Bok Tower Gardens

Cheryl Peterson, Bok Tower Gardens

Dicerandra immaculata var. immaculata (Lakela’s Mint) (Lamiaceae) is a short-lived perennial endemic to the Atlantic Coastal Ridge. It has only a three-mile historical range and few remaining populations. Population modeling predicts near complete loss of plants within eight years unless habitat is improved enough to support large enough populations to withstand stressful events such as drought. Prescribed fire has not been implemented as a habitat-maintenance tool because of the dense urban interface. Regular volunteer workdays have instead been used to eliminate the biggest threats to the persistence of Lakela’s Mint by hand-pulling love vine, thinning the dense overgrowth, and herbicide-treating invasive grasses. A positive response of the mint population, tracked through bi-annual monitoring, is evident. Within one year, plants in an improved area increase in size and reproductive output by ~30%, and seedling recruitment has been observed in long-unoccupied plots. This project shows that regular workdays can be an effective strategy to rebuild Lakela’s Mint populations that are rapidly declining due to loss of quality habitat where implementing fire is not possible.

Contributing Author(s): 
Date Recorded: 
Friday, October 9, 2020

Stephanie Koontz, Archibold Biological Station, Cheryl L. Peterson, Bok Tower Gardens, Valerie C. Pence, Cincinnati Zoo and Botanical Garden, Eric S. Menges, Archbold Biological Station

Translocations are an increasingly utilized tool for rare plant conservation. Urbanization along the Lake Wales Ridge, in southcentral Florida, has led to 85% loss of native Florida scrub and sandhill. The few remaining intact patches hold a plethora of endemics. Our program has translocated several species from unprotected to protected parcels. All translocations are monitored post-outplanting and demographic data used to evaluate success. Here we present case studies for three federally listed species and discuss the challenges in restoring rare plants. Ziziphus celata has few remnant, mostly unprotected populations. Further contributing to its rarity is slow growth and limited sexual reproduction. We implemented 10 translocations between 1998 and 2012. Analyses of vital rates through 2016 determined annual survival of both wild and translocated plants is high (>90%), but growth of transplants is 1/10th the rate of wild plants. Many wild plants flower annually, yet <3% of transplants have reached reproductive maturity. Setting benchmarks for translocation success is challenging when dealing with a slow-growing, reproductively challenged species. Crotalaria avonensis has two protected and one unprotected site. Fruit set is low, requires insect pollination, and seedlings are rare. In 2012, we introduced genetic material from the unprotected site to a protected parcel. Transplants have thrived and expanded through clonal and seedling recruitment, from 84 original transplants to 208 plants in 2019. Germination of sown seeds was also a success (47%) with many surviving, flowering and fruiting. The first decade of this translocation may qualify as a success, but the ultimate test comes in long-term population responses to land management activities and climate change. Dicerandra christmanii has <10 sites, only one is protected. It relies on periodic fire to maintain open sandy gaps within the scrub matrix and persists from post-fire seedling recruitment. We have augmentated (2010) and introduction (2012) populations. Both translocations grew exponentially, but the question remained, were populations demographically viable. Using long-term demographic data from wild plants and integral projection models, we determined vital rates and predicted population trajectories were similar between wild and translocated populations. Wild populations provide a priori knowledge of a species’ basic biology and ecological requirements to inform more successful translocations.

Contributing Author(s): 
Date Recorded: 
Wednesday, March 4, 2020

Philip Gonsiska,Bok Tower Gardens

Ziziphus celata is an endangered shrub endemic to Polk and Highlands Counties in central Florida. Germination in this species has generally been very low, and previous observations have suggested that upwards of 75% of seeds set by Z. celata may not be viable. In January 2019, cutting tests were conducted to estimate the viability of Z. celata seeds harvested in summer 2018. Dissected seeds were categorized as “normal”, empty, moldy, “spongy”, and those having shrunken embryos. Those in the “normal” category were thought to be viable. Of the 103 seeds dissected, 36 (34.95%) appeared “normal”, 35 (33.98%) were empty, 24 (23.3%) were moldy, six (5.83%) had shrunken embryos, and two (1.94%) were “spongy”. In earlier work, soaking seeds in a 0.1% liquid smoke solution resulted in a germination rate of 26.7%, which thus far is the highest germination rate in our data set from any experimental seed treatment applied to Z. celata. Therefore, seeds from 2018 were soaked in either a 0.1% liquid smoke solution or reverse osmosis water for 24 or 48 hours. They were then sown in 72-cell trays along with unsoaked control seeds. These trays will be monitored for germination for six months, and the realized germination rate will be compared to the hypothetical percentage of viable seeds from the cutting tests. Preliminary results of this experiment will be presented.

Contributing Author(s): 
Date Recorded: 
Thursday, May 2, 2019

Philip Gonsiska, Whitney Costner, Cheryl Peterson, Bok Tower Gardens

Warea amplexifolia (Clasping Warea) (Brassicaceae) is an annual endemic to sandhill habitat in the northern third of the Lake Wales Ridge in central Florida. It typically germinates between February and early May and flowers from August through October. The main threats to W. amplexifolia are development and lack of land management. In 2000, there were fewer than 20 populations; only ten small populations may still exist. The Rare Plant Conservation Program at Bok Tower Gardens monitors seven reintroduction/augmentation sites for this species. One of these is in a natural area that is part of Mountain Lake, a gated community immediately adjacent to the Gardens. Mountain Lake is the site of a naturally-occurring population, seeds from which have been used in five subsequent outplantings there between 2011 and 2017. The site received little management until 2016, when trees and brush were cleared, and part of the site was burned. In spring of 2017, 418 W. amplexifolia plants were added, along with plants of several other native associated species. Although this project is ongoing, preliminary qualitative comparisons with an introduction at Lake Louisa State Park suggest that W. amplexifolia is more successful when introduced into habitats that already have established canopy and groundcover. If these observations are supported by the data, this information will be used to guide future introduction efforts.

Contributing Author(s): 
Date Recorded: 
Friday, May 4, 2018