A native evergreen, guarana is a sprawling, shrub like vine native to the Amazon region. The guarana tree produces red berries that have been used like coffee in its native Brazil for centuries. When ripe, the berries split open at the end and look similar to a human eyeball. A legend of the Satare-Maure Indians of Brazil tells that a beautiful woman named Onhiamuacabe gave birth to a child whose father was said to be a "mysterious being". The child was eventually put to death for eating some type of forbidden nuts. At his burial site a guarana bush began to grow from his eye. Native Indians still consider the effects of guarana to be supernatural in nature. The seeds of the berry are dried, roasted and then brewed to make a drink that is at first bitter and slightly astringent, later becoming sweet. Older texts contain reference to a substance called guaranine, said to be chemically identical to caffeine. More recently, many chemists argue that the substance is caffeine, making guarana the highest source of caffeine available in nature. Guarana seeds contain 2.5 times the amount of caffeine that coffee does.