USFS Sensitive species; S1 NE; S3 SD, MT and WY.
A perennial, regional endemic found on exposed, eroding soils in western SD, southeastern MT, northeastern WY, and northeastern NE. The largest population, found near Scenic, SD, numbering possibly 12 million specimens, showed a predilection for a specific badland formation, the Chadron Formation claystone. When in bloom in such numbers, the air was perfumed like a field of clover. Which it nearly is, being a legume. Most occurrences are in the Powder River Basin in WY.