From Plant Press, Vol. 25, No. 3, July 2022.
The 19th Smithsonian Botanical Symposium, co-hosted by the Smithsonian’s Department of Botany and the United States Botanic Garden (USBG), made a welcome return to the National Museum of Natural History’s (NMNH) Baird Auditorium on May 13, 2022, three years after the last time the event was held in person. The Symposium, “Life on the Edge: Exceptional Plants in Exceptional Places,” was a hybrid event, bringing together five engaging speakers to present their research to both in-person and virtual audiences from around the world. The invited speakers included scientists specializing in conservation, ecology, systematics, and genetics whose research explores plant adaptation and survival in extreme parts of the natural world. The speakers talked about their research on plants (and lichens) growing in exceptional environments, from the tepuis of the Guayana Shield and the steep cliffs of Hawaii to the South African Fynbos, the Mojave Desert, and even New York City. They spoke about natural history and evolution, and the challenges plants endure in the face of climate change and increasing pollution.
Eric Schuettpelz, NMNH Chair of Botany, welcomed the audience to the symposium and Rebecca Johnson, NMNH Associate Director for Science and Chief Scientist, provided opening remarks. In her comments, Johnson talked about a project, “Life on a Sustainable Planet,” currently in development at NMNH, and she tied the project to the theme of the symposium. She described the new project as, “understanding, explaining, and amplifying the reach, relevance, and impact of the work here at the Smithsonian,” and the relevance to the tens of thousands of species 'on the edge'. Susan Pell, USBG Deputy Executive Director, also provided opening remarks and gave an orientation to the USBG, including a description of the living collections, current online and in-person programming, and their scientific and conservation partnerships.
Kenneth Wurdack, NMNH Department of Botany, presented the annual José Cuatrecasas Medal for Excellence in Tropical Botany to Fabián A. Michelangeli, curator of tropical botany at the New York Botanical Garden in the Institute of Systematic Botany where he conducts research on Melastomataceae. Michelangeli, who did double duty as invited speaker and award recipient, accepted the award as a tribute to his advisors, colleagues, and “most of all, [his] students and postdocs that have helped [him] be a little bit relevant.”
The first presentation of the symposium was delivered by Jenna Ekwealor from Smithsonian’s OCIO Data Science Lab. Her talk, "The secret lives of desert moss,” explored the vegetative growth and the sexual reproduction of these exceptional desert plants. Her talk focused on species in the genus Syntrichia, which includes many dryland specialists and the most desiccation-tolerant plants known. After finding a population of Syntrichia caninervis growing underneath rocks in the Mojave Desert, she set out to characterize this habitat including understanding the community composition, measuring and quantifying the light transmitting through the rock, and characterizing the hypolithic microclimate. She characterized the Mojave moss community as including Syntrichia caninervis (abundant both on the surface and under quartz rocks), Tortula inermis (more abundant under quartz rocks), and Bryum argenteum (found just once on the surface). She found that rocks buffer from extreme temperatures—cooler under the rocks during the day and warmer at night, except during snowfall where the rocks provide a warming effect during day and night. She found higher measures of humidity under the quartz, thus providing protection from desiccation. In measuring light intensity transmitting through the quartz, she found that mosses receive low light under rocks, but they also get different quality of light—bigger wavelengths and less ultraviolet radiation.
In the second half of her presentation, Ekwealor spoke about an extreme sex ratio bias in Syntrichia caninervis. Studies show that phenotypic males are rare, with at least five females for every male. Many individuals of this species can be non-expressing without making sex organs. Do males express their sex less frequently or are males actually rare in this species? Ekwealor used a new restriction-fragment length polymorphism technique that amplifies a gene on the sex chromosome to determine genotypic sex in Syntrichia. She found an 18:1 ratio of females to males in non-expressing individuals, demonstrating that males really are rare in this Mojave population. The next step, she explained, is to understand why—is female clonal growth rate faster or is male mortality higher? She found evidence that both processes are present and said that more work is necessary to tease these hypotheses apart.
