But across the creek is another huge thicket of wisteria, growing stronger. And ivy sprouts are appearing in cleared sections. Somewhere up a hill is the Lost Grill -- a barbecue amenity marooned in honeysuckle, totem of the work yet to be done.
Young spots an exceptionally ugly vine defiantly persisting in a cleared section.
"I think I am going to hit it," Young says. "I am ready to say, 'Die, porcelainberry, die!' "
He pulls a folding saw out of his backpack.
Climb Time
Charles Darwin studied vines.
"Plants became climbers," he wrote, " . . . to reach the light and to expose a large surface of their leaves to its action and to that of the free air."
That much seems obvious.
The genius and mystery of vines is how they climb. Unlike a tree, they don't waste energy building a platform. They grow thick and woody only after they've reached the top.
"They're very smart plants," says Diane Pavek, research coordinator in the Washington region for the National Park Service. "What a great idea to be green, and put all your energy to where you can get up to the light, and then create your woody stem."
Different styles for different vines. Bittersweet and wisteria wind around tree trunks on their way to the top. Porcelainberry sends out tendrils. Ivy has tiny roots to grip the bark.
Vines have light-sensitive and touch-sensitive hormones. To twine around a branch, the cells on the side facing away from the branch elongate, allowing the vine to curl toward the branch.
Where vine meets void is a dramatic forest frontier. Leafless vine tips grow several feet horizontally into space, groping with relentless evolutionary imperative. Success is never enough. Vines always want more.
Finding nothing, the exploring scout eventually curls back on itself with a kind of resignation.
How does it choose direction? What if the breeze brushes it against a sapling? Will it know? Is finding the next ride a matter of blind luck?
We don't know. No one has done the science, until now.
Kevin Vaughn has set out to answer the question: How do vines vine?
He is a cell biologist with the Department of Agriculture's Agricultural Research Service, based in Stoneville, Miss.
"What I've found out so far," he says, "is all the plants that start to vine, start out as not a vine."
That is, they emerge from the soil as ordinary plant seedlings. After growing several inches, they switch to a vining mode -- they get longer, produce tendrils.
Vaughn is studying what changes occur between the last pre-vining point and the first vining point. If you understand the transformation, you might be able to develop a chemical to suppress it.
"We want to discover why these vining weeds are so very successful," says Vaughn, "and then try to use that as their Achilles' heel."
Battling the Green Monster
In 2000 the National Park Service launched what is now a $5 million program to deploy 16 Exotic Plant Management Teams across the country.
