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Research Project:  Safeguarding Torreya taxifolia

Hank Bruno, Trails Manager, The Gardens at Callaway; GPCA Torreya Committee Chair

Torreya taxifoliaThe Florida Torreya (Torreya taxifolia) faces extinction due to habitat destruction and widespread infection by a chronic fungal disease. For 160 million years Torreya, also known as stinking cedar, had been an integral part of the Beech/Magnolia forest.

It is hard to generate public sympathy for a prickly conifer whose pungent foliage earned the common name "stinking cedar." We should be more understanding. The dramatic decline of this species began in the 1950s, about the time Lake Seminole was built. Torreya habitat is steep-walled ravines in Decatur County, Georgia and a few localities along the Apalachicola River in Florida. The exact cause of the continuing decline of Torreya is uncertain; clearly dam construction did not help. There is another reason to be concerned with this species' survival. Florida Torreya is related to the Pacific Yew (Taxus brevifolia) from which we get Taxol, a cancer fighting drug. Taxol has also been experimentally produced in an endophytic fungus associated with Torreya grandifolia, a Japanese species. The U.S. Fish and Wildlife Service proposed a plan for the recovery of Torreya taxifolia in 1986. The Georgia Plant Conservation Alliance began working with the species in 1995. The GPCA project is designed to monitor the existing habitat and natural populations, produce seedlings and cuttings with the goal of maximizing genetic variation, establish outplantings at safeguarding sites, and increase public awareness through education.

Above: Torreya taxifolia

CONSERVATION ALERT: GEORGIA INSTITUTIONS PLANT ENDANGERED TREES TO PROTECT SPECIES
Florida Torreya (Torreya taxifolia) Federally Endangered

Species Profile
The Florida Torreya is a pyramid-shaped evergreen tree that once reached heights of 40-50 feet with a trunk diameter of nearly 2 feet. The pungent, sharply pointed needles (the source of one of its other common names—Stinking Cedar) are 1-1.5 inches long. They are dark shiny green above and silvery white below. The bark is brownish orange and has a shredded appearance. The wood is so rot resistant that fence posts made from the trees have been known to last as long as 60 years! This primitive member of the Yew family bears male and female flowers on separate plants. The reproductive structures appear in early spring, and the nutmeg-like "fruits" mature in fall of the following year.

Habitat
The Florida Torreya calls the dark, rich, sandy limestone soils of the Apalachicola River region home. The trees are found growing in the Beech/Magnolia/Pine forests that cover the hammocks, slopes, ravines and bluffs along the river in Florida and adjacent Lake Seminole in Georgia. Florida Torreya trees are usually found growing in steephead ravines due to the cool, moist microclimate found there. The trees benefit from water seepage and a tree canopy that allows for diffuse sunlight during the summer and an open canopy in the winter.

Torreya's History
The Florida Torreya is one of the oldest tree species on earth. Fossil records indicate that the Florida Torreya was once scattered throughout the Northern Hemisphere and is over 165 million years old! Scientists think the species was driven south by glaciers that once covered the northern latitudes. When the glaciers retreated, the Florida Torreya became isolated in small pockets of the southeastern United States. The species thrived in its new habitat for thousands of years.

Hardy Bryant Croom discovered the tree in the 1830s and named it for the famous botanist John Torrey of New York. The estimated population of Florida Torreya in the Apalachicola River region once reached over 600,000 individuals. In 1914 botanist Roland Harper listed it as one of the region's most abundant trees. Most of the large trees were harvested during the first half of the 20th century for use as Christmas trees, riverboat fuel, shingles, and fence posts.

Late in the 1950s the Florida Torreya experienced a severe population crash. By the early 1960's, scientists discovered that almost all the adult trees had been killed by a fungal blight that caused lesions and death of the leaves and stems. Many factors may have contributed to the decline of the Florida Torreya such as repeated drought and the spread of an introduced soil pathogen (Phytophthora cinnamoni). While the exact cause of the decline has not been determined, most scientists believe that construction of Lake Seminole and logging contributed to the destruction of Florida Torreya's habitat. Changes such as altered water seepage patterns, increased sunlight, and fire suppression further stressed a species already in trouble from years of exploitation.

