Last year I discovered a terrible thing about duckweed - it seeds!!! I'd religiously removed every speck from my small pond, but in June it came back. There were specks of very fine white dusty stuff on the surface and then pale green single leaves started to appear and multiply. I got them all out, but the same thing has happened this year, so perhaps it's a case of "one year's seeds, seven year's weeds". Don't mind really as it's an excuse to sit around with a net for half an hour and fish bits out.
Thing is, where do the seeds come from? I've never seen anything even remotely resembling a flower on duckweed.
Sue
