(cloudberry)
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Photo of Rubus chamaemorus by Jacob Frank
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Cloudberry is a low-growing herb in the rose family (Rosaceae) with white flowers, large five-
lobed and delicious pink-yellow berries. This species occurs in black spruce
muskeg, bogs and
tussock tundra from the lowlands into the subalpine zone of Denali. Plants grow from
rhizomes, reaching 5-30 cm tall. The one to three leaves grow alternately along the stem. Leaves are slightly leathery, dark green and much-netted. They are rounded or kidney shaped in outline, with five shallow lobes and
toothed edges. Flowering stems reach the same height as the leaves or taller, each plant producing a single flower (or often none at all). The
pedicels are white-hairy. Cloudberry is
dioecious—plants produce solely male or female flowers—but both kinds of flowers have five white petals and five green, hairy, triangular
sepals. The petals are rounded and slightly fringed at the tips. A flower has either many
stamens or many
pistils. Flowers also often have vestigial organs of the other sex—a female flower may have a whorl of sterile, stunted
stamens. Male flowers are slightly larger than female. Female flowers develop into a raspberry-like fruit, an aggregate of juicy drupelets, typically shades of orange or salmon-colored, sometimes red. Plants can look similar to the other small, berry-producing
Rubus in the park, nagoonberry (
R. arcticus). That plant has three-parted leaves (not five-parted), pink flowers (not white) and red fruits (never salmon-colored).
Cloudberry is a perennial plant. Male plants leaf out later than females, in a study in Sweden (
Ågren 1987). Whether plants set flower varies greatly year by year and many female flowers are aborted (
Ågren 1987). The fruit, which is an aggregate of
drupes, usually ripens 5-6 weeks after flowering (
Ågren 1987). Males and females flower at the same time, flowering last 2 weeks, individuals usually flower 2-3 days. Plants take seven years from germination to the time they begin flowering (
Ostgard 1964).
Cloudberry is
dioecious:
staminate flowers occur on one plant,
pistillate on another. This separation of sexes is to prevent self-fertilization and promote genetic diversity. The main pollinators are syrphid flies and bumblebees in Scandinavia (
Agren et al. 1986). Female flowers produce a very limited amount of nectar, and are less favored by pollinators. However, the majority of plants are not in flower in a given season, and natural populations typically have a higher proportion of males than females, though this varies widely by site (
Korpelainen 1994;
Agren et al. 1986). The berries are eaten birds and mammals and dispersed in their scat. Cloudberry can spread clonally, new plants growing from the same
rhizome, and this seems to be a major form of propagation in the species (
Korpelainen 1994).
The sweet, juicy, aromatic berries are some of the most flavorful wild fruits in Alaska, and are prized. In central Alaska, cloudberry is usually not found fruiting abundantly enough for it to be gathered in large quantities, and it is often eaten on the spot. In Scandinavia, cloudberry preserves are highly valued, and sold at high prices. The juice is also made into liqueur, and a product is marketed from Finland and Quebec. Cloudberry juice and fruit has also been ingested by the Yup'ik for treating diarrhea and hives (Schofield 1992).
Disclaimer for Known Uses.
Cloudberry is a widespread circumpolar species that occurs across boreal North America, ranging eastward from Alaska through all the Canadian provinces to Greenland and south into New England, but only occurring in the southern islands of the Canadian Archipelago. Rubus chamaemorus occurs in suitable habitat throughout Alaska. This species is abundant in low elevations in the northern part of Denali, occurring less frequently in valleys on the south side of the Alaska Range.
Details are shown in the Plots & Charts found at right, depicting recent Denali data.
Cloudberry grows on low slopes (average incline 4 degrees), with cover of 2.25% on areas below 4 degrees. When on slopes above five degrees, it has a preference for north slopes. It demonstrates a strong negative correlation to increasing elevation, and is most abundant at less than 300 m (reaching 4.25% cover). However, cloudberry still has a fairly wide range of elevational tolerance: occurring from 153 to 1109 m with an average elevation of 487 m.
Details are shown in the Plots & Charts found at right. For more on how to interpret these figures, visit Understanding Data Presented.
R. chamaemorus generally grows on acidic, nutrient poor soils (
Korpelainen 1994).
Poorly-drained wet to moist sites.
