This name is a synonym of Cirsium clavatum var. osterhoutii (Rydb.) D.J.Keil.
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record B9667291-4814-4209-AD1E-0297577D93C3) with original publication details: Fl. Rocky Mts. 1006 1917.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:58940-2.
This name was in version 1 of The Plant List, record gcc-1438, and has not been changed.