Only in doing the research for this journal did I realize that duckweed is the standard for much of the pure research in plant science. Duckweed (Lemna sp.) comes from a family that includes some of the smallest flowering plants on the planet.   They are the workhorses, the fruit flies if you will, of plant research. The exact genome is just now being worked out and the result of this research will open vast new areas to study.      The minute fronds of this plant float around on tiny, bulbous, air-filled leaves, rapidly budding off daughter fronds that quickly fill the canal. While they multiply, they absorb pollutants from the water. When they die they do not sink into the water to rot and re-pollute, but continue to float on the surface, where they can be easily skimmed; not entirely labor-free but certainly an economical way to purify a waterway.