Not a palm tree but an aroid of some kind....possibly a calla (Zantedeschia sp.) or perhaps a alocasia or similar (although these are generally not winter hardy in anything less than a subtropical climate). Not sure what might be common in a garden in Portugal :-)

Various Alocasia and Colocasia are hardy here. Alocasias generally point up at the tip, Colocasias generally point down. Looks like some kind of Callisia creeping along under it. Check C. congesta.

That, creeping hairy root-stock looks like it is really moving along.

That plant's -going places-. -Seein' things-. ;-)