|fruit on a bed of Sphagnum rubellum|
Vaccinium oxycoccos is a species of flowering plant in the heath family. It is known as small cranberry, bog cranberry, swamp cranberry, or, particularly in Britain, just cranberry. It is widespread throughout the cool temperate northern hemisphere, including northern Europe, northern Asia and northern North America.
This cranberry is a small, prostrate shrub with vine-like stems that root at the nodes. The leaves are leathery and lance-shaped, up to 1 cm (0.39 in) long. Flowers arise on nodding stalks a few centimeters tall. The corolla is white or pink and flexed backward away from the center of the flower. The fruit is a red berry which has spots when young. It measures up to 1.2 cm (0.47 in) wide. The plant forms associations with mycorrhizae. It mainly reproduces vegetatively.
Vaccinium oxycoccos is a widespread and common species occurring broadly across cooler climates in the temperate northern hemisphere. It is an indicator of moist to wet soils which are low in nitrogen and have a high water table. It is an indicator of coniferous swamps. It grows in bogs and fens in moist forest habitat. It grows on peat which may be saturated most of the time. The soil in bogs is acidic and low in nutrients. The plant's mycorrhizae help it obtain nutrients in this situation. Fens have somewhat less acidic soil, which is also higher in nutrients. The plant can often be found growing on hummocks of Sphagnum mosses.
In North America, other species found in this forest understory habitat include leatherleaf (Chamaedaphne calyculata), bog rosemary (Andromeda glaucophylla), bog laurel (Kalmia polifolia), pitcher plant (Sarracenia purpurea), Labrador tea (Rhododendron groenlandicum), cloudberry (Rubus chamaemorus), rhodora (Rhododendron canadense), glossy buckthorn (Rhamnus frangula), sundew (Drosera spp.), cottonsedge (Eriophorum virginatum and E. angustifolium), and species of sedge and lichen. The plant easily colonizes bog habitat that has recently burned. It survives fire with its underground rhizomes.