U.S.

Associated Press
In this April 26, 2012, photo, Brian Colleran, a coordinator for the knotweed program for the state of Vermont, examines Japanese knotweed in Bethel, Vt. The flood waters of Tropical Storm Irene and work to remove silt and restore roads afterward had an unintended consequence: they spread Japanese knotweed, an invasive plant that has already clogged some river banks and roadsides in Vermont. (AP Photo/Toby Talbot)

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