Behind-the-scenes in the Center for Plant Conservation National Collection beds at the Gardens are over 240 plants of the federally endangered shrub Florida Ziziphus (Ziziphus celata). This ex situ or “captive” population is important to help preserve the genetic diversity of this species, and is the most genetically diverse population that exists. Many of the populations in the wild exist as duplicates of a single clone, and because of that, although the wild plants may flower prolifically and pollinators are abundant, those plants are unable to breed and produce fruit.
However, the population in the National Collection contains many compatible individuals that are able to interbreed and produce fruit. Plants flower in the winter and the fruits slowly mature and ripen in the spring. In April and May is when the annual Ziziphus harvest sets into motion and Conservation staff begin collecting the fruit. The fruit is stored in drying racks to allow the flesh surrounding the seed to dry down until the fruit is completely desiccated. Once the harvest is complete, most of the seeds are further dried to a specific relative humidity and packaged for long-term cold storage.
A subset of the seeds are used for germination trials, and the plants produced from the trials are used for population introduction efforts on protected conservation lands. Population introductions that use many plants from different maternal lines helps ensure the new populations can interbreed once plants reach sexual maturity and produce a seed bank. However, seed germination for this species is very low and has not been documented in the wild. So, for now, the ex situ population at the Gardens remains exceptionally important for seed production and the preservation of this species. With our partnering agencies, we hope to one day produce genetically robust and self-sustaining populations in the wild.
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Article was written by the Rare Plant Conservation team.