The endangered Florida Torreya tree struggles along Apalachicola ravines
by Lilly Anderson-Messec, Director of North Florida Programs and TorreyaKeepers Coordinator. Originally published in the Tallahassee Democrat November 11, 2021 (link)
Nestled in the unique and biodiverse steephead ravines along the mighty Apalachicola River, an evergreen tree found nowhere else in the world teeters on the brink of extinction.
Since European colonization, Torreya taxifolia has been known by many names; Florida Torreya, stinking cedar, Florida nutmeg, polecat wood, fetid yew, and gopherwood. Many of these refer to the tree’s pungent odor when the leaves are bruised, or the wood is cut.
To me, the scent is similar to the aroma of tomato plants but much more concentrated. Its Latin name honors New York botanist John Torrey, who first acknowledged it as a new species based on samples sent in 1833 from Florida.
At that time, Florida Torreya was a standard component of the lush and biologically rich steephead ravines found mainly on the eastern side of the Apalachicola River in the Florida Panhandle. These unusual ravines wind for miles inland from the river, eroded slowly over millions of years by the area’s unique geology.
They are exceptionally steep and deep, an unexpected sight in Florida. A nearly vertical drop of up to 80 feet down is typical and will culminate in clear, cool sandy-bottom streams that flow year-round.
'Endemics' have a narrow natural rangeThe cool microclimate formed by the cold water and lush canopy harbor many relictual species of flora and fauna that, just like the Torreya, are not found anywhere else in the world.
Species such as these, constricted to a particular place, are known as “endemics,” and these ravines are rich with them. Because they have such a narrow natural range, many endemics are also endangered species, including the Florida Torreya.
Torreya are conifers – evergreen trees with needle-like leaves that bear their seed in cones – and Torreya taxifolia is one of the most endangered conifers in the world.
Although its range has always been narrow, it was once so common in these ravines that its lightweight, durable, and robust wood was regularly harvested for various uses. However, by the 1930s, their health began to decline quickly.
By the 1960s, virtually every mature Florida Torreya had died, leaving only resprouts from the surviving root systems. Just a small percentage of wild Torreya remain today, and those that do are a shadow of their former selves.
Once growing to mature heights of 30 to 60 feet tall, the few remaining Torreya now rarely reach above 10 feet, with the majority ranging between two to five feet tall. Few trees reach sexual maturity before dying back to their roots again and (hopefully) resprouting. We now consider this species functionally extinct since they have no sustained reproduction in the wild.
So, what is killing the Florida Torreya?
The reasons for its decline have been hotly debated, though habitat degradation due to development, silviculture, climate changes, and other human causes have all contributed. The trees are also susceptible to damage by deer rubbing. Over the years, many hypotheses have been purposed for the disappearance of Torreya, however, the primary culprit of the death and decline of this species was named in 2011: Fusarium torreyae.
This fungal pathogen was unknown to science until recently identified and described by Dr. Jason Smith at the University of Florida. Jason suspects this fungus evolved in Asia along with relatives of Torreya taxifolia native to that region and was likely introduced through the import of those non-native species for horticultural uses, though more work will be needed to know for sure.
This is just one example of how we “roll the dice” ecologically when we import and plant non-native plants. The plants you add or remove from your yard can have devastating effects on our ecosystems. Choosing native plants is always the best option.
Deadly fungus and blightWhen the trees are stressed, the fungus causes leaf blight and stem cankers, ultimately killing it back down to the roots or killing the plant entirely. The tree may resprout but remains infected and will repeat this process. Trees can be infected without showing any signs of disease but may begin to show signs if stressed.
All Torreya taxifolia trees tested have been infected with the fungus, so even if they don’t show signs of disease, it is probable that all plant material of this species is infected.
Most worryingly, the Fusarium has been proven to infect a variety of other tree species, including native hemlock and pines, and hardwood species as well! For this reason, it is NOT recommended to plant Torreya taxifolia outside of its narrow native range to avoid the unforeseen consequences of spreading this fungal pathogen.
Native hemlocks especially are already threatened by the invasive of the Asian wooly adelgid bug which has caused extensive mortality on the East coast. We know the loss of any species within an ecosystem has rippling effects that can be catastrophic.
More research is needed to understand how this novel Fusarium functions in order to best treat it. This work continues in Dr. Jason Smith’s lab at UF, and the Atlanta Botanical Garden has begun a study to determine the effectiveness of various fungicides on Fusarium torreyae, so hope for the survival of this species is not lost.
Lilly Anderson-Messec is the Director of North Florida Programs for the Florida Native Plant Society (FNPS), the Director of the FNPS TorreyaKeepers Project, and a volunteer writer for UF/IFAS Extension Leon County, an Equal Opportunity Institution.