This name is a synonym of Allium macropetalum Rydb..
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 274793) with original publication details: Contr. W. Bot. 10: 30 1902.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:8860-2.
This name was in version 1 of The Plant List, record kew-274793, and has not been changed.