Fauna
Flower

Purple Locoweed

Oxytropis lambertii

Also known as Colorado Locoweed, Lambert's Crazy Weed, Purple Pointloco

Purple locoweed produces vibrant magenta to violet spikes of pea-like flowers above silvery, silk-haired foliage in high plains and prairie habitats. Native to central and western North America, this perennial legume thrives in dry, rocky soils using a deep taproot. The plant produces swainsonine, a toxic alkaloid that causes severe neurological damage in grazing livestock known as locoperoid poisoning.

Toxic PlantPerennialFlowering
Purple Locoweed reference1 / 7
Matt Lavin / CC BY-SA 2.0 · cc-by-sa
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Least ConcernConservation statusIUCN Red List categoriesLCNTVUENCREWEXLeast ConcernRed List categories, explained →
Key facts
Diet & preyAutotrophic (Photosynthetic)
Predators
  • Locoweed Weevil
  • Grasshoppers
  • Small Mammals
ThreatsHerbicide application and agricultural land conversion
HabitatsDry prairies, gravelly hills, pine woodlands, and mountain meadows
Life spanPerennial (10+ years)
Classification
  1. OrderFabales
  2. FamilyFabaceae
  3. GenusOxytropis
  4. SpeciesOxytropis lambertii
Range & activity
Range data is not available yet.
Safe observation
Interaction riskHigh
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is high
Contains swainsonine, which causes severe neurological poisoning in horses and cattle if ingested.
Why it is dangerous
Produces swainsonine, an alkaloid synthesized by endosymbiotic fungi that damages the central nervous system of cattle, horses, and sheep.
How to recognize a risky encounter
Look for silvery pinnate leaves without leafy stems, topped by terminal spikes of vibrant magenta to purple pea flowers with sharply pointed keels.
What to do
Keep livestock away from infested areas, and avoid harvesting or crushing large quantities without protective gloves.
Responsible observation
  • Identification: Look for stemless silvery-green pinnate leaves arising directly from the crown beneath dense spikes of reddish-purple flowers.
  • Pasture Safety: Keep grazing livestock out of fields where locoweed blooms early in spring before grasses emerge.
  • Photography: Capture the distinct pointed flower keels up close without removing native vegetation.
Related species
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