In restaurants, iced tea is usually served unsweetened except in the Southeastern United States where iced tea is much more common and is available both sweet and unsweetened and "iced tea" is often considered to be "sweet tea" unless otherwise specified. The reason for the presweetening is that it may be difficult to dissolve sugar in iced tea, even with constant stirring. The result can be insufficiently sweetened tea or gritty, undissolved sugar crystals in the tea. Some restaurants have begun serving iced tea that has been pre-flavored with fruit essences, particularly passion fruit, often as the only iced tea made available.