This psychedelic shrub is illegal. Texas wants to pay millions studying it.

For years, people have flown to clinics in Mexico to take ibogaine, the extract of an ancient African shrub that induces mind-bending hallucinations. Under medical supervision, patients undergo psychedelic trips that can last more than a dozen hours in hopes of alleviating their struggles with addiction or brain trauma. And while ibogaine is illegal in the United States, Texas is on the verge of spending up to $50 million to jump-start clinical trials, which advocates hope could hasten federal approval for using ibogaine as medication. Texas lawmakers passed legislation creating...