This name is a synonym of Phoradendron serotinum var. rotundifolium (Trel.) M.C. Johnst..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50065084) with original publication details: Gen. Phoradendron 42 1916.
This name was in version 1 of The Plant List, record tro-50065084.