"Tangerine trees and marmalade skies" are to be found in the lyrics of "Lucy in the Sky with Diamonds," one of the Beatles' greatest hits. Some have claimed that the first letters of Lucy, Sky and Diamonds supposedly refer to LSD, the famous hallucinogen that the Fab Four undoubtedly had some experience with. LSD, or lysergic acid diethylamide, does not occur in nature, but closely related compounds do.
The seeds of the morning glory plant, for example, harbour lysergic acid amide, which is a well-established hallucinogen, though less potent than LSD. The ancient Aztecs are known to have prepared a beverage, known as ololiuqui, from the seeds of the morning glory, which they used in religious ceremonies. A Spanish missionary in the sixteenth century observed that "the natives communicate with the devil, for they usually talk when they become intoxicated with ololiuqui, and they are deceived by various hallucinations which they attribute to the deity which they say resides in the seeds."
LSD itself was synthesized in 1938 by the Swiss chemist Albert Hofmann who had been studying hallucinogenic compounds found in the ergot fungus that can grow on rye. He embarked on a synthesis of chemical derivatives of these substances with the hope that they may be of pharmacological use. During his experiments, he accidentally ingested a tiny amount of LSD, probably as a result of not washing his hands. He had a remarkable experience which he later described: "I sank into a not unpleasant intoxicated condition…I perceived an uninterrupted stream of fantastic pictures, extraordinary shapes with intense kaleidoscopic play of colours." He tried a higher dose and quickly realized that there was a great downside to LSD. "A demon had invaded me, had taken possession of my body, mind and soul…I was seized by a dreadful fear of going insane." Today we know that large doses of LSD, which are still in the milligram range, interfere with the activity of serotonin, an important neurotransmitter and this can have catastrophic effects. It is best to limit one's experience with LSD to listening to Lucy in the Sky with Diamonds.