Oakes' evening-primrose, Oenothera oakesiana

Ever notice the variation in size of flowers in some species of evening-primrose? Now comes one explanation. It seems some family members prefer self pollination. Research by Button, Dart, Eckert and Villalobos with one west coast plant shows that petals in self-pollinating populations become smaller and paler. Exhaustive measurements, including spectrometer analysis of color, clearly showed a correlation in size, color, and the degree of self pollination. After all, what do those plants need petals for? Better to put the effort into growing seeds. Of course we all hope they stick with pollination like we see here. We need petals! This species grows in CT, DE, IL, IN, KY(X), MA, MD, ME, MI, MN, NC, NH, NJ, NY(T), OH(T), PA, RI, VA, VT, WI, MB, NB, NF, ON, QC, and on SPM. Keweenaw Co MI, 7/12/14.