This name is a synonym of Cirsium clavatum var. americanum (A.Gray) D.J.Keil.
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record F583B32A-13C1-4915-B053-445F93AA8EFF) with original publication details: 559 1917.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:59153-2.
This name was in version 1 of The Plant List, record gcc-36894.