Hemp, Cannabis sativa, has been called the world's most versatile plant. Materials made from hemp fiber have been discovered in tombs dating back to 7000 B.C. During the Middle Ages hemp was used to treat fevers, insomnia, and malaria. Columbus's ships had sails of hemp, and during colonial times it was universally grown because its strong fibers made superior ropes, sails, cloth, and paper. In fact, hemp was used for money in most of the Americas from 1631 until the early 1800s, and the original drafts of the Declaration of Independence and the Constitution were written on hemp paper....