This name is a synonym of Cicuta maculata var. angustifolia Hook..
The record derives from WCSP (in review)
(data supplied on 2012-03-23)
which reports it as a synonym with original publication details: Bull. Montana State Univ., Biol. Ser. 15: 42 1910.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:58599-2.
This name was in version 1 of The Plant List, record kew-2720728, and has not been changed.