A
tumbleweed is a structural part of the above-ground anatomy of a number of species of
plants, a
diaspore that, once it is mature and dry,
detaches from its root or stem, and
tumbles away in the
wind. In most such species the tumbleweed is in effect the entire plant apart from the root system, but in other plants a hollow fruit or an
inflorescence might serve the function. Tumbleweed species occur most commonly in
steppe and
arid ecologies, where frequent wind and the open environment permit rolling without prohibitive obstruction.