This name is a synonym of Ageratina thyrsiflora (Greene) R.M.King & H.Rob..
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record 5064E80F-1330-4297-97AC-E86FEEDC551A) with original publication details: 9 1903.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:134195-2.
This name was in version 1 of The Plant List, record gcc-134743.