Smithsonian Botanical Symposium

Carlos Magdalena, Royal Botanic Gardens Kew
The many facets of botanical horticulture
In this talk, Carlos will draw on his 20 years of experience in botanical horticulture and recount some highlights of his career. In doing so, it will become apparent that the term “botanical horticulture” encompasses far more than meets the eye. While plant cultivation in a botanic garden is at the core of most botanical horticulturists’ job description, the range of skills and activities involved in conservation surpasses this. To safeguard species in a holistic manner, the emphasis cannot and should not be solely on single species conservation, but also consider the wider context that the work is set in. This includes but is not limited to local flora, habitat restoration efforts and practices, and engagement with local partners. Carlos’ talk will challenge what you understand botanical horticulture to be and explore the interdisciplinary links in plant conservation.

Carlos Magdalena is a Scientific & Botanical Research Horticulturist at the Royal Botanic Gardens, Kew, where he has been working since 2003. Over the course of more than 20 years, he has specialized in the cultivation of tropical plants. He has participated in numerous international projects and is renowned for his work to preserve critically endangered species. An expert in aquatic plants, he has been instrumental in efforts to preserve the world’s tiniest waterlily - Nymphaea thermarum - from the brink of extinction. Recently, he has led the work to describe the largest species of waterlily to science, Victoria boliviana. His 2017 book, “The Plant Messiah,” has inspired new generations of horticulturists and conservationists, raising the profile of plant conservation in the public eye. The book was translated into 10 languages and was an international success.

Jennifer Cruse-Sanders, State Botanical Garden of Georgia
From dwarf sumac, Rhus michauxii, to turkey beard, Xerophyllum asphodeloides, (and other species in between): How conservation horticulture has helped to preserve imperiled species in the southeastern U.S.
Globally, plant species diversity is fundamental for supporting ecosystem function, landscape resilience, and food security. And yet, plant species diversity is threatened with some of the highest rates of extinction in our world. It is imperative that conservation horticulture methods for propagation and restoration of species are not only developed widely, but are also shared generously to meet the pressing grand challenges we face. As one example, the southeastern U.S. is a global biodiversity hotspot, recognized as such for high rates of endemism and perceived threats to natural ecosystems. The state of Georgia, in the southeastern U.S., with some of the highest numbers of plant species diversity in the U.S., has more than 700 plant species that are imperiled and facing significant conservation challenges. Even more significant are diverse plants considered common species that are not tracked through conservation programs but are nearly disappearing before our eyes. This program will share highlights from our efforts to conserve rare species through horticultural interventions and our efforts to make common plants even more commonly available for essential conservation needs that anticipate a growing need in our communities.

Jennifer Cruse-Sanders' is the Director of the State Botanical Garden of Georgia, which celebrates its 56^th anniversary in 2024. The State Botanical Garden is a 323-acre university garden with 33 acres of cultivated gardens and more than five miles of trails through significant natural areas. As part of Public Service and Outreach at the University of Georgia in Athens, GA, the garden serves the communities of Georgia and beyond through educational programming, horticultural expertise, display gardens and conservation programs.  Jennifer has a M.S. and Ph.D. in Botany from the University of Georgia, and she completed her B.A in Biology at Boston University. She is the recipient of the 2016 Marsh Award for International Plant Conservation from Botanic Garden Conservation International, the 2016 Carl N. Becker Stewardship Award from the Natural Areas Association, and 2015 USDA Forest Service, Wings Across America International Award for Urban Communities in Conservation. Through collaborative partnerships, she has helped to build networks for conservation across the southeastern U.S. and develop community sustainability programs to establish native plants and pollinator habitats in greenspaces.

Colin Khoury, San Diego Botanic Garden
Distributions, conservation assessments, and conservation action for crop wild relatives
Crop wild relatives - the wild progenitors and cousins of agricultural crops - are valuable genetic resources used by plant breeders to increase pest and disease resistance, stress tolerance, nutritional value, and other traits critical to productivity, quality, and sustainability. Many of these species are threatened in their natural habitats and are under-represented in seedbanks and other ex situ conservation repositories, limiting the portfolio of useful plant diversity that may be available to present and future generations. In this presentation, I detail efforts at local to global scales to better understand the distributions and conservation status of the wild relatives of important crops, and to take action to address conservation concerns.

