Sybil,
So far as I know, Cudrania is typicall grafted onto Osage Orange(Maclura
pomifera) understock.
A fellow NAFEXer shared some dormant scions with me last spring, and I
worked them onto OO suckers I dug out of the cow pasture - and tried one
piece on a seedling mulberry. Those on OO did fine, but the one on
mulberry leafed out and then died.