A leafstalk is the thin stem that connects a leaf to a plant's branch or main stem. Scientists call it a petiole, but leafstalk describes exactly what it is: the stalk of the leaf.

If you look closely at a maple tree or a houseplant, you'll notice the leaf doesn't attach directly to the branch. Instead, there's usually a slender stalk holding it out, like a little arm reaching away from the plant. This leafstalk can twist and bend, positioning the leaf to catch the most sunlight. On a windy day, leafstalks let leaves flutter and move without tearing off the plant.

Some leafstalks are barely noticeable, while others are quite long. Celery, for instance, is mostly leafstalk: those crunchy ribs are the stalks that would normally connect celery leaves to the main plant. Not all leaves have leafstalks, though. Leaves that attach directly to the stem without a stalk are called sessile.

The length and flexibility of a leafstalk affect how a leaf behaves: a long, thin leafstalk makes a leaf dance in the breeze, while a short, sturdy one keeps the leaf more stable.