What is ground plum?

By Erika Van Krevelen, Community Volunteer Ambassador, Mississippi National River and Recreation Area

Buffalo pea in bloom. Helzer family prairie near Stockham, Nebraska. Copyright Chris Helzer/The Nature Conservancy.

If you never look down while walking through the prairie you're missing out, for here grows the ground plum, a sprawling member of the pea family. The ground plum may be called by several other common names, like groundplum milkvetch or buffalo plum, as well as by its Latin name, Astragalus crassicarpus. This culturally significant plant has another name in the Dakota language: ptetháwote, or “food of the buffalo”. 

In late spring, the ground plum boasts beautiful white or purple flowers that are visited by pollinators like bees, moths, and butterflies. After pollination, the flowers soon transform into firm fruit about one inch in diameter. As one of its names suggests, buffalo and other prairie-dwelling animals eat the plum-like fruit. They are also a traditional food source in Dakota culture. As the fruit matures, they dry into a pod that holds many seeds. In fact, since it is such a prolific seeder, Dakota tradition is to soak its seeds among corn seeds before planting to encourage the corn to grow many seeds as well. 

Buffalo pea, or ground plum (Astragalus crassicarpus) with ripe pods. The pods are delicious when they are still green and tender. The Nature Conservancy’s Niobrara Valley Preserve, Nebraska. Copyright Chris Helzer/The Nature Conservancy.

Like most members of the pea family, the ground plum’s roots fix nitrogen; that is, they can take atmospheric nitrogen and turn it into a form that is usable for plants. Upon the ground plum’s death, this nitrogen is shared in the soil with neighboring plants. This nutrient is essential for healthy plant growth, underscoring the ecological significance of the plant as well. 

The ground plum thrives in dry, sunny areas like the Grey Cloud Dunes Scientific and Natural Area and Mni Owe Sni / Coldwater Spring. Move gently through the prairie, as this low-growing plant won’t broadcast its presence. Instead, it will be found humbly growing at your feet, providing nourishment for the people, wildlife, and plants around it. 

This fall, volunteers helped plant more than 4,000 plants within an oak savanna landscape at Mni Owe Sni/Coldwater Spring. Included were pȟeží wačháŋǧa/sweetgrass, ptetháwote/ground plum, and tíŋpsina/prairie turnip, among other plants valued by many Dakota people for their traditional foods and medicinal uses.

The information source on the traditional uses of ground plum is from Marlena Myles' “Plants of Hemnichan.” Learn more about Dakota plants and their traditional food and medicinal uses on Marlena Myles’ Free Resources webpage.

Plant names were sourced from the book, ‘Cultural Plants of the Lower Sioux Indian Community’ by Kyle Herdina and this document.