Blueberries are perennial flowering plants with indigo-colored berries from the section Cyanococcus within the genus Vaccinium (a genus that also includes cranberries and bilberries). Prostrate shrubs can vary in size from 10 centimeters (3.9 in) to 4 meters (13 ft) in height. In the commercial production of blueberries, the smaller species are known as "low-bush blueberries" (synonymous with "wild"), while the larger species are known as "high-bush blueberries". They have a sweet taste when mature, with variable acidity. Blueberry bushes typically bear fruit in the middle of the growing season: fruiting times are affected by local conditions such as altitude and latitude, so the height of the crop can vary from May to August depending upon these conditions.