Thursday, December 11, 2008

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 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.


Janet Creamer said...

Hi Justin,

We observed something similar in Shawnee State Forest during Flora-Quest. White Slant-lined moths hang underneath Mayapples. Here is a picture I found on the web of the moth tucked in.

By the way you and Dana would probably love Flora-Quest. It is great exploring with really skilled naturalists. This year it is May 1-3rd.

Tell Dana I said Hi! I miss you guys coming out for Environmental Adventure Day at Southeastway Park.

Janet Creamer
Indianapolis, IN

Justin said...

Hi Janet,

Good to hear from you. Gotta love the plant/moth interactions.

The Flora-Quest sounds like fun. We'll keep the dates in mind. We have a baby on the way, so our schedule will be tight this year.

Dana says "hi".

Scott said...

Nice work, Justin. In reading your account, I felt like I was there myself, chasing moths with you. It's amazing the things that go on at night about which we have no idea. I admire your persistence. I don't see a lot of Gaura up here, but when I do I don't ususally think much of it. You've changed my perspective for good on this one.

Justin said...


Thanks for the encouragement. I have been meaning to write the Gaura story of some time, but thesis got in the way.

Next time we all get together in the growing season we should head out and look for nocturnal pollinators and the plants they love. I know headlamps are designed to look at plants indoors, but maybe they work outside to.


Keith said...

Wow - excellent observations, Justin! I, too, have largely ignored Gaura biennis, but now have a newfound interest. Thanks!

ellery said...

Great story, Justin. Makes me wish we didn't have so much snow on the ground...

James C. Trager said...

And speaking of nomenclature changes, the latest work on Oenothera and relatives proclaims the proper name of this plant species to be Oenothera gaura.

No name changes for the Schinia of which I am aware...

Justin said...

Hey James,

Welcome. Thanks for adding your comments to the site.

Oenothera gaura?

That is one I am holding out on until I can read the literature. I'm guessing that it is based on molecular work and the philosophy of monophyly, both of which have gotten a bit overzealous for my taste.