North America Native Plant

Harrison’s Milkvetch

Botanical name: Astragalus harrisonii

USDA symbol: ASHA4

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Harrison’s Milkvetch: A Rare Utah Native Worth Protecting If you’re a native plant enthusiast exploring Utah’s unique flora, you might have come across Harrison’s milkvetch (Astragalus harrisonii). This perennial legume represents one of those special plants that makes Utah’s high desert landscape so botanically fascinating—and so fragile. What Makes Harrison’s ...

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 ⚘

Harrison’s Milkvetch: A Rare Utah Native Worth Protecting

If you’re a native plant enthusiast exploring Utah’s unique flora, you might have come across Harrison’s milkvetch (Astragalus harrisonii). This perennial legume represents one of those special plants that makes Utah’s high desert landscape so botanically fascinating—and so fragile.

What Makes Harrison’s Milkvetch Special?

Harrison’s milkvetch belongs to the vast Astragalus genus, which includes hundreds of species commonly known as milkvetches or locoweeds. These plants are particularly important in arid western ecosystems, where they’ve evolved to thrive in challenging conditions that would leave other plants gasping for moisture.

As a perennial, this milkvetch returns year after year, developing deep root systems that help stabilize soil and access water sources other plants can’t reach. Like other members of the legume family, it has the remarkable ability to fix nitrogen in the soil, essentially creating its own fertilizer while improving conditions for neighboring plants.

Where Does It Call Home?

Harrison’s milkvetch is native to the lower 48 states, with its known distribution centered in Utah. This limited range is part of what makes this plant so special—and so vulnerable.

A Word of Caution: Rarity Matters

Here’s where things get serious, fellow gardeners. Harrison’s milkvetch carries a Global Conservation Status of S2S3, which indicates this species is quite rare and potentially vulnerable. This isn’t just another pretty wildflower you can casually add to your garden border.

What does this mean for you as a gardener?

  • If you’re interested in growing this species, source seeds or plants only from reputable native plant societies or conservation organizations
  • Never collect seeds or plants from wild populations
  • Consider this plant only if you’re committed to responsible native gardening practices
  • Focus on supporting local conservation efforts rather than personal cultivation

Growing Conditions and Care

While specific growing information for Harrison’s milkvetch is limited due to its rarity, we can make educated guesses based on its Astragalus relatives and Utah habitat:

  • Soil: Likely prefers well-draining, alkaline soils typical of Utah’s high desert
  • Water: Drought-tolerant once established, requiring minimal supplemental watering
  • Sun: Probably thrives in full sun conditions
  • Climate: Adapted to Utah’s temperature extremes and low humidity

Better Alternatives for Your Garden

Given Harrison’s milkvetch’s rarity, consider these more common Utah native alternatives that offer similar benefits:

  • Utah milkvetch (Astragalus utahensis)
  • Two-grooved milkvetch (Astragalus bisulcatus)
  • Other locally common Astragalus species
  • Native legumes like lupines or clovers

Supporting Conservation Instead

Sometimes the best way to grow a rare plant is to support its conservation in the wild. Consider:

  • Volunteering with local native plant societies
  • Supporting habitat restoration projects
  • Participating in citizen science botanical surveys
  • Advocating for protection of critical habitats

Harrison’s milkvetch reminds us that not every beautiful native plant belongs in our gardens. Some species serve us best by thriving in their natural homes, where they can play their irreplaceable role in Utah’s desert ecosystems. By respecting these boundaries, we become better stewards of the incredible botanical diversity that makes the American West so special.

Harrison’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 harrisonii Barneby - Harrison'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