Distribution: Polk and Highlands counties, Florida, USA; Federally and state listed Endangered.

Habitats: Florida ziziphus is known from five sites. All sites occur on yellow sands (Tavares, Astatula and Candler), which historically supported longleaf pine/wiregrass sandhill, turkey oak sandhill and yellow sand oak/hickory scrub. However, three of the five sites have been converted to pastures. Of the two remaining sites, one is a remnant longleaf pine/wiregrass sandhill and the other is a relatively open oak/hickory scrub. Florida ziziphus seems to prefer more open sites with little or no canopy. In addition to the in situ populations, there is also a Center for Plant Conservation ex situ population at Bok Tower Gardens. This population comprises all known in situ genotypes.

Life History: Florida ziziphus is a clonal woody shrub to 2 m in height (Weekley and Race 1999). "Plants" (= presumably physiologically independent ramets) may be single-stemmed arborescent individuals or dense multi-stemmed clumps. The latter condition is probably most often a response to mowing. Plants resprout following fire and generally recover their pre-burn heights within two to three years. In the absence of fire (or mowing) plants sometimes die back and then resprout either at the base on the old plant or within a meter or two of the old plant. Most in situ populations are uniclonal. The largest population, located in a dairy pasture in Highlands County, consists of four separate subpopulations and at least four genotypes.

Like many other woody shrubs adapted to xeric habitats, Florida ziziphus has spiny, geniculate branches and small leaves that are shed in the dry season. Flowers are about 1/2 cm in diameter and are 5-merous. As in many other members of the buckthorn family, there is a nectar ring surrounding the pistil and the anthers are initially enclosed by clasping petals that reflex at anthesis to release pollen.

Phenology: Flowering occurs in January-February when plants are mostly leafless. Flowers open throughout the day and remain open for three or four days. Mature plants often produce tens of thousands of flowers.

Breeding System and Pollination: Florida ziziphus is self-incompatible (Weekley and Race 2001). Its floral characteristics (fragrance, presence of nectar ring) suggest that it has a generalist insect pollination syndrome. Floral visitors include a variety of bees, flies and butterflies.

Genetics: Allozyme electrophoresis (Godt, et al 1997) and RAPDs (Weekley et al., 2002) concurred in identifying fewer than a dozen genotypes among the extent populations of Florida ziziphus.

Population Dynamics: Clones appear long-lived. Individual stems are usually short-lived, and groups of stems or entire clones may dieback synchronously. Following dieback, large numbers of new stems may emerge from root crowns. This species is clonal, producing many stems in small areas, and expands the size of the clone under many circumstances.

Interesting Facts: This species was thought to be extinct before its rediscovery in the 1980’s. It is one of the rarest of all the Florida scrub endemics and also one of the most endangered due to its lack of seedling recruitment and viable seed production in wild populations. It is the subject of an experimental introduction (begun in 2002) of multiple genetic individuals and mating types to a new, protected site. The nearest relatives to Florida Ziziphus occur in Baja California.

Data Collected by Archbold Biological Station’s Plant Ecology Lab: During the species’ winter flowering season, much effort has been made to examine which experimental crosses can yield fruit and seeds. Genetic data using several techniques has been collected on these individuals. Data on plant size and survival are collected annually in early spring from all known wild populations. Germination trials and experiments have also been conducted over several years, including an ongoing growth chamber experiment to determine the effects of cold stratification, temperature and photoperiod of germination.

Data Availability: Data on cross compatibility and germinability are available on the Web site.

See Also: Weekley, C., T. Race and D. Hardin. 1999. Saving Florida Ziziphus: Recovery of a rare Lake Wales Ridge endemic. The Palmetto, Vol. 19, No. 2, Summer 1999.  &

Weekley, C. 2004. Experimental introduction of Florida Ziziphus at Lake Wales Ridge National Wildlife Refuge. Saving Our Scrub 3(1):4-5, May 2004. PDF file of entire 8-page newsletter issue.

Contact Person: Carl W. Weekley

1. Godt, M.J.W., T. Race and J.L. Hamrick. 1997. A population genetic analysis of Ziziphus celata, an endangered Florida shrub. Journal of Heredity 88(6):531-533.
2. Weekley, C.W. and T. Race. 1999. 10-year status report on Ziziphus celata, a federally listed endemic plant of the Lake Wales Ridge, Florida. Unpublished report prepared for US Fish and Wildlife Service, Vero Beach, FL. 22+ pp.
3. Weekley, C.W. and T. Race. 2001. The breeding system of Ziziphus celata Judd and D.W. Hall (Rhamnaceae), a rare endemic plant of the Lake Wales Ridge, Florida, USA: implications for recovery. Biological Conservation 100:207-213.
4. Weekley, C.W., T.L. Kubisiak and T.M. Race. 2002. Genetic impoverishment and cross-incompatibility in remnant genotypes of Ziziphus celata, a rare shrub endemic to the Lake Wales Ridge, Florida. Biodiversity and Conservation 11:2027-2046.

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