Mamillaria microthele Muhlenpf. Allg. Gart. Zeit. p. 11
(1848),
not Lem. (1838).
Differs from the last form (var. greggii) chiefly in its
cespitose habit, much larger tubercles, and two unusually stout
and short central spines (fide Engelmann, who examined specimens
in Coll. Salm-Dyck).
Credited to Mexico in general, but said by Budd to occur within
the southern border of Pecos County, Tex.
** Central spines present and one or more hooked.
+ Mostly globose and simple plants (occasionally somewhat
cylindrical).