Why does a mint leaf smell stronger when you rub it?

Have you ever found a mint leaf in a garden? Pinch it gently, then sniff your fingers. Ahh, a fresh, cool smell!

A mint leaf sitting still smells only a little. But when you rub it, the smell grows big and strong. Why does a mint leaf smell stronger when you rub it?

Let's look very closely at a mint leaf. Tiny round pockets cover its skin, too small to see without a magnifying glass. Each pocket holds a little drop of oil, snug inside.

This oil carries the mint's scent, which means the smell that a thing gives off. The shut pockets keep the oil tucked away. So a still leaf lets out just a little smell.

Now your fingers rub the leaf. Rubbing squeezes and scrapes the tiny pockets. Pop, pop, pop! Lots of them break open at once.

The oil spills out onto the leaf and onto your fingers. It does not stay put for long. What do you think the oil does next?

Mint oil dries away into the air very fast, the way a wet spot dries, only much quicker. It turns into scent that you cannot see. A soft puff of it gathers around your hand.

When you breathe in, that puff slips into your nose. Your nose catches the scent and tells you, mint!

So much spilled oil dries into the air at once, far more than from a still leaf. More oil in the air makes more scent. So your nose smells mint much more strongly.

Your rubbing fingers break the tiny oil pockets, so lots more mint scent floats out. More scent in the air means a stronger smell for your nose.

The rubbed mint leaf rests back among its green neighbours. A fresh, cool puff of scent still curls around your fingers, like a tiny garden held in your hand.