gives Vitis labrusca the name of "slip skin" grapes. Another trait of labrusca that aids ampelographers in identification of vines and hybrid varieties descended from the species is the large, thick leaves of the vines that have a hairy underside with dense brown or white hairs. Like many other American vine species, Vitis labrusca has some natural resistance to many grape diseases, including phylloxera. However, its resistance and grafting compatibility is not as high as that of other species, such as Vitis aestivalis, Vitis rupestris and Vitis berlandieri, and it is not often used for commercial rootstock. It is a robust plant, and in many states can be considered weedy or invasive. Wine regions Vitis labrusca can be found along the eastern seaboard of North America from Nova Scotia down to Georgia and westward to the Mississippi river. Among American Viticultural Areas (AVA)s that produce wine from labrusca or hybrids derived from labrusca include Upper Mississippi Valley, Mississippi Delta, Ohio River Valley, Southeastern New England, Lake Erie as well as several AVAs in the states of New York, Virginia, Ohio and Michigan. In the Canadian Province of Ontario, the use of Vitis labrusca varieties is not permitted by the VQA regulatory and appellation system, except for Vidal, a hybrid grape varietal. Unlike vinifera, hybrids and Vitis labrusca varieties can better withstand the severe continental conditions of eastern North America with severely cold winters and hot, humid summers. (However, labrusca doesn't do quite as well as varieties like Vitis rotundifolia in the humidity of southeastern US). In fact, in areas of the United States where vinifera does flourish in the west, the conditions during the growing season are often too arid for labrusca vines. "Foxy" musk According to University of California, Davis viticulture expert A. J. Winkler, outside of the vinifera Muscat family of grapes, Vitis labrusca varieties have the most pronounced aromas among wine grape varieties. The description of "foxy", not derived from the animal, serves as a catch-all term to describe the unique, earthy and sweet muskiness that can be perceived in fresh Concord grapes as well as grape juice made from Concord and other labrusca varieties like Niagara. In the 1920s, scientists were able to isolate the aroma compound responsible for the "foxy" musk as methyl anthranilate. See also List of grape varieties Bangalore Blue References External links Plants of the World Online: Vitis labrusca Flora of North