(small cranberry)
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Photo of Oxycoccus microcarpus by Carl Roland
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Oxycoccus microcarpos is a tiny wetland-dwelling dwarf shrub, the flowers with characteristic reflexed pink petals. This species frequently grows on mats of
Sphagnum moss in boggy sites where the stems trail through the moss, rooting at
nodes, and flowering stems emerge periodically, reaching only a few cm high. The leaves are 4-5 mm long, green above, white below,
ovate to
elliptic, the margins inrolled. The leaves are leathery, and they are covered in a thick layer of cuticular wax (
Jacquemart 1997). Bog cranberry has a reddish flowering stem, which is short-hairy, and has a few scale-like
bracts below the middle. Each stem bears one flower. The head nods downward, the five pale pink petals, 5-7 mm long, completely curled back. The
filaments of the 8
stamens are fused, pubescent at the base, making a red to orange tube with the
anthers at the top, and the
style protruding. The fruit is a tart, juicy red berry, 5-7 mm, disproportionately large compared to the rest of the plant. The berries develop behind the petals, the remnant of their bases seen at the top of the fruit.
O. microcarpos can be hard to spot initially (look carefully among peat moss mats), but it is easy to identify by its tiny
revolute ovate leaves, trailing stems, reflexed pink petals and oversized red berries laying on
Sphagnum.
Oxycoccus microcarpus is early-flowering perennial with evergreen leaves. Its blossoms are susceptible to early summer frosts (
Jacquemart 1997). Flower buds are formed in the fall, and open in the next spring.
This species is
monoecious with bisexual flowers. Bog cranberry is both insect-pollinated and self-fertile. Unlike related
Vaccinium species, it does not seem to reduce fruit set when self-pollinated (Froborg 1996). In general, seed set in the species is low compared to the number of flowers produced. The fruit is a disproportionately large berry, eaten by birds and mammals. A study in Newfoundland found an average of 8 seeds produced per fruit, and that seeds remained dormant for 2 years in the soil (
Vander Kloet and Hill 1994).
Humans can eat the tart berries, but the tiny species is usually not abundant enough for them to be collected in any quantity. Cooked powdered leaves were used by the Yup'ik to treat nausea and as a laxative past-season berries were boiled in water as a spring tonic, and mashed berries were applied to 'red-spotted' waist rashes as a poultice by the Inupiat (Garibaldi 1999). One traditional Yup'ik story says that sandhill cranes lost their eyes, and, after trying many different eyes, used bog cranberries—the reason they have red eyes now (Jernigan et al. 2015).
Disclaimer for Known Uses.
Oxycoccus microcarpus is an incompletely circumpolar species that occurs widely in the Northern Hemisphere. In North America, this species occurs over the northern half of the continent, from the Great Lakes and mid-Atlantic seaboard to Greenland in the East, from Alaska to Oregon and northern Idaho in the west, and in all Canadian provinces. This species occurs across boreal regions of Alaska, and occurs in isolated localities on the North Slope. Oxycoccus is widespread and common in boreal regions of Denali on both sides of the Alaska Range, usually in Sphagnum bogs.
Details are shown in the Plots & Charts found at right, depicting recent Denali data.
This is an abundant wetland species, and its elevational distribution reflects this: it occurs in over 60% of lowland (under 300 m) plots. It does occur from 80 to 1000 m in the Park, and is found in approximately 25% of plots from 300-700 meters. Bog cranberry is typically found on even terrain (average slope for all occurrences: 3 degrees). If this species is found on inclines, they are generally north-facing. The specimens on north-facing slopes were found on a wider range of elevations and inclines than those on southern aspects.
Details are shown in the Plots & Charts found at right. For more on how to interpret these figures, visit Understanding Data Presented.
Bog cranberry is found growing on acid, nutrient poor substrates, usually directly in peat moss mats.
Poorly-drained, wet sites.