North America Native Plant

Diehl’s Milkvetch

Botanical name: Astragalus flexuosus var. diehlii

USDA symbol: ASFLD

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Diehl’s Milkvetch: A Rare Native Gem Worth Knowing About Meet Diehl’s milkvetch (Astragalus flexuosus var. diehlii), a little-known native perennial that deserves a spot in the conversation about southwestern native plants. While you might not find this particular variety at your local nursery, understanding its story helps us appreciate the ...

Rare plant alert!

Region: Conservation status by state

Status: S5T2T4: 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 varieties is apparently secure: Uncommon but not rare, and usually widespread. Possibly cause for longterm concern. Typically more than 100 occurrences in the region or more than 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. ⚘

Diehl’s Milkvetch: A Rare Native Gem Worth Knowing About

Meet Diehl’s milkvetch (Astragalus flexuosus var. diehlii), a little-known native perennial that deserves a spot in the conversation about southwestern native plants. While you might not find this particular variety at your local nursery, understanding its story helps us appreciate the incredible diversity of native plants in our region.

What Makes Diehl’s Milkvetch Special

This perennial beauty belongs to the pea family and represents a unique variety of the flexible milkvetch. Like its relatives, Diehl’s milkvetch likely produces delicate, pea-like flowers and has the characteristic compound leaves that make milkvetches so distinctive in the landscape.

Where You’ll Find It Growing Wild

Diehl’s milkvetch calls the American Southwest home, naturally occurring in Arizona, Colorado, and Utah. This limited range makes it a true regional treasure that’s perfectly adapted to the unique conditions of the high desert and mountain regions.

A Word About Rarity

Here’s where things get interesting – and important. Diehl’s milkvetch has a conservation status that suggests it’s uncommon to rare in its native habitat. This means we need to be thoughtful stewards if we’re lucky enough to encounter this plant in the wild or consider it for our gardens.

If you’re interested in growing this particular variety, it’s crucial to source seeds or plants only from reputable native plant suppliers who can guarantee the material was obtained responsibly and legally. Never collect from wild populations, as this could harm already vulnerable plant communities.

Garden Potential and Growing Conditions

While specific growing information for this variety is limited, milkvetches as a group are generally:

  • Drought-tolerant once established
  • Lovers of well-draining soil
  • Happy in full sun locations
  • Low-maintenance perennials
  • Adapted to poor soils

Based on its native range, Diehl’s milkvetch would likely thrive in USDA hardiness zones 4-8, making it suitable for many mountain and high desert gardens.

Why Consider Native Milkvetches

Even if Diehl’s milkvetch isn’t readily available, exploring other native milkvetches in your area can bring similar benefits to your landscape:

  • Support for native pollinators and wildlife
  • Nitrogen fixation that improves soil health
  • Authentic regional character in garden design
  • Low water requirements once established

The Bigger Picture

Plants like Diehl’s milkvetch remind us that our native flora includes countless specialized varieties and species that have evolved to thrive in very specific conditions. While we may not all be able to grow this particular plant, learning about it deepens our appreciation for the complexity and beauty of our regional ecosystems.

Consider supporting conservation efforts and native plant societies in Arizona, Colorado, and Utah – organizations working to protect rare plants like Diehl’s milkvetch ensure these botanical treasures will be around for future generations to discover and admire.

Alternatives to Consider

If you’re drawn to the idea of growing milkvetches, check with local native plant societies or extension offices about other Astragalus species that might be more readily available and appropriate for your specific location. Many regions have their own native milkvetches that can provide similar ecological benefits without the conservation concerns.

Diehl’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 flexuosus Douglas ex G. Don - flexile milkvetch

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