Dennis McKenna, who is an ethnopharmacologist and professor working with the University of Minnesota's Center for Spirituality and Healing, has traveled to the Amazon more than a dozen times to study hallucinogenic and medicinal plants. McKenna was photographed examining an ayahuasca plant at the University of Minnesota greenhouses in St. Paul, Minn. Monday, June 3, 2013. MPR Photo/Jeffrey Thompson

To the untrained eye, a certain greenhouse of plants at the University of Minnesota's St. Paul campus may seem like nothing special. But Dennis McKenna, an ethno-pharmacologist, sees much more than that.

Some can cure disease, like the Madagascar periwinkle.

"It is the source of two really important drugs to treat childhood leukemia," McKenna said.

Other plants in the greenhouse are the source of psychedelic drugs that some scientists say could be therapeutic.

McKenna, who teaches at the university's Center for Spirituality and Healing, is an authority on hallucinogens derived from plants such as ayahuasca, a tea brewed in South America's Amazon basin and used as part of religious ceremonies.

"It's used to ... get information from the spirit world about sickness, about illness, about what plant might be appropriate to use for a patient who is sick," McKenna said.

McKenna came to Minnesota 20 years ago to work at Aveda, a company famous for the use of plants in personal care products.

In addition to his work at the university, he teaches in Peru and consults with nonprofit research groups investigating therapeutic uses of psychedelics.

FIRST-HAND EXPERIENCE

At 16 in his small Colorado hometown, McKenna and a friend ate seeds from the jimson weed because they'd heard it would do something to them. The "something" turned out to be a three-day-long psychedelic experience that McKenna confesses was very unpleasant.

"And especially to our moms who didn't know what was going on," he said.

McKenna called his first experience drinking ayahuasca tea in 1991 at a church in Brazil profound. He and several hundred others sat in a circular temple as an officiant distributed paper cups of what McKenna calls a brownish liquid with a foul aftertaste.

An hour and two servings later, he said he felt the force of the ayahuasca course through him as though he was headed upward in a high-speed elevator. McKenna said he felt energized and was aware of a combination of force and light.

The first part of his vision was from a point of view thousands of miles over the Amazon basin where he could see the curvature of the earth and swirls of eddies of clouds, and in the center an enormous vine anchored to the earth far below.

One of two plants used to make an ayahuasca brew was photographed by University of Minnesota professor Dennis McKenna in 2002. Courtesy of Dennis McKenna

McKenna said he was awestruck. He said in the next part of the vision he was transported from space to beneath the earth as a water molecule lost among the root fibers where he felt coolness of the soil. Then he felt what he describes as an osmotic force as he was squeezed into the plant's vascular system, floating, suspended in a stream, into a vaulted tunnel, a green light at the end, and then into the leaf.

At the end he said he was wracked with a sense of overwhelming sadness mixed with fear for the delicate balance of life on this planet, the fragile processes that drive and sustain life. McKenna said he wept, felt misery, anger and rage directed toward our, "rapacious destructive species scarcely aware of its own devastating power."

Finally, he remembers a quiet voice telling him, "You monkeys only think you are running things. You don't think we'd allow this to happen," a voice he interpreted to be coming from the entire community of species that constitute the planet's biosphere.

At the end of the vision, which McKenna said lasted perhaps 20 minutes and included emotions from despair to ecstasy, a sense of relief, tempered with hope, washed over him.

LITTLE KNOWN ABOUT HEALTH BENEFITS

McKenna said that first hallucinogenic experience with ayahuasca enhanced his intellectual understanding of the inner workings of plants.

"I was given a front seat inside the plant and got to observe the process of photosynthesis," McKenna said.

But little is known about the possible beneficial, mind altering, effects of psychedelics.

In the late 1960s and early 1970s Congress and President Richard Nixon approved legislation that banned the use hallucinogens and shut the door on most research.

McKenna said some studies appear to show that the hallucinogen psilocybin found in a species of mushroom helps relieve anxiety in people with terminal illnesses.

Ayahuasca is cooked by native Amazonians in Brazil in 2001. Ayahuasca is a combination of the vine and root of two different plants, and, when ingested, is said to offer spiritual healing and enlightenment. Courtesy of L.E. Luna

He said it might help a patient approach death differently.

" 'Yes I know that I'm dying, but I'm alive now and what I want to do is live every day that I'm alive to the fullest,' " McKenna said, as if he were a patient.

McKenna said another psychedelic appears to help some alcoholics and smokers break their addictions and may help sufferers of post traumatic stress disorder cope with life.

"There's a spiritual dimension to healing. Conventional medicine is kind of uncomfortable with that concept. That's why psychedelics are so important. They can work at that interface between pharmacology and spirituality," McKenna said.

McKenna said less than 10 percent of the world's plants have been researched for possible medicinal uses.