Can an innocuous aquatic plant manufacture disease-curing proteins? Drug companies already use genetically engineered bacteria to produce therapeutic proteins such as Factor IX, a blood component that hemophiliacs lack. Others are trying to insert genes into the cells of animals so that the animals can produce specific proteins in their milk.

Anne-Marie Stomp, a professor of forestry at North Carolina State University, says humble duckweed could best both bugs and beasts. The tiny plant may top animals because it is "clonal"-it buds off copies of itself-which means genetic changes will stay intact in succeeding generations. The fast-growing plant can produce more sophisticated proteins than bacteria, says Stomp, and can thrive in an industrial setting. Stomp has started a company, Biolex, to teach the plants to secrete proteins for easy collection.