Glyphosate, the main ingredient in Monsanto's Roundup herbicide, has spawned a new generation of superweeds that are spreading rapidly across the United States.

Since farmers planting Monsanto's genetically engineered Roundup Ready crops no longer need to worry about overdosing their crops with herbicide, they tend to spray more of it. And just as antibiotic overuse has resulted in antibiotic resistant drugs, constant use of Roundup and its active ingredient, glyphosate, has given rise to an epidemic of glyphosate resistant superweeds.

Use the interactive map HERE to find where superweeds have made their appearance. And learn more about three superweeds in particular: pigweed (Palmer amaranth), horseweed (Conyza canadensis), andragweed (Ambrosia trifida).