Hi:
Duckweed labs are great because they are simple, they usually work to some degree, and they take VERY little space (you can use clear plastic drinking cups under a light bank). I am using a lab I learned from a colleague at Vassar using duckweed in interspecific competition (requires collecting two species of duckweed) under two different nutrient regimes (adjusting Hoagland's solutions to have more or fewer of some macro or micro nutrients). The students learn how to do a factorial design - this is for an upper level ecology class. The other thing that is simple to do with duckweed is to look at intraspecific competition - you can actually reproduce the Logistic curve of population growth over time, showing the asymptote ('K' = equilibrium number of duckweed). That might be better for intro bio labs. For that experiment, you can just collect duckweed from any outdoor pond or fish pond.
Bernadette Roche
Department of Biology
Loyola College
4501 N. Charles St.
Baltimore, MD 21210
broche at loyola.edu
410-617-5591
