Image courtesy David J. Driapsa
Thomas Edison planted a four-inch diameter sapling, Ficus bengalensis, on the grounds of his Fort Myers, Florida winter estate in 1925. The tree, collected in India, was a gift from rubber magnate Harvey Firestone. The tree now covers approximately one acre, with a canopy height of sixty-four feet.
Champion trees of this species are not recorded by American Forests, but the Florida Record of Champion Trees does record them, and this giant Banyan is a registered Florida State Champion. There are several challenger trees in south Florida of nearly the same size, but this one is the largest, and its association with the Wizard of Menlo Park gives it great distinction.
During the last decade of his life Thomas Edison directed his invention machine to establishing a source of domestic rubber for war time production. He had served as a consultant to the U.S. Navy during World War I, and saw first-hand that the United States was vulnerable to having its foreign sources of rubber cut off, all coming from overseas and vitally important to American industry and national defense.
Thomas Edison, Harvey Firestone, and Henry Ford charted the Edison Botanic Research Corporation in 1925 to develop that domestic source of rubber. This was the dawn of the synthetic chemical revolution, and plants were still widely used in industry, as you will recall Edison fifty years earlier used carbonized bamboo as the filament for perfecting his electric light bulb.
The genus Ficus contains a white sticky sap that is about three percent latex. The substance is harvested to make rubber. Edison first experimented with different Ficus species, planting trees in rows in the experimental arboretum on his Fort Myers winter estate. Many of those trees still exist. Nearby, at Naples, he tested the Ficus trees in Henry Nehrling’s arboretum, where more than one hundred species were grown. As it turned out, Edison considered Ficus too slow growing for a source of domestic rubber, and thought the high American labor costs would erode profit. He experimented with thousands of other plants, even sending plant collectors searching across the nation. Edison eventually focused his research on common goldenrod (Solidago spp.). The ubiquitous plant grew rapidly and had an acceptable content of latex. Several crops a year could be grown in Florida and harvested by machinery to reduce overhead production costs. Edison perfected a ten foot tall super strain of goldenrod through hybridization experiments.
The emerging science of synthetic chemicals eclipsed the usefulness of goldenrod as a source of rubber, and the Edison Botanic Corporation folded. Edison was not alone in searching for a domestic source of rubber, and through the process many species of Ficus trees were introduced into south Florida through the United States Department of Foreign Plant Introduction headed up by the famous plant explorer, Dr. David Fairchild. As a result, the landscapes of South Florida today are graced by majestic Ficus trees of many species.
David Driapsa is ex-officio chair of the HP PPN and currently serving as HALS Liaison and First District Officer for the Historic American Landscapes Survey in Florida. He can be reached at firstname.lastname@example.org.