This name is a synonym of Watsonia marginata (L.f.) Ker Gawl..
The record derives from iPlants
(data supplied on 2012-03-23)
which reports it as a synonym (record 322815) with original publication details: Hort. Kew. 1: 59 1789.
This name was in version 1 of The Plant List, record kew-322815.