ORANGE, Va. — When it grows high and thick in midsummer, the crop that might fill Virginia's gas tanks, revitalize its farm belt and keep its mud and manure out of the Chesapeake Bay looks like, well, weeds.

At a Virginia Tech agricultural research center in this small town west of Fredericksburg, the switchgrass plot is an unruly, waving thicket of 7-foot-tall green stalks. But it only looks neglected: This is one of the center's most prized plants, a formerly obscure prairie grass now projected to be a major source of farm-grown fuel.

"That'd be some energy, right there," said Dave Starner, the center's superintendent, holding a freshly cut bundle of it.

Researchers across the country think that switchgrass could help supplant corn as a source for the fast-growing ethanol industry. In Virginia, some officials are trying to make the state the Iowa of the new cash crop. They're urging farmers to grow it and envision dozens of refineries that will turn the stalks into fuel.

"It's the future of the rural community and the world as you know it," said Ken Moss, an entrepreneur in south-central Virginia who is using some state funds for a factory that turns switchgrass into a substitute for heating oil.

But such efforts have hit a snag: Scientists haven't perfected the process that turns switchgrass into ethanol. So for today, the Crop That Could Change Virginia is just hay with better publicity.

The plant behind all the hoopla, Panicum virgatum, looks a bit like a corn plant without the cob. It has a thin, rigid stalk with a feathery tassel of seeds. Scientists say switchgrass probably grew wild across the eastern two-thirds of the United States for centuries before Europeans arrived.

But, except for plant biologists and some biofuel researchers, few Americans had heard of the plant before last year's State of the Union address. President Bush listed switchgrass among potential sources for ethanol, a gasoline substitute sought as a replacement for imported oil.

Researchers say switchgrass has much to recommend it over corn, the source of almost all U.S. ethanol. For one thing, it isn't also food — the ethanol-driven demand for corn has pushed up prices on a range of items, from tortillas to steak. For another, switchgrass requires little of the irrigation and fertilizer necessary to grow corn, a prima donna among crops.

Environmentalists have also praised the plant for the ability of its roots to filter out pollutants that often wash off farm fields.

"It's better for the land. It's better for the water," said Josh Dorner, a Sierra Club spokesman. Compared to corn, he said, "it's far and away the way to go."

Virginia has relatively little switchgrass planted — fewer than 20 farmers are thought to be growing it on less than 1,000 acres. But Virginia Tech scientists say the grass could play a major role in creating a massive biofuel economy.

In a recent white paper, they suggested that switchgrass, along with woodchips, could provide a quarter of Virginia's gas, diesel fuel and heating oil needs and support 68 small fuel refineries in the state.

One reason for the optimism is obvious at the Virginia Tech research center in Orange. Months of dry weather had stunted the corn, but the switchgrass was still green and tall.

In the southern part of the state, officials are especially eager. They have been ready to embrace a new crop since tobacco, a standby since colonial times, began to fade. And now comes a crop that embraces them: Virginia Tech data show that, because of the state's relatively mild climate, switchgrass might grow much better in Virginia than in Iowa.