Colin Khoury is the Senior Director of Science and Conservation at the San Diego Botanic Garden, a 37-acre garden in Encinitas, California, working to conserve plants and educate people about the wonders of plant life. Colin holds a Ph.D. from Wageningen University in the Netherlands and a Master of Science from the University of Birmingham, UK, and has held posts at academic, nonprofit, industry, government, and international organizations in the US, Europe, and South America. His primary research areas include conservation science, crop diversity, food security, plant genetic resources, and crop wild relatives.

Dustin Wolkis, National Tropical Botanical Garden
Applied seed conservation biology to support seed banking
Seed banking provides the most efficient means of ex situ plant conservation. Conventional seed banking practices involve desiccating seeds to low moisture contents and storing them at a specific temperature below freezing. However, not all species can be conserved by conventional seed banking methods. Although many species produce desiccation tolerant seeds, some cannot be dried and even some desiccation tolerant species are sensitive to long-term freezing stress. Besides problems with desiccation tolerance and short life spans in conventional storage, other challenges to the ex situ conservation of seeds include the inability to acquire seeds, and the failure of viable seeds to germinate. Collectively, species exhibiting one or more of these traits have been termed “exceptional.” The flora of the Hawaiian Islands harbors 90% vascular plant endemism, yet globally has experienced the highest number of contemporary plant extinctions. Using the Hawaiian flora as a model system this presentation will explore some of the mechanisms underlying species defined as exceptional and discuss methods in which to overcome obstacles to ex situ seed banking. The applied projects presented will be broadly relevant beyond seed science including species and land managers and to the field of conservation horticulture.

Dustin Wolkis is the Scientific Curator of Seed Conservation at the National Tropical Botanical Garden (NTBG) headquartered on Kauaʻi, in Hawaiʻi. In his role he curates NTBG’s conservation seed collection and is the principal investigator for seed conservation research. Dustin is especially interested in seed longevity and wild species exhibiting anomalous responses to conventional seed storage methods. Dustin received his Ph.D. from the University of Copenhagen in 2023 and holds a MS in Plant Biology and Conservation from Arizona State University. He is Deputy Chair of the IUCN Species Survival Commission Seed Conservation Specialist Group, and Affiliate Graduate Faculty in Botany at the University of Hawaiʻi at Mānoa. He enjoys fantasy novels, playing drums, and spending as much time as possible with his family at the beach and in the mountains on Kauaʻi.

Abby Meyer, Botanic Gardens Conservation International
Conservation horticulture capacity at botanic gardens
Conservation horticulture refers to the skills and knowledge required to maintain plants of conservation concern in ex situ living collections. This is a fundamental and expanding area of expertise that is often and uniquely manifested through the work of botanic gardens. As we face major environmental and social crises around the world, the conservation and outreach work of botanic gardens is becoming more and more imperative. Specialists in conservation horticulture are more important than ever as the plant conservation community scales-up our collective efforts to halt species extinction. This presentation will describe the current state of conservation horticulture in botanic gardens globally and provide examples of how BGCI is working with partners to promote awareness of and capacity for this critical area of expertise.

Abby Meyer leads the U.S. office of Botanic Gardens Conservation International, based at The Huntington Library and Botanical Gardens in Los Angeles, California. Abby works to provide tools and information to build botanic garden plant conservation collections and capacity. She is particularly interested in tracking botanic garden progress toward the targets of the Global Strategy for Plant Conservation and the parallel North American Botanic Garden Strategy for Plant Conservation. Abby received a bachelor’s degree in Horticulture from the University of Nebraska-Lincoln and a master’s degree in Public Horticulture Administration in the Longwood Graduate Program at the University of Delaware and Longwood Gardens. Prior to her work with BGCI, she was a Putnam Research Fellow at The Arnold Arboretum of Harvard University where she developed new approaches for assessing the conservation value of living plant collections.

