The cranberry is the small, hard, intensely tart red berry of a low North American wetland shrub, prized for its sharp acidity, astringent bite and bright crimson colour rather than for sweetness. Too sour and bitter to eat raw by the handful, it is the berry of holiday sauce, sweetened dried "craisins", deep-red juice cocktails and bog harvests where whole fields are flooded and rafts of floating fruit are corralled into a scarlet slick.