Marijuana startups are blooming - here's who's poised to cash in

Marijuana may not be America's largest cash crop, as was long rumored, but it's still probably a $4 billion annual business.

As of last year, it's also legal to grow, own, and use recreationally Colorado and Washington, with Alaska, the District of Columbia, and Oregon soon to follow. It's approved for medical and other limited use in 18 more states.

Entrepreneurs are racing to take advantage of the new laws and changing attitudes toward the drug. Here are the players and startups you need to watch.