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Page 99 ï~~2010 THE MICHIGAN BOTANIST 99 NOTEWORTHY COLLECTION MICHIGAN Arctium lappa L. (Asteraceae). Great Burdock. Previous knowledge. A native of Eurasia, Arctium lappa was brought to North America as a medicinal plant by early European settlers (Hanrahan & Frey 2005). Its range in North America includes 31 states and 7 provinces (USDA 2009). In the Great Lakes area the species is known in Wisconsin, Michigan, Illinois, Indiana, Ohio, Pennsylvania, New York, and Ontario (USDA 2009). Arctium lappa occurs in waste places, roadsides, fields and forest clearings to 2,200 m in elevation (Keil 2006). A search of A. lappa on the internet produced numerous websites devoted to medicinal and edible information on this species. Were not for its potential for invasiveness (similar to A. minus), A. lappa might be worthy as a source for commercial bird seed. Significance of the report. Voss (1996) states of A. lappa, "Evidently not common (and perhaps no longer found) in Michigan." This station represents the northernmost known locality in Michigan. The Wexford County site (Figure 1) FIGURE 1. Arctium lappa and general habitat at site of Wexford County collection. Photo taken 21 September 2008.
Page 100 ï~~100 THE MICHIGAN BOTANIST Vol. 49 100 THE MICHIGAN BOTANIST Vol. 49 FIGURE 2. Typical seed heads of Arctium lappa and A. minus (left and right) at site of Wexford County collection. Photo taken 21 September 2008. joins four other counties with records: Lenawee, Monroe, Van Buren, and Washtenaw (Anton A. Reznicek, pers. comm. 11 March 2009) all in southernmost Michigan. The first specimen was taken by Herbert F. Gates in Van Buren County 24 August 1906. The next specimen was taken by Oliver A. Farwell in Monroe County 22 August 1923. The Washtenaw County specimen was taken by W.O. Moore 29 July 1956. Subsequent to the publication of Vol. 3 of Michigan Flora (Voss 1996), a specimen was taken by Robert W. Smith in Lenawee County 22 August 1998 (Anton A. Reznicek, pers. comm. 11 March 2009). Diagnostic characters. Arctium lappa is a biennial herb that grows to 3.0 m in height. In contrast to the hollow lower petioles of A. minus, the petioles of A. lappa are mostly solid (Gleason & Cronquist 1991). The floral heads of A. lappa occur in corymbiform clusters as opposed to racemiform or paniculiform clusters in A. minus (Keil 2006). The individual floral heads of A. lappa are typically 2.5-4 cm wide vs. 1.5-2.5 cm wide in A. minus, whereas the achenes are 6-7 mm long in the former vs. 4-5.5 mm long in the latter (Gleason & Cronquist 1991) (Figures 2 and 3). The blooming period is recorded as July through October (Keil 2006). Overall, the impression of this species in the field is that of A. minus "on steroids." Specimen citation. WEXFORD CO.: Along the south side of County Road 34 (FR 7520) at its intersection with FR 7258 (at the southwest corner), Township
Page 101 ï~~2010 THE MICHIGAN BOTANIST 101 2010 THE MICHIGAN BOTANIST 101 S) FIGURE 3. Pale imnmature seeds of Aretium lappa and smaller darker mature seeds of A. minus (top and bottom) at site of Wexford County collection. Photo taken 21 September 2008. 22 N, Range 11 W, Section 29 (NE 14 of the SE 14) in Manistee National Forest, 16 September 2008, Dister 7 (MICH). There were approximately 20 plants in fruiting condition (tallest at 1.6 m) and another 20 or more in non-fruiting condition (i.e., 1St year basal rosettes); the population occurs along a 16.1 m length of roadside (6.1 m wide on the east and 0.9 m wide on the west). The habitat is a roadside corridor opening that lies below a dirt road (CR 34) and adjacent to a red pine (Pinus resinosa) plantation. Associated species include Ambrosia artemisiifolia, Hypericum perforatum, Oxalis sp., Phleum pratense, Pilea pumila, Plantago rugelii, Polygonum punctatum, Pteridium aquilinum and Rubus strigosus, A. minus, and possible hybrids with A. lappa, occur on both sides of CR 34. Lastly, this population of A. lappa was destroyed by the U.S. Forest Service in September 2009 as a precautionary measure.
Page 102 ï~~102 THE MICHIGAN BOTANIST Vol. 49 LITERATURE CITED Gleason, H. A., & Cronquist, A. (1991). Manual of Vascular Plants of Northeastern United States and Adjacent Canada, Second Edition, The New York Botanical Garden, Bronx, New York. Hanrahan, C., & Frey, R. (2005). "Burdock Root." Gale Encyclopedia of Alternative Medicine. The Gale Group, Inc. Encyclopedia.com. http://www.encyclopedia.com/doc/1G2-3435100136.html. Accessed 20 November 2009. Keil, D. J. (2006). Arctium. In: Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 15+ vols. New York and Oxford. Vol. 19, pp. 168-171. USDA, NRCS. (2009). The PLANTS Database. National Plant Data Center. Baton Rouge, LA. http://plants.usda.gov. Accessed 12 March 2009. Voss, E. G. (1996). Michigan Flora, Part III, Dicots (Pyrolaceae-Compositae), Bulletin 61, Cranbrook Institute of Science and University of Michigan Herbarium, Ann Arbor. - David C. Dister 2365 North Lakeshore Drive Ludington, MI 49431 email@example.com