Why do plants in icy, windy places grow so low?

Have you ever stood outside on a cold, windy day and felt the wind sting your cheeks and tug at your coat? Brr. That wind can make your fingers feel icy in no time.

Far away, on high mountain tops and icy lands in the far north, the wind blows like that day after day. The plants there grow tiny and flat, pressed close to the ground. So why do plants in icy, windy places grow so low?

These cold, open lands have a name: the tundra, which means a cold land where no trees can grow. Nothing tall stands on the tundra to slow the wind down. So the wind races across it, fast and cold.

But the wind does not blow at the same speed everywhere. High above the ground, it rushes along freely. Right next to the ground, rocks, bumps and pebbles rub against the moving air and slow it down.

A strong, icy wind is hard on a plant. It dries out the leaves, carries away their warmth, and can bend and snap tall stems. So where on the tundra could a little plant hide from the worst of the wind?

Down low, hugging the ground! Tundra plants grow flat and short, so the fast wind rushes over their tops. Their leaves stay out of the strongest blasts and keep their water inside.

Many tundra plants grow into a tight, round bump with tiny leaves packed close together. We call a plant like this a cushion plant, which means a plant shaped like a soft little pillow. The wind slides over its smooth, round top instead of pushing through it.

There is a second reason to stay low. On sunny days, the dark ground soaks up sunshine and warms up, like a stone left in the sun. The air just above the ground grows warmer than the air higher up, so a low plant sits in the warmest spot on the tundra.

A cushion plant holds on to that warmth. Its leaves are packed so tight that the warm air stays trapped inside, like your hand in a cozy mitten. Inside, the plant stays warm enough to keep growing.

Tundra, cushion plant. On the tundra, the cold wind races fastest up high, so plants grow low to stay out of it and to soak up warmth from the sun-warmed ground.

So the next time the wind tugs at your coat, you can think of those brave little plants, snug and low on the tundra.