Seven iconic fruits are listed by Deuteronomy as emblematic of the Land of Israel: "A land of wheat and barley, of vines, figs, and pomegranates, a land of olives trees and (date) honey" (8:8). They are indigenous to Israel and suit the climate and ecology. A few years ago in a drought year, farmers in Israel were reduced to uprooting their cherry trees and planting less thirsty dates and pomegranates instead.
If you eat a few different fruits in one sitting, only one blessing is necessary to cover all of them. If one of those fruits happens to be one of the seven species, the blessing you say on it covers all the other fruit After eating one of the seven fruits you say the blessing, me'ein shalosh, which gives thanks for the fruits and for the Land of Israel where they flourish. There is a tradition of eating the seven fruits on Tu Bisvhat.