In banning it, California, Nevada and Texas have said the plant crowds out native species and consumes precious water.

The Tennessee Exotic Pest Plant Council lists it as a ‘‘Significant Threat.’’ Virginia officials have labeled it ‘‘moderately invasive.’’ The West Virginia Division of Natural Resources has categorized giant reed as ‘‘occasionally invasive.’’ But that might change if it were to be promoted as a commercial crop, says Elizabeth Byers, a vegetation ecologist with the agency’s wildlife diversity unit.

‘‘I certainly wouldn’t want to see any invasive species used as biomass,’’ she says. ‘‘Because they can escape.’’

North Carolina is keeping an eye on Arundo, but the folks in Oxford say past need not be prologue.

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Earlier this fall, Chemtex International christened the world’s first commercial-scale cellulosic ethanol plant in the northwest Italian city of Crescentino. Turning inedible biomass into sugars, the company hopes to produce up to 20 million gallons of fuel a year.

By mid-2013, Chemtex wants to break ground on a like-sized plant that would employ 67 people in North Carolina. It has set its sights on the little city of Clinton, in the heart of hog country.

David Crouse, a soil scientist at North Carolina State University, says energy grass production and the Tar Heel State are ‘‘a logical match’’ — depending on which grass it is.

Spread across the state’s coastal plain are about 100,000 acres of so-called sprayfields, onto which industrial farming operations pump millions of gallons of hog and chicken waste per year. In order to comply with federal clean water regulations for runoff of nutrients such as nitrogen, many of those fields are already planted with energy grasses, chiefly coastal Bermudagrass.

In terms of yield, Arundo far outpaces the competition — up to 20 dry tons per acre, versus 3 to 6 tons for Bermuda. So planting Arundo would require far less land to supply Chemtex’s fiber needs. The problem is, the fields’ owners also need to worry about absorbing the nitrogen in the manure and the jury is still out as to whether Arundo would be a good fit.

‘‘If it’s not, it’s not where we need to be on the swine farms,’’ Crouse says.

Brake and his colleagues in Oxford are trying to figure that out.

On a farm a few miles from the biofuels center, a dense patch of what look like anorexic palm trees waves in the light autumn breeze. They tower over the 6-foot-2 farming director.

Brake planted this quarter-acre plot of Arundo donax in 2010. He’s been applying fertilizer at four different rates — zero to 120 pounds per acre — to gauge the plants’ nutritional needs, as well as their ability to absorb nitrogen.

Even in the tightly packed, red-clay soil, they have thrived. Brake steps into the thicket and struggles to wrap his arms around a clump.

‘‘It’s about maybe 3 foot in diameter,’’ he says.

So far, yields from North Carolina test plots have averaged from 5.8 dry tons per acre at the Oxford site to just over 11 tons in the sandy loam soils in which most Chemtex suppliers would be planting, though NCSU soil scientist Ron Gehl notes these are not yet ‘‘mature stands.’’

Brake grabs an Arundo stalk and walks until it’s parallel with the ground. Tiny seeds cascade to the ground, clinging to a visitor’s wet shoes.

‘‘You afraid of becoming Johnny donax-seed?’’ he asks with a chuckle. The seeds are sterile, he says reassuringly.

Brake points to a joint on the stalk where a small sprout or ‘‘node’’ peeks out.

‘‘Each node is a potential plant,’’ he explains. ‘‘That makes it easy to propagate.’’

And that’s what gives so many pause.

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In the 16 years since Arundo was first identified in California’s Sonoma Creek Watershed, Mark Newhouser has developed an attack strategy.

First, workers spray the mature cane with herbicide, then move in with the large flail mowers. If that doesn’t do the trick, it’s time for chain saws.

‘‘And then you'd still have all of these stumps of cane sticking up everywhere,’’ he says. ‘‘You can’t even walk through there.’’

The cost: Up to $25,000 per acre.

To address such concerns in North Carolina, state agriculture officials teamed up with the biofuels center last year to craft a set of ‘‘best management practices’’ for energy crops. Among them are not planting directly adjacent to streams and irrigation canals, and establishing buffer zones of at least 20 feet around production fields.