The Love Affair of Gaura biennis and Schinia gaurae

I don't know if it was the cool temperatures, the abundant rainfall or some other stochastic influence, but Gaura biennis was extremely flamboyant in the Ozarks this summer. Everywhere I went, large, diffuse inflorescences of white turning to shades of pink were found.

Admittedly, I have mostly ignored Gaura biennis over the years; finding it gangly and somewhat weedy. But it really out-did itself this year and I took notice. Camera in hand, tripod in tow, I headed down my gravel driveway to a nice specimen for a quick photo. Knowing them to be nocturnal bloomers and having noticed that the flowers were at their peak in the morning when I left the house and mostly shriveled by my evening return, I got to them just after sunrise.

After taking some quick photos, the kind where you don't really see the subject for the equipment, while rushing to beat the light, wind or self-imposed time constraints, I began to study the flowers. In this conscious effort to slow-down and enjoy the moment, the flowers struck me as peculiar. The perianth was tilted about 45 degrees toward the sky, and the stamens where all lined up perpendicular to the ground with the style between the stamens but dropped below their line by a few millimeters. It was the arrangement of the stamens that most drew my attention. I couldn't help but notice that they formed a triangle in outline. Further study revealed a ring of nectaries encircling the base of the style and that the anthers split along the uppermost edge. This made me think about pollinators.

Returning to the house, I grabbed my copy of "Butterflies and Moths of Missouri" and looked for moths that feed on Gaura that might fit what has to be an interesting pollination syndrome. I found that Schinia gaurae (the Clouded Crimson)(picture below from pbase.com) feeds, nectars, rests and lays eggs on species of Gaura and primarily on Gaura biennis. Still curious, I googled for images of this fun little moth. Several of the images demonstrated that the moth is almost the identical size and shape of the stamen arrangement on the Gaura biennis flowers. I also noticed that the back end of its wings are somewhat fluffy, not unlike miniature feather dusters. To cap it off, the adult moth's peak emergence is well in line with the bloom dates of G. biennis.

So at this point I am thinking that Schinia gaurae obviously visits the flowers to get a little nectar and as it aligns itself to drink, the fluffy wing bases get dusted with pollen. It just makes too much sense. Unfortunately, the only references I can find says that G. biennis is pollinated by long-tongued bees. My dream of a "form meets function" world instantly goes up in a cloud of disappointment. After all, what do these Gene Simmons bees have to do with my elaborate Gaura stamens? Are there really nocturnal bees? I needed more info.

I decide to wait until the dead of night before I visit my little population of flowers. At 1am I just can't stand it any longer. I jump in the truck which has become nothing more than a mobile flashlight at this point, and head down the driveway. I get out and eye every flower....nothing. I look closer and find the nectaries, which were dry during the day, are now pumping huge luscious drops of nectar. I must taste one, and I do. It's sweet, but hardly a meal for a curious primate. I also notice that the style is now in line with the anthers and not below them as in the flowers from the day, or should I say night, before. In the anticlimax, I stand a moment, hoping to hear an owl or something to salvage the night, when I notice an erratic flash in the headlights. It's a moth. Surely it is just drawn to the light. It lands on a flower. It's Schinia gaurae!!!! It lights, aligns itself, and drinks. The stamens are covered, the wings are in contact with the anthers and I am ecstatic. I watch for a while, then jump in the truck and head home for a beer and some contemplation about how wonderfully cool life and life on earth is.

Of course, the scientist in me realizes that this merely constitutes circumstantial evidence and in no way proves that Gaura biennis is pollinated by Schinia gaurae. And since I still don't know what the interaction of the plant with long-tongued bees is, they cannot be ruled out. But the novice naturalist, the child, the innocent believer in me is satisfied. At least until next year.