Rubus chamaemorus (also known as cloudberry) is a species of flowering plant in the rose family, Rosaceae. It has numerous common names varying by region, such as Nordic berry, Arctic berry, baked apple, knotberry, aqpik, and lowbush salmonberry.

A herbaceous perennial, it produces amber-colored fruit similar in structure to the blackberry. It is native to cool temperate regions, alpine and Arctic tundra, and boreal forest. Although not cultivated commercially, the fruit is edible.

Unlike most Rubus species, the cloudberry is dioecious, and fruit production by a female plant requires pollination from a male plant. The plant germinates from seeds spread by animals that consumed the fruit, then reproduces locally by rhizomes. Vegetative growth can be extensive, with rhizomes growing 10 meters (33 feet) or longer.

The cloudberry grows 10–25 centimetres (4–10 in) high. The short stems are unbranched and have 1-3 leaves. The leaves have five to seven handlike (palmate) lobes. After pollination, the white (sometimes reddish-tipped) flowers form raspberry-sized aggregate fruits, which are more plentiful in wooded rather than sun-exposed habitats. Consisting of between five and 25 drupelets, each fruit is initially pale red, ripening into an amber color in early autumn. After pollination the sepals close around the developing fruit, opening again when the fruit is ripe.

Cloudberries are rich in vitamin C, citric acid, malic acid, α-tocopherol, anthocyanins, and the provitamin A carotenoid, β-carotene in contents that differ across regions of Finland due to sunlight exposure, rainfall, and temperature. The ellagitannins lambertianin C and sanguiin H-6 are also present. Genotype of cloudberry variants may also affect polyphenol composition, particularly for ellagitannins, sanguiin H-6, anthocyanins and quercetin.

Cloudberries are a circumpolar boreal plant, occurring naturally throughout the Northern Hemisphere from 78°N, south to about 55°N, and are scattered south to 44°N mainly in mountainous areas and moorlands. In Europe, they grow in the Nordic countries, but are rare in the Baltic states (Estonia, Latvia, and Lithuania) and Poland. They are present in the English Pennines and the Scottish Highlands, while a single, fragile site exists in the Sperrin Mountains of Northern Ireland. They occur across northern Russia east towards the Pacific Ocean as far south as Japan in the island of Hokkaido. Svalbard was historically too cold for cloudberries but since 2023, warming has resulted in the establishment and survival of cloudberry plants on the islands.

In North America, cloudberries grow wild across Greenland, most of northern Canada, Alaska, northern Minnesota, New Hampshire, Maine, and New York.

Wide distribution occurs due to the excretion of the indigestible seeds by birds and mammals. Further distribution arises through its rhizomes, which are up to 10 m (33 ft) long and grow about 10–15 cm (4–6 in) below the soil surface, developing extensive and dense berry patches. Cuttings of these taken in May or August are successful in producing a genetic clone of the parent plant. The cloudberry grows in bogs, marshes, wet meadows, and tundra, and at elevations of 1,743 m (5,719 ft) above sea level in Norway, requiring acidic ground (between 3.5 and 5.0 pH).