Monday, September 17, 2007

Darwin's dream pond


The largest flower is the giant arum of Sumatra, 8 feet tall and 4 feet in diameter. It smells so awful it's not on anyone's list of favorites. The tiniest blossom is that of duckweed. The flower is reportedly so small that a magnifier is required to see it, and so rare, apparently, that although I have examined lots of of these tiny plants, I've yet to see a blossom.

What duckweed lacks in size it makes up for in numbers. Although each plant is the size of a salt grain, it has a prodigious capacity for reproduction by budding off copies of itself. The pond near my campus office is covered with a pea-green mat of duckweed, floating masses of grain-sized plants that drift with every breeze into op-art swirls and eddies. Ducks cruise the slime, trailing clear wakes that slowly close to green. Frogs plop into the pond; the duckweed parts and closes over them. I plunge my hand into the water; it comes up in a green glove.

Under a magnifier, the duckweed resolves into a myriad of minuscule lima beans, little bags of watery goo. Questions come to mind: What do these tiny plants live on? Why do they so reluctantly flower? How are they pollinated?

This is Darwin's dream pond, a freshwater Sargasso Sea, a primeval arena of eat and be eaten. I examine my green glove with the magnifier. Larvas, rotifers and who knows what else, hiding and feeding among the plants. Protozoans, too, must swarm here, too small to see at this level of magnification. The pond scum is as thickly populated as the African veld.

I plunge both hands into the duckweed, bring up two green gloves. In Southeast Asia, they eat this stuff. We would eat it, too, if we were less squeamish. Spread out on the surface of the pond, duckweed has an unsavory appearance. Under the magnifier, each tiny plant looks like a juicy grape. All part of the web of life that scums the planet.