When planted in full sun and acidic, moist to wet soils, this unobtrusive groundcover offers tasty berries and extensive wildlife value. The trailing evergreen shrub spreads quickly to form a dense mat of petite, glossy leaves and pink flowers that give way to red fruits. Individual leaves usually remain green for two years. Small cranberry tends to flower and fruit better in full sun, but it also does well in partly sunny conditions. Proper pH and moisture are important for healthy growth. Looser soils are preferable, but a few sources say the plant will adapt to clay. In addition to its ability to spread by rhizomes, small cranberry can reproduce through dispersal of its seeds. The primary mode of transportation is the scat of mammals and birds, but the seeds also travel by water. Some fruits overwinter and find an opportunity to germinate in the spring.
Classified as an obligate wetland plant (it almost always occurs in wetlands), small cranberry is threatened in Ohio where it's often found on acidic sphagnum mounds in bogs, usually in drier areas of the bog (other common names are swamp or bog cranberry). It may be more common than indicated because it's easy to overlook; its long, horizontal stems are often hidden in sphagnum mosses so that only the erect shoots of the current year's growth are visible. It doesn't usually flower prolifically, and it can persist in a leafy, non-flowering state if overtaken by taller vegetation. The stems are capable of rapid elongation, sometimes resulting in as much as a meter of growth during a growing season (Vander Kloet et al. 2012). Based on this vigorous growth habit, researcher Eriksson (2002) theorized that some colonies could become extensive and persist for hundreds of years.
This species is very similar to large cranberry (V. macrocarpon), which has larger leaves and fruits and green (not red) bracts on the floral pedicels. It is also somewhat similar in growth habit to creeping snowberry (Gaultheria hispidula), but snowberry's stems are hairy, and the leaves are rounder with stiff, brown hairs on the undersides. Like large cranberry, V. oxycoccos also has a long history of collection and/or cultivation for food and medicine in its native range of the northeastern US, Canada, and Eurasia. Native Americans often gathered the berries in fall and preserved them under the snow until spring. The fruits are rarely cultivated for modern commercial use, however.
Native habitats include open, wet areas such as bogs, fens, and marshy lakeshores. The sites are acidic and with pH values between 2.5 and 5.0.
Plant Characteristics:
Grows 3-5" tall and spreads rapidly to 3' to form mats.
Prefers full sun and tolerates part shade.
Prefers moist to wet, mild to very acidic soils, including peaty, sandy, and loamy.
Blooms appear between April and August, though typically in July, as solitary, pinkish-white flowers on long, reddish stalks. Flowers have 4 small sepals and 4 lance-shaped petals that curl sharply upwards, exposing 8 anthers with hairy filaments. Round, 1/2" fruits ripen August-November. They change from green to red spotted to deep red as they mature.
Alternate leaves are ovately shaped, dark green above, and whitish underneath. They are up to 3/8" long and usually rolled inward along the smooth margins.
Reproductive System: Male and female parts appear on the same plant (monoecious), and small cranberry is highly self compatible; however, insect pollination is required for effective fertilization.
Wildlife Value:
Host plant for 223 species of Lepidoptera larvae, including the beggar, crocus geometer and polyphemus moths; red-spotted admiral butterfly; and specialist Cerasus fishii. Primary pollinators are bumble and honey bees. Berries are eaten by birds and small mammals. Members of the genus Vaccinium support the following specialized bees: Andrena bradleyi, Andrena carolina, Panurginus atramontensis, Habropoda laboriosa, Colletes productus, Colletes validus, and Osmia virga.
Medicinal, Edible, and Other Uses:
Cranberries have long been a food source for humans. A growing body of research suggests that the polyphenols found in our native cranberries may be important in reducing the risk of cardiovascular disease. The fruits are also rich in vitamin C. They are an excellent source of flavonols, having higher concentrations than apples.
The raw fruits are said to be superior in taste to those of cultivated cranberries. They can be dried or used in preserves, pies, and savory dishes. The fruits are high in pectin, so they can be mixed with fruits that are low in pectin to help them set when making jam.
The juice of the fruit is used to clean silver. A red dye is obtained from the fruit.
Caution: Large amounts of the fruits may cause diarrhoea or other gastrointestinal disturbances.
Resources:
Lady Bird Johnson Wildflower Center: https://www.wildflower.org/plants/result.php?id_plant=VAMA
Minnesota Wildflowers: https://www.minnesotawildflowers.info/shrub/small-cranberry
New Jersey govt: https://www.nj.gov/dep/parksandforests/natural/heritage/docs/vaccinium-oxycoccos-small-cranberry.pdf
Ohio Dept of Natural Resources: https://tinyurl.com/y57ud86d
Plants for a Future: https://tinyurl.com/4drmp8r3
National Wildlife Federation: https://nativeplantfinder.nwf.org/Plants/3423
US Dept of Agriculture: https://plants.usda.gov/DocumentLibrary/plantguide/pdf/cs_vaox.pdf