There is no historical or official basis for referring to Spain as "the motherland" (la madre patria). This term is not used in Spanish political discourse, constitutional language, or common parlance.
The term madre patria historically refers to a colonial power in relation to its colonies (e.g., Spain as "motherland" to its former American territories). Within Spain itself, the concept doesn't apply—the country is the patria (fatherland) of Spaniards.
In Spain's autonomous communities (Catalonia, Basque Country, Galicia), some nationalist movements explicitly reject "Spain as patria," viewing their own region as their primary patria. This political complexity further undermines any monolithic "motherland" label.