Pu-erh is a type of tea made from a "large leaf" variety of the tea plant Camellia sinensis and named after Pu'er county near Simao, Yunnan, China. While unaged and unprocessed raw pu-erh is technically a type of green tea, ripened or aged raw pu-erh has occasionally been mistakenly categorised as a subcategory of black tea due to the dark red colour of its leaves and liquor. However, pu-erh in both its ripened or aged forms has undergone secondary oxidization and fermentation caused both by organisms growing in the tea as well as from free-radical oxidation, thus making it a unique type of tea.