Ecology

The Franklin Tree

Amanda Markle
Strawberry Hill Nature Preserve

(10/2021) When you visit Strawberry Hill, you may notice a small tree surrounded by a short rock wall, tucked in between the Nature Classroom and the pavilion. Strawberry Hill is fortunate enough to be home to a great diversity of trees, but to the keen observer, this one stands out. The only one of its kind on our campus, with glossy, oblong leaves and gray bark, this tree saves its most surprising and spectacular feature for late summer and early fall when large and wonderfully fragrant flowers appear, sending local pollinators into a frenzy.

As autumn progresses, the blooms fall away, and its leaves turn a bright red-orange. Identifying this tree can be a challenge- it’s missing from many regional field guides, and identification apps struggle to classify it as anything more specific than a dicot. For the amateur dendrologist willing to put in a little more research, a fascinating story awaits, one of a truly unique tree rescued from the brink of total extinction by a pair of botanists in the 18th century- the story of the Franklin tree.

The Franklin tree (Franklinia alatamaha) is native to the Alatamaha River Valley in what is now the state of Georgia, but the men who found it there and ultimately saved it from disappearance have their roots in Pennsylvania. John Bartram, born in 1699, was a Quaker farmer living near Philadelphia. Though he had no formal higher education, John was well-read and took it upon himself to study and research the native plants of North America. His curiosity drove him to travel the eastern American colonies, searching for and meticulously documenting the plants he found there.

John would bring home specimens that particularly piqued his interest, devoting a small portion of his farm to cultivating these finds. As his collection grew, he made contacts with gardeners and botanists in Europe, and his hobby soon grew into a thriving business. Every fall, John would send his "Bartram Boxes", full of seeds and interesting specimens he found on his travels, across the Atlantic. His efforts were instrumental in introducing dozens of native North American trees and flowers to the European continent, including rhododendron and magnolia; botanical historians even credit him as the first documented cultivator of the Venus flytrap. His efforts and skill eventually earned him the post of King’s Botanist for North America, a position that came with a salary of £50 per year.

In 1739 John’s son William was born, and John’s interest in botany and natural history passed to the next generation. As an adult, William became heavily involved in maintaining and adding to his father’s botanical garden. He joined his father for many expeditions, searching for new specimens and documenting his travels and exploration in his book Bartram’s Travels. In October of 1976, John and William traveled south and were exploring the Alatamaha River Valley, when they came upon a small area of what John referred to in his journal as "several very curious shrubs."

Being late in the season, they failed to collect any seeds during that expedition. The younger Bartram returned to the area several times over the next few years and was eventually able to return to the spot and collect viable seeds. William brought seeds back to his father in Philadelphia in 1777; John died later that year. Four years later, in 1781, William succeeded in growing flowering plants from the seeds he had collected. After studying the tree for several years, William decided to name the species after the river valley from which it came, and his father’s close friend, Benjamin Franklin, and the Franklin tree officially joined the ranks of documented native North American plants.

John and William’s discovery, and William’s later successful cultivation of this "curious shrub" came just in time. The Bartram’s only ever found the Franklin Tree in an area of just a few acres. William later wrote, "We never saw it any other place, nor have I ever seen it growing wild, in all my travels, from Pennsylvania to Point Coupe, on the banks of the Mississippi."

By 1790, the Franklin tree had gone extinct in the wild. The reasoning for the Franklin tree’s fate has been debated; some believe that the small patch found in what is now Georgia was the last holdover of a much larger population that had thrived in the cooler climates of the north but was decimated by glaciation. Others believe that only a small population of Franklin trees ever existed, and what was once there was driven to extinction by over-collection by early botanists or wiped out by a natural disaster. Another theory is that the cultivation of cotton plants in the American South introduced fungal disease that eventually led to the Franklin tree’s demise. Whatever the reason, within a decade of William’s first successful cultivation, Franklinia alatamaha had disappeared in the wild. All Franklin trees currently known in existence are decedents of the ones grown in the Bartram botanical garden.

In addition to its beauty and rarity, the Franklin tree stands out for several other reasons. It blooms far later in the season than is typical for North American trees, sometimes even maintaining its blooms until the first frost, creating a stunning visual of its large white flowers against the backdrop of its bright red autumn leaves. The Franklin tree is a member of the tea family and is prized for its fragrant flowers, which are often compared to orange blossom or honeysuckle. Franklin trees, unlike almost any other flowering plant, have a prolonged zygomatic dormancy.

Pollination occurs when the plant blooms in late summer and early fall, and soon after double fertilization takes place, a complex mechanism itself found only in angiosperms. In double fertilization, one sperm cell fertilizes an egg cell to form a zygote, while the other forms an endosperm by fusing with two polar nuclei. The development of the Franklin tree is unique in that once fertilized, the zygote becomes dormant immediately, delaying development until the following summer, while the endosperm may develop for up to 3 months before pausing during the winter months, and restarting in the summer.

The Franklin tree now only exists as a cultivated species. It can be notoriously difficult to grow, preferring highly acidic, sandy soil, and easily succumbing to excessive moisture, drought, or any disturbance of its roots. Franklin trees seem to fare better in cooler climates, lending credence to the theory that before the last ice age its typical range was further north than the small grove discovered by the Bartrams. Indeed, rising average temperatures continue to shrink the Franklin tree’s range. For those dedicated, and perhaps lucky enough to successfully grow one, possession of a Franklin tree grants you membership into an exclusive club. Several efforts have been made to document all living Franklin trees in America; a 1999 census counted 1,896. Each living Franklin tree is a direct line to the fascinating story of a unique and beautiful tree, rescued from oblivion in the nick of time.

Amanda Markle is the Environmental Education Manager of the Strawberry Hill Foundation. Strawberry Hill inspires stewardship of our natural world by
connecting the community with educational opportunities.
 Learn more by visiting StrawberryHill.org.