Reproductive Ecology of a Rare Florida Endemic Mint, Macbridea alba

Brenda Molano-Flores, Illinois Natural History Survey, University of Illinois: Urbana-Champaign, Sara Johnson, Department of Natural Resources and Environmental Science at University of Illinois: Urbana-Champaign, & Janice Coons, Eastern Illinois University

Macbridea alba (Lamiaceae) is a federally threatened and state endangered perennial herbaceous mint. It is endemic to grassy pine flat woods and occupies a range of conditions from wet savannas and sand hills, to disturbed roadsides. Several studies have been conducted to assess genetic diversity, pollinators, breeding system, and seed germination in Macbridea alba. In addition, work associated with seed banking and flowering in relation to fire has only been published in abstract form making replicability difficult and most of this work has been limited to a few populations. Results from these studies point to: 1) low levels of genetic diversity, 2) need for pollinators such as Bombus spp to facilitate gene flow and fruit/seed production, 3) seed germination is high, 4) vivipary occurs, 5) seeds have limited long-term storage capacity and a lack of dormancy, 6) and flowering may decrease as time since fire increases. However, two areas that have not been fully explored are the reproductive success (i.e., fruit set, seed set, and germination) and pre-dispersal seed predation across multiple populations and their role in the long-term persistence of Macbridea alba populations. In 2019, seven Macbridea alba populations within Apalachicola National Forest were visited to better understand the reproductive ecology of the species. At each site, infructescences were collected and fruit set, seed set, herbivory, and pre-dispersal seed predation were documented. Also, information about vivipary, i.e. premature germination of the seed within the calyx, was gathered. Lastly, collected seeds were used to assess seed germination. Our preliminary results are showing variation among populations for all the metrics that have been measured. Based on these findings, we can better understand the life history strategies and reproductive ecology of this rare plant for conservation both in-situ and ex-situ in the future.

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