Impatiens parviflora DC. (Balsaminaceae): First Record from Wisconsin and the Great Lakes Region of a Potentially Invasive Species

Previous Knowledge.Impatiens parviflora (small balsam, small-flowered touch-me-not) is an annual herb native to central Asia.It became established in Europe in the mid-19 th century, and today is a common and widespread invasive plant throughout eastern, central, and northern Europe (Chmura & Sierka 2006, Hejda 2012).Reczynå ska et al. (2015) called it "the most commonly observed alien plant in Central European deciduous forests."The PLANTS Database (USDA-NRCS 2016) does not list Impatiens parviflora for any U.S. state, but includes it for the Canadian provinces of British Columbia, New Brunswick, Nova Scotia, Prince Edward Island, and Quebec.In 2013 thousands of plants were discovered in the understory of a mesic forest in Oregon (D. Maze s.n., July 8, 2013, OSC#241051; P.F.Zika 26231 & D. Maze, July 19, 2013, OSC#241857).As of this writing, North American observations of Impatiens parviflora have been posted on the citizen science website iNaturalist (2016) from Prince Edward Island, the Vancouver area of British Columbia, the Seattle area of Washington, and the Portland area of Oregon, as well as my observation from Eau Claire, Wisconsin.Discussion.Impatiens parviflora was introduced to botanic gardens in Europe beginning about 1830 (Coombe 1956).Coombe speculated that the spread of the species across Europe was probably due to a single introduction of seed, because the European populations are very uniform in contrast to the polymorphism exhibited by populations in the species' native mountains of Asia.Whether or not this is true, the species has proven itself to be an extremely successful invader and has proved highly adaptable in Europe over time.Today it is common in moist deciduous forests, particularly those with some degree of disturbance and along forest edges (Chmura & Sierka 2006).It is best at colonizing areas with a sparse herb layer, but is much less successful in areas with a thick herbaceous cover (Chmura & Sierka 2006).Unlike many exotics, it has also successfully invaded undisturbed forest (EPPO 2016).Impatiens parviflora shows high ecological plasticity in its ability to inhabit soils of varying acidity, fertility, and moisture (Reczynå ska et al. 2015), although it is intolerant of waterlogged soils (Coombe 1956).Although it was previously absent from central European oak forests, it began establishing itself in those habitats in the 1960s and now is

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