This name is a synonym of Desmodium cuspidatum var. longifolium (Torr. & A.Gray) B.G.Schub..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 13064353) with original publication details: Fl. N. Amer. 1(3): 365 1840.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:78386-2.
This name was in version 1 of The Plant List, record tro-13064353.