Mate is a traditional tea from South America. It is brewed from the leaves and stem of the Ilex paraguariensis tree which is a species of the holly family. Exposed to flames after harvesting, the tea has a refreshing taste with a slightly smoky flavour. Mate is a traditional tea from South America. It is brewed from the leaves and stem of the Ilex paraguariensis tree which is a species of the holly family. Exposed to flames after harvesting, the tea has a refreshing taste with a slightly smoky flavour.