Walk into any Minnesota gas station or smoke shop and you are bound to see kratom — from colorful seltzer cans to simple white powder bags or capsules — on shelves or locked behind clear displays. Kratom is derived from Mitragyna speciosa, a tree found in Southeast Asia. Sold in the form of powder, capsules and drinks, the substance is used as a recreational drug, as well as to self-treat pain, anxiety and opioid use disorder and withdrawal, acc…