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In sub-Saharan Africa, the invasive witchweed is responsible for annual maize losses amounting to $7bn.

Witchweed's way of life is one of the strangest in nature.

Then a graduate student from India took a careful look at the sick corn and recognized among its roots the underground stems of witchweed, which had never before invaded the Western Hemisphere.

After a month of underground parasitic life, the witchweed makes a partial reform, like a successful mobster who buys a legitimate business and joins the church.

Witchweed seeds are invisible when mixed with soil, and they can be carried by farmers' boots, auto tires, shipments of farm products or almost anything else that moves.