ST. PAUL — Minnesota joined the ranks of 21 other states Thursday where marijuana is a legal medicine with a law that is one of the nation’s most restrictive.

Democratic Gov. Mark Dayton signed legislation that sets up a medical marijuana program with tight controls over qualifying conditions and the way it is administered. People won’t be able to smoke marijuana legally or access it in leaf form.

“I pray it will bring to the victims of ravaging illnesses the relief they are hoping for,” Dayton said in a written statement.

The compromise bill upset some medical marijuana advocates, who say many people who need relief won’t get it. But legislative backers say it is a positive first step that satisfied concerns of law enforcement and doctor groups. Dayton had said he wouldn’t get behind a bill that those two entities opposed.

Medical conditions eligible for the treatment include cancer, glaucoma and AIDS. A physician assistant or advanced-practice registered nurse would certify a patient suffered from a qualifying illness.

If all goes as planned, the drug will be available in pill, oil and vapor form in mid-2015. Two manufacturing facilities and eight dispensaries will be permitted statewide.

The law sets up a task force to assess the impact of medical cannabis.

A ceremony could still occur at a later date.