Spirodela polyrrhiza ?



Aquatic plant for identification -1: Can you identify the small leaved free floating aquatic plant. I guess it is Wolffia, pls confirm. And also identify the species.
Location: Chennai
Date : October 2011
I m sorry for the large file size. I will reduce the photo with better programs next time. My other guess for this plant is is Lemna sps.
It may be Spirodela polyrhiza (Araceae). Fronds purplish beneath; and roots are many as seen in the posted picture.
I think there are more than one species floating there which is not so unusual.
Lemna, Spirodella, Wolffia.....
Please check...
Yes there are many species. But I am aiming at what Vijaysankar metioned as Spirodella polyrrhiza.
Here's one more close up of the same plant.