This name is a synonym of Ranunculus laxicaulis Darby.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 27103111) with original publication details: Boston J. Nat. Hist. 5(2): 210–211 1845.
This name was in version 1 of The Plant List, record tro-27103111, and has not been changed.