When Japanese researchers placed silver vine branches next to a living catnip plant in a garden where free-roaming cats could come and go, the choice was decisive: five out of six cats rubbed and rolled on the silver vine, while none showed the same behavior toward catnip, despite it being the plant most beloved by cat owners across Europe and North America.
The finding upends a basic assumption about how plant chemistry shapes animal behavior. It turns out that having more active compounds doesn't guarantee a stronger response. In fact, the catnip extract in the study contained roughly 170 times more bioactive compounds than the silver vine extract, yet cats consistently preferred the vine when given a choice. The results, published in the Journal of Chemical Ecology, come from a research team at Iwate University and Nagoya University who conducted a series of carefully designed experiments in Morioka, Japan.
Over ten nights of outdoor observation, researchers recorded visits from identifiable cats to their test garden. The pattern held when they tested plant extracts side by side under the same free-choice conditions: cats again showed a stronger tendency to respond to silver vine. To rule out the possibility that this preference was unique to local free-roaming cats, the team expanded the study to include 22 purebred cats from facilities across Japan, representing breeds originating from Europe, the United States, and the Middle East. In a large indoor environment where the cats could move freely, fifteen responded only to silver vine extract, three only to catnip, and one to both.
The puzzle deepened when chemical analysis revealed something counterintuitive. The catnip contained abundant cis-trans nepetalactone, a major compound known to trigger the feline response, and laboratory tests confirmed these chemicals worked when presented to individual caged cats. So why did cats ignore catnip when given a genuine choice? "One might expect a plant containing more active compounds, and compounds that clearly work in laboratory tests, to trigger a stronger behavioral response under free-choice conditions," says Professor Masao Miyazaki, who led the research. "But that was not what we observed."
The researchers offer a tantalizing hypothesis: the living catnip plant may have been releasing too much of its active compounds at once. An overwhelming odor—continuously rising from fresh leaves—might be detected by cats but prove less appealing than the more subtle stimulus of silver vine. The idea isn't entirely new. In "The Gardeners Dictionary," published in 1768, Philip Miller noted that cats were especially fond of catmint when it was withered, a curious observation that suggests intensity of scent has long mattered to feline preference.
Both plants have long been associated with pest defense. Previous work by the same research group showed that the compounds in both silver vine and catnip can repel mosquitoes, suggesting that cats' attraction to these plants may serve an evolutionary function—a form of natural self-medication or pest control through direct contact.
The finding holds practical implications for anyone seeking to engage their cat. In Japan, silver vine has long been the preferred choice. Now there's scientific evidence backing that tradition, at least when cats encounter both plants simultaneously and can decide for themselves.