Spring Beauty Colors

On our first Wildflower Walk of 2019, the spring beauty, Claytonia virginica, were carpeting the forest floor along the Mail Trace Road.  These are tiny flowers, not particularly striking unless you bend down for a close look.

They have tiny streaks of color called nectar guides.  These are paths like a painted stripe leading to the nectary where the flower's pollen is waiting to be spread.  The nectary contains the rewards for the pollinator, sweet nectar, oils, resins, and scents and sometimes the pollen itself.  For the pollinator it is about reward, for the plant it is pure sex.

What was striking was the variety of colors in the petals.  They ranged from an almost pure white with faint pink streaks to the background white almost blotted out by the wide deep purple
nectar guides, converting it to what almost looks like a different species.  There was soon a lot of discussion of why the different colors side by side.  Could it be the time of blooming or the temperature variations in the soil?

It turns out that others have asked this same question.   A study by Frank M. Frey out of Indiana University found that the differences were genetic, controlled by two different compounds and created 4 distinct color morphs ranging from all white to mostly crimson.  The results are simplified to my level in this description from Indefenseofplants.com.

"...pollinators, which for Claytonia are solitary bees, do, in fact, prefer crimson color morphs. This helps to explain the greater number of crimson colored flowers in any given area because the more pollinator visits, the higher overall fitness for that plant. What it does not explain though, is why white morphs exist in the population at all."  

"The flavonols that produce white pigmentation also beef up the plants defenses. Frey found that white colored flowers experienced significantly less predation than crimson flowers. Herbivory has serious consequences for Claytonia and plants that receive high levels of herbivore damage are far more likely to die. Because of this, white morphs, even with significantly less reproductive fitness, are able to maintain themselves in any given population."