North America Non-native Plant

Astragalus Trimestris

Botanical name: Astragalus trimestris

USDA symbol: ASTR17

Native status: Not native but doesn't reproduce and persist in the wild

Astragalus trimestris: A Botanical Mystery in Your Garden Search If you’ve stumbled across the name Astragalus trimestris in your native plant research, you’ve encountered quite the botanical puzzle! As someone who spends countless hours digging through plant databases and scientific literature, I have to be honest with you: this particular ...

Astragalus trimestris: A Botanical Mystery in Your Garden Search

If you’ve stumbled across the name Astragalus trimestris in your native plant research, you’ve encountered quite the botanical puzzle! As someone who spends countless hours digging through plant databases and scientific literature, I have to be honest with you: this particular plant name doesn’t appear to exist in current botanical records.

The Case of the Missing Milkvetch

The genus Astragalus, commonly known as milkvetch or locoweed, is absolutely massive – we’re talking about one of the largest plant genera in the world with over 3,000 species! These plants are found across temperate regions and include everything from tiny alpine cushions to sprawling prairie perennials. However, Astragalus trimestris doesn’t show up in any of the major botanical databases, herbarium collections, or recent taxonomic work I’ve consulted.

What This Means for Gardeners

Here’s the deal: you might have encountered this name in an old reference, a mislabeled plant, or perhaps it’s a synonym that’s fallen out of use. Sometimes botanical names get shuffled around as taxonomists better understand plant relationships, and occasionally names that were once proposed never actually get formally published or accepted.

Better Astragalus Alternatives for Your Garden

If you’re interested in growing plants from the Astragalus genus, here are some well-documented native species you might consider instead:

  • Astragalus canadensis (Canadian Milkvetch) – A showy prairie species with cream-colored flower spikes
  • Astragalus crassicarpus (Ground Plum) – Low-growing with inflated seed pods that look like tiny plums
  • Astragalus purshii (Pursh’s Milkvetch) – A western species with purple flowers
  • Astragalus americanus (American Milkvetch) – Another eastern prairie native

How to Verify Plant Names

When you’re researching native plants, it’s always wise to double-check botanical names using reliable sources like:

  • The USDA PLANTS Database
  • iNaturalist
  • Your local native plant society
  • University extension services

The Bottom Line

While I can’t give you growing tips for Astragalus trimestris (since it doesn’t appear to be a valid species), I encourage you to explore the many wonderful, verified Astragalus species that could bring both beauty and ecological benefits to your native garden. These milkvetches are fantastic for pollinators, many are nitrogen-fixers that improve soil health, and they’re perfectly adapted to their native regions.

If you have more information about where you encountered this plant name, I’d love to help you track down what you’re actually looking for. Sometimes the best garden discoveries come from a bit of botanical detective work!

Astragalus Trimestris

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 trimestris L.

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