Florida Ziziphus Research and Conservation

Florida ziziphus (Ziziphus celata, Rhamnaceae) is one of the rarest and most endangered plants in Florida. It is a thorny clonal shrub endemic to yellow sand xeric habitats that historically supported longleaf pine/wiregrass sandhills and similar vegetative communities. Most Florida ziziphus habitat has been converted to citrus groves and cattle ranches. Today, Florida ziziphus is known only from a few sites on the Lake Wales Ridge in southern Polk and northern Highlands Counties. Only four of the 14 known populations occur in publicly protected sites. Most populations are self-sterile due to limited genetic diversity and the isolation of populations.
The Plant Ecology Lab has conducted research on the genetics, reproductive biology, and demography of Florida ziziphus for over a decade. Genetic studies have used isozymes, RAPDs, and microsatellites to quantify limited genetic variation in wild populations. Breeding system experiments have demonstrated that Florida ziziphus is self-incompatible and that most genotypes are also cross-incompatible. The combination of limited genetic variation and a limited range of mating types explains why most populations are self-sterile. Demographic research has shown that populations are stable with high survival but variable levels of clonal recruitment. Without augmentation, most populations are predicted to undergo slow decline in numbers. We have also examined the responses of Florida ziziphus to management treatments such as prescribed burning.
These research results have helped inform conservation actions to enhance the recovery of Florida ziziphus. Archbold plant ecologists have been working to develop and implement a recovery plan for Florida ziziphus since 1996. Recovery requires creation of genetically diverse, sexually viable populations on publicly protected lands containing appropriate habitat. Implementation of the recovery program is overseen by the Florida Ziziphus Ad Hoc Recovery Team, a committee comprising Archbold and other plant scientists, agency personnel, and land managers. To date, we have introduced Florida ziziphus transplants and seeds to half a dozen sites, including The Nature Conservancy’s Tiger Creek Preserve and the Lake Wales Ridge National Wildlife Refuge. To follow current developments in the recovery program, see the documents below.

Florida Ziziphus Recovery Team meeting, 7th January, 2010 | Florida Ziziphus Strategic Plan 2006 | (Revised) Proposal for the Experimental Introduction of Florida Ziziphus at Lake Wales Ridge State Forest (2010) | Florida Ziziphus 2009 annual report to Division of Forestry

Florida ziziphus introduction crew following 2007 experimental introduction at Tiger Creek Preserve. Bottom row, left to right: Moses Michelson, John Lovell, Lauren Sullivan, and Gretel Clarke. Top row, left to right: B Pace-Aldana, Kate Prengaman, Sarah Hicks, and Stacy Smith. (Photo by Carl Weekley.)

Florida ziziphus plant growing in one of the pasture sites. (Photo by Carl Weekley.)

Florida ziziphus fruits on a plant in the multi-genotype off-site population at Bok Tower Gardens. (Photo by Carl Weekley.)

Archbold Plant Ecology Lab intern hand-pollinating Florida ziziphus flowers at Bok Tower Gardens. (Photo by Emily Morris.)

Archbold Plant Ecology Lab research assistants Stephanie Valligny and Jeremy Ash installing irrigation system for introduced Florida ziziphus transplant. Transplants are caged to prevent disturbance by animals. (Photo by Steve Morrison.)