Vaccinium oxycoccos, V. microcarpum
The common cranberry (Vaccinium oxycoccos) is a prostrate, low-growing shrub reaching 10–80 cm in length. Its overwintering leaves are 6–15 mm long, elliptic or tapering, glossy and green above and whitish underneath. The pink flowers of the shrub grow in pairs or groups at the ends of its branches. The cranberry flowers in June–July. The berry is globose, 10–15 mm in diameter or teardrop-shaped and widening either at the tip or base. The berry is red or a deep bluish red and acidic to the taste.
The small cranberry (V. microcarpum) is more delicate than the common cranberry, 10–30 cm long. The leaves of this prostrate, low-growing shrub are overwintering, 3–8 mm long and triangular-ovate. The flowers of the small cranberry grow individually on the shrub, are dark red and bloom in June–July. The berries are much smaller than those of the common cranberry. The small cranberry is teardrop-shaped, red or blackish red and has a mild taste.
The small cranberry is most frequently found in northern Finland. The common cranberry grows in all parts of Finland with the exception of the northernmost reaches of Lapland. The common cranberry grows in nutrient-poor, sunlit fens and pine bogs. The small cranberry, in contrast, grows in drier soil. The habitat of the cranberry has diminished in recent years due to the draining of bogs and peat extraction.
The cranberry yields especially large crops on the boggy margins of lakes and ponds and in wet open bogs. Cranberries can be picked from the end of September until the first snow and then again from under the snow in spring. It is worth picking cranberries also after the first sub-freezing temperatures of autumn as well as in the spring, when their sugar content has risen and they are less acidic.
Like most berries, the cranberry is a good source of vitamin C. Because of its tough skin, the cranberry is also a good source of fibre. The bitter taste of the cranberry is due to the presence of various natural acids: malic, citric and benzoic acid. Polyphenol compounds typical to the cranberry are flavonols such as quercetin and myricetin. Cranberries also contain other polyphenols that have been the subject of research, such as lignans and proanthocyanidins.
Cranberries are used in berry soups, porridges, casseroles and baked goods. Cranberries contain benzoic acid, which preserves the berries naturally. Autumn cranberries are rich in pectin, which is a natural gelling agent and makes them an excellent ingredient for marmalade and jam. The sweeter cranberries picked in spring are suitable for making juice or sima, a fermented Finnish beverage.