Milton, in his Comus, says hæmony is of “sovereign use 'gainst all enchantments, mildew, blast, or damp.” Coleridge says the word is hæma-oinos (blood-wine), and refers to the blood of Jesus Christ, which destroys all evil. The leaf, says Milton, “had prickles on it,” but “it bore a bright golden flower.” The prickles are the crown of thorns, the flower the fruits of salvation.
This interpretation is so in accordance with the spirit of Milton, that it is far preferable to the suggestions that the plant agrimony or alyssum was intended, for why should Milton have changed the name? (Greek, haima, blood.) (See Comus, 648-668.)
Dioscorides ascribes similar powers to the herb alyssum, which, as he says, “keepeth man and beast from enchantments and witching.”
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894