The mechanism of seed dispersal in polygonum virginianum
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The achenes of Polygonum Virginianum Linnaeus have a particularly efficient mode of dispersal. The long two-parted styles are persistent and become lignified during the process of development. If, after maturity, these projecting styles are struck by any object with sufficient impact, the achenes are thrown off with force enough to carry them a distance of three or four meters. This paper relates the results of a histological study of the tissues in question. Since achenes fly off with a force entirely disproportionate to that which strikes them, it may be assumed that there is some tension existing in the pedicels which, when released, throws the achenes from the plant. It has been supposed that the existing tension was given by changes in the tissues of the pedicel as they became dry. The attempt was made to discover whether changes might be found in the structure or arrangement of the tissues sufficient to account for the phenomenon of dispersal.