- Name also: Mossberry, Northern Cranberry, Small Cranberry (in USA, compare V. microcarpum)
- Family: Heather Family – Ericaceae
- Growing form: Perennial dwarf shrub.
- Height: Around 5 cm (2 in.), creeping shoots 10–80 cm (4–30 in.) long. Stem limp, creeping, thread-like, tip finely haired.
- Flower: Corolla wheel-shaped, 6–10 mm (0.24–0.4 in.) broad, red–pink, fused, very deeply 4–5-lobed. Lobes recurved. Sepals 4, finely haired. Stamens 4 or 8. A single carpel. Inflorescence a 2–4-flowered group terminating branches; flower-stalks long, erect, hairy.
- Leaves: Alternate, short-stalked, overwintering. Blade elliptic–ovate, tapered, leathery, dark green and shiny on top, underside light-coloured, with entire, revolute margins.
- Fruit: Spherical, 10–15 mm (0.4–0.6 in.) broad, dark red, juicy, acidic berry, sweeter after frost.
- Habitat: Quite barren bogs and swamps.
- Flowering time: June–July.
Cranberry is one of the rare plants that thrives on barren bogs, growing on top of bog mosses. Its oldest parts gradually bury themselves in the peat but its delicate stems creep along the surface. The lack of competition means that it doesn’t have to lean towards the light, and only the flowers rise up out of the bog to attract pollinators – and even these are no more than 5 cm (2 in.) high. Cranberry is one of the most important useful plants that grows on Finnish bogs, and it can yield up to seven hundred kilos per hectare. The best cranberry grows on different kinds of open, sedge and low-growing swamps as well as mossy open bogs.
Cranberries can be used to make juice, jam and even liqueur. It is especially suited to making jam because of the amount of pectin it contains. Cranberry juice was earlier used medicinally to relieve e.g. different kinds of infectious diseases, fevers and acid problems. Cranberry’s sharp, sour berries are the last to ripen in Finland, only maturing with the first winter frosts in September or October. Berry-picking trips are much easier if the plants’ growing area has already frozen. The berries become sweeter and softer throughout the winter, but they remain edible right through to the following spring – if a mole, bird or other creature doesn’t eat it first. Many people are of the opinion that frostbitten berries picked from under the spring snow have the best flavour.
Small cranberry (V. microcarpum) is almost as common. It is clearly smaller and usually grows in drier soils than cranberry. Small cranberry’s berries are quite small, so they are often undisturbed. A good indicator is the flower-stalks, which on cranberry are hairy, but on small cranberry are glabrous. Small cranberry usually has one flower, while cranberry has 2–4.