Morphological Plasticity and N-fixation of Pterocarpus officinalis Jacq. as an Index of Acclimation in Differing Wetlands 
Authors: Isabel Alayón Rivera^1,3, Solimar Pinto Pacheco^2,3, and Elvira Cuevas^1,3
Affiliations: ¹Department of Biology, Faculty of Natural Sciences, UPR-Río Piedras, ²Department of Environmental Sciences, Faculty of Natural Sciences, UPR-Río Piedras, ³Center for Applied Tropical Ecosystems and Conservation, UPR-Río Piedras

Abstract
Pterocarpus officinalis Jacq. is a N-fixing tree species that inhabits Caribbean wetlands, where individuals are exposed to varying waterlogging conditions that can affect their survivorship and productivity. Our objective was to determine how they acclimate to varying environmental conditions by assessing their ecophysiological response under contrasting hydrological conditions. Do leaf traits respond to variable soil saturation? Does provenance of juveniles influence leaf traits when exposed to the same environment? Research is being carried out in Puerto Rico at the common garden experiment at Northeastern Ecological Corridor with juveniles from Dorado and Punta Viento provenance. Specific Leaf Area (cm2/g), leaf water content (LWC; %) and soil gravimetric water content (GWC; %) were determined for adults and juveniles during moist (Sep-Oct 2023) and waterlogged (Feb-Mar 2024) conditions. We hypothesize that leaf traits will respond to soil saturation variability among tree age and provenance. Results indicate the waterlogged period had significantly higher GWC (p-value <0.0041) than the moist period for all groups. Consequently, Dorado and Punta Viento juveniles had significantly higher LWC during waterlogged conditions (p-value <0.0039 and p-value <0.0001,respectively) due to greater water availability and tree development. Our results aid a scientifically based understanding of species response that can be used for wetland management, restoration and reconstruction.

Joining Forces to Support Conservation of Exceptional Tree Species in the United States
Author: Pamela Allenstein
Affiliation: American Public Gardens Association, Wilmington, Delaware. 

Abstract
American Public Gardens Association and the USDA Forest Service are working together to safeguard tree species native to U.S. forests which cannot be conserved through traditional seed banking methods. Our Tree Gene Conservation Partnership awards matching grants to Association members to support collaborative projects which scout and collect targeted taxa in wild populations, then distribute propagules among public gardens for safeguarding in living collections. This partnership launched in 2015 has awarded over $300,000 in grants contributing to the conservation of 43 tree species in 25 states and Puerto Rico. Diverse collaborations among over 70 public gardens, state and federal agencies, universities, forest industry, and conservation alliances have participated in the partnership. 

Growing Endangered and Vulnerable Maryland Plants in Suburban Gardens
Author: Edward M. Barrows
Affiliation: Professor Emeritus, Department of Biology, Georgetown University, Washington, D.C. 

Abstract
With little effort, I have grown legally-obtained Larix laricina (Tamarack, deciduous conifer), Phacelia covillei (Blue Scorpionweed, annual herb), and Valeriana pauciflora (Large-flowered Valerian, perennial herb) in my naturalistic garden in Bethesda, Maryland about 0.5 mile from the Potomac Gorge. Larix laricina and V. pauciflora are Maryland endangered species, and P. covillei is a U.S. vulnerable species. Two L. laricina seedlings, collected from a floating-bog mat in Kiwassa Lake, New York in 1998, grew into small trees. One tree died in 2019; perhaps from its oozing, trunk cankers, dry soil, or both; and the other tree is growing well in 2024. Several P. covillei plants, collected from the Gorge in 2005, self-seeded, gave rise to thousands of plants growing in my garden in 2024, and flowered annually. I obtained a Gorge Valeriana pauciflora specimen from the U.S. Botanic Garden in 2005 and planted its ramets in pots. They produced stolons which overgrew their pots, started three vigorous colonies in my garden’s ground, and bloomed annually. Offspring of my P. covillei and V. pauciflora are also thriving in other local suburban gardens.

