What is the most potent and notorious hallucinogen?

Lysergic Acid Diethylamide (LSD) is known to be one of the most potent hallucinogens, primarily due to its highly concentrated psychoactive effects at very low doses. LSD's potency is attributed to its ability to bind effectively to serotonin receptors in the brain, particularly the 5-HT2A receptor, leading to profound alterations in perception, mood, and cognitive processes. It can elicit intense visual and auditory hallucinations and significantly alter an individual's thought processes.

While mushrooms, which contain psilocybin, are also powerful hallucinogens, LSD typically produces stronger and more unpredictable psychological effects at lower quantities. Cannabis, although sometimes psychoactive, does not induce hallucinations to the degree of LSD. Psychedelic mushrooms, while similar in effects to LSD, do not match its intensity and duration. Thus, LSD stands out as the answer when considering both potency and notoriety among hallucinogenic substances.