Blueberries are perennial flowering plants with indigo-colored berries in the section Cyanococcus within the genus Vaccinium (a genus that also includes cranberries and bilberries). Species in the section Cyanococcus are the most common fruits sold as “blueberries” and are native to North America (commercially cultivated highbush blueberries were not introduced into Europe until the 1930s.)
They are usually erect, but sometimes prostrate shrubs varying in size from 10 centimeters (3.9 in) to 4 meters (13 ft) tall. In commercial blueberry production, smaller species are known as “lowbush blueberries” (synonymous with “wild”), and the larger species are known as “highbush blueberries”.
The leaves can be either deciduous or evergreen, ovate to lanceolate, and 1–8 cm (0.39–3.1 in) long and 0.5–3.5 cm (0.20–1.4 in) broad. The flowers are bell-shaped, white, pale pink or red, sometimes tinged greenish. The fruit is a berry 5–16 millimeters (0.20–0.63 in) in diameter with a flared crown at the end; they are pale greenish at first, then reddish-purple, and finally dark blue when ripe. 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.
The genus Vaccinium has a mostly circumpolar distribution with species in America, Europe and Asia, but also Africa.
Many commercially sold species with English common names including “blueberry” are currently classified in section Cyanococcus of the genus Vaccinium and come predominantly from North America. Many North American native species of blueberries are now also commercially grown in the Southern Hemisphere in Australia, New Zealand and South American countries.
Several other wild shrubs of the genus Vaccinium also produce commonly eaten blue berries, such as the predominantly European bilberry (Vaccinium myrtillus), that in many languages has a name that means “blueberry” in English. See the Identification section for more information.
Note: habitat and range summaries are from the Flora of New Brunswick, published in 1986 by Harold R. Hinds and Plants of the Pacific Northwest coast, published in 1994 by Pojar and MacKinnon
- Vaccinium alaskaense (Alaskan blueberry): one of the dominant shrubs in Alaskan and British Columbian coastal forests
- Vaccinium angustifolium (lowbush blueberry): acidic barrens, bogs and clearings, Manitoba to Labrador, south to Nova Scotia and in the USA, to Iowa and Virginia
- Vaccinium boreale (northern blueberry): peaty barrens, Quebec and Labrador (rare in New Brunswick), south to New York and Massachusetts
- Vaccinium caesariense (New Jersey blueberry)
- Vaccinium corymbosum (northern highbush blueberry)
- Vaccinium darrowii (southern highbush blueberry)
- Vaccinium elliottii (Elliott blueberry)
- Vaccinium formosum (southern blueberry)
- Vaccinium fuscatum (black highbush blueberry; syn. V. atrococcum)
- Vaccinium hirsutum (hairy-fruited blueberry)
- Vaccinium myrtilloides (sour top, velvet leaf, or Canadian blueberry): clearings, thickets and peat bogs, Northwest Territories (Canada) to Labrador, south to Nova Scotia, and Montana to Virginia
- Vaccinium operium (cyan-fruited blueberry)
- Vaccinium pallidum (dryland blueberry)
- Vaccinium simulatum (upland highbush blueberry)
- Vaccinium tenellum (southern blueberry)
- Vaccinium virgatum (rabbiteye blueberry; syn. V. ashei)
Some other blue-fruited species of Vaccinium:
- Vaccinium koreanum
- Vaccinium myrsinites (evergreen blueberry)
- Vaccinium myrtillus (bilberry or European blueberry)
- Vaccinium uliginosum
Commercially offered blueberries are usually from species that naturally occur only in eastern and north-central North America. Other sections in the genus, native to other parts of the World, including western North America, South America, Europe, and Asia, include other wild shrubs producing similar-looking edible berries, such as huckleberries (North America) and bilberries (Europe). These species are sometimes called “blueberries” and sold as blueberry jam or other products.
The names of blue berries in languages other than English often translate as “blueberry”, e.g., Scots blaeberry and Norwegian blåbær. Blaeberry, blåbær and French myrtilles usually refer to the European native bilberry (V. myrtillus), while bleuets refers to the North American blueberry.
Cyanococcus blueberries can be distinguished from the nearly identical-looking bilberries by their flesh color when cut in half. Ripe blueberries have white or light green flesh, while bilberries and huckleberries are red or purple throughout. Bilberries are most often found singularly or in pairs, while blueberries are most often found in clusters.
