Catnip, Silver Vine, Tatarian honeysuckle and valerian root are the four plants cats reliably go after. In 1768 the English botanist Philip Miller already had the scene right: cats rolling, tearing and chewing at withered catnip, and ignoring it when the plant was still growing quietly in the bed.
Two things explain why these plants work, why they do not work equally, and why about one cat in three can walk past catnip as if it were grass.
Hypothesis 1: the chemical cocktail
Catnip (Nepeta cataria) leans almost entirely on one compound, nepetalactone. It binds to receptors in the cat's nose and, for about two in three cats, that is the whole story. The remaining third are genetically unable to respond to that molecule. Freshness and quantity do not fix it.
Silver Vine (Actinidia polygama) should, on paper, be weaker. It contains far less total attractant chemical than catnip, on the order of forty times less cis-trans nepetalactone. In 2017, Sebastiaan Bol tested both plants on a large group of domestic cats and found the opposite of what the dose would suggest: more cats responded to Silver Vine, including about 75% of the ones that ignored catnip completely.
A 2021 paper in Science Advances is the reason that result now makes sense. Silver Vine does not rely on a single note. It releases a mixture dominated by nepetalactol, with actinidine, iridomyrmecine and dihydroactinidiolide alongside it. When a cat rubs or bites the plant, that mixture hits more than one olfactory route. A cat that cannot detect nepetalactone still has something to respond to.
Valerian root and Tatarian honeysuckle have neither of catnip's main molecules. They carry actinidine, a related compound that fits the same family of scent receptors. That is enough for some cats, not as many as Silver Vine, and the reaction is usually milder.
Chemical variety, not total dose, is what predicts whether a cat will bother.
| Plant (Part Used) | Nepetalactol | Nepetalactone | Actinidine | Iridomyrmecine | Dihydroactinidiolide |
|---|---|---|---|---|---|
| Silver Vine (Leaves & Fruit Gall) | +++ | + | ++ | ++ | ++ |
| Catnip (Leaves) | — | +++ | — | — | — |
| Valerian Root (Root) | — | — | ++ | — | — |
| Tartarian Honeysuckle (Wood/Bark) | — | — | + | — | + |
Note: +++ is highly dominant, + is present, and — is absent.
Hypothesis 2: the lab is not the living room
A laboratory is a poor model of a house. In a constrained test, the cat has little else to do, so both catnip and Silver Vine look highly effective. Detection is being measured, not whether the cat would have walked over of its own accord.
Under free-choice conditions, with other smells and objects in the room, detection is not enough. The plant has to be interesting enough to produce voluntary engagement. Cats ignore catnip in that setting more often than they ignore Silver Vine. The more complex mixture cuts through background better. Catnip still works. It is simply less reliable at earning the cat's attention when the cat has a choice.
That is the practical difference in a flat, where a toy is competing with a windowsill, a radiator, and last night's leftover cardboard box.
Why they roll in it at all
When cats chew and rub on these plants, they transfer molecules such as nepetalactol onto their fur. The same chemical family is a potent mosquito repellent. Wild cats that go after the plant pick up a coating that reduces insect bites, which is a reasonable evolutionary reason to keep the behaviour.
The household version of that behaviour is a cat rubbing a toy into its cheeks and then carrying it off. Same motion, fewer mosquitoes.
What this means for a toy
A single-herb toy is a bet on one receptor pathway. For the third of cats that cannot use the catnip pathway, that toy is an empty object with a faint smell. Pairing catnip with Silver Vine covers both routes, which is the whole point of using two plants rather than doubling down on the famous one.
There is a longer account of how we apply this, including why the buds stay whole until the cat bites them, on the science page.
We build Le Croissant around that pairing: organic catnip buds and Silver Vine fruit, at least 30g of it, inside reinforced OEKO-TEX cotton, hand-stitched in the South of France. The chemistry is the reason for the blend. The quantity is the reason it still works months later.