A Regional Definition for the Website
This website is designed to be a comprehensive repository of information concerning all members of the Violet family (Violaceae) confirmed in the Great Plains and eastern North America regions. The traditional definition of “eastern North America” for floras is usually the land east of the western borders of Ontario and Minnesota southward to Louisiana, and north of Mexico (indicated by the dashed blue line on the map). The traditional definition of the Great Plains region is the land east of the Rocky Mountains up to the Midwest forest region (indicated by the red line on the map). Taking these two regions together essentially equals "eastern North America" as defined by Wikipedia (see “Nearctic realm”, https://en.wikipedia.org/wiki/Nearctic_realm), as it relies on bioregions. Another way to define the region is "everything east of the Rocky Mountains". I have used the Level I ecoregions 1.0-5.0, 8.0-9.0 and 15.0 that are east of the Rocky Mountains and other western ecoregions to draw the line, adapting the EPA “Ecoregions of North America”, Level I map here (https://www.epa.gov/eco-research/ecoregions-north-america), with a small pragmatic adjustment at the northwest corner of the Yukon at the north end, and excluding a small area of Mexico at the south end.
According to the "Flora of North America" treatment of Violaceae by Little and McKinney (2015), 38 taxa (excluding hybrids) are found exclusively in western North America. This website treats 71 non-hybrid native and introduced Viola taxa as well as Cubelium concolor and the introduced Pombalia parviflora, that are restricted to the Great Plains and eastern North America regions collectively; and additionally two Pombalia species and 20 native and introduced Viola taxa that occur on both sides of the line separating western North America from our region. Only 16% of the 133 taxa occurring in North America are distributed in both regions. But quite a few eastern Violaceae extend at least a short distance into the Great Plains. Including the Great Plains region with eastern North America for this website made good biological sense, and it added only a few more violet taxa.
Literature Cited
Little, R. J., and L. E. McKinney. 2015. Violaceae. Flora of North America: Cucurbitaceae to Droseraceae. Oxford University Press, New York, NY.
