Tumbleweed, a name used in the United States for any plant that is uprooted or breaks away from its roots and is freely driven about by the wind. Tumbleweeds are most plentiful in the Great Plains. The most common species are the Russian thistle, some species of amaranth, and the winged pigweed. Tumbleweeds are much-branched plants that are roughly spherical in shape. They break away from their roots or are uprooted in autumn when fully mature. As they tumble about open areas, they scatter their seeds. Occasionally large masses of tumbleweeds become bothersome. For example, they can block canals or pile up against buildings or fences.

The Russian thistle is Salsola kali; the winged pigweed, Cycloloma atriplicifolium. Both belong to the goosefoot family, Chenopodiaceae. The most common tumbleweed of the family Amaranthaceae is the tumble pigweed, Amaranthus albus.