Sex and the single tree.

A few miles south of Washington, DC, along the banks of the Potomac River, lies Mount Vernon, the home of this nation's first President. We all know about the role George Washington played in the birth of this country. He and Martha had no children, but at least one heir still resides at the Mount Vernon estate. How can this be, you ask?

Overlooking the carriageway leading to the Washington mansion grows a very old and famous landmark, a tree. Planted by Washington in 1775, just as this nation was about to be born, it stands as a living legacy to the man who planted it and to 213 years of freedom. The arboreal giant, a tulip poplar (Liriodendron tulipifera) towers more than 100 feet.

Like the father of our country, the tree has famous roots but no off spring to speak of. During AFA's 1986 search for famous and historic trees, it ranked as one of our most significant trees and was considered a living artifact by some.

Our interest in these special trees blossomed after the late Henry Clepper, AFA's much-missed historian and coauthor of the book Famous and Historic Trees, prompted us to take action on behalf of the trees. Henry hoped that at least some of these historic trees could be perpetuated before they disappeared.

The search for productive seed on the Washington tree proved fruitless. Dean Norton, Mount Vernon horticulturist, says the tree has not produced any seedlings that he can remember. We wondered if the tree was just too old to muster up healthy seed.

We turned to the National Arboretum and tree geneticist, Dr. Frank Santamour, who is well known for his work in breeding trees for the urban landscape. He confirmed some of our fears but also offered hope. Washington's tree could not be expected to produce anywhere near the healthy seed that a younger tree would. It looked like we were going to have to learn a lot about the sex life of tulip trees in a hurry if we wanted to assist the tree in this historic task. Tulip trees are pollinated by insects that must travel between two trees to make a healthy cross. Since the Washington tree is so big and so isolated from other trees of its kind, it is not surprising that the tree has been unsuccessful in producing viable seed. An expert in pollination techniques and some specialized equipment were needed. Santamour, always interested in a little sex when it's for the good of the country, offered to assist in solving the first problem.

Since the lowest branch was about 30 feet above the ground, a large bucket truck would be needed to get Santamour in a position to reach the flowers. jeff Bond of Guardian Tree Expert Co. came to the rescue. Guardian is known in the area as a topnotch tree-care company and ironically had done much of the tree work on the Mount Vernon estate.

While Santamour worked out a method for gathering pollen from one of the most potent tulip poplars on the Arboretum grounds, Norton watched the flower bud development of the Mount Vernon tree. It was a sunny spring day when the scientists and the tree were ready for a little action. Tourists were streaming across the grounds and into the mansion as the Guardian truck prepared to take Santamour into the branches. He loaded a tool box filled with pollen on a sticky substance and Q-tips into the bucket and lifted off the ground in search of ripe seed pods.

Before lifting off he gave us a quick genetics lesson on spotting a ripe, but unopened flower pod. A trained eye can usually pick them out, but the final test is to pinch. When you pinch, a ripe pod will fill with air just before it opens and flexes.

Someone asked Santamour what happens when he finds a ripe pod in this way. "It slaps you in the face," he replied. After he recovers from the reprimand, the pod casing and flower petals are removed. Pollen, collected at the National Arboretum and sprinkled onto the sticky substance (which makes the pollen easier to handle), is then applied to the seed pod with the Q-tips.

All in all, the day was quite a performance. Santamour fertilized about 100 flowers. (Was his face red from being slapped or from failed attempts?) He joked about stopping for a break and a cigarette.

Guardian and Santamour were willing to come back in the fall, when the pollinated seed needed to be clipped off. The seed pods then went to St. Louis, Missouri, for germination and growing. In October, we will be able to see some seedlings at the 4th Urban Forestry Conference. About 1,000 seedlings came to life this spring, less than we had hoped for, but a lot more than George's tree had been able to do on its own.