WITNESS to history.

ACTOR JAMES WHITMORE SPEAKS UP FOR A NEW DOCUMENTARY--AND FOR AMERICA'S HISTORIC TREES.

As a camera crew deftly manipulates a 20-foot-long camera lens, actor James Whitmore adjusts his shirt and checks his lines on the TelePrompTer.

He is a bonus for tourists spending a sunny afternoon touring George Washington's Mount Vernon estate, and many gather under the trees to watch and listen as the man best known for his historical portrayals--and as the kindly gardener in Miracle-Gro ads--points to a nearby tulip poplar Washington planted more than 200 years ago.

"These trees around us are part of our lives and our history," Whitmore recites. "And while no one can predict the future, one thing is for certain. Our trees will be there, guarding our children and their grandchildren, standing as silent witnesses to all that unfolds, for generations to come."

Those trees and nearly 20 others are featured in an upcoming hour-long PBS documentary, "Silent Witnesses: America's Historic Trees," which recounts American history through the "eyes" of trees. Whitmore, a self-professed history lover, is narrating.

And holding court.

"I'm in love with you!" yells Betty Perano of St. Charles, Missouri.

"Thank you. Bless your heart," Whitmore responds with a grin and a wink. He would repeat those words often that day.

The connection between trees and history is a natural one for the Tony Award-winning actor. In a national tour of "Bully!" Whitmore played one of his favorite presidents, Theodore Roosevelt, whose family coat of arms means, "He who plants, conserves.

"Did you know that Theodore Roosevelt was a frequent visitor to Mt. Vernon?" Whitmore asks as he arrives on the set, launching into a story about the Roosevelt and one of his secretaries of state.

People mark important occasions in different ways. For Whitmore, it's often been trees.

His mother planted a maple upon the birth of each of Whitmore's three sons. The story of Johnny Appleseed, who made his fortune by planting apple trees from Massachusetts to Ohio, is a favorite. And Whitmore frets over Monterey pines on his oceanfront property that have fallen to pitch canker.

A gaggle of teenagers stop along a nearby gravel path to catch a glimpse of the star. Whitmore responds with hugs and smiles, removing his ever-present pipe to wish them well. It's a special day for him. Not only is he doing work related to his favorite subject, but it's also his 78th birthday.

"[Trees] have been witness to all our grandeur, all our silliness, all our mistakes, and all our victories," Whitmore says during a break in the filming, explaining why he chose to lend his powerful voice to the cause. "They act as a portal or a door, showing us that we ought to go back and do the things right that we have and not do the things we haven't done right."

Whitmore has starred in dozens of films and plays based on historical events, earning two Academy Award nominations and his Tony for Best Supporting Actor in Command Decision. He has starred in more than 50 films and recently completed a two-episode guest spot on ABC's Emmy Award-winning series "The Practice," making him a familiar figure for young and old.

His passion for history grew during his tour of duty in the Marines during World War II, which "changed a lot of things I once thought were true," says Whitmore, adding that Americans should study history to understand their past.

"Just being a citizen of probably the greatest country that's ever existed means you gotta know something about it. It's just terribly important to understand the past. History is much more fascinating than fiction."

He says he's thrilled to narrate the special because AMERICAN FORESTS' Famous & Historic Trees program "gets people interested in history," Whitmore says. "Take Johnny Appleseed, a hardheaded business guy. There are very few hard-headed business guys who are barefoot!"

"Silent Witnesses," produced by WJCT Public Television in Jacksonville, Florida, and sponsored by online gardening service garden.com with help from the Scotts Company, will feature images of historic trees with stories from the descendants of their original caretakers. It draws its trees from a list maintained by AMERICAN FORESTS' Famous & Historic Trees program, which collects seeds from trees connected with famous people and events, then grows and sells the progeny as a way to connect people with history.

In making the documentary, the production crew has recorded nearly 800 hours of film over the past year and a half, according to WJCT executive producer Ellyne Lonergan.

Nearly 20 million people could see the PBS special, Lonergan says. So far 160 markets have picked up the special, which most plan to air the third week of April. In addition to teaching people about history, AMERICAN FORESTS hopes the upcoming PBS documentary will instill in people a respect for the value trees bring to everyday life.

"AMERICAN FORESTS is doing some fine work in helping people to see that they need trees," Whitmore says. "I believe that everybody should plant a tree once a year.

That said, Whitmore did his yearly duty by helping plant a 5-foot George Washington tulip poplar on the Mt. Vernon grounds. James Rees, Mt. Vernon's executive director, Whitmore friend Noreen Siegel, and Rick Crouse, AMERICAN FORESTS senior vice president for marketing and development, joined the effort.

It's been a fan fest wherever the popular Whitmore appears. At Gettysburg National Military Park earlier in the week, the actor greeted fans, practiced lines, and battled logistical problems, like rain and wind. Today it's the periodic roar and thunder of planes flying into and out of nearby Reagan National Airport. Despite the ruckus, spirits run high as Whitmore practices lines with production staff, accepts birthday wishes, and fields fans' questions.

Filming at Gettysburg went well, but "I don't think you can ever have a 'good time' there," Whitmore says, referring to the bloody Civil War battle where more than 51,000 Union and Confederate soldiers lost their lives or were wounded or captured. But on his 78th birthday, Whitmore seems more whimsical than serious.

"Now I'll have to get a coffee table," he quips as he unwraps a beautiful coffee table book on Mt. Vernon, a gift from officials at the historical site. AMERICAN FORESTS planted 79 Global ReLeaf trees--for each of Whitmore's years plus one for good luck--in our Global ReLeaf Forests site in New York's Beaverkill watershed. Tree planting there is helping to repair trout spawning streams.

Whitmore also took home a ready-to-plant White Plains sycamore, a direct descendant of the still-living tree that witnessed the Revolutionary War Battle of White Plains. The tree had personal significance, too: Whitmore was born in White Plains, New York.

"I know just the spot for it," he says. "I'll put it in a place overlooking the ocean."

When asked which species he would choose if there were a "James Whitmore Tree," he names the "glorious" ponderosa pine. "If I could be a tree, I'd be a ponderosa pine because you would be up above and could look down over everything!"

Just as the documentary shows people how trees have, in effect, looked down over the expanse of American history, Whitmore says he hopes it helps people better understand the challenges these national treasures face.

"Trees need our help," he said. "We don't respect them as much as we should."

Janine Guglielmino is American Forests' associate editor.