Sunday, July 25, 2010

The Slime Molds In My Garden

Today is the third consecutive day of rain. The monsoon season has started. Yes, a real monsoon: heating of the dry ground causes a thermal low that draws moisture in from the Gulf of California. It's late this year. There was a false start at about the right time a few weeks back, but this is the real thing.

I've been fascinated by slime molds, but I've only recently realized that they live in my own garden. After the first day of rain, I did some badly-needed weeding and noticed some white foamy stuff around a few plants. Bird poop? It was under some bird feeders. Insect spit? It didn't quite look like either. This morning showed quite a bit of the stuff, which I think is slime mold, but if an expert wants to tell me otherwise, I'll be glad to hear.

It's those white patches - quite a few of them in this part of the flowerbed. Here's a closer look at one of them.

Slime molds are fascinating because they live at the interface between unicellularity and organization into a multicellular organism. Most of the time they are independent single-celled amoebas. Then something tells them to make spores, and they come together in something like an organism. Some of those independent cells form a base and stalk, and others form spores to be broadcast. How do they decide which ones do what? Are they genetically similar enough that it doesn't matter? Or do some have a breeding advantage over others?

Here are a couple more images of that same colony, each about an hour later than the one before. They seem to like to be elevated slightly above the ground and formed on the remains of cotton plant stems in my composted cotton mulch, although not all of them insisted on that.

That last is with a different camera, more pixels so that I can enlarge it. But I'm not seeing much more when I do.

If the slime molds do anything interesting (and observable), I'll post on it.

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