Plant Biology Commons^™

[Review Of The Book A Conspectus Of The North American Isoetaceae, By D. F. Brunton, J. T. Kartesz, M. Nishino, And P. C. Sokoloff]., Lytton John Musselman

Biological Sciences Faculty Publications

Isoetes (Isoetaceae; Lycopodiopsida; quillworts) constitutes a highly successful, cosmopolitan genus with over 200 species. Isoetes is derived from isos Greek for equal and eter for year, referring to the typically long persisting leaves of the sole genus in this ancient plant family. The leaves resemble a ‘quill-of-feather,’ hence the common name ‘Quillworts,’ wort, from old Germanic wurti, meaning plant. In large measure due to its simple form, inconspicuous appearance and negligible economic value, it represents one of the least studied and least collected of all North American genera. Isoetes constitutes a taxonomically enigmatic group with numerous polyploid species that arose …

05 - Freeze Severity And Black Mangrove Growth: Influence Of Plant Origin On Side Shoot Development, Kathryn Bourlier, Katelyn Overstreet, Erik Yando

Undergraduate Research Symposium

Despite a reduction in freeze events and subsequent expansion in the southeastern US, freeze impacts still play a critical role in mangrove morphology and local range limits. Freeze events can impair growth, limit survival, and commonly prompts side shoot development. This study examines the relationship between plant origin, freeze severity, and side shoot development in black mangroves. Our findings show that plants from each location exhibited distinct morphological responses, with similarities more closely linked to environmental conditions rather than geographic proximity. Our work offers insights into thermal tolerance thresholds and implications for mangrove stature in coastal wetlands.

Frozen Green Leaves As Potential Nutrient Subsidies In North American Mangrove Ecosystems, Katelyn Overstreet, Emily M. Dangremond, Ilka C. Feller

Biological Sciences Faculty Publications

Avicennia germinans, the black mangrove, has shifted its range limit northward, and increased in abundance in the Southeastern United States. In January 2018, a 3-day freeze event caused substantial defoliation of green leaves in A. germinans near its northernmost range limit in St. Augustine, FL. During their recovery, plants that lost their leaves grew similarly to plants fertilized with nitrogen, leading to the hypothesis that freeze-killed green leaves (frozen green) may have acted as a fertilizer. To assess the value of frozen green litter as a nutrient subsidy, we performed an experiment in which A. germinans seedlings were grown …

Wetlands In Our Backyard: A Review Of Wetland Types In Virginia State Parks, Kirsten Bauer, Benjamin K. Campbell

Virginia Journal of Science

Wetlands constitute a significant component of Virginia’s natural resources and heritage. Though historically they have been discounted—and often denigrated—the exceptional value of wetlands is currently growing in recognition and appreciation. In addition to the value provided by extracted resources and ecological regulation, wetlands also offer people the opportunity to enrich themselves through cultural, educational, and recreational pursuits. The state parks of Virginia provide access to a variety of ecosystems, including a wide array of wetland types. In this review, we document the diversity of wetlands in Virginia State Parks through a typology that groups wetland systems into the three principal …

Geomorphic Gradients In Shallow Seagrass Carbon Stocks, Jahson Berhane Alemu, Siti Maryam Yaakub, Erik S. Yando, Rachel Yu San Lau, Cheng Chang Lim, Jun Yu Puah, Daniel A. Friess

Biological Sciences Faculty Publications

Seagrass meadows are important sinks of organic carbon (C_org), in particular the near-surface C_org pool (≤ 15 cm) compared to deeper sediments. Near-surface carbon is highly susceptible to disturbance and loss to the atmosphere, however, inadequate accounting for variability in this pool of carbon limits their uptake into carbon accounting frameworks. We therefore investigated the spatial variability in seagrass near-surface C_org and biomass C_org across different geomorphic (estuary, lagoonal and reef-associated) and community typologies (pioneer and persistent). Near-surface C_org stock in vegetated areas (25.78 Mg C_org ha⁻¹ ± 26.64) was twice that …

How Wetland Plants Deal With Stress, Taylor M. Sloey

Biological Sciences Faculty Publications

We all get stressed. To deal with that stress, some of us may exercise, take a bubble bath, cry, or simply leave the stressful situation. But how can you cope with stress if you are rooted in place? Plants that live in estuaries are exposed to many types of stresses from the environment, including flooding, high salt levels, low soil oxygen, and waves. Fortunately, wetland plants have developed ways to survive within these conditions, from excreting salt, to growing faster, to even breaking down cell walls to maximize air flow. Plants can tolerate different levels of stress depending on their …

Semi-Supervised Adversarial Domain Adaptation For Seagrass Detection Using Multispectral Images In Coastal Areas, Kazi Aminul Islam, Victoria Hill, Blake Schaeffer, Richard Zimmerman, Jiang Li

Electrical & Computer Engineering Faculty Publications

Seagrass form the basis for critically important marine ecosystems. Previously, we implemented a deep convolutional neural network (CNN) model to detect seagrass in multispectral satellite images of three coastal habitats in northern Florida. However, a deep CNN model trained at one location usually does not generalize to other locations due to data distribution shifts. In this paper, we developed a semi-supervised domain adaptation method to generalize a trained deep CNN model to other locations for seagrass detection. First, we utilized a generative adversarial network loss to align marginal data distribution between source domain and target domain using unlabeled data from …

Small-Scale Population Connectivity And Genetic Structure In Canada Thistle (Cirsium Arvense), Mahboubeh Hosseinalizadeh Nobarinezhad, Lavanya Challagundla, Lisa E. Wallace

Biological Sciences Faculty Publications

Premise of research. Population connectivity, the exchange of genes among geographically separated subpopulations, is thought to be a key process for the maintenance of genetic diversity and the survival of invasive species in newly colonized areas. Plant populations' degree of genetic connectivity, which occurs via pollen and seed dispersal, leads to different degrees of genetic admixture and genetic structure. Environmental barriers and differential selection pressures that are variable across time and space tend to alter genetic structure within and among populations via restriction or facilitation of gene flow. Canada thistