Hemp was raised for its fiber - which is similar to cotton but more durable - in the United States until legislation outlawed all Cannabis plants because they contain THC. Today, marijuana contains as much as 25 percent THC, whereas hemp plants contain less than 0.3 percent.

Hemp was once a popular crop in the upper Midwest because it tolerates a cool climate and marginal soils that won't support other crops but, after drug legislation, hemp fiber was replaced by plastic and other alternatives. Recent popular demand for hemp products has led some states to consider the economic and environmental benefits of hemp. North Dakota legislation aims to reintroduce it as a crop, and Minnesota is considering similar legislation. At the same time, California and other states permit the medicinal use of marijuana.

"I can't think of a plant so regarded as a menace by some and a miracle by others," says Weiblen, who is one of the few researchers in the United States permitted to study Cannabis genetics. In 2006, Weiblen and colleagues developed a DNA "fingerprinting" technique capable of distinguishing among Cannabis plants in criminal investigations.

Source: University of Minnesota