Page  194 ï~~194 THE MICHIGAN BOTANIST Vol. 44 A NEW LOCATION FOR THE BOREAL SPECIES PINGUICULA VULGARIS L. (LENTIBULARIACEAE) IN WISCONSIN Derek S. Anderson Minnesota Department of Natural Resources St. Paul, Minnesota 55155 Josh Horky Department of Biology and John Thomson Herbarium University of Wisconsin - Superior Superior, Wisconsin 54880 Butterwort (Pinguicula vulgaris L.) is a member of the bladderwort family (Lentibulariaceae). It is a carnivorous, boreal species with a circumpolar distribution. In North America, this plant reaches the southern extent of its range in the northern United States (Voss 1996). The habitat of butterwort is described as "wet rocks and shores, and farther north also in bogs and wet meadows" (Gleason and Cronquist 1991). On Lake Superior, butterwort has been observed on the rock outcroppings that abound around much of the lake. However, on the south shore of Lake Superior in Wisconsin, there appears to be little suitable habitat for the plant. Until recently, the plant had only been observed on Devils, Ironwood, Otter, and Outer Islands in the Apostle Islands group of Ashland County (Tans 1987, Judziewicz 1993). In the islands, the plants were growing on the steep sandstone cliffs and ledges found on the rugged shorelines of these islands. Population trend studies of Judziewicz and Nekola (2000) found that the larger populations on Devils and Outer Islands tend to be stable as they grow in the seepage joints of the sandstone and are continually kept moist, while the smaller populations on Ironwood and Otter Islands grow in moss mats on fallen sandstone slabs affected by wave splash and as a result are susceptible to decline in dry, calm seasons. Searches to locate butterwort by Judziewicz in the later part of the 1990s (Judziewicz personal communication) and by Anderson in 2002 and 2003 failed to locate any plants in the sandstone cliffs of the Apostle Island National Lakeshore on the "mainland" of Bayfield County. In late July of 2005 butterwort was finally verified in Wisconsin outside of the Apostle Islands on the southwest shore of Lake Superior when a small population consisting of approximately ten plants was observed among breakwater rocks in the city of Superior. The plants were growing on a thin moss mat that was situated on a small, narrow rock ledge in a crevice among the large boulders used for a breakwater. There were no other vascular plants growing from the moss at the time of the observation. One rosette contained a dried scape from earlier in the year. The greatest mystery of this population is its origin. The closest known populations of the plant are located over 30 km away, along the north shore of Lake Superior in Minnesota.

Page  195 ï~~2005 THE MICHIGAN BOTANIST 195 This find would indicate that the seeds of this plant are capable of traveling great distances through Lake Superior (Judziewicz, personal communication). LITERATURE CITED Gleason, H. A. & A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. 2nd Edition, 7th printing (2004). New York Botanical Garden. 993 pp. Judziewicz, E. J. & R. G. Koch. 1993. Flora and vegetation of the Apostle Islands National Lakeshore and Madeline Island, Ashland and Bayfield Counties, Wisconsin. Michigan Botanist 32: 43-193. Judziewicz, E. J. & J. C. Nekola. 2000 [as 1997]. Recent Wisconsin records for some interesting vascular plants in the western Great Lakes region. Michigan Botanist 36: 91-118. Tans, W. 1987. Lentibulariaceae: The Bladderwort Family in Wisconsin. Michigan Botanist 26: 52-62. Voss, E. G. 1996. Michigan Flora, Part 3: Dicots Concluded. Cranbrook Institute of Science and University of Michigan Herbarium, Bloomfield Hills and Ann Arbor, Michigan. 622 pp.