A Bouncing Bulb is A magical plant that must be restained, else it will bounce around.
Bouncing Bulb History
Bouncing bulbs’ main stem is a large purple bulb, and has a cluster of leaves growing on the top. While young bouncing bulbs are small enough to be (relatively) easily handled, mature bulbs can become the size of doorways. Bouncing bulbs become hostile when they feel threatened, and try to hit the possible attacker by jumping at it. A Knockback Jinx would be enough to halt a young bulb, but a grown bulb would likely require a Fire-Making Spell to wither and weaken it. Bouncing Bulbs are a required component of the Pompion Potion. Bouncing Bulbs are covered in Herbology class at Hogwarts School of Witchcraft and Wizardry, usually in a student’s fourth year.