- Name also: Blueberry, Whortleberry, Huckleberry, Hurtleberry
- Family: Heather Family – Ericaceae
- Growing form: Perennial dwarf shrub. Rhizomatous.
- Height: 10–40 cm (4–15 in.). Stem erect, abundantly branched, woody, old stems round, brown, young stems bristly, green, glabrous.
- Flower: Corolla broadly urceolate (pitcher-shaped), greenish yellowish–reddish, 4–6 mm (0.16–0.24 in.) long, fused, shallowly 4–5-lobed. Calyx very shallowly 5-lobed. Stamens 4 or 8. A single carpel. Flowers solitary in axils.
- Leaves: Alternate, short-stalked, withering by winter. Blade elliptic–ovate, tapered, finely serrated, bright green, semi-matt.
- Fruit: Spherical, 6–8 mm (0.24–0.32 in.) broad, dark blue and glaucous (wax-covered) or black and shiny, occasionally off-white, inside dark red, juicy berry.
- Habitat: Young and grove-like forest heaths and swamps, also dry forest heaths and fell moors.
- Flowering time: May–July.
Bilberry is one Finland’s most common forest plants and one of the most common coniferous forest dwarf shrubs. It is the type species of the myrtillus-type forest according to the Finnish forest site type classification system. Even so, however, it has been becoming significantly less abundant in recent decades. It doesn’t thrive in a dry, sun-baked environment, and large-scale industrial forestry is the most important reason for its decline. A common species like bilberry also has a big effect on other plants and animals and the building and functioning of communities. Bilberry is also important to people as it is one of the most well-liked and economically important Finnish forest berries.
Bilberry shoots, which stay green throughout the winter, make an excellent winter food for reindeer, hares and elks, not to mention moles spending their winters beneath the snow. Most of the plant’s biomass is safe below the soil in its rootstock, so it recovers relatively quickly from plant-eaters’ visits. It sheds its leaves in autumn, but not before it has decorated the land with beautiful autumnal shades of orange. Bilberry shoots require a sufficiently thick layer of snow to protect them throughout the winter or they die of excessive cold.
Bilberry flowers early in the spring as its leaves are unfolding, and the weather in May plays a major role in determining the autumn berry harvest. The essential factor is the amount of pollinators: bilberry flowers attract many different kinds of insects, from small flies and beetles to bees and butterflies, bumblebees being the most important pollinators. If the weather is cool, however, cold-blooded insects don’t fly and pollination does not occur. Bilberry flowers are also sensitive to frost, and one cold night can destroy the whole crop when the fruit is just starting to form. Even in bad years, plants that are growing on islands and other conducive places with a similar climate are often still able to produce fruit.