Plant Science at the United States Botanic Garden: Creating a Five-Year Strategic Plan for Science
Authors: *Destiny J. Davis^1,2, Devin Dotson¹, Steve Jones¹, Kyle Wallick¹, Ray Mims¹, Grace Anderson¹, and Susan K. Pell¹
Affiliations: ¹United States Botanic Garden, ²American Association for the Advancement of Science. *presenter

Abstract
With a legacy dating back to 1820, the United States Botanic Garden (USBG) has a long history of botanical science. To unite our history with current global challenges, we are reinvigorating science at the USBG by centering our scientific efforts around our most valuable resources–the plants in our care, our expertise, and our facilities. The USBG has developed a five-year strategic plan for science to formalize its scientific efforts in line with its mission to inspire people to appreciate, study, and conserve plants to enrich society locally and globally. Developed by an interdisciplinary team of USBG employees, the Plan for Science lays the foundation for a science program guided by the USBG strategic plan and the USBG Collections Management and Curatorial Policy. The Plan for Science outlines three major priorities—plant conservation, horticultural excellence, and science communication—to formalize ongoing work and inspire future scientific projects. Leveraging its federal funding and position within the legislative branch, the USBG convenes collaborations across sectors to magnify scientific impact. We aim to expand these strategic partnerships, create internal research opportunities, support horticultural innovation and collaboration, and infuse USBG scientific projects with engaging educational opportunities and impactful communication strategies. A summary of the development process, goals within the Plan for Science, and an overview of current and future scientific work will be presented.

Field Demonstrations for Water Chestnut (Trapa spp.) Management – Year 1
Authors: Lynde Dodd¹, *Ryan McIntyre^2,3, Kristina Hellinghausen^2,4, Nancy Rybicki³, Christopher Mudge¹, and Benjamin Sperry¹
Affiliations: ¹U.S. Army Engineer Research and Development Center; ²Oak Ridge Institute for Science and Education, Oak Ridge, TN; ³George Mason University, VA; ⁴Univeristy of North Texas, Denton, TX. *presenter

Abstract
Collaborative applied research conducted under the U.S. Army Corps of Engineers’ Aquatic Plant Control Research Program is currently developing management strategies of introduced water chestnut species, Trapa natans and T. bispinosa var. iinumai. While much information exists on management in the U.S., specifically targeting T. natans, knowledge gaps exist in translating management strategies from one congener to another, and whether currently employed strategies are successful in reducing impact and spread of this invasive aquatic plant. Demonstrations and lessons learned from Year 1 of a 2-year project work focus on determining what management approach works best in an operational setting to control two water chestnut species. While not all known strategies are reviewed, those currently being implemented and recent findings from greenhouse and mesocosm studies were demonstrated during the summer of 2023 at field sites in NY for T. natans, and in VA and MD for T. bispinosa. Preliminary results indicate that foliar herbicide applications work well to reduce biomass for both species of water chestnut, but that biomass harvesting strategies employed for T. natans will need further investigation for implementation large-scale for T. bispinosa control. Findings from this 2-year study will be used to refine water chestnut management strategies.

The Evolutionary History of the Cherry/Plum Genus Explains Modern Horticultural Crops Adapted to Diverse Environments
Author: Richard G.J. Hodel
Affiliations: Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, DC and Data Science Lab, Office of the Chief Information Officer, Smithsonian Institution, Washington, DC

Abstract
In the cherry/plum genus, Prunus (Rosaceae), there are several economically important fruit crops, including almonds, apricots, cherries, peaches, and plums. Some of these, such as almonds and apricots, evolved to thrive in warm, sunny, dry climates. Meanwhile, cherries and plums typically occupy cooler, wetter climates. Why has this clade been so successful at producing crop species that survive in different environments? The answer may lie in the evolutionary history of this clade. I merged genomic, environmental, and phenomic data associated with herbarium specimens from the US National Herbarium to reconstruct the evolutionary history of this genus. Biogeographic analyses revealed that over the past ~55 million years, the genus has occupied a wide range of tropical habitats, as well as developing adaptations allowing it to transition into the north temperate zone. Genomic analyses suggest that hybridization and/or genome doubling may have provided the novelty enabling this group to adapt to many different environments. A machine learning approach with digitized herbarium specimens identified shifts in key morphological features that may have facilitated adaptation to novel environments. The evolutionary history of this clade may explain its abundance of successful horticultural crops, and suggest ways to conserve functional diversity in the future. 

