guarana

Guarana (, from the Portuguese guaraná ), Paullinia cupana, syn. P. crysan, P. sorbilis) is a climbing plant in the maple family, Sapindaceae, native to the Amazon basin and especially common in Brazil. Guarana features large leaves and clusters of flowers, and is best known for the seeds from its fruit, which are about the size of a coffee bean. As a dietary supplement, guarana is an effective stimulant: its seeds contain about twice the concentration of caffeine found in coffee seeds (about 2–4.5% caffeine in guarana seeds compared to 1–2% for coffee seeds).