North America Native Plant

Purple Locoweed

Botanical name: Oxytropis lambertii var. bigelovii

USDA symbol: OXLAB

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Synonyms: Oxytropis lambertii Pursh ssp. bigelovii (A. Gray) W.A. Weber (OXLAB2)  âš˜  Oxytropis patens (Rydb.) A. Nelson (OXPA5)   

Purple Locoweed: A Beautiful but Cautionary Native Wildflower Meet purple locoweed (Oxytropis lambertii var. bigelovii), a striking native wildflower that’s as gorgeous as it is controversial. This perennial forb brings vibrant purple blooms to western landscapes, but comes with some important considerations that every gardener should know before adding it ...

Purple Locoweed: A Beautiful but Cautionary Native Wildflower

Meet purple locoweed (Oxytropis lambertii var. bigelovii), a striking native wildflower that’s as gorgeous as it is controversial. This perennial forb brings vibrant purple blooms to western landscapes, but comes with some important considerations that every gardener should know before adding it to their native plant collection.

What is Purple Locoweed?

Purple locoweed is a native perennial herb that belongs to the legume family. As a forb, it lacks woody tissue and dies back to ground level each winter, returning with fresh growth in spring. This hardy plant has been gracing the American West for millennia, developing an impressive tolerance for harsh conditions that would challenge many garden favorites.

You might also encounter this plant listed under its synonyms Oxytropis lambertii ssp. bigelovii or Oxytropis patens in older botanical references.

Where Does It Call Home?

Purple locoweed is native to six western states, thriving across diverse landscapes from high plains to mountain foothills. You’ll find it naturally occurring in Arizona, Colorado, Kansas, New Mexico, Utah, and Wyoming, where it has adapted to everything from prairie grasslands to rocky slopes.

Garden Appeal: The Good and The Cautionary

Let’s start with the positives – purple locoweed is absolutely stunning when in bloom. Its dense clusters of purple to violet flowers create eye-catching displays that can rival any cultivated perennial. The silvery-green compound leaves provide attractive texture even when the plant isn’t flowering, and its low-growing habit makes it perfect for filling in naturalized areas.

However, here’s where things get serious: purple locoweed contains toxic alkaloids that can be harmful to livestock and potentially dangerous to pets and humans if consumed. The common name locoweed actually refers to the erratic behavior it can cause in grazing animals that eat too much of it.

Is Purple Locoweed Right for Your Garden?

This native beauty might be perfect for your landscape if you:

  • Want to support native pollinators with a drought-tolerant option
  • Have a large naturalized area away from pets and livestock
  • Live in USDA hardiness zones 3-8
  • Appreciate low-maintenance native plants
  • Are creating a prairie or wildflower meadow

However, you should probably skip purple locoweed if you:

  • Have young children who might be tempted to taste garden plants
  • Keep rabbits, goats, or other grazing pets
  • Live near livestock operations
  • Prefer formal garden settings

Growing Purple Locoweed Successfully

If you’ve decided this native wildflower fits your landscape, you’ll be pleased to know it’s relatively easy to grow – as long as you don’t kill it with kindness!

Ideal Growing Conditions

  • Full sun exposure
  • Well-draining soils (clay, sandy, or rocky)
  • Minimal to moderate water once established
  • Good air circulation

Planting and Care Tips

Purple locoweed thrives on neglect once established. Plant in spring after the last frost, water regularly during the first growing season to help roots establish, then back off significantly. Overwatering is probably the biggest mistake you can make with this drought-adapted native.

The plant typically reaches 6-12 inches in height and spreads slowly through underground roots. It’s not aggressive, so you won’t need to worry about it taking over your garden.

Wildlife and Pollinator Benefits

Despite its toxicity concerns, purple locoweed plays an important ecological role. Native bees and butterflies appreciate its nectar-rich flowers, and the plant provides habitat for various beneficial insects. Just remember that while it supports wildlife, it’s not suitable for areas where domestic animals graze.

The Bottom Line

Purple locoweed offers gardeners a chance to grow a truly native wildflower that’s both beautiful and historically significant to western ecosystems. Its drought tolerance and pollinator appeal make it valuable for the right setting. However, the toxicity factor means it requires thoughtful placement and isn’t suitable for every garden situation.

If you’re looking for similar native alternatives without the toxicity concerns, consider other purple-flowered natives like wild bergamot, purple prairie clover, or native asters that can provide similar aesthetic appeal with greater peace of mind.

Purple Locoweed

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

Oxytropis DC. - locoweed

Species

Oxytropis lambertii Pursh - purple locoweed

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