October 31, 2008—Situated more than 3,500 feet up in Belize's highest cloud forest, there's a ridge known as Doyle's Delight, and it's mushroom heaven. Last year, Timothy J. Baroni, a fungus scientist at the State University of New York at Cortland, and some colleagues found more than 40 new species there in less than two weeks.

Among his most recent finds: a new species of salmon-colored fungus that also represents a new genus of polypore, a well-studied group long used in Asian herbal medicines. Certain polypores may be useful in treating immune diseases or in helping cancer patients recover.

More than a quarter of all modern medicines come from molds, mushrooms, and other fungi. The drugs include penicillin and cyclosporine, an immunosuppressant that reduces the chances a person will reject an organ transplant.

But scientists believe we've discovered only 5 to 10 percent of Earth's estimated 1.5 million fungus species, so a wealth of molds and mushrooms remains to be explored.

"We have a medicine cabinet at our disposal, and the medicines don't have labels yet," says Baroni, who has received funding from the National Geographic Society's Committee for Research and Exploration.

Baroni focuses on finding and naming new mushrooms; other scientists will identify their food and medicinal uses. But Baroni says mushrooms have another vital property—they might help save the natural world.

Wild fungi can be crucial indicators of their environments health. Scientists believe air pollution killed edible mushrooms in Germany's Black Forest in the 1980s, long before it harmed plants and trees. So far no one is using fungi systematically to monitor ecosystems. But, says Baroni, "If you knew what [fungi] to monitor for, you could see if we are polluting supposedly untouched parts of our planet."

—by Hayley Rutger, for National Geographic magazine