A tall annual of waste ground, rubbish tips and docks, found as a casual or sometimes persistent alien arriving with bird-seed, oil-seed, soya beans or grain. Lowland.
A. trifida was cultivated in Britain by 1699, but arose principally as a grain contaminant and was first recorded from the wild in 1897. It underwent a dramatic decline before 1970, as importation of loose cargoes at docks ceased and seed cleaning techniques improved.
Native of N. America.
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