Pru is a bottled root beverage from the eastern provinces of Cuba. Pru is made from chinaberry, ubi roots, soap berry, ginger, sweet pepper leaves, raw cinnamon and brown sugar, and is served cold. It is said that Pru has been referred to as root champagne or root beer. HavanaTimes.org recently posted an article about Pru which can be found here. The author has very good things to say about the drink.
As Cubans have migrated from the eastern part of the country to Havana, other parts of Cuba, and beyond, Pru has become available in more locations. The HavanaTimes.org indicated Pru might already be available in Miami. I have not found any commercial producers of Pru, but as U.S. relations with Cuba normalize, perhaps Pru will become readily available to root beer lovers.