[Microscopic examination of Guaraná powder--Paullinia cupana Kunth]

Guaraná is a product from the seeds of the Amazonian liana Paullinia cupana that is also cultivated since a couple of years. It is rich in caffeine and serves in Brasil for the production of stimulants, soft drinks, and sweets. In the drug scene it is sometimes trafficked as natural stimulant or drug surrogate. Microscopic examination shows the presence of starch and tannins and provides a simple, quick and cheap method to distinguish guaraná from drugs of abuse.