] Now in the current issue of the journal Science,
] researchers say they have found spotted knapweed's deadly
] secret: a potent and previously unknown poison that it
] releases through its roots into the soil to kill off
] neighboring plants. By eliminating its neighbors, the
] weed can appropriate all the water and nutrients that the
] other plants would have taken, and it has plenty of new
] space to spread out in.

Forensic Botanists Find the Lethal Weapon of a Killer Weed