(Asplenium tutwilerae growing in the Kaul Wildflower Garden at the Birmingham Botanical Gardens)
A Study of the Tutwiler spleenwort
(by: Hunter McBrayer)
I have had many opportunities throughout my internship to visit many special places located in and around the state of Alabama. I have been able to study, in situ, many different plants and the ecosystems they are in. Being primarily focused in conservation of the native plants of the southeastern United States, I have met many of Alabama’s best and most influential experts and studied some of the most imperiled plants in the area. There is one plant however that has had my unbroken attention since the first day at the Birmingham Botanical Gardens. This plant is Asplenium tutwilerae, Tutwiler’s spleenwort (syn. Asplenium ebenoides).
Tutwiler’s spleenwort is a diminutive fern that only grows in Hale County, Alabama in an area called Havana Glen. There are many reasons that this plant has captivated me, but the main reason is that there are approximately 120 plants that grow naturally in the wild, making it one of the rarest plants in the world.
The story of Tutwiler’s spleenwort is quite interesting to any plant enthusist and it started over 130 years ago. Julia Strudwick Tutwiler, future Alabama prison and education reformer, had heard of an area near her home that had several plants that she was interested in seeing. Tutwiler stumbled across the Havana Glen area and discovered the fern. Being an amateur botanist, Tutwiler quickly realized that it was unlike any that she had ever seen. She wrote about her find to Daniel Eaton, editor of the Journal of the Torrey Botanical Club. Upon her examination of the plant, she hypothesized that it was a hybrid species between Asplenium platyneuron, ebony spleenwort, and Asplenium rhizophyllum, walking fern. This hypothesis seemed true and relatively unsurprising to the botanical community because species in the Asplenium genus readily hybridize, making a sterile hybrid. A similar hybrid, Asplenium ebenoides, had been discovered in Pennsylvania, and was thought to be the same product as what Tutwiler had found. In 1896, Lucien Underwood, a botanist from Auburn University, traveled to the site and found that the fern was propagating profusely, which is uncommon in hybrids (much like a mule, which is the sterile hybrid of a donkey and a horse). This apparent ease of proliferation brought many new questions about the plants origin to the table. Then, in 1930, Edgar Wherry from the University of Pennsylvania found that the number of ferns continued to increase, even through one of the supposed parents had disappeared from the site. Finally in 1954, University of Michigan cytologist Herb Wagner provided an explanation for the proliferation of the species; it had doubled the total number of chromosomes, making it a fertile plant in a process called reticulate evolution.
Although his discovery took place in 1954, it was not until 2007 that the plant was renamed. Alabama Botanists Larry Davenport and Brian Keener proposed a renaming of the plant from Asplenium ebenoides to Asplenium tutwilerae, giving credit to Julia Tutwiler.
Being a place of plant conservation, the Birmingham Botanical Gardens harbors a large variety of rare and imperiled plants. The Gardens retains and propagates many of these plants. We hope to continue the efforts and eventually be able to repatriate the ferns back to Havana Glen.
(Propagation of Asplenium tutwilerae at the Birmingham Botanical Gardens)