Abstract
Let \(\mathfrak{P}\) be a nonempty set of primes. We prove that any \(\mathfrak{P}\) -bounded nilpotent group is \(\mathfrak{P}\) -potent and the tree product T of a finite number of \(\mathfrak{P}\) -bounded nilpotent groups with proper locally cyclic edge subgroups is residually a finite \(\mathfrak{P}\) -group iff any vertex group of T has no \(\mathfrak{P}{\kern 1pt} '\) -torsion and any edge subgroup of T is \(\mathfrak{P}{\kern 1pt} '\) -isolated in the vertex group containing it. We prove also that the tree product of a finite number of groups with locally cyclic edge subgroups is residually a finite \(p\) -group if all its vertex groups have this property and any edge subgroup is separable in the corresponding vertex group by the class of finite \(p\) -groups.