North America Native Plant

Bicknell’s Milkvetch

Botanical name: Astragalus consobrinus

USDA symbol: ASCO16

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Synonyms: Astragalus castaneiformis S. Watson var. consobrinus Barneby (ASCAC)   

Bicknell’s Milkvetch: A Rare Utah Native Worth Protecting If you’re passionate about native plants and happen to garden in Utah, you might have heard whispers about Bicknell’s milkvetch (Astragalus consobrinus). This little-known perennial legume is one of those plants that makes you appreciate the incredible diversity hidden in our native ...

Rare plant alert!

Region: Conservation status by state

Status: S2S3: Status is uncertain but is somewhere between the following rankings: 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) ⚘ 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 ⚘

Bicknell’s Milkvetch: A Rare Utah Native Worth Protecting

If you’re passionate about native plants and happen to garden in Utah, you might have heard whispers about Bicknell’s milkvetch (Astragalus consobrinus). This little-known perennial legume is one of those plants that makes you appreciate the incredible diversity hidden in our native landscapes—but it’s also one that comes with some important considerations before you think about adding it to your garden.

What Makes Bicknell’s Milkvetch Special

Bicknell’s milkvetch is a true Utah endemic, meaning it exists nowhere else on Earth except within the borders of the Beehive State. This perennial member of the pea family produces delicate white to cream-colored flowers that bloom in small clusters, creating a subtle but charming display against its compound leaves made up of tiny leaflets. Like other milkvetches, it has that classic legume flower shape that looks almost like a tiny sweet pea blossom.

The plant was previously classified under the synonym Astragalus castaneiformis var. consobrinus, but botanists now recognize it as its own distinct species—a testament to its unique evolutionary story in Utah’s diverse landscapes.

Where You’ll Find It Growing Wild

Bicknell’s milkvetch calls Utah home, specifically thriving in the state’s unique high-desert environments. You’ll find it growing naturally in well-drained, often alkaline soils where many other plants struggle to survive.

A Word of Caution: This Plant is Rare

Here’s where things get important: Bicknell’s milkvetch has a Global Conservation Status of S2S3, which indicates it’s considered rare to uncommon throughout its range. This means we need to be extra thoughtful about how we interact with this species. While it’s wonderful to appreciate native plants, this particular milkvetch should only be grown using responsibly sourced material—never collected from the wild.

If you’re interested in growing this rare beauty, work only with reputable native plant nurseries that can verify their plants come from ethically propagated stock, not wild collection.

Growing Bicknell’s Milkvetch: Not for Beginners

Let’s be honest—this isn’t a plant for every gardener or every garden. Bicknell’s milkvetch is adapted to very specific conditions and can be quite finicky about getting what it needs.

Ideal Growing Conditions

  • Sunlight: Full sun exposure
  • Soil: Extremely well-drained, often alkaline soils
  • Water: Minimal once established—this plant despises wet feet
  • Hardiness: Generally hardy in USDA zones 4-7

Best Garden Settings

If you do decide to grow Bicknell’s milkvetch, it’s best suited for:

  • Specialized native plant gardens focused on Utah flora
  • Rock gardens with excellent drainage
  • Xerophytic (drought-adapted) landscapes
  • Conservation collections

Wildlife and Pollinator Benefits

Like other members of the legume family, Bicknell’s milkvetch likely provides nectar for native bees and other small pollinators. Its flowers, while modest in size, offer the classic landing platform that many native bees have co-evolved to use efficiently. As a nitrogen-fixing plant, it also contributes to soil health in its native ecosystem.

Should You Grow It?

Bicknell’s milkvetch presents a fascinating case study in native plant gardening. While it’s undoubtedly a special plant worth celebrating, it’s not one to grow lightly. Consider this species if you:

  • Are an experienced native plant gardener in Utah
  • Have the specific growing conditions it requires
  • Can source plants responsibly
  • Want to contribute to conservation efforts

For most gardeners interested in supporting Utah’s native flora, there are many other native milkvetches and legumes that are less rare and easier to grow successfully. However, if you’re committed to preserving Utah’s unique botanical heritage and have the right conditions, growing Bicknell’s milkvetch with responsibly sourced plants can be a meaningful way to participate in conservation.

Remember, sometimes the best way to appreciate a rare plant is to support its conservation in the wild while choosing more common native alternatives for our home landscapes. Whatever you decide, make sure your gardening choices help protect these special plants for future generations to discover and admire.

Bicknell’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 consobrinus (Barneby) S.L. Welsh - Bicknell'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