Fabián Michelangeli from the New York Botanical Garden gave the second presentation, “Endemism and adaptations in the flora of the lost world.” He began with some history about the first scientific explorations of tepuis, table form mountains in the Guayana Shield. He also spoke about tepuis in popular culture, such as Conan Doyle’s book, “Lost World”, and Disney’s movie, ‘Up”. In describing the geology, he talked about how these 40-45 summits were formed, and in describing the variety of plant environments, he talked about how tepuis are very biologically rich with about 2,600 plant species and 885 endemic species. A few species endemic to tepuis are found on multiple summits, but many more species are locally endemic to a single or a couple of summits. He explained that species richness correlates well with isolation and summit area, following classical island biogeography patterns, but more data is needed as sampling effort varies—some summits are easily accessible by hiking and have thousands of specimens in herbaria, whereas other summits can only be reached by helicopter and have not been sampled as frequently.
In describing the flora of tepuis, Michelangeli said that Orchidaceae, Melastomataceae, Rubiaceae, Asteraceae, and Bromeliaceae are the plant families with the most species. He expressed surprise that Fabaceae and Euphorbiaceae, two very large tropical families, are conspicuously absent from tepuis, and that the presence of uncommon families that are important elements of tepuis are dominant, like Xyridaceae and Rapateaceae. He explained that cosmopolitan tribes within families like Asteraceae that are very common in the Andes or the Amazon are not the same tribes that are common on the top of tepuis. While displaying stunning photographs of flowering plants, he explained that the combination of high elevation, high radiation, low pH, and few nutrients has created a unique tepui syndrome of plants with small thick leaves and few compound leaves. Low nutrients has also led to a diverse selection of carnivorous species that have evolved on rock environments and in bogs. He wrapped up his talk by speaking about the threats of mining and other illegal activities that threaten the flora of tepuis.
After the first coffee break, Tanisha Williams from Bucknell University spoke about “Protecting the Fynbos: climate change insights from South Africa.” After a brief introduction about the effects of climate change on global biodiversity, she turned her focus to South Africa, an exceptional place with a rich flora. Certain local regions of South Africa are already experiencing extreme levels of heat, droughts, and floods. A video she shared touched upon the Cape Town water crisis and the inequalities of water access on the local communities. Centering in on the Fynbos, a shrubland biome with a Mediterranean climate housed in the Cape Floristic Region, Williams spoke about the diverse flora and the various ways that plants have adapted to this ecosystem.
Using Pelargonium (Geraniaceae) as a case subject, Williams talked about how Fynbos plants are responding to rapid climate change. In her research she examined phenological records, conducted common garden experiments, and modeled species distributions. She shared herbarium records that showed a 12-day advancement of flowering over the past century. Her garden experiments showed that Pelargonium species exhibited significant levels of morphological variation in response to the environment, but responses by the plants were not favorable in hot and dry environments. Her species distribution maps showed that the species will respond to a precipitation gradient, with habitats shrinking through 2070. Williams expressed hope, though, that Fynbos species have the ecological and evolutionary tools to mitigate and respond to climate change. She ended her talk by recommending Black Botanist Week, a social media campaign that promotes, encourages, creates a safe space for, and finds more Black people who love plants.
Ben Nyberg from the National Tropical Botanical Garden followed with “A conservation airlift: applications of drone technology in plant conservation.” He described the Hawaiian Island of Kaua'i as having a rich flora with nearly 90% endemism and 250 single-island endemic species within an area of 550 m2. The island’s most diverse plant families include Campanulaceae, Rutaceae, and Rubiaceae. With 90 species on the edge of extinction, Nyberg described how exploration, seed collection, and propagation are all important in conserving these exceptional species. Rare plant refugia models place hotspots for rare species in cliff environments, spots often too steep or difficult to reach. Nyberg described the use of drones for botanical surveys in these hard-to-reach areas. In describing his methods, he shared awe-inspiring high-resolution images and videos retrieved from drones showing rare and threatened species along precipitous Kaua'i cliffs. He spoke about his methods in assessing the images, tagging species, creating 3D maps, and developing models to locate other individual plants. He demonstrated these methods by showing how Hibiscadelphus woodii, once believed to be extinct, was rediscovered with drone technology. He then shared a table of 10 Critically Endangered species where, with the use of drones, the number of known individuals in each population was found to be double, triple or more.
