This is widespread in remnants of native grasslands of the central and northern Great Plains, but it has a relatively abrupt eastern boundary from n. Ark. to s. Mich. (K). The species remains virtually unknown in the Ohio Rv. watershed (except the upper Wabash Rv.) and in southeastern states east of the Mississippi Rv. Rafinesque (1824, 1840) reported "Amorpha canescens Raf." and then "Am. tomentosa Raf." from Ky.; the latter appears to have been synonymous. However, no colls. are known. An estimated translation of Rafinesque's (1840) latin diagnosis for tomentosa is as follows: plants generally tomentose; leaves without stipules; petioles subterete; leaflets 40-50, subsessile, broadly lanceolate, with acute cuspidate apex, canescent below, opaque; calyx imbricate, with acute lobes; legume ovate, the calyx persistent with subequal lobes. He added: "on Wabash and West Kentucky, folioles [leaflets] as small as in A. nana, realy [sic] lanceolate with a long cuspis"