The trees live on

In 1783, President Washington commissioned his staff at Mount Vernon to plant sycamore trees on the verdant grounds. More than 220 years later, Mount Vernon horticulturalists have planted a clone of a sycamore tree from that era on the grounds and are cloning other trees already on the property dating to Washington’s salad days.

Tree cloning isn’t as scientifically intricate as human cloning, nor is it anything new. Plato, for example, referred to cloning fruit trees in his writings.

Today, fruit growers, vineyard operators and even historical gardeners clone plants and trees for a wealth of reasons. Each plant is an exact duplicate, down to the DNA, of the source material.

At Mount Vernon, horticulturalists have taken tissue samples from 13 trees still standing from George Washington’s days in hope of creating replacements when the trees fall from natural disaster or old age.

“We’ll be able to plant an exact duplicate,” says Dean Norton, Mount Vernon’s director of agriculture.

The 13 trees at Mount Vernon — which include white mulberries, white ashes, poplars and American hollies — “are the only living witnesses we have to George and Martha’s time,” he says.

Mount Vernon officials began cloning the trees in August 2001 with help from an Oregon nursery that specializes in the procedure. Additional clones are sent to Harvard University’s Arnold Arboretum for safekeeping.

Plus, the genetic information gleaned from the plants will be stored so scientists worldwide can study it.

Mr. Norton says cloning must be completed using existing plants, not their seeds. The latter source, he says, would give the horticulturalist only 50 percent of the genes from a particular parent, not an identical copy.

Although the practice of tree cloning is common, Mr. Norton hadn’t heard of any institution trying to clone historic trees for conservation purposes until recently. Now, he says, Mount Vernon has heard from the caretakers of Sherwood Forest in England looking for advice on cloning its aged trees.

The cloning process can be time-consuming, in part because of the age of the trees in question.

“When you’re working with old tissue, it doesn’t go well,” he says.

David Milarch, co-founder of Champion Tree Project International, says trees lose a certain amount of hormones and enzymes as they age, which makes reproduction harder.

Mr. Milarch says we are dependent on plant clones, even if we’re not aware of it.

“When you eat an apple or a grape, you’re eating a clone. Most of the vegetables in our salad are clones,” says Mr. Milarch, whose project promotes the reproduction of the country’s oldest and hardiest trees in the hopes that their clones will prove similarly hale. Cloning comes into play when the fruit in question produces no viable seeds, such as a seedless orange or grape.

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