where do tumble-weeds come from?

Question

How are they formed? Are they from one specific plant or are they clumps of random twigs and branches or are they something completely different?

Answer 1

The tumbleweed is often thought of as the symbol of the American West. Actually, it isn't native to North America at all, but was brought to this country (unintentionally) by Ukranian farmers. The tumbleweed really is a weed, and its real name is the Russian thistle. Tumbleweeds aren't considered as having any redeeming value except for the fact that they are interesting to watch as they tumble about. There are actually people (not many) who harvest tumbleweeds and sell them, and the people that buy them apparently fashion interesting crafts and decorative items from tumbleweeds. As a matter of fact, the City of Chandler, Arizona constructs their official Christmas tree every year from tumbleweeds!

Tumbleweeds grow on dry plains, in fields, and on roadsides, generally in grain-growing areas.
Most people wouldn't recognize a Russian thistle plant growing off the main road, but is a round, bushy, plant that grows to about 3 feet. At maturity it breaks off at the base and because it is rounded, it tumbles in the wind. There is a natural purpose to this tumbling--the tumbleweed can produce up to 250,000 seeds, and the tumbling serves to spread those seed wherever it tumbles, guaranteeing that there will be more tumbleweeds in the future.
More Tumbleweed Trivia

There may be another value to tumbleweeds--a study has revealed that tumbling tumbleweeds soak up depleted uranium from contaminated soils at weapons testing grounds.
The song "Tumbling Tumbleweeds" was written in 1932 by Bob Nolan of the Sons of the Pioneers.

Answer 2

Tumble county, Arizona. A dried plant gets up-rooted by the wind and starts rolling along the ground.

Answer 3

I was told from some guy in Texas that they are one plant that died and broke from its roots and rolls along in the wind.