companies helps protect wild populations while still allowing gardeners to enjoy and preserve these special plants.

Why Grow Western Milkvetch?

You might wonder why you’d want to grow such a specialized plant. Here are some compelling reasons:

  • Conservation value: Growing rare natives helps preserve genetic diversity
  • Soil improvement: Like other legumes, it enriches soil naturally
  • Regional authenticity: Perfect for creating landscapes that reflect local ecosystems
  • Educational value: Great conversation starter about native plant conservation

Growing Conditions and Care

While specific growing information for this variety is limited, we can draw from knowledge of related Astragalus species and Nevada’s growing conditions:

Western milkvetch likely thrives in well-draining soils and can handle the temperature extremes typical of Nevada’s climate. Most milkvetches prefer full sun and are quite drought-tolerant once established, making them excellent candidates for water-wise gardening.

As a perennial, western milkvetch will return year after year, gradually developing a deeper root system that helps it survive harsh conditions. The plant’s nitrogen-fixing abilities make it a valuable addition to native plant gardens where soil improvement is a goal.

Garden Design Ideas

Western milkvetch works beautifully in:

  • Native plant gardens focused on Nevada flora
  • Xeriscapes and drought-tolerant landscapes
  • Conservation gardens
  • Educational demonstration gardens

The Bottom Line

Western milkvetch isn’t your typical garden center find, and that’s exactly what makes it special. If you’re drawn to rare native plants and committed to conservation gardening, this Nevada native could be a meaningful addition to your landscape. Just remember to source it responsibly and appreciate the role you’re playing in preserving America’s botanical heritage.

While we don’t have complete information about all aspects of growing this particular variety, its rarity makes it a plant worth learning about and, when possible, worth growing with care and respect for its conservation status.

Western 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 robbinsii (Oakes) A. Gray - Robbins' milkvetch

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