Current Status
Today the Florida Torreya population is estimated to be around 200 individuals. With numbers this low, Florida Torreya is one of North America's most critically endangered trees. These trees are confined to a few counties in northern Florida mostly along the limestone bluffs of the Apalachicola River and one county in southwestern Georgia in the hardwood ravines bordering Lake Seminole. The existing trees are either root sprouts or stump shoots from old trees felled by disease or logging. Since most Florida Torreya trees in the wild no longer reach maturity, they seldom form seed to reproduce.

Conservation Action
Monitoring programs demonstrate a continued decline in the Torreya population. Many scientists believe that Florida Torreya's extinction in the wild is inevitable. While the future may not be bright for this rare tree, many institutions are conducting research on Florida Torreya. Reintroduction of the species to its native habitat has had little success. However, safeguarding sites have been selected around the country to preserve the species, if only in cultivation.

The Georgia Plant Conservation Alliance (GPCA) is helping protect the Florida Torreya from extinction by planting trees in grove-like settings at its partner institutions. These safeguarding collections of trees are clones of the wild trees. Colleagues at the Center for Plant Conservation in St. Louis, Missouri, Smith College in Northampton, Massachusetts, and the Atlanta Botanical Garden collaborated on propagating the trees by collecting cuttings from wild Torreya, cataloguing their location data, and raising the trees at botanical gardens. Each tree is assigned a special code that enables scientists to track that clone back to the original tree in the wild. Many of the trees in cultivation no longer exist in the wild, raising the importance of protecting this species in cultivation. Partner institutions in GPCA are assigned one or more populations of Florida Torreya trees to plant and protect. GPCA's goals include protecting trees at the various institutions, learning what makes them thrive, applying that knowledge to helping the trees survive in the wild, and encouraging the trees to reproduce sexually to provide seedlings that can be reintroduced to the wild if the disease plaguing the Florida Torreya is ever brought under control.

Institutions Safeguarding Florida Torreya Include

  • Atlanta Botanical Garden
  • Coastal Plain Research Arboretum
  • Elachee Nature Science Center
  • Georgia Southern Botanical Garden
  • Smithgall Woods/Dukes Creek Conservation Area
  • State Botanical Garden of Georgia
  • The Gardens at Callaway

FIRST TORREYAS LEAVE THE NEST
Laura Anne Middlesteadt, Public Relations, Atlanta Botanical Garden

After six years of tender loving care at the Atlanta Botanical Garden, 19 individuals of Torreya taxifolia (stinking cedar) were planted out on DNR land in north Georgia last spring. Staff from ABG, the Georgia Department of Natural Resources and Smithgall Woods participated in the planting. Stinking cedar, a Georgia/Florida native, currently faces extinction due to a fungal disease. Most of the few remaining trees in the wild do not reach reproductive age. Male and female cones are produced on separate individuals. Conservation of Torreya has been one of GPCA's four priority projects since its inception in 1995.

The Atlanta Botanical Garden is one of several holding sites for genetic material of the species. ABG staff have nurtured and propagated more than 150 genetically different individuals of stinking cedar since 1990. The trees that were planted at Smithgall were the first of this group to be planted out. They represent 10 different genetic clones, all originally from Georgia. "This is a tree that faces almost certain extinction without some action on our part," Ron Determann, Atlanta Botanical Garden, said. "We're very pleased that some individuals are fruiting and setting seed now."

The location of the outplanting at the Smithgall Woods/Dukes Creek Conservation Area in White County is north of the species' natural distribution. Determann and DNR botanist Tom Patrick hope that the fungus which attacks the trees will not be present at the new site. The trees, which were three to four feet in height at planting, were sited in both open woods and full sun areas near the Smithgall Visitor Center on Georgia Highway 75 Alternate just south of Helen.

"The trees are doing really well," said Linda Moore, Smithgall grounds supervisor. "We haven't lost any and they've all put on new growth."

The Smithgall Woods/Dukes Creek Conservation Area is open to the public for recreational purposes. For more information, call 706-878-3087.

For an update on this research project, see GPCA News.

Right: Old Torreya taxifolia felled by disease