The bilberry stains your tongue because its color runs right through the fruit
Bilberries look like small blueberries, but bite one and the flesh is dark too, not pale. The pigments soak through skin and pulp alike, which is why a handful turns hands, teeth and tongue purple and why Britons once dyed food and cloth with them. Northern Europe still gathers almost all of them wild.
Vaccinium myrtillus is a low, much-branched shrub, usually 10 to 51 centimetres tall, that spreads by underground stems into wide patches and can live for 30 years with roots reaching a metre down. Its small oval leaves, named for their likeness to myrtle, turn red in autumn and fall. Nodding, urn-shaped flowers in pale pink or greenish tones appear in April and May, and from July to September the plant bears round black-blue berries up to a centimetre across with a frosty bloom. Each berry holds about 25 seeds and is roughly 85% water.
Unlike the cultivated highbush blueberry, whose colour stays in the skin, the bilberry carries its anthocyanin pigments in the flesh as well. Rare plants produce white, yellow or red fruit. Leaves contain tannins, arbutin and other compounds, and the plant is rich in triterpenes that laboratories are still studying. Its lignin output, a chemical defence, seems unaffected by climate stresses that alter it in many other plants.
The species grows right around the northern hemisphere, from almost every European country through northern and central Asia to Japan, Greenland and western North America, on acidic heaths, moors and open conifer woods up to 2,350 metres. Local names are a small dictionary of their own: blaeberry in Scotland, whortleberry, whinberry, wimberry, and urts or hurts in Cornwall and Devon. Bilberry itself seems to come from Old Norse, close to the Danish name. The genus name may come from Latin words for cow or berry.
Cooks use the fruit in pies, tarts, jams, syrups and sweets, and demand in Northern Europe is high even though nobody farms the plant commercially. Supplements are sold, though there is no evidence they affect health, and traditional Austrian medicine made teas and liqueurs from it.
Source: Vaccinium myrtillus
