Stimulant; Depressant; Intoxicant
 
Mitragyna speciosa is a leafy tree that grows from 3-20 meters tall. Its leaves contain 7-Hydroxymitragynine and mitragynine. The leaves are chewed as an opiate substitute and stimulant in Thailand and South-East Asia, primarily among the working class. It has a relatively long history of human use.
 
https://www.erowid.org/plants/kratom/kratom.shtml