No need to explain 4/20 in these parts, what with medical marijuana continuing to be such a hot topic in Colorado. Some politicians are all for it, others say we don't need it, and all the while, pot makes news daily.

The potent mix of politics, business and medicine is a recipe for a short memory, which is why we've put together, just in time for April 20, this brief history of medical marijuana usage in information-graphic form. Research by Cory Lamz and art by Jay Vollmar. Be an informed toker:

More from our Marijuana archive: "4/20 in Boulder preview: 'An orgasm of cannabis consumption.'"