Allium schoenoprasum L.
Allium schoenoprasum ssp. sibiricum, Allium schoenoprasum var. laurentianum, Allium sibiricum
Basis for Listing
Allium schoenoprasum (wild chives) is a circumboreal species, which occurs in Minnesota along the southern margin of its range and is apparently limited to a very specific habitat type. It occurs on rocky shorelines and ledges along Lake Superior (North Shore Highlands Subsection) and the north-facing rocky ridges above the St. Louis River (Toimi Uplands Subsection). There are only about a dozen records of this species in Minnesota. The species was known to be rare and habitat-specific when it was designated a threatened species in 1996. However, at that time northeastern Minnesota had not yet been systematically surveyed for rare plant species. Now, after several years of targeted field inventories by botanists of the Minnesota Biological Survey, only a few additional populations have been documented, many fewer than had been hoped for. The species was absent from many apparently suitable sites, and several of the previously documented populations could not be relocated. Furthermore, the significant increase in development pressures and recreational activities in the vicinity of the known populations could endanger the long-term viability of the species in Minnesota. For these reasons, the status of A. schoenoprasum was changed from threatened to endangered in 2013.
Allium schoenoprasum closely resembles domestic chives, which was derived from wild A. schoenoprasum. It differs by having coarser and relatively shorter leaves and fewer bulbs (Tardiff and Morisset 1990). There may be only 1 bulb; if more than 1, then they will be clustered. There are usually 2 leaves, which remain green over winter; the leaf blade is hollow, round in cross-section, 20–60 cm (8 – 24 in.) long, and 2–7 mm (0.08 – 0.28 in.) wide. The inflorescence is a compact and erect umbel, with 30–50 flowers. Apparently, bulbils are not produced. The 2 spathe bracts are persistent through anthesis; they are 3- to 7-veined, lanceolate to broadly ovate in shape. The flowers are pale purple to deep lilac, campanulate in form, 8–12 mm (0.32-0.47 in.) in length, becoming papery in fruit, and permanently enveloping capsule (McNeal and Jacobsen 2002).
Allium schoenoprasum occurs in Minnesota along the southern margin of its range and is apparently limited to a very specific habitat type. Known plants on the shore of Lake Superior are rooted in exposed mats of tundra-like vegetation that develop in shallow crevices in the bedrock. It is sometimes associated with the rare Pinguicula vulgaris (butterwort) and Bistorta vivipara (alpine bistort). A large population of A. schoenoprasum at Jay Cooke State Park has been known since 1940 and was recently reconfirmed. These plants occur in shallow pockets of soil in bedrock crevices on north-facing rocky ridges just above the high-water line of the St. Louis River. Most of the historical collection sites appear to be from similar habitats on terraces and ledges along Lake Superior and Bassett Lake.
Biology / Life History
Allium schoenoprasum is perennial and relies on slender bulbs that overwinter in the soil. It is insect-pollinated and reproduces only by seed. The dispersal agent for the seeds is unknown, though it likely involves small mammals or ground-foraging birds that gather the seeds.
Conservation / Management
Residential, commercial, and recreational developments along the shore of Lake Superior are increasing rapidly, and the habitat of A. schoenoprasum is coming under increased pressure from these activities. Activities as seemingly innocuous as hiking can result in damage to the fragile shoreline habitats of this species and other rare shoreline plants. Because remaining occurrences of A. schoenoprasum are in small habitats that may total no more than a few dozen acres statewide, this land must be deliberately protected from activities that could jeopardize the survival of this species.
Best Time to Search
The best time to search for A. schoenoprasum is during the active growing season, especially June to mid-July, when in flower, or mid-July to early September, when in fruit.
References and Additional Information
Coffin, B., and L. Pfannmuller, editors. 1988. Minnesota's endangered flora and fauna. University of Minnesota Press, Minneapolis. 473 pp.
Gleason, H. A., and A. Cronquist. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. Second Edition. New York Botanical Garden, Bronx, New York. 910 pp.
Kartesz, J. T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2 volumes. Second Edition. Timber Press, Portland, Oregon.
Lakela, O. 1965. A flora of northeastern Minnesota. University of Minnesota Press, Minneapolis, Minnesota. 541 pp.
McNeal, D. W., Jr., and T. D. Jacobsen. 2002. Allium. Pages 224-276 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 26. Oxford University Press, New York, New York.
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.
Ownbey, G. B., and T. Morley. 1991. Vascular plants of Minnesota: a checklist and atlas. University of Minnesota Press, Minneapolis. 320 pp.
Tardiff, B., and P. Morisset. 1990. Clinal morphological variation of Allium schoenoprasum in eastern North America. Taxon 39(3):417-429.