Creation & Use of the Newly Created Southeast Texas Native Seed Mix (SET NSM) to Replace Non-Native Grasses in 8-County Greater Houston Region (Texas)
Author: Deborah January-Bevers
Affiliation: President, Houston Wilderness, Texas

Abstract
The newly created Southeast Texas Native Seed Mix (SET NSM) is a collection of twelve native grass species developed over a 2-year period of data analysis in two demonstration areas in north and south Harris County (Texas), planted in Vertosol and Alfisol soils respectively, as an alternative to use of non-native grasses such as Bermudagrass and St. Augustine. Non-native grasses have been widely planted in this 8-county region for decades on thousands of acres of residential, commercial and public lands – including along the myriad of waterways, channels and detention basins leading to Galveston Bay and the Gulf of Mexico. There are significant opportunities to improve human health, climate resilience, and biodiversity by planting the SET NSM in place of nonnatives because the SET NSM is fast growing and able to be included in large-scale contract specifications that allow for deeper root systems to store water and reduce erosion in flood conditions, provide resilience to drought conditions, improve air and water quality, enhance regional soils and provide critical habitat. This poster details the testing and analysis process performed by the collaborative of scientific, governmental and NGO groups to create the 12-species SET NSM and discusses the current steps to assist with access to and communication about use and availability of the SET NSM through a Regional Access to Native Seed Mix (RANSM) Coalition - comprised of SET NSM buyers and Texas native seed growers.

Conservation Genetic Analysis of Ozark Milkvetch (Astragalus distortus; Fabaceae)
Authors: Emily Poindexter¹, Ashley Morris², and Andrea Weeks¹
Affiliations: ¹George Mason University, Fairfax, Virginia; ²Furman University, Greenville, South Carolina

Abstract
Ozark Milkvetch (Astragalus distortus Torrey & A. Gray; Fabaceae) is a small, herbaceous perennial that is native to the south-central United States and Maryland, Virginia, and West Virginia. Across the south-central U.S. the species is commonly found in sunny glades and grasslands, whereas in the mid-Atlantic states it grows exclusively on shale barrens and is Imperiled (Maryland, West Virginia) and Critically Imperiled (Virginia). This project uses comparative genetic methods to resolve questions about the species’ taxonomy, genetic diversity, and evolutionary history. Presently, two taxonomic varieties of Ozark Milkvetch are recognized. Astragalus distortus var. engelmannii can be found in Texas, Louisiana, and Arkansas, overlapping with A. distortus var. distortus, which spans the species’ entire range. A population genetic analysis will show if these varieties are genetically distinct and evolutionarily separate groups and will determine if the Mid-Atlantic metapopulation warrants separate taxonomic recognition. Additionally, understanding the genetic diversity within and among mid-Atlantic populations of Ozark Milkvetch will be invaluable for guiding regional and ongoing conservation efforts for this species. 

Arbuscular Mycorrhizal Fungi Associated with Coffee Plants in Puerto Rico
Authors: Jeiliany Rodríguez Pizarro, Diana P. Buitrago, and Paul Bayman
Affiliation: Department of Biology, University of Puerto Rico - Río Piedras Campus

Abstract
Arbuscular mycorrhizal fungi (AMF) form mutualistic symbioses with more than 80% of terrestrial plants. The benefits that AMF provide to plants include increasing nutrient absorption (mainly phosphorus), exclusion of pathogens, and resistance to water and thermal stress. Due to climate change, an increase in temperature is expected to affect various crops, including coffee. It is imperative to identify AMF that promote resistance in coffee; DNA sequencing is a much more precise way of identifying species. DNA was extracted from soil samples collected at four coffee farms in Adjuntas, Lares, Ciales and Orocovis, Puerto Rico for a total of 32 samples. For each sample, pH and elevation were obtained. The next steps are to sequence the soil samples and map trends in AMF community composition. With this information, coffee seedlings could be inoculated with specific AMF to determine which best protect them from pathogens, increased temperature, and water stress.

