Psoralea esculenta

Psoralea esculenta, common name prairie turnip or timpsula, is an herbaceous perennial plant native to prairies and dry woodlands of central North America, which bears a starchy tuberous root edible as a root vegetable. The plant is also known as Pediomelum esculentum. English names for the plant include tipsin, teepsenee, breadroot, breadroot scurf pea, large Indian breadroot and pomme blanche. The prairie turnip was a staple food of the Plains Indians.

A related species, Psoralea hypogaea, the little breadroot, is also edible, although the plant and root are smaller. Another species, Psoralea argophylla, was probably harvested for food only in times of famine.[a]

The prairie turnip has a range on the Great Plains from Manitoba south to Texas and from Wisconsin west to Montana. It grows best in full sun on well-drained and rocky or sandy soil. The plant is referred to by the Indians of Iowa as Tipsina, the seed-bearing plant is due to climatic conditions especially in high, dry spots and can be found near rivers or in the steppe.[b] The relative scarcity of the plant today compared to its previous abundance may be because most prairie has been converted to farmland or managed grassland.

The prairie turnip is a perennial, living 3 to more than 6 years.[3] In spring, several densely haired stems emerge from the ground and reach up to 30 cm (12 in), bearing palmately compound leaves divided into five leaflets. In early summer the plant produces abundant blue or purple flowers in terminal clusters 5 to 10 cm (4 in) long, leading to flattened, slender-tipped pods. Harvest of the tubers is during flowering. The flowers and flower stalk break off and disappear soon after flowering, making the plant difficult to locate. The plant grows from one or more sturdy brown roots which form rounded, spindle-shaped tubers about 7 to 10 cm (4 in) below the surface, each 4 to 10 cm (4 in) long.