"Annie watched a ball of tumbleweed"

A tumbleweed is the above-ground part of a plant, commonly Salsola tragus. When mature and dry, it breaks off from the root and rolls with the wind, dispersing seeds. Usually, the tumbleweed consists of the entire plant apart from the roots, but in a few species it is a flower cluster. Tumbleweed is most common in steppe and desert plants.