SILVERLEAF SCURFPEA--Psoralea argophylla
Description:  Silverleaf scurfpea is a perennial forb arising from a taproot, typically as a single stem and branching into a bushy top 1 to 2 feet tall.  Open patches form from laterally spreading and sprouting roots.  Leaves are alternate, consisting of 3 to 5 palmately arranged leaflets covered with white, silky hairs.  Small blue flowers in clusters from upper leaf axils are present from June to September.  In late summer an abscission layer forms in the stem near the ground, allowing the plant to break away, tumble with he wind, and scatter seed.
Distribution, habitat:  Distribution of this native is bounded by southern Alberta and Saskatchewan, Wisconsin, Missouri, New Mexico, and Colorado.  Silverleaf scurfpea is frequently abundant in the northern Great Plains and is found throughout South Dakota.  It grows best on hillsides and steep slopes or well drained flats.  It is a common associate of little bluestem and western wheatgrass communities.
Comments:  Silverleaf scurfpea is not readily grazed by livestock but is taken to some extent by deer and pronghorn.  In the early 1900s a child reportedly died from eating seeds of silverleaf scurfpea.  Many tribes made a tea for curing constipation, and ground foliage mixed with grease was used as a body rub for high fever.  Dakota Indians used a decoction of the plant to wash horse wounds.
Palmleaf scurfpea, P. digitata, is similar but is green rather than white-pubescent.  The calyx (united sepals) enclosing the fruit is conspicuously enlarged.  This scurfpea is limited to sandy soils from southwestern South Dakota southward.
Picture and information can be found on pages 188 and 189 of Grassland Plants of South Dakota and the Northern Great Plains, by James R. Johnson and Gary E. Larson.  Published in 1999 by South Dakota State University, Brookings, SD.