This name is a synonym of Xanthium orientale subsp. californicum (Greene) Greuter.
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record 2EFFEEE3-BE3A-491A-B9DD-FF87E31D95AD) with original publication details: 63 1899.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:269238-2.
This name was in version 1 of The Plant List, record gcc-145043.