South Dakota Native Plant Research
Fabaceae : Oxytropis lambertii

Fabaceae : Oxytropis lambertii


Download Seed: The smooth dark seeds of purple locoweed are around 2 mm long. (57 KB)

Download Seedling: Seedling of purple locoweed growing in research greenhouse at SDSU. (58 KB)

Download Leaves are made up of 7-19 leaflets. (908 KB)

Download Flowering: Flowers are spreading to erect. (464 KB)

Download Fruiting: The pods are 8-25 cm long. (392 KB)

Download research garden: Seedling of purple locoweed after one seasons growth. (106 KB)

Family Name


Common Name

Purple locoweed

Native American Name

Lakota: sunktȟápȟežuta


Oxytropis lambertii is an acaulescent perennial herb growing from a branching caudex, forming clumps of leaves that appear silvery due to a covering of short stiff and ax-shaped hairs. The leaves are up to 15 cm long with 7 to 19 linear-lanceolate leaflets, 5-40 mm long and 1-6 mm wide, with membranous, hairy stipules 7–24 mm long and having sharply pointed tips. Inflorescences develop on multiple, silvery-haired flowering stems (scapes), 10–30 cm long including the peduncle, each with 6 to 25 flowers per raceme. The calyx has a dense white covering of hairs, the sepals forming a tube that is 6-7 mm long with teeth 1.5-3 mm long. The papilionaceous flowers have red to blue to purple petals, the banner 15–25 mm long, the wings 12-20 mm long and the keel 13-19 mm long. The fruit is an silvery-haired, erect, sessile leathery or woody legume, 1–2 cm long, including the long beak. Purple locoweed blooms from May into August on prairies, plains, river bluffs and hillsides in much of South Dakota.

Additional Notes

Purple locoweed is toxic, as the name implies it causes neurological damage to livestock that ingest it. In a native plant garden, it can be an attractive specimen, the flowers are beautiful and are frequented by bumblebees. However, planting should not be available to animals or young children, as it can cause severe damage if ingested, and has no current treatment.

Horticulture Notes

Seed Collection: Collect seed in June-August after they have turned brown.

Germination: The seeds have little dormancy. Scarification with sandpaper will sometimes improve germination, but some seeds will germinate if planted in the spring.

Soils: Well drained soils of most types.

Light: Full sun

Water: Dry to mesic.

Fabaceae : Oxytropis lambertii