Wednesday, April 15, 2009

Fun with Falsies

On Saturday, Sue and I drove up to Boonville to visit our pals Jane and Tim at their beautiful home overlooking the Missouri. It was sunny—oh, it was a wonderful day to be outdoors.

It was also going to be an opportunity for photography, particularly for Tim, Jane, and Sue, who are much more serious and talented and skilled when it comes to taking pictures. Me, I’m just a monkey with an autofocus, lucky for every picture that doesn’t look like a big blur. Unfortunately, because Tim had a cold, he declined to travel with us for our photo outing and picnic.

I’ll share some pictures and info about the Lisbon Bottoms area of the Missouri River for an upcoming post, but this afternoon, my love of biology, on the level of the organism, overcomes the glories of landscape.

The following pictures were taken in Tim and Jane’s yard. All have something false in them.

First, a false morel, Gyromitra esculenta, one of about three or four that Jane had found growing on an old maple stump in front of her house. Once you know what a real morel looks like, you won’t ever mistake the false for the delectable edible kind.

And by the way, it should be morel season now. I sure hope to be photographing some morels soon. And then picking them, cooking them, and eating them!

A few more notes on the false morel: Some people consider them edible if you cook them well enough, but all the authorities say no: gyromitrin, the toxin, creates a byproduct called MMH, which is apparently the same thing as rocket fuel. Eating it in small amounts might not kill you or make you ill, but over time it could cause tumors. Um, so just don’t eat it.

Next, some kind of spurge that’s growing in Jane’s yard. I guess it’s in the genus Euphorbia, but hell if I know. She says it’s hardy to the point of weediness, but its attractiveness makes up for it.
Here’s why I count it as “false”: Take a close look at the flowers. Do they look like any kind of flower you’re familiar with? If you said “poinsettia,” or “snow on the mountain,” then you guessed right. And if you know that, then you also know that this is a tricky flower. In these flowers, the parts that look like “petals” are actually modified leaves, or bracts. And the parts that look like stamens are—well, they’re stamens, all right, but each stamen is a separate male flower consisting of only a stamen. Got it? And then, in the center of the flower, the thing that looks kind of like a pistil is actually a separate female flower, consisting of only a pistil. The whole shebang (that is, the entire flower head or inflorescence) is called a cyathium. Members of the spurge family, or Euphorbiaceae, are the only plants that have cyathia as the inflorescence type. (I think. Close relatives of the family might have cyathia, too. Call a botanist if you need to know.)

Finally, my last picture is of another example of natural falsification. This critter that looks like a bee is actually a fly, a dipteran. It’s in the same group as mosquitoes, houseflies, and gnats; bees are grouped in with ants and wasps as hymenopterans.
But this critter looks like a bee, doesn’t it. Still, the flylike eyes, the paired (not quadrupled) wings, the antennae, all give it away. In fact, this fly, and others in the fly family Syrphidae, are widely acknowledged to be remarkably “nice”—they don’t bite, sting, transmit malaria or West Nile virus, or otherwise harass us.

This kind of mimicry—where a species evolves coloration or another recognizable characteristic that looks like something “nasty” in order to avoid being eaten—is called Batesian mimicry (after a nineteenth-century English lepidopterist named Henry Bates). A textbook example of this kind of mimicry is the monarch butterfly and the viceroy butterfly, where the monarch is poisonous to most predators, and the viceroy isn’t poisonous but just looks a lot like the monarch. Birds that throw up within a half hour of ingesting a monarch quickly learn to avoid eating fluttery insects that look anything like a cardiac-glycoside-laden monarch.

Thus, when a harmless and delicious fly looks like a stinging bee or wasp, you have a case where, as John Alcock puts it in Sonoran Desert Summer, “Birds relish flies but are less fond of stinging Hymenoptera, and with good reason; a flycatcher stung in its mouth by a bumblebee or paper wasp receives a huge dose of toxin relative to its weight and can be expected to suffer proportionally. Humans quickly learn to avoid bees and wasps by their color patterns. Insect-eating birds are equally adept at this form of learning.”

Here’s the part I don’t get: This little fly, commonly called a flower fly or a hover fly, in the family Syrphidae, is apparently in the genus Epistrophe.

Epistrophe?—Now the English major in me is curious. An epistrophe is a literary device where the same word or words are repeated at the end of a succession of phrases or sentences. A famous example is from Paul’s first letter to the Corinthians: “When I was a child, I spoke as a child, I understood as a child, I thought as a child.” Another famous example is from Lincoln’s Gettysburg Address (“government of the people, by the people, for the people”). Get it?

So how did this genus of flies get named Epistrophe? I want to know.

Until then, I’ll just relax and enjoy my pictures of a fungus of deception, flower of deception, and fly of deception.

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