Catnip

Catnip is a plant native to North America. Fresh leaves of the catnip plant have a mintlike scent, while dried leaves smell like alfafa. Watching a cat respond to catnip amuses most people. Pawing, clasping, rolling onto the side, and rhythmic kicking with the back feet is behavior similar to that displayed when they detect and capture prey. Some cats enjoy catnip and revel in its effects, while other cats appear to avoid it., despite prior displays of catnip sensitivity. 

Generally male and female cats of ca reproductive age are more sensitive to catnip than very young or old cats. Catnip is not toxic to pets. It contains chemical which is similar to human hallucinogens.