Vaccinium myrtillus

Vaccinium myrtillus or European blueberry is a species of shrub with edible fruit of blue color, commonly called "bilberry", "blaeberry", "wimberry", "whortleberry". It has much in common with the American blueberry ("Vaccinium cyanococcus"). It is more precisely called common bilberry or blue whortleberry, to distinguish it from other "Vaccinium" relatives. Regional names include blaeberry (Scotland), urts or hurts (Cornwall & Devon), hurtleberry, huckleberry, myrtleberry, wimberry, whinberry, winberry, blueberry, and fraughan. Chromosome count is 2n =24.
Range.
"Vaccinium myrtillus" is found natively in Continental Northern Europe, the British Isles and Ireland, Iceland and across the Caucasus into northern Asia. It is a non-native introduced species in Western Canada and the Western United States. It occurs in the wild on heathlands and acidic soils. Its berry has been long consumed in the Old World. It is related to the widely cultivated North American blueberry.
Uses.
Fruit.
"Vaccinium myrtillus" has been used for nearly 1,000 years in traditional European medicine. "Vaccinium myrtillus" fruits have been used in traditional Austrian medicine internally (directly or as tea or liqueur) for treatment of disorders of the gastrointestinal tract and diabetes. Herbal supplements of "V. myrtillus" (bilberry) on the market are used for cardiovascular conditions, diabetes, as vision aids, and to treat diarrhea and other conditions. Researchers are interested in bilberry because of its high concentrations of anthocyanins, which may have various health benefits. The United States' National Institutes of Health (NIH) cautions, "There’s not enough scientific evidence to support the use of bilberry for any health conditions."
In cooking, the bilberry fruit is commonly used for the same purposes as the American blueberry, such as pies, cakes, jams, muffins, cookies, sauces, syrups, juices, and candies.
Leaf.
In traditional medicine, bilberry leaf is used for different conditions, including diarrhea, scurvy, infections, burns, and diabetes.
Confusion between European blueberries and American blueberries.
Since many people refer to "blueberries" whether they mean the bilberry (European blueberry) "Vaccinium myrtillus" or the American blueberries "Vaccinium corymbosum", there is confusion about the two closely similar fruits. One can distinguish the European species from their American counterpart by the following differences: 
Adding to the confusion is the fact there are also wild American blueberry varieties, sold in stores mainly in the US and Canada. These are uncommon outside of North America. Even more confusion is due to the huckleberry name, which originates from English dialectal names 'hurtleberry' and 'whortleberry' for the bilberry. In the Scandinavian languages "Vaccinium myrtillus" is called blåbär (or blåbær), which literally means blueberry. Therefore many Scandinavians will call bilberry blueberry when speaking English. This adds to the confusion.