ONE figure towers over the Katonah Museum of Art‘s South Lawn, bark-skinned, wild-haired, branching arms and fingers splayed. Another poses by the museum’s entrance, and three more take their places in the sculpture garden, blending in with the over-100-year-old Norwegian spruces as if they belong to the landscape, yet gesticulating in a way that is distinctly human.

The monumental works in “Joseph Wheelwright: Tree Figures,” from 16 ½ to 27 feet tall, began life upside down as live trees rooted in the soil on the artist’s 40-acre property in East Corinth, Vt.

“I start by looking for trees with bifurcated trunks,” said Mr. Wheelwright, a sculptor who lives in Boston with his wife, Susan MacGregor Wheelwright.

“If the hips and the swing of the legs look good, I poke down into the roots to see what the tree is going to give me for shoulders. Sometimes you can follow the root structure all the way out to the fingers.”

Having identified a promising specimen, Mr. Wheelwright, 63, fells the top portion of the tree, which will not be part of the figure, and then, using customized equipment, uproots and inverts the remainder.

“It’s a big deal,” he said. “You have to use a crane to gently remove it, or sometimes I build a ramp so when the tree falls it pulls the roots up and out.”

Completing the sculpture involves adapting and adding to the existing growth to form the head and facial features and position the arms and hands.

“I use every part of the tree that is appealing, but I don’t have any rules about not using other materials,” Mr. Wheelwright said. Often the heads are carved from laminated pine planks and then covered with bark.

The figures are made from an assortment of species. The three pieces in the museum’s sculpture garden, “Yellow Birch Figure,” “Cherry Figure” and “Oracle,” are made from yellow birch, cherry and pine trees.

Mr. Wheelwright has found that hornbeams, relatively short hardwood trees, are particularly suited to his purposes.

“They have fewer roots, but they always send out a few strong shoulders,” he said. “Smoke Jumper,” by the entryway, was created from hornbeam and then bronzed (it is the artist’s second bronzed large-scale tree figure).

The five tree figures in Katonah, sculptured from 2006 to 2008, are part of a group of 10 that Mr. Wheelwright, who also carves massive stone heads, has produced since 2003.

Since the 1970s, he has also been fashioning smaller figures from roots and branches. Five of those pieces, bronzed and ranging from 10 to 32 inches tall, are on view in the museum’s atrium through the end of the year.

Decades of trolling for sources in the forest have convinced Mr. Wheelwright that trees and humans share a common ancestor.

“There’s no question that we are descended from the same organism,” he said. “You see it all the time: an armpit will form at the bottom of a branch; then it will mound like a shoulder. And many times I’ve seen fingers that seem to grow like a hand, with a spray of three or four, and then something thicker that heads down like a thumb. It’s quite astonishing.”

Putting the tree figures on display at the Katonah Museum was a labor-intensive project that involved flatbeds, forklifts and slings.

“It took a week to get them here and unload them and set them up in the garden,” Nancy Wallach, the museum’s director of curatorial affairs, said.

The installation, she said, was one of the museum’s most ambitious to date, in terms of both the size of the sculptures (the heaviest weighs about two tons) and the complexity of securing them in the ground.

The tree figures will remain on view through next spring, giving museumgoers the opportunity to experience the works as the seasons change.

“Just wait till it snows,” Ms. Wallach said. “Can you imagine?”

“Joseph Wheelwright: Tree Figures,” through May in the Marilyn M. Simpson Sculpture Garden and on the South Lawn at the Katonah Museum of Art, 134 Jay Street (Route 22). For more information: katonahmuseum.org or (914) 232-9555.