Vaccinium uliginosum L.
Vaccinium uliginosum var. alpinum
Basis for Listing
Vaccinium uliginosum (alpine bilberry) is a typical shrub of boreal, arctic, and alpine regions and has a nearly continuous circumpolar range. There are a few southward incursions into more temperate regions, including mountainous habitats in New England as well as muskeg and rocky habitats in the Great Lakes region. Vaccinium uliginosum was discovered in Minnesota near Grand Portage in Cook County by the L. S. Cheney Expedition in 1891. It was collected again in 1937 a few kilometers away, on an island in Lake Superior (Butters and Abbe 1953). The island site was revisited in 1980, but V. uliginosum could not be found. Other islands in the area were also searched without success.
In 1982, the population near Grand Portage was rediscovered after a period of 91 years. Although the description of the original collection site is too vague to be certain, it seems likely that the plants found in 1982 are at the same site as those found in 1891. Based on this history, V. uliginosum was listed as threatened in Minnesota in 1984. A status of endangered was considered, but it was thought wise to wait until the Minnesota Biological Survey could conduct a thorough botanical survey of northeastern Minnesota. The survey is now complete, and no additional populations of V. uliginosum were found. For this reason, the status of V. uliginosum was changed to endangered in 2013.
Vaccinium uliginosum is a low-growing shrub, with one or a few upright or decumbent stems, reaching a height of about 30 cm (12 in.). The branchlets of the year are brown to greenish brown and minutely hairy; branchlets of the previous year are brown to reddish brown, minutely hairy or glabrate, not warty. The bark is ± smooth gray to brown or reddish brown. The leaves are simple, alternate, and deciduous, sessile or on short hairy petioles to 1 mm (0.04 in.) long. The leaf blades are elliptic to broadly elliptic or obovate, sometimes nearly circular, 10-22 mm (0.4-0.9 in.) long, 7-17 mm (0.3-0.7 in.) wide; base tapered or occasionally rounded; apex obtusely tapered to rounded, with a small stout apiculus; margins entire and flat; upper surface dark green and glabrous; lower surface pale green and minutely hairy, especially on veins. The flowers are 4- or 5-merous (5-merous in Minnesota), bisexual, white or pink, 4-6 mm (0.16-0.24 in.) long, borne singly or in fascicles of 2; pedicels 2-6 mm (0.08-0.24 in.) long and glabrous; corolla short-cylindrical to urn-shaped, the lobes 1.0-1.5 mm (0.04-0.06 in.) long; style about equaling the corolla or a little shorter and glabrous (Smith 2008).
Visually, V. uliginosum is a low-growing stiffly branched deciduous shrub, with small roundish leaves. It could easily be mistaken for the common Arctostaphylos uva-ursi (bear-berry), which in contrast to V. uliginosum has narrower evergreen leaves that are consistently obovate and flowers with a superior ovary.
Vaccinium uliginosum is a polymorphic species, with populations in arctic and alpine regions throughout the northern hemisphere. A number of varieties and subspecies have been proposed based largely on leaf pubescence, growth form, and fruit characteristics (Young 1970). The Minnesota population does not closely conform to any of the published subspecific taxa, and it is uncertain how it should be treated.
In the Great Lakes region, this arctic/subarctic species is known to occur at only a few places, all of which are along the north shore of Lake Superior (North Shore Highlands). It occurs in moist rock crevices on exposed rocky shorelines and at the margins of rock pools (Voss 1996). In Minnesota, the only known population of V. uliginosum is on a massive outcrop of igneous bedrock (rhyolite) that projects prominently into Lake Superior. It apparently does not occur on the more common gravel or boulder-strewn beaches. The plants root deeply in crevices and form a low dense mat. It occurs with other rare species, such as Pinguicula vulgaris (butterwort) and Bistorta vivipara (alpine bistort).
Biology / Life History
Vaccinium uliginosum is a low-growing shrub, with a tough woody stem and deciduous leaves. The flowers, as is typical for the genus, are designed for insect pollination. The fruit is a fleshy berry, 6-8 mm (0.24-0.31 in.) in diameter. The seeds within the fruit are dispersed by animals, which eat the fruit and pass the seeds through their digestive system.
As of 2002, there were 11 discontinuous patches, probably clones, covering a combined area of about 2 m² (20 sq. ft.). Although these numbers seem precariously low, it is not known if they represent an actual decline. The biology of the species would indicate that it could maintain such a small population for an indefinite period. This is because V. uliginosum can reproduce vegetatively, rather than rely on the periodic and chancier recruitment of seedlings. The exact method of vegetative reproduction is not clear; it may be by the process of layering or the production of invasive rhizomes. Either way, the result is long-lived clones (Smith 2008).
Conservation / Management
The one known site of V. uliginosum in Minnesota is fairly isolated and seems reasonably well protected from damage that might be caused by human activities, at least for now. Yet the population is so small that it could be inadvertently damaged even by casual foot traffic. Natural events, such as storm waves or ice scouring could also threaten the continued existence of this population. That said, it has survived at this site for more than 100 years (possibly more than 1000 years), so it must be capable of withstanding the forces of nature. Perhaps the best management recommendation that can be offered at this time is to maintain the conditions that currently exist on the site. Also, it may be most beneficial for long-term conservation to increase the awareness of the concentration of rare features on Minnesota’s beautiful, but vulnerable, Lake Superior coastline.
Best Time to Search
The best time to search for V. uliginosum is when flower or fruit can be expected, which is normally from about mid-June through mid-September.
Conservation Efforts in Minnesota
A fairly thorough plant inventory of Minnesota’s portion of the Lake Superior region has been conducted by the Minnesota Biological Survey. Botanists agree that this species has been well-searched for years and that new populations are unlikely to be found. The survey results form a sound basis for developing a conservation plan.
Welby Smith (MNDNR), 2008 and 2018
(Note: all content ©MNDNR)
References and Additional Information
Butters, F. K., and E. C. Abbe. 1953. A floristic study of Cook County, northeastern Minnesota. Rhodora 55:21-55.
Coffin, B., and L. Pfannmuller, editors. 1988. Minnesota's endangered flora and fauna. University of Minnesota Press, Minneapolis. 473 pp.
Minnesota Department of Natural Resources. 2003. Field guide to the native plant communities of Minnesota: the Laurentian mixed forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 352 pp.
Minnesota Department of Natural Resources, Division of Ecological Resources. 2008. Rare species guide: an online encyclopedia of Minnesota's rare native plants and animals [Web Application]. Minnesota Department of Natural Resources, St. Paul, Minnesota. Accessed 1 July 2009.
Schori, M. 2004. Conservation assessment for alpine bilberry (Vaccinium uliginosum) L. U.S. Forest Service, Eastern Region, Milwaukee, Wisconsin. 45 pp.
Smith, W. R. 2008. Trees and shrubs of Minnesota. University of Minnesota Press, Minneapolis. 703 pp.
Voss, E. G. 1996. Michigan Flora. Part III: Dicots (Pyrolaceae-Compositae). Cranbrook Institute of Science Bulletin 61 and University of Michigan Herbarium, Ann Arbor, Michigan. 622 pp.
Young, S. B. 1970. On the taxonomy and distribution of Vaccinium uliginosum. Rhodora 72:439-57.