Ask Mr. Smarty Plants

This is an interesting question but, as far as I can determine, no one has done a study on floral color and its correlation with geography.  There have been some studies looking at geograpical separation of color variations within a species (e.g., M. Masco et al.  2004. Geographic variation in flower color patterns within Calceolaria uniflora Lam. in Southern Patagonia.  Plant Syst. Evol. 244: 77-91), but no studies across species. 

We can compare flower color percentages in geographically similar and different areas of North America using our  Native Plant Database.  The National Wildlife Federation estimates that there are 19,000 flowering plants in North America.  Our Native Plant Database contains 7,024 native vascular plants.  Among those are 118 non-flowering plants, the ferns, so we can figure that there are 6906 native North American flowering plants in our databases.  We can use the COMBINATION SEARCH feature to get some statistics on the commonest flower colors over all of North America and then for Colorado and its five adjacent neighbors—Wyoming, Utah, New Mexico, Nebraska and Kansas—that share some geographic features and, finally, for three states that are very different from Colorado geographically—Florida, Washington, and New York.

NORTH AMERICA

White = 27.8%  Yellow = 24.7%  Pink = 13.0%  Purple = 13.1%  Green = 9.9%  Red = 6.6% Blue = 6.5%    

COLORADO

White = 25.5%  Yellow = 28.3%  Pink = 11.5%  Purple = 12.2%  Green = 10.9%  Red = 6.3% Blue = 6.6%

WYOMING

White = 25.9%  Yellow = 27.7%  Pink = 11.1%  Purple = 12.1%  Green = 11.6%  Red = 5.5% Blue = 6.4%

UTAH

White = 26.1%  Yellow = 27.7%  Pink = 12.6%  Purple = 12.6%  Green = 10.7%  Red = 6.8% Blue = 6.2%

NEW MEXICO

White = 25.3%  Yellow = 28.4%  Pink = 12.3%  Purple = 12.1%  Green = 9.9%  Red = 6.9% Blue = 5.8%

KANSAS

White = 28.2%  Yellow = 26.7%  Pink = 11.7%  Purple = 14.5%  Green = 15.5%  Red = 5.5% Blue = 6.4%

NEBRASKA

White = 30.0%  Yellow = 28.0%  Pink = 10.5%  Purple = 13.4%  Green = 16.2%  Red = 5.0% Blue = 5.9%

FLORIDA

White = 25.8%  Yellow = 24.9%  Pink = 12.0%  Purple = 12.3%  Green = 15.9%  Red = 6.0% Blue = 5.5% 

WASHINGTON

White = 27.1%  Yellow = 25.7%  Pink = 12.7%  Purple = 12.5%  Green = 13.2%  Red = 5.1% Blue = 6.3%

NEW YORK

White = 30.1%  Yellow = 24.0%  Pink = 11.5%  Purple = 11.5%  Green = 17.1%  Red = 5.4% Blue = 5.2%  

If we look at Colorado and its three neighbors with mountains—Wyoming, Utah and New Mexico—the percentages of yellow and white are pretty similar, i.e., there is a greater percentage of yellow than white.  Compare this to the percentages of yellow and white in Kansas and Nebraska, Colorado's non-mountainous neighbors, and you see that they have greater percentages of white than yellow.  The three non-neighbor states all have more white than yellow flowers, too.  So, does this really mean anything?  Probably not.  This is an imperfect comparison at best since our Native Plant Database is a 'work in progress' and it doesn't yet include all North American flowering species; plus, we don't have the designation for flower color for all those plants that are in our database.  Furthermore, flowers of some species have multi-colored flowers and/or different color varieties.  There is also the problem of color perception—the same flower may be called pink by one person and violet or lavender by another.  Does a cream-colored flower go in the yellow or in the white category?  For more discussion of flower color differences and perception please see the answer to a previous question.

If our data were better, perhaps we could decide if there were significant differences in flower colors between geographic areas.  Then, what would we attribute those differences to—the temperature, the humidty, the soils?  It is a complicated problem to analyze so I guess this is the real answer—we don't really know if the predominance of a particular flower color correlates with geographic location, but we hope someone is studying this.