The traditional wines of Michigan were sweet wines, often made from grape varieties native to North America, such as the Catawba, Concord, and Niagara, or from hybrid grapes partly developed by crossing native species with "vinifera" grapes. North American native grapes have the advantage of being adapted to local growing conditions, with consequent high fruit yield. In addition, growers can switch back and forth between the production of sweet wine and grape juice. Of Michigan's under grape cultivation, only 12%, , were devoted to wine grapes as of 2007.