Not that long ago, weeds spread at a much slower rate. Seeds would spread to nearby soil and move perhaps a few feet each year or would be transplanted by birds who flew with them several miles away. In today’s interconnected world, though, weeds can hitch a ride on a truck, boat, or even an airplane. What once might’ve taken generations to spread weeds from one region to another now takes no time at all.
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Source: Phys.org