Lemna, Valisneria, Azolla, AEsculus asamicus in abundance.
"Journals of Travels in Assam, Burma, Bhootan, Afghanistan and TheNeighbouring Countries" by William Griffith
Three species are reported from Michigan, of which the commonest is Lemna minor.
"The Plants of Michigan" by Henry Allan Gleason
DUCKWEED, the popular name of several species of Lemna, nat.
"The New Gresham Encyclopedia" by Various