Plant materials
Whole duckweed and water lettuce plants were collected from
freshwater ponds, Can Tho City, South Vietnam (9.27 N 106. E), in
September of 2009 (the wet season), then washed with tap water
and individually dried in the sun. These dried materials, which
served as the basis for all experiments, were packed and protected
from water vapor in the air by a silica gel-desiccant, then stored at
3 .C in a fridge.