Bee-friendly Beef: Integrating Native Wildflowers into Traditional Grazing Systems
Authors: Erin Shibley and Natalie Izlar
Affiliation: Smithsonian's National Zoo and Conservation Biology Institute, Virginia Working Landscapes

Abstract
Pollinator communities in the eastern U.S. have experienced significant population declines due to land use conversions and decreased floral resource availability. The “Bee-friendly Beef” study explores an approach to pollinator conservation through the integration of native wildflowers into traditional grazing systems. In partnership with Virginia Tech and the University of Tennessee, researchers from the Smithsonian’s Virginia Working Landscapes (VWL) are working with six cattle producers in Northern Virginia to conduct a series of on-farm trials to document the impacts of planting wildflowers into livestock pastures dominated by nonnative vegetation communities. In 2022, each producer planted a native wildflower seed mix in areas ranging from 1.25-6 acres in actively grazed pastures. VWL researchers are monitoring wildflower establishment success and persistence and pollinator abundance and preference on these working cattle farms. Two seasons of monitoring post-wildflower planting are revealing site-specific and interspecies variation in wildflower establishment success. Preliminary data on pollinator communities indicate greater abundance of multiple taxa in wildflower-enhanced pastures compared to control pastures. After a final year of data collection in 2024, study results will be used to help inform native wildflower planting resources and recommendations for livestock producers to support pollinator-friendly grazing practices while maintaining production goals.

Unraveling the Diversity and Evolutionary Dynamics of North American Grapes: Crucial Insights for Conservation and Breeding Programs
Authors: *Alicia Talavera^1,2, Richie Hodel^1,3, Gabriel Johnson¹, Elizabeth Zimmer¹, Alex White³, and Jun Wen¹ 
Affiliations: ¹Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, DC, ²Departamento de Botánica y Fisiología Vegetal, Universidad de Málaga, Spain, ³Data Science Lab, Office of the Chief Information Officer, Smithsonian Institution, Washington, DC. *presenter

Abstract
Grapes are the most economically important fruit crop in the world. Despite their importance, their systematics, drivers of diversification and the species delimitation remain poorly understood. Hybridization has been suggested as a driving force in Vitis, however, phylogenomic analyses are needed to unravel evolutionary processes and testing species delimitation in several North American species complexes. In this study we explore two of its most puzzling species complexes: V. cinerea and V. aestivalis. Both complexes include essential species for horticulture, serving as rootstock resistant to phylloxera, and offering good wine-making properties. Evolutionary relationships of these species complexes were assessed in a broad framework of North American Vitis, using newly developed baits for Vitaceae and dense taxon sampling within these complex species. Hybridization events were tested, and principal component analyses of the environmental variables were used to assess ecological differentiation in the diversification. The results of this study are essential for conservation of the diversity in North America, since it provides evidence to propose better conservation strategies in the global trend of decline in biodiversity. But also, it is fundamental for breeding programs. Moreover, the data generated will be available in public repositories and it will be greatly beneficial to the grape community across the world.

2001    Linnaean Taxonomy in the 21st Century
2002    The Convention on Biological Diversity
2003    Botanical Frontiers in Southeast Asia
2004    Botanical Progress, Horticultural Innovations, and Cultural Changes
2005    The Future of Floras: New Frameworks, New Technologies, New Uses
2006    Island Archipelagos: Cauldrons of Evolution
2008    Partners in Evolution: Interactions, Adaptations, and Speciation
2009    Genes, Genomics and Genome Evolution in Plants
2010    Food for Thought: 21st Century Perspectives on Ethnobotany
2012    Transforming 21st Century Comparative Biology using Evolutionary Trees
2013    Avoiding Extinction: Contemporary Approaches to Conservation Science
2014    Location, Location, Location...New Advances in the Science of Biogeography
2015    Next Generation Pteridology: An International Conference on Lycophyte & Fern Research
2016    Bats, Bees, Birds, Butterflies and Bouquets: New Research in Pollination Biology
2017    Exploring the Natural World: Plants, People and Places
2018    Plants in the Past: Fossils and the Future
2019    What Darwin Couldn't Know: Modern Perspectives on Crop Plant Origins
2021    Plant Symbiosis: The Good, the Bad, and the Complicated
2022    Life on the Edge: Exceptional Plants in Exceptional Place
2023    New Horizons in the Study of Neotropical Floras