This name is a synonym of Beaucarnea recurvata Lem..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 18404175) with original publication details: Proc. Amer. Acad. Arts 26: 157 1891.
This name record (from Tropicos) was not included in version 1 of The Plant List. It is possible the same name was included from a different data source, to check this you can search for Dasylirion inermis in version 1 of The Plant List.