What plant do cats love most? In Europe and North America, many people would say catnip, while in Japan the answer would more likely be silver vine (matatabi in Japanese). A research team from Iwate University and Nagoya University found that domestic cats respond more reliably to silver vine than to catnip when they are free to approach or ignore the plants. In outdoor experiments, free-roaming cats repeatedly rubbed and rolled on fresh silver vine but showed little response to nearby catnip plants. The same pattern was observed in 22 captive purebred cats tested in a large indoor environment. Surprisingly, chemical analysis showed that catnip contained abundant active compounds, including nepetalactone isomers, and laboratory cage tests confirmed that catnip-derived compounds can trigger the typical feline response. The findings show that chemical activity in the laboratory does not always predict real-world behavior, highlighting the importance of studying animals under conditions that allow natural choice.