South Dakota Plants to Know: Astragalus crassicarpus Back »

Figure 1: (Above) Buffalo bean at the Oahe Downstream Recreation Area
Photo by: Amanda Bachmann

This year, the South Dakota Plants to Know series is going to feature the native plants of the Prairie Butterfly Garden at the Oahe Downstream Recreation Area. This garden was established in 2013 by the USFWS South Dakota Field Office and the SD Game Fish and Parks Department. The plants made it through the winter, and the garden is ready for visitors (and butterflies).

Our first ‘plant to know’ for 2014, is Astragalus crassicarpus – commonly known as buffalo bean or ground plum. This species is a member of the legume family and it provides visual interest all summer long starting with its pink/purple flowers and ending with interesting seed pods.

Buffalo bean is mostly low-growing with pinnately compound foliage (each leaf is comprised of smaller leaflets, Figure 1). It was one of the first plants to flower this year at the Oahe garden and provided some early-season food for the bees and butterflies. The flowers are very pea-like and are pink to purple in color (Figure 2). The pods of this species are edible; however other Astragalus species are toxic. Never consume any plant material without a positive identification.

Figure 2: (Above) Buffalo bean flower.
Photo by: Amanda Bachmann

This plant is also the larval host for the Afranius Duskywing butterfly. This small butterfly is found in western South Dakota, but butterflies and bees all over the state will appreciate the addition of buffalo bean to your garden.

Plants to Know At a Glance

Scientific name Astragalus crassicarpus
Common names Buffalo bean, groundplum milkvetch
Plant size 1 – 2 ft.
Flower color Pinkish purple, purple
Bloom period May – June
Growing conditions Sun, well-drained soil
Why you should plant it Tolerates a range of garden conditions, larval host for Afranius Duskywing butterfly
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