This name is a synonym of Sedum laxum subsp. heckneri (M. Peck) R.T. Clausen.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 8902030) with original publication details: Proc. Biol. Soc. Wash. 50(32): 121–122 1937.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:231740-2.
This name was in version 1 of The Plant List, record tro-8902030.