This name is a synonym of Schoenoxiphium caricoides C.B.Clarke.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 459928) with original publication details: Fl. Cap. 7: 303 1898.
This name record (from WCSP) was not included in version 1 of The Plant List. It is possible the same name was included from a different data source, to check this you can search for Carex dregeana in version 1 of The Plant List.