Blueberries may be cultivated, or they may be picked from semiwild or wild bushes. In North America, the most common cultivated species is V. corymbosum, the northern highbush blueberry. Hybrids of this with other Vaccinium species adapted to southern U.S. climates are known collectively as southern highbush blueberries.
So-called “wild” (lowbush) blueberries, smaller than cultivated highbush ones, are prized for their intense color. The lowbush blueberry, V. angustifolium, is found from the Atlantic provinces westward to Quebec and southward to Michigan and West Virginia. In some areas, it produces natural “blueberry barrens”, where it is the dominant species covering large areas. Several First Nations communities in Ontario are involved in harvesting wild blueberries. Lowbush species are fire-tolerant and blueberry production often increases following a forest fire, as the plants regenerate rapidly and benefit from removal of competing vegetation. “Wild” has been adopted as a marketing term for harvests of managed native stands of lowbush blueberries. The bushes are not planted or genetically manipulated, but they are pruned or burned over every two years, and pests are “managed”.
Numerous highbush cultivars of blueberries are available, each of which has a unique flavor, with diversity between them. The most important blueberry breeding program has been the USDA-ARS breeding program based at Beltsville, Maryland, and Chatsworth, New Jersey. This program began when Frederick Coville of the USDA-ARS collaborated with Elizabeth Coleman White of New Jersey. In the early part of the 20th century, White offered pineland residents cash for wild blueberry plants with unusually large fruit. ‘Rubel’, one such wild blueberry cultivar, is the origin of many of the current hybrid cultivars.
The rabbiteye blueberry (Vaccinium virgatum syn. V. ashei) is a southern type of blueberry produced from the Carolinas to the Gulf Coast states. Other important species in North America include V. pallidum, the hillside or dryland blueberry. It is native to the eastern U.S., and common in the Appalachians and the Piedmont of the Southeast. Sparkleberry, V. arboreum, is a common wild species on sandy soils in the Southeast. Its fruits are important to wildlife, and the flowers are important to beekeepers.
The blueberry harvest in North America varies. It can start as early as May and usually ends in late summer. The principal areas of production in the Southern Hemisphere (Australia, Chile, New Zealand and Argentina) have long periods of harvest. In Australia, for example, due to the geographic spread of blueberry farms and the development of new cultivation techniques, the industry is able to provide fresh blueberries for 10 months of the year – from July through to April. Similar to other fruits and vegetables, climate-controlled storage allows growers to preserve picked blueberries. Harvest in the UK is from June to August.
Blueberries are sold fresh or processed as individually quick frozen (IQF) fruit, purée, juice, or dried or infused berries, which in turn may be used in a variety of consumer goods, such as jellies, jams, blueberry pies, muffins, snack foods and cereals.
Blueberry jam is made from blueberries, sugar, water, and fruit pectin. Blueberry wine is made from the flesh and skin of the berry, which is fermented and then matured; usually the lowbush variety is used.
Nutrients, phytochemicals and research
Blueberries have a diverse range of micronutrients, with moderate levels (relative to respective Dietary Reference Intakes) of the essential dietary mineral manganese, vitamin C, vitamin K and dietary fiber (table). One serving provides a relatively low glycemic load score of 4 out of 100 per day.
Blueberries contain anthocyanins, other pigments and various phytochemicals, which are under preliminary research for their potential role in reducing risks of diseases such as inflammation and cancer. Similar to red grape, blueberries may contain resveratrol.
Most studies have been conducted using the highbush cultivar of blueberries (V. corymbosum), while content of polyphenols and anthocyanins in lowbush (wild) blueberries (V. angustifolium) exceeds values found in highbush cultivars.
In preliminary research, feeding blueberries to rats reduced brain damage in experimental strokeand may cause increased production of vascular nitric oxide that influences blood pressure regulation. Additional research showed that blueberry consumption in rats altered glycosaminoglycans that are vascular cell components affecting control of blood pressure.
Other animal studies found blueberry consumption lowered cholesterol and total blood lipid levels, possibly affecting symptoms of heart disease.
Supplementation of diets with wild blueberry juice may affect memory and learning in older adults, while reducing blood sugar and symptoms of depression.