Nyberg also described how drone technology can assist in plant collecting and seed propagation. He shared images and videos of his team using drones to collect seeds and cuttings from inaccessible, cliff-dwelling species, like Lysimachia iniki, Kadua st-johnii, and Isodendrion pyrifolium. He spoke about finding undescribed species, such as a new Schiedea, and the ability to take cuttings from these plants to then grow them in greenhouses for further research. He explained that frequent extreme storms have led to landslides that have further degraded cliff habitat. To restore these habitats, he said that drones can be used to spray a hydro-mulch mix for plant propagation.
After the second coffee break, Jessica Allen of Eastern Washington University gave the final presentation, “Urban lichens: symbioses in the built environment,” which brought the conversation much closer to home for many audience members. She described urban environments as extreme, where it is hotter, drier, more disturbed, and with more pollution than surrounding natural areas. And yet, she said, densely urbanized areas are incredible living laboratories for studying biodiversity due to the detailed baseline for organisms that live there. She turned to lichens, in which she described as “not plants, but they are exceptional, an obligate symbiosis between fungi and algae, and both of those partners have to live together to form these beautiful and diverse organisms.” She detailed historic surveys of lichens in New York City, from J. Torrey’s 1819 study (61 lichen species) and A. Halsey’s 1823 study (191 species), to C.C. Wood’s 1914 study (51 species) and I. Brodo’s 1968 study (8 species). Allen conducted her own lichen survey in 2017 and counted 106 species. She explained that the fluctuation in species count is due to the changing built environment of the city and the shifting air quality.
Allen recounted which species have been lost, such as Usnea strigosa (not seen since the 1800s), which ones have persisted, such as Cladonia caespiticia, and which ones have recolonized the city, such as Flavoparmelia caperata. She described an unsuccessful transplant study in which she attempted to bring back to the city Cladonia subtenuis and Usnea mutabilis. She argued that assisted recolonization is challenging and that lichens need to come back on their own. She concluded her talk with a list of outstanding questions in urban lichenology, from whether there are specific genotypes adapted to urban conditions to which genes are under selection in urban populations.
The symposium ended with a panel discussion moderated by Susan Pell (USBG) with questions from the in-person and virtual audiences to the five speakers. Questions included: where do you think we are on the discovery curve of understanding plant dynamics in extreme environments?; how do you advocate outside of the botanical community for the conservation of the species or habitats that you study?; what advice would you give to botany students just starting out?; how do plants and lichens adapt to climate change?; what are synergies that you see between water conservation engagement and land conservation engagement?; where does horticulture overlap with botany and how do we create more collaborations?; and in a 30-second elevator pitch, what's the most fascinating aspect of your research or what would you want everybody to take away from your presentations here today? To hear the fascinating responses to these questions by all five speakers, a video of the panel discussion is available on YouTube.
“Wish to be wrong, because when you are wrong that's when the questions come. If you want to be wrong, you become a better scientist.”
- Fabián Michelangeli, in answering the panelist question, “what advice would you give botany students just starting out?”“Even these little, tiny mosses that are in the desert and seem very niche are actually really fundamentally connected to all of us.”
- Jenna Ekwealor, in giving a 30-second elevator pitch about what she would want everybody to take away from her presentation.
The symposium attracted nearly 400 people. Those who viewed the proceedings online watched from 20 countries from around the world. All speaker presentations, opening remarks, the presentation of the José Cuatrecasas Medal, and the roundtable panel discussions were recorded and are available for viewing at NMNH’s Natural History for Scientists YouTube page.
The 20th Smithsonian Botanical Symposium is scheduled to take place at the National Museum of Natural History and the U.S. Botanic Garden on Friday, May 19, 2023. The topic is still to be determined. Check the Department of Botany’s website for updates.
Video playlist of the 19th Smithsonian Botanical Symposium:
Comments