Dennis McKenna is an ethnopharmacologist and has studied plant hallucinogens for more than 20 years. In 1975, he co-authored the book Invisible Landscape, with his brother Terence McKenna. The book was based on their investigations of Amazonian hallucinogens in 1971. He also acted as co-star of his brother’s book True Hallucinations, which further described their experiences while in the Amazon. Dennis is a good friend and a hero of mine. It is always a pleasure to welcome him back to the program.