What is the name of the magical flower in A Midsummer Night's Dream that causes love?

In A Midsummer Night’s Dream, the magical flower that causes love is called love-in-idleness.

Oberon tells Puck to find a “little western flower” known as love-in-idleness. Cupid’s arrow is said to have struck it, turning the originally white flower purple and giving its juice magical power. When the juice is placed on a sleeping person’s eyelids, that person falls in love with the first living creature seen after waking.

The potion drives much of the play’s comic confusion. Puck mistakenly applies it to Lysander, who wakes loving Helena instead of Hermia. Later, the enchantment is corrected for Lysander, while Demetrius remains in love with Helena, restoring the intended romantic pairings.

Love-in-idleness is commonly identified with the wild pansy, Viola tricolor, also called heartsease. That botanical identification explains why “pansy” may seem tempting, but the flower’s name in Shakespeare’s text is love-in-idleness. The plant is a fictionalized love-potion device rather than a real flower proven to cause romantic attraction.