The story of Phyllis and Demophoon is from Ovid's Heroides and relates how Phyllis, Queen of Thrace, fell in love with Demophoon, son of Theseus and Phaedra, when he stayed at her court on his return from the Trojan War. He stayed in Thrace several months, and on sailing for Athens he promised to return to Phyllis within a month. He did not return, and the Gods took pity on poor Phyllis by transforming her into an almond tree. When Demophoon finally returned to Thrace and heard of Phyllis' fate he ran to the tree and embrassed it. The tree suddenly burst into blossom, momentarily turning back into Phyllis.

Several member of the Pre-Raphaelite brotherhood objected to the nudity of Demophoon and asked him to cover the character up. Burne-Jones refused and resigned from the brotherhood.