A tumbleweed is a dried-up plant that breaks off from its roots and rolls across open land, pushed by the wind. Picture a big, round bush made of tangled branches bouncing and tumbling across a desert or empty field. You've probably seen them rolling through ghost towns in old Western movies.

These plants start out green and alive, anchored to the ground. But when they dry out at the end of their life cycle, they become brittle and lightweight. A strong wind snaps them free, and off they go, sometimes rolling for miles. As they tumble along, they scatter their seeds, which is the plant's clever way of spreading to new places.

The most famous tumbleweed, called Russian thistle, isn't even native to America. It arrived accidentally in the 1870s, mixed in with flax seeds from Russia. Now it's everywhere in the American West.

People use “tumbleweed” to describe empty, deserted places. If someone says “there were tumbleweeds rolling through the cafeteria,” they mean it was so empty and quiet you could imagine those lonely plants blowing through. The image of a tumbleweed rolling past has become a symbol of abandonment and silence, which is why you'll often hear a whistling wind sound effect along with a tumbleweed in cartoons when a joke falls flat or a room suddenly goes quiet.