A.b. nana has no stems, period, only the rhizome. If there fragments of rhizome still attached to the leaf petioles, new roots may well arise from those rhizome fragments. Those platlets will be fragile and delicate for a time, and will do best with the roots in substrate, but not the junction of the leaf petiole and whatever rhizome fragment is still there.
The leaves have a blade - the broad flat green part, and the petiole connecting the blade and rhizome. It requires at least some tiny fragment of the rhizome to get roots. These are not African Violets - you cannot get new plants and roots from the leaf petioles. You can get new plants from any piece of the rhizome, with both new leaves and new roots, but it is not fast.