North America Native Plant

Mourning Milkvetch

Botanical name: Astragalus atratus var. mensanus

USDA symbol: ASATM

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Synonyms: Astragalus mensanus (M.E. Jones) Abrams (ASME7)   

Mourning Milkvetch: A Rare Desert Gem Worth Protecting Meet the mourning milkvetch (Astragalus atratus var. mensanus), a perennial wildflower that’s as elusive as it is intriguing. This little-known member of the pea family calls the desert regions of California and Nevada home, making it a true southwestern native with a ...

Rare plant alert!

Region: Conservation status by state

Status: S4S5T1: Status is uncertain but is somewhere between the following rankings: Subspecies or variety is critically Imperiled: Extremely rare due to factor(s) making it especially vulnerable to extinction. Typically 5 or fewer occurrences or very few remaining individuals (<1,000) ⚘ 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 ⚘ 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. ⚘

Mourning Milkvetch: A Rare Desert Gem Worth Protecting

Meet the mourning milkvetch (Astragalus atratus var. mensanus), a perennial wildflower that’s as elusive as it is intriguing. This little-known member of the pea family calls the desert regions of California and Nevada home, making it a true southwestern native with a story worth telling.

What Makes Mourning Milkvetch Special?

The mourning milkvetch belongs to the vast Astragalus genus, commonly known as milkvetches or locoweed. As a perennial plant, it returns year after year, quietly going about its business in the harsh desert landscape. Like other members of the pea family (Fabaceae), this plant has the remarkable ability to fix nitrogen in the soil, essentially creating its own fertilizer while helping neighboring plants thrive.

You might also encounter this plant listed under its synonym, Astragalus mensanus, in older botanical references. But regardless of what you call it, this desert dweller has adapted to some pretty tough conditions.

Where Does It Grow?

The mourning milkvetch has a limited native range, found only in California and Nevada. This restricted distribution is part of what makes it so special – and so vulnerable.

A Word of Caution: Rarity Matters

Here’s where things get serious. The mourning milkvetch appears to have a conservation status that suggests it’s quite rare. When dealing with rare native plants, we gardeners have a responsibility to be extra thoughtful about our choices.

If you’re considering growing this plant, please ensure any seeds or plants come from reputable, ethical sources that don’t harvest from wild populations. Better yet, consider supporting conservation efforts for this species rather than attempting to cultivate it in your garden.

The Mystery of Growing Conditions

Unfortunately, detailed growing information for this specific variety is limited. Based on its desert heritage and family characteristics, we can make some educated guesses:

  • Likely prefers well-draining, sandy or rocky soils
  • Probably drought-tolerant once established
  • May need minimal water and good drainage
  • Could be adapted to alkaline soils common in desert regions

Supporting Desert Biodiversity

While we don’t have specific information about the mourning milkvetch’s wildlife benefits, most Astragalus species support native pollinators and can provide food for specialized insects. In their native habitats, these plants play important ecological roles that we’re still learning about.

Alternative Native Choices

If you’re drawn to the idea of growing native milkvetches but want to be more conservation-minded, consider looking for more common Astragalus species that are appropriate for your region and readily available from ethical sources. Your local native plant society can provide guidance on which species are suitable for cultivation and where to find responsibly sourced plants.

The Bottom Line

The mourning milkvetch represents the fascinating but fragile diversity of our native flora. While its rarity makes it unsuitable for casual garden cultivation, learning about plants like this reminds us of the incredible variety of life adapted to specific places and conditions.

Instead of trying to grow this rare beauty, consider supporting habitat conservation, participating in citizen science projects, or choosing more common native alternatives that can provide similar ecological benefits without putting pressure on vulnerable wild populations.

Sometimes the best way to appreciate a plant is to help protect it in its natural home.

Mourning 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 atratus S. Watson - mourning milkvetch

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