Duckweed it is
a small aquatic plant that floats on the surface of ponds, wetlands, and nutrient-rich
lakes. Worldwide, there are over 40 species of duckweed (family Lemnaceae),
with 20 species found in the United States. Each plant consists of one or more
fronds. The fronds look like little leaves but actually are a combination of
leaf and stem, attached to a rootlet that dangles down in the water. Although
duckweed is a flowering plant, it rarely flowers. Usually it reproduces through
buddingnew fronds grow from buds on the parent plant. Eventually these
new fronds grow their own roots and break off to become independent plants.
Duckweed is useful for conducting bioassay experiments with
water samples because you can measure its growth rate by counting how many
new fronds develop over a five-day period. By measuring the number of new fronds
on duckweed plants growing in a test solution and comparing that to the number
of new fronds in a control solution, you can test the sensitivity of duckweed
to different compounds, or various concentrations of a single compound. Lemna
minor is the species most commonly used for bioassays.
Duckweed bioassay method
compounds and dilutions for duckweed bioassays
More information about duckweed
Other bioassays links
How are bioassays used in the real world?
Lettuce seed bioassays