Orbexilum onobrychis (Nuttall) Rydberg. Subgenus: Orbexilum. Phen: Jun-Aug; Aug-Oct. Hab: Calcareous or mafic woodlands and barrens, prairies. Dist: Primarily a species of prairies and prairie-like areas of OH and KY west to se. IA and e. MO, O. onobrychis also occurs (at least formerly) as rare disjunct populations south to the Mountains and Interior Low Plateau of w. NC (Sawyersville, 1891), nw. SC, w. VA, e. TN, nw. AL, c. TN, and n. AR. No basis can be found for the alleged occurrence of this species in Spartanburg County, SC.
Origin/Endemic status: Native
Synonymy: = Ar, C, Il, K1, K3, K4, S, SE3, Tn, Va, Grimes (1988), Grimes (1990), Isely (1998), Turner (2008); = Psoralea onobrychis Nutt. – F, G, RAB, W