Guarana Seed is a berry indigenous to the Amazon rainforest, and it has been harvested for centuries. It is a signature ingredient and 
flavor in Brazilian culinary culture, and, not unlike the acaí berry, has recently been "discovered" and misunderstood in the United States as a "miracle" substance. More so than just a natural stimulant, guarana seed is a naturally unique flavor with a rich history.
Origin
Guarana seed is a tropical berry indigenous to the Amazon Basin, located in the northern parts of Brazil and Venezuela. The name derives from the Brazilian Guarani tribe by whom the plant was first harvested for medicinal and culinary uses. The Guarani believe the herb to have magical medicinal properties to restore energy; whether magical or not, the "energy effect" is undoubtedly present in the seed, as a guarana seed contains nearly twice the caffeine content of a coffee bean.
Botany
The botanical name for guarana is Paullinia cupana, named for the German scientist C.F. Paullini who first discovered the plant along with the Guarani tribe in the 18th century. Guarana seed is a climbing plant of the maple tree family; it produces large flat leaves and berry or flower clusters that ripen into the guarana seed that grows to about the size of a coffee bean. Guarana is a highly successful plant, as the high levels of caffeine work as a toxic repellent against harmful diseases that may attack the berries. The color of guarana berries and seed varies between bright red and brown, while the seeds on the inside are charcoal black and are surrounded by white padding.
Chemical Composition
As aforementioned, the caffeine content in guarana seed is nearly twice the concentration as is found in a coffee bean, averaging at around 5.5 percent gauranine (virtually identical to caffeine). The remainder of the seed contains nearly 50 percent vegetable fiber, 8.3 percent starch, 7.6 percent water, nearly 6 percent guarana acid, 7.5 percent pectin, malic acid, mucilage, dextrin and salts, colorant and acids.
Cultural Role
Guarana seed is relatively unknown outside of Brazil and Venezuela, though inside Brazil it is exceedingly popular in soft drinks and in powder forms. In Brazil it is not marketed for its caffeine high as it is in the United States, but rather for its unique taste. Guarana seed is also used as a flavoring powder that can be added to drinks or in recipes, in syrup and in chocolate bars and chewing gum. In the United States, however, guarana seed is pedaled as a miracle energy drug in herbal vitamin supplements and energy drinks.
Theories/Speculation
The story of guarana seed comes from the Guarani tribe, where the myth of the "divine child" holds that a village child was killed by a serpent deity, after which another deity planted the child's eyes in the ground and from that guarana sprang. The connection to "eyes" stems from the visual appearance of the contrast of the black seeds against the white surround and red shell of the berry.
