University of Florida

Scott L. Stewart: Research

This page contains information related to my current research interests and projects. If you have any questions concerning a project or topic you see here contact me.

Dissertation Synopsis

My dissertation research aims to investigate the integrated conservation of native Florida Orchidaceae. Integrated conservation is the conservation of species through understanding each species' ecological, biological, reproductive, propagation, and habitat requirements. The first step in this integrated conservation plan is to simply identify and monitor known sites of selected research orchid species. This provides baseline information on distribution and population structure in nature. The second step is to understand the ecology of research species. This involves monitoring plants year-round to develop an understanding of each species' life-cycle, development habits, habitat types, and responses to environment. Along with the aforementioned data, information on pollinator mechanism and pollinators will be gathered. This will allow us to better understand the complete reproductive biology of each research species. Asymbiotic and symbiotic seed germination will also be investigated. The symbiotic seed germination studies will involve the isolation, identification and utilization of specific orchid mycorrhizal fungi in the in vitro germination of research species. Asymbiotic germination will also be studied, involving a survey of asymbiotic media, survey of carbohydrate source suitability, and experiments testing the effects of various plant growth regulators on in vitro germination and development. Finally, genetic diversity within and between existing populations of each research species will be measured with amplified fragment length polymorphism (AFLP). All these data will lead to the development of effective methods of plant production and recovery.

Current and Recent Research Topics

Integrated conservation of native Florida Orchidaceae -- This research topic utilizes five rare native Florida orchids--Habenaria distans, H. macroceratitis, Spiranthes floridana, S. brevilabris, and S. odorata--as model species to demonstrate the methods used in the integrated conservation of orchids. Along with the three abovementioned orchid species, I am also using several other native and naturalized Florida orchid species to gain a better understanding of mycorrhizal specificity, pollination ecology and biology, and mass propagation methods. A few of these other species include Habenaria repens, H. odotopetala, H. quinqueseta, all other Florida Spiranthes, Dendrophylax lendenii, Eulophia alta, and Cyrtopodium punctatum.

In vitro tuberization of terrestrial orchids as a means to improve plant reintroduction -- This research is incorporated into the integrated conservation of native orchids. Inducing tubers in vitro and using those tubers in ex vitro translocation allows for the use of plant tissues that possess a greater desiccation tolerance than seedlings with photosynthetic leaves. Paralleling the work of several Australian native orchid researchers, I will investigate the physiological, environmental and hormonal control of orchid tuber formation in an attempt to induce tubers in vitro.

Identification of Florida orchid mycorrhizae -- As part of the integrated conservation of Florida native orchids, the isolation and identification of fungal mycorrhizae from Florida orchids will be undertaken. Root samples of all Florida orchids from at least one occurrence within the state will be surveyed for mycorrhizae. Identification will follow classical methods of isolate morphology, monilioid cell morphology, isolate color, and enzyme assays. All fungi identified as orchid mycorrhizae will be catalogued and stored both in the orchid mycorrhizae collection housed in the Environmental Horticulture Department at the University of Florida and at the University of Alberta Microfungus Herbarium (UAMH).

Micropropagation of Florida terrestrial orchids -- This research is also tied directly to the integrated conservation of native orchids. Orchid seedlings originating from seed theoretically represent an excellent method of population genetic diversity maintenance, however only a limited number of plants can be produced from seed germination and those plants may take years to reach a suitable size for use in restoration efforts. Seed production in the wild must also be able to sustain both the natural population and restoration needs. Other compounding factors for the use of seed germination as a restoration means include low seed viability, genetic homology through inbreeding depression, and the introduction of deleterious alleles through outbreeding depression. Micropropagated orchids may represent a possible avenue to circumvent the aforementioned problems found in seed germination. A portion of my research is dedicated to the development of micropropagation protocols for Florida native terrestrial orchids.

Native Orchid Restoration, Conservation, and Ecology Project -- Coordinating with representatives from the U.S. Fish and Wildlife Service, Florida Panther National Wildlife Refuge, Fakahatchee Strand State Preserve, and Big Cypress National Preserve, the conservation and recovery of Dendrophylax lendenii, ghost orchid, is being undertaken. This leafless epiphytic orchid is considered state endangered in Florida and is restricted to the southernmost counties, only existing in deepwater sloughs. Little is known about the ghost orchid's current distribution, status, ecology, propagation, or fungal associations. Our research hopes to shed some light on these important factors and result in the development and implementation of a species conservation and recovery plan. In 2005 the IUCN-World Conservation Union/Species Survival Commission / North American Orchid Specialist Group named Dendrophylax lendenii as one of three North American Flagship Orchid Conservation Species. This research is directed from the Florida Panther National Wildlife Refuge (USFWS) under the co-direction of Scott Stewart and Larry Richardson. Other native orchid species the Project is currently focusing research effort on include: 1) Spiranthes odorata, 2) Eulophia alta, and 3) Cyrtopodium punctatum. The Naples Zoo and Botanical Garden is another cooperator with the project.