Really looks good. I'll have enough duckweed by the fall to send you some. I get covered everytime I go for a swim.
I have the same exact plant and it was labeled as echinodorus tenellus (which it is NOT). I am definitely leaning on the C. willisii species. Anyway, I think you gotta be a little extra patient. I had gotten a small pot and split them into separate plants, 6 months ago. They didn't look like much in the beginning. the first three weeks they might have put out a leaf or two and they always seemed to look "lifeless" as they seem to lie flat. However, since then many people have told me I got a "highlight" setup, and suggested to make some lighting changes which I did. I ended up decreasing my lighting time periods. The results were less algae growth and better plant growth. Most important was the C. willisii health. the plants are getting lush and full.My C. willisii x lucens 'bronze' carpet plants haven't done much since splitting and replanting. Each plantlet has put on 1 new leaf, and so far they are still 'low-growing'. I was heavily tempted to 're-bunch' it all and buy some Hemianthus micranthemoides this afternoon after Church (we took a trip to PetsMart for some food and they actualy had some nice aquatic plants...even some of that lacey-topped Java Fern that I forget the name).
But, I really want to give these little guys a chance to reacclimate and start spreading. I'm a very impatient person by nature, but I'm giving these plants every bit of patience I can muster. I don't think they'll let me down. Maybe in another couple weeks they'll start spreading again.
BTW, "Hagrid's Woods" is looking WONDERFUL!