A massive, gnarled Osage orange tree (Maclura pomifera) at River Farm, the headquarters of the American Horticultural Society in Alexandria, Virginia, has officially been recognized as the largest tree of its species in the United States by the 2011 National Register of Big Trees. The previous record-holder was an Osage orange growing at Red Hill, Patrick Henry’s home in Brookneal, Virginia.
The National Register of Big Trees is coordinated by American Forests, a Washington, D.C.-based nonprofit. Champions of more than 700 individual tree species are determined based on a formula that takes into account each tree’s trunk circumference, height, and crown spread. The three measurements are combined to calculate the points allocated to each tree. River Farm’s Osage orange tree scored 413 points, narrowly beating out its co-champion tree in New Castle, Delaware, which scored 412 points. Both trees surpassed the previous champion’s 403 points.
River Farm’s Osage orange was measured by a professional arborist with The Care of Trees, a national tree care firm that is responsible for the maintenance of all trees at the Society’s headquarters. The Osage orange tree measured 58 feet tall with an average crown spread of more than 90 feet. It is estimated that River Farm’s tree is at least 200 years old.
Because the historic native range of Osage orange trees was a fairly narrow area from southwest Arkansas and southeast Oklahoma through east central Texas, the origin of the River Farm tree—as well as other large Osage oranges growing on the East Coast—is a mystery. According to Jeff Kirwan, professor emeritus of forestry at Virginia Tech and coauthor with Nancy Ross Hugo of Remarkable Trees of Virginia, “The leading hypothesis now is that Indians were actively planting these trees outside their natural range before Europeans arrived. The native Americans were phenomenal horticulturists and often are underappreciated for these abilities.”
The Osage orange belongs to the same plant family as mulberries and figs. Female trees bear large fruits that resemble lumpy, greenish softballs, so, for landscaping purposes, the fruitless male trees are generally preferred. Osage orange trees are wind, drought, disease, and insect resistant. In fall, the long, pointed leaves turn deep yellow.