Catnip (Nepeta cataria) dramatically affects several members of the cat family (Felidae) causing them to sniff, roll over, and undulate the skin on their back (amongst other things).
Although it generally only affects about 50% of cats, the effects are profound - often lasting 15 minutes or so.
Although many of the active-ingredient chemicals (e.g. Nepetalactone) have been identified and isolated, no-one has any idea why they affect felids in the ways they do.
In 2017, a new study published in BMC Veterinary Research, compares Catnip with Silver Vine (Actinidia polygama) – or to be more specific, Silver Vine that has been parasitised by the gall midge Pseudasphondylia matatabi, producing fruit-galls. The vine galls were found to be around 40% more effective than catnip. Source