Blueberry (Vaccinium sp.) belongs to the Ericaceae (the Azalea family). It is a deciduous shrub that is native to North America. This shrub can reach 2-3 m in height. The small, white urn-shaped flowers bloom in April through May. This shrub was introduced into Japan in the middle days of Showa Era (about 60 years ago). The fruits are berries, and ripen bluish-purple in early summer to mid summer. They are used as an ingredient of jam, jelly and cake. The many cultivars have been raised, and are classified into three strains; the Northern Highbush strain which suits for cold climates, the Rabbiteye strain and the Southern Highbush strain which both suit for warm climates. In Washington county, the blueberry crop plays a major role in the county's economy. Maine accounts for 10 % of all blueberries grown in North America.