Why do some seeds have wings?

Have you ever seen a seed spin down from a tree, round and round like a tiny helicopter? Pick one up, and you can feel its thin, papery wing between your fingers.

That flat, papery part looks just like a wing. But a seed is not a bird, and it cannot flap. So why do some seeds have wings?

Let's look up into a big maple tree. When its seeds are ready, the tree lets them go. Each seed can grow into a new tree one day.

Under the big tree, the leaves block out the sun and make lots of shade. A new tree needs sunshine to grow. So a seed that drops straight down lands in a dark spot, where it is hard to grow.

That is where the wing helps. As the seed falls, the wing makes it spin round and round. The spinning makes the seed fall slowly, like a floating feather. While it floats down so slowly, what do you think the breeze will do?

The breeze gives the slow seed a push, away from the tree. The seed starts to drift, which means floating slowly along while the wind pushes it. A fast seed would drop straight down, but a slow seed has time to drift.

Whoosh! A big puff of wind pushes the drifting seed even farther. It sails over the grass and past the garden fence, far away from the big tree's shade.

At last, the seed drifts down into an open, sunny spot. No big tree blocks the light here. The warm sun shines right where it lands, so the seed has a good place to grow.

A wing slows a seed down, so it can drift away to a sunny spot. There, far from the big tree's shade, the warm sun helps it grow.

Down in the sunny grass, the little winged seed lies still. Far behind it, the big maple tree sways in the breeze.