1. "Marijuana" is a Mexican term that originally was applied to low-quality tobacco.
2. The plant was cultivated in China for therapy and recreation over 4,700 years ago.
3. More than 20 prescription medicines containing cannabis were sold in U.S. pharmacies at the turn of the 20th century. Pot-based medications were commonly available until 1942, when cannabis was stricken from the U.S. Pharmacopeia, the official compendium of drugs considered effective. From 1937 to 1942 the federal government collected a tax of $1 per ounce for such drugs.
4. More than 20,000 studies on cannabis and its components have been published, according to NORML (National Organization for the Reform of Marijuana Laws), an advocacy group. Of these, around 100 have looked into therapeutic value on human subjects.
5. The federal government is in the pot-growing business. Under a federal contract, the University of Mississippi in Oxford cultivates cannabis for use by researchers, who have to be cleared by the National Institute on Drug Abuse.
6. The plant has nearly 500 chemical compounds, more than 60 of which are called cannabinoids.
7. Fourteen states and the District of Columbia have legalized medical cannabis: Alaska, California, Colorado, Hawaii, Maine, Michigan, Montana, Nevada, New Jersey, New Mexico, Oregon, Rhode Island, Vermont, and Washington. Patients in these states may still face federal prosecution for using, growing, or possessing pot for medical purposes.
8. Federal law prohibits physicians from prescribing or otherwise actively supplying patients with the drug. But in 2002 the U.S. Supreme Court backed an appellate court ruling that physicians who discuss it with patients, or provide oral or written recommendations, are protected.