Using plants that had been grown in greenhouses for two years, they found that plants with more diversity in their genes did nearly twice as well as inbred plants, Kephart said.

In a separate part of the study, Lofflin and Kephart compared germination rates of seeds that had been stored for differing lengths of time. "We got real low germination for older seeds," she said. Those more than 5 years old did not grow.

Amy Betzelberger, who is about to start her junior year at Illinois State University, Normal, stood prepared to explain her poster, titled "Cell Growth in the Green Algal Order Coleochaetales (Charophyceae)."

These organisms are much like plants, she began to explain. What? Aren't algae actually plants?

"Green algae are the predecessors of plants," she said. "Not all algae are."

In both green algae and plants there are two basic types of cell growth, she said: diffuse and tip growth. Diffuse growth happens where cell wall material is added throughout the cell, while tip growth happens only at the cell's end.

The study by herself, Karen F. Doty and Martha E. Cook, also of Illinois State, was aimed at further refining understanding of the way green algae grows.

The annual meeting of the four professional societies continues through Thursday.

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E-mail: bau@desnews.com