Is it permissible for a mother to give her Zakat al-mal to her needy son?

It is permissible for a father to pay his Zakat to his son who is capable of earning, if his earnings do not cover his essential needs or if he is in debt. As for a young son who is not earning, it is not permissible to pay Zakat to him, because his maintenance is obligatory upon his living and capable father, or failing that, upon his capable mother.