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 3C8BD5B9-06A5-4BDB-8813-E32553F49071) with original publication details: Pittonia 4 62 1899.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:315889-2.
This name was in version 1 of The Plant List, record gcc-132382.