Keeping Up With Conservation: Florida Ziziphus Seed Harvest

Each May, thousands of seeds are collected from the plants in the National Collection beds. Although a handful of seeds are occasionally produced each year from one wild population, the National Collection is effectively the only place in the world where seeds are reliably produced.

The annual seed harvest from the National Collection can be large, ranging from ~4,000 seeds to as much as ~16,000 seeds. In 2022, a total of 4,893 seeds were produced from the National Collection plants. During collection, seeds were kept separate by maternal parent, and spread onto screening in newly constructed drying racks, which were designed and built by volunteer Joe Fabach to keep seed predators from reaching the seeds. Once the pulp was air dried, the seeds were then counted and sorted. A subset of the seeds were provided to Archbold Biological Station to sow directly into the soil of an introduced population, and the rest partitioned for annual germination trials from 2022 through 2030.

The 2022 germination trial was set up using these ‘fresh’ seeds from all maternal parent plants, along with seeds collected in previous harvest years and which had been stored at three different temperatures: ambient, -7°C, and -20°C. A total of 2,290 seeds were sown into individual cells of 60-well greenhouse trays on a sun table in the greenhouse. These seeds represented 146 maternal parent plants, four harvest years, and all three storage temperatures. Seeds of this species can take 8-9 months to germinate, so this trial is expected to run through spring 2023. Seedlings produced from this trial will be genotyped, through DNA extractions of their leaves, and used to create genetically diverse new populations in the wild.

Article was written by Cheryl Peterson, Conservation Program Manager at Bok Tower Gardens.