From Smith's Dictionary of Greek and Roman Biography and Mythology

PHYLLIS

a daughter of king Sithon, in Thrace, fell in love with Demophon on his return from Troy to Greece. Demophon promised her, by a certain day. to come back from Athens and marry her, and as he was prevented from keeping his word, Phyllis hung herself, but was metamorphosed into an almond-tree, just at the moment when at length Demophon came, and in vain embraced the tree. In some of these passages we read the name of Acamas instead of Demophon.