They invade farmland, they cause cancer, and they may hold the key to the production of a host of futuristic synthetic products.

And for Professor of Biology Rolla M. Tryon and his wife, Lecturer in Biology Alice F. Tryon-two of the world's experts on the fern-individual research on the fuzzy, apparently harmless plant created a husband-wife team which has gone on to make pioneer advances in understanding the dual-natured fern.

While this mysterious plant may seem to inspire only nature lovers, the fern, which can grow virtually anywhere, is not only a key tool in basic science, but is rapidly gaining a foothold in areas ranging from industry to medicine.

Although studies of ferns began in the time of the Roman Empire, scientists still find the flowerless plant mysterious, and botanists like the Tryons are trying to solve puzzling questions about its highly unusual system of reproduction, its potential applications, and some of its devastating effects all over the globe.

Having devoted most of their lives to studying the plant, the Tryons have traced it to some of the globe's more exotic regions and in the process have classified and experimented with many of the estimated 15,000 types, ranging from the 80-foot-high fern tree to the "deadly" one-inch bracken.

"Their work is providing a critical, systematic framework for any subsequent research in the field, it's tremendously important for any other kind of studies," says Associate Professor of Biology Andrew H. Knoll.

As a graduate student at the University of Wisconsin. Alice Tryon recalls that one of her professors directed her toward research "counting the hairs on a maple leaf," which she says was "a real bore".

Hoping to pique her botanical interest, she approached Rolla Tryon, then a post-doctoral student, who advised her to study ferns instead.

At first she objected "because all ferns looked the same, but he helped me out a lot," she says. "I finished my thesis, and ten years later, he was still working on the same project," she adds.

After Alice got involved. I become more interested in it," Rolla Tryon jokes.

The two came to Harvard from Wisconsin in 1957, and both still teach courses in the Biology department.

Since they first arrived, fern studies have progressed in quantum leaps, and scientists have learned that the innocent-looking plant is not as harmless as it appears.

For example, recent studies have determined that one type of fern, bracken, a popular Japanese food, may cause stomach cancer.

Moreover, bracken has in several global regions devastated croplands and pastures, thereby endangering livestock that eat the fern. Yet even weed killing sprays can not eliminate the stubborn plant, and in Scotland alone, the bracken has monopolized more than 400,000 acres of cleared land.

"We've found something that kills it, but the problem is that it kills everything else as well." Alice Tryon says.