This name is a synonym of Juncus balticus subsp. littoralis (Engelm.) Snogerup.
The record derives from IOPI
(data supplied on 2012-03-23)
which reports it as a synonym (record 314504) with original publication details: Fl. Bor.-Amer. 2: 189 1840.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:132016-2.
This name was in version 1 of The Plant List, record kew-314504, and has not been changed.