Blueberries are flowering plants of the genus Vaccinium with dark-blue berries. Species in the section Cyanococcus are the most common fruits sold as "blueberries" and are mainly native to North America. They are usually erect but sometimes prostrate shrubs varying in size from 10 centimetres (3.9 in) to 4 metres (160 in) tall. In commercial blueberry production, smaller species are known as "lowbush blueberries" (synonymous with "wild"), and the larger species as "highbush blueberries". The leaves can be either deciduous or evergreen, ovate to lanceolate, and 1–8 centimetres (0.39–3.1 in) long and 0.5–3.5 centimetres (0.20–1.4 in) broad. The flowers are bell-shaped, white, pale pink or red, sometimes tinged greenish.

The fruit is a false berry 5–16 millimetres (0.20–0.63 in) diameter with a flared crown at the end; they are pale greenish at first, then reddish-purple, and finally blue on ripening. They have a sweet taste when mature, with variable acidity. Blueberry bushes typically bear fruit from May through June though fruiting times are affected by local conditions such as altitude and latitude.