Several species of the genus Vaccinium, plant order Ericales, ranging from low-growing, almost prostrate plants to vigorous shrubs reaching a height of 12–15 ft (3.5–4.5 m). The fruit, a berry, is usually black and covered with bluish bloom, generally occurring in clusters and has numerous small seeds, a characteristic that distinguishes the blueberry from the huckleberry, which has 10 rather large, gritty seeds. Although there are blueberry species on other continents, all cultivated varieties in the United States are American in origin.