Catnip is a plant that produces a peculiar effect on many cats: it makes them act wild, rolling around, purring loudly, and behaving almost silly. The plant contains a chemical that triggers this reaction when cats smell it. Within seconds of encountering catnip, a normally dignified cat might flop on the floor, rub against it ecstatically, or zoom around the room. The effect lasts only a few minutes before wearing off completely, and the cat returns to normal.

People often put dried catnip in cat toys or sprinkle it on scratching posts to entertain their pets. Not all cats react to catnip: about one in three cats shows no interest at all, and kittens under six months old typically don't respond to it either. The reaction is inherited genetically, like having blue eyes or being able to roll your tongue.

The plant itself looks rather ordinary, with gray-green leaves and small white or purple flowers, and it's related to mint. Wild catnip grows in many parts of North America, and you might spot cats rolling around in patches of it outdoors. Despite its dramatic effect on cats, catnip is generally harmless for them.