Which substance is not classified as a controlled stimulant?

The substance identified as mescaline is not classified as a controlled stimulant because it functions as a hallucinogen rather than a stimulant. Mescaline, derived from the peyote cactus, primarily alters an individual's perception, mood, and cognition rather than increasing alertness or energy levels typical of stimulant drugs.

In contrast, the other substances listed—amphetamines, methamphetamine, and Dexedrine (which is a brand name for dextroamphetamine)—are all central nervous system stimulants known for their ability to enhance focus, increase energy, and elevate mood. These substances are classified as controlled due to their potential for abuse and dependency, as they increase dopamine levels in the brain, contributing to their stimulant effects. Thus, they are regulated under controlled substance laws, while mescaline's classification as a hallucinogen places it in a different category.