Tumbleweed

from WordNet (r) 3.0 (2006)

tumbleweed
    n 1: any plant that breaks away from its roots in autumn and is
         driven by the wind as a light rolling mass
    2: prickly bushy Eurasian plant; a troublesome weed in central
       and western United States [syn: {Russian thistle}, {Russian
       tumbleweed}, {Russian cactus}, {tumbleweed}, {Salsola kali
       tenuifolia}]
    3: bushy annual weed of central North America having greenish
       flowers and winged seeds [syn: {winged pigweed},
       {tumbleweed}, {Cycloloma atriplicifolium}]
    4: bushy plant of western United States [syn: {tumbleweed},
       {Amaranthus albus}, {Amaranthus graecizans}]

from The Collaborative International Dictionary of English v.0.48

Tumbleweed \Tum"ble*weed`\, n. (Bot.)
   Any plant which habitually breaks away from its roots in the
   autumn, and is driven by the wind, as a light, rolling mass,
   over the fields and prairies; such as witch grass, wild
   indigo, {Amarantus albus}, etc.
   [1913 Webster]