This name is a synonym of Carduus nutans L..
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record 595243B3-1189-4E8D-BAD0-D815B65B7AFD).
This name record (from TICA) 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 Carduus nutans in version 1 of The Plant List.