Vaccinium myrtillus (European blueberry)

Vaccinium myrtillus is a species of shrub with edible fruit of blue color, commonly called "bilberry", "wimberry", "whortleberry", or European blueberry. 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, urts (Cornwall), hurtleberry, huckleberry, wimberry, whinberry, winberry, blueberry, and fraughan.

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 bilberries and American blueberries
Since many people refer to "blueberries", no matter whether they mean the bilberry (European blueberry) Vaccinium myrtillus or the American blueberries, there is confusion about the two closely similar fruits. One can distinguish bilberries from their American counterpart by the following differences:

• bilberries have dark red, strongly fragrant flesh and red juice that turns blue in basic environments; blueberries have white or translucent, mildly fragrant flesh
• bilberries grow on low bushes with solitary fruits, and are found wild in heathland in the Northern Hemisphere; blueberries grow on large bushes with the fruit in bunches
• bilberries are usually harvested from wild plants, while blueberries are usually cultivated and are widely available commercially
• cultivated blueberries often come from hybrid cultivars, developed about 100 years ago by agricultural specialists, most prominently Elizabeth Coleman White, to meet growing consumer demand; the bushes grow taller and are easier to harvest
• bilberry fruit will stain hands, teeth and tongue deep blue or purple while eating (it was used as a dye for food and clothes), while blueberries have flesh of a less intense color, and are thus less staining
• when cooked as a dessert, bilberries have a much stronger, more tart flavor and a rougher texture than blueberries

Adding to the confusion is the fact there are also wild American blueberry varieties, sold in stores mainly in the USA 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.
en.wikipedia.org