North America Native Plant

New Mexico Spiny Milkvetch

Botanical name: Astragalus kentrophyta var. neomexicanus

USDA symbol: ASKEN

Life cycle: perennial

Habit: subshrub

Native status: Native to the lower 48 states  

Synonyms: Astragalus kentrophyta A. Gray ssp. neomexicanus (Barneby) W.A. Weber (ASKEN2)   

New Mexico Spiny Milkvetch: A Rare Gem for Desert Gardens If you’re looking to add a unique, drought-tolerant native to your garden, the New Mexico spiny milkvetch might just be the perfect choice. This fascinating little shrub brings both beauty and ecological value to the right landscape, though it comes ...

Rare plant alert!

Region: Conservation status by state

Status: S5T3: 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. ⚘ 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. ⚘

New Mexico Spiny Milkvetch: A Rare Gem for Desert Gardens

If you’re looking to add a unique, drought-tolerant native to your garden, the New Mexico spiny milkvetch might just be the perfect choice. This fascinating little shrub brings both beauty and ecological value to the right landscape, though it comes with some important considerations for responsible gardeners.

Meet the New Mexico Spiny Milkvetch

Known botanically as Astragalus kentrophyta var. neomexicanus, this perennial shrub is a true New Mexican native. As its common name suggests, this plant is exclusive to the Land of Enchantment, making it a special addition for gardeners wanting to showcase their regional flora.

This low-growing shrub typically stays under 1.5 feet tall and rarely exceeds 3 feet at maturity, making it perfect for smaller spaces or as a unique groundcover alternative. Don’t let its modest size fool you – this tough little plant packs a lot of character into its compact form.

Where You’ll Find It Growing Wild

The New Mexico spiny milkvetch is found exclusively in New Mexico’s high desert and montane regions. Its limited geographic distribution makes it a true regional specialty – you won’t find this plant anywhere else in the world!

Why Consider This Plant? (And Why You Should Be Careful)

Before we dive into the why plant it discussion, there’s something important you need to know: this plant has a Global Conservation Status of S5T3, indicating some conservation concern. This means if you’re interested in growing New Mexico spiny milkvetch, you should only source it from reputable native plant nurseries that propagate their own stock responsibly – never collect from the wild.

That said, here’s why this plant might be worth seeking out:

  • It’s incredibly drought-tolerant once established
  • Produces lovely purple to pink flowers that attract native pollinators
  • Perfect for authentic New Mexican landscapes
  • Requires minimal maintenance once happy
  • Excellent for xeriscaping projects

Garden Role and Design Applications

This spiny little shrub shines in specific landscape settings. It’s particularly well-suited for:

  • Rock gardens and xeriscapes
  • Native plant gardens focused on regional flora
  • Drought-tolerant landscape designs
  • Naturalized desert garden areas

Its low-growing, cushion-like form makes it an interesting textural element, while its seasonal flowers provide pops of color that native bees and butterflies appreciate.

Growing Conditions and Care

New Mexico spiny milkvetch thrives in USDA hardiness zones 4-8, making it surprisingly cold-tolerant despite its desert origins. Here’s what this plant needs to succeed:

Sunlight: Full sun is essential – this plant won’t tolerate shade well.

Soil: Well-draining soil is absolutely critical. This plant is adapted to lean, rocky soils and will struggle in heavy clay or consistently moist conditions.

Water: Once established, it’s extremely drought-tolerant. In fact, overwatering is more likely to kill this plant than underwatering.

Planting and Care Tips

Successfully growing this species requires mimicking its natural habitat:

  • Plant in spring or fall when temperatures are moderate
  • Ensure excellent drainage – consider raised beds or adding gravel to heavy soils
  • Water regularly the first year to help establishment, then reduce significantly
  • Avoid fertilizing – this plant prefers lean soils
  • Mulch with gravel rather than organic materials

Pollinator and Wildlife Benefits

While small, the flowers of New Mexico spiny milkvetch provide valuable nectar for native bees and butterflies. As a member of the legume family, it also helps fix nitrogen in the soil, potentially benefiting neighboring plants.

The Bottom Line

New Mexico spiny milkvetch is a plant for the patient, dedicated native plant gardener. Its rarity means you’ll need to source it responsibly, and its specific growing requirements mean it’s not a plant for every garden. However, for those gardening in appropriate conditions with a focus on authentic regional flora, it can be a rewarding and unique addition that supports local ecosystems while requiring minimal resources once established.

Remember: always purchase from reputable sources that propagate their own plants, and never collect from wild populations. With responsible gardening practices, you can enjoy this rare desert gem while helping to preserve it for future generations.

New Mexico Spiny 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 kentrophyta A. Gray - spiny milkvetch

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