In Hamlet, what plant's juice is used to poison the king?

In Hamlet, the Ghost says that the king was poisoned with the juice of hebenon. Claudius pours the substance into his sleeping brother’s ear, causing the skin to break out in a diseased-looking crust and killing him.

The revelation appears in Act I, Scene 5, when the Ghost identifies himself as Hamlet’s dead father. He says Claudius stole upon him during his “secure hour,” meaning while he was asleep in the garden. The poison’s swift, grotesque effects establish the murder as both unnatural and politically treacherous.

Hebenon is spelled “hebona” in some early quartos and “hebenon” in the First Folio, the spelling used in this quiz. Shakespeare gives no definite botanical identification. Scholars have proposed henbane, yew, ebony, or other poisonous substances, but none is certain. The word is also a unique term in Shakespeare’s surviving plays.

That uncertainty creates a common mix-up with hemlock or nightshade. Those are recognizable poisonous plants, but neither is the named substance in Hamlet. A fair answer to the textual question is hebenon; the identity of the real-world plant remains disputed.