The plant was originally cultivated for fiber in China c. 2800 BC, and later spread all the way across Asia, reaching Europe sometime in the Middle Ages. As the narcotic effects of its leaves and blossoms were discovered, it was also thought to be helpful in treating many conditions, from asthma to depression. Eventually it became infamous as the source of the drugs marijuana and hashish.
Because of its use in the illegal drug trade, cultivation of hemp is mostly banned the Western world. However, it is still grown as a legal commercial crop in China and eastern Europe. Rope, yarn, and string are all made from the strong, durable fibers of the stalks. The seeds are 30 percent oil, and sometimes that is extracted for use in paints and soaps. The seeds are also used in commercial birdseed.
Hemp grows best in temperate zones, with sandy, well-drained soil and rainfall throughout the growing season. Individual plants are all-male or all-female, and can reach a height of 16 feet, though the commercial varieties are usually grown to no more than 10 feet.