yes, definitely Phalaris, but hard to say more about the species, may be Ph. minor, which is quite widespread in Greece

a spikelet dissected would be reliable: in each spikelet there are two sterile flowers at the bottom of a fertile lemma and all this hidden by the long glumes. The size of the sterile lemmas is important for delimitation between Ph, brachystachys and Ph. minor, a related species is is also Ph. canariensis, but that one has more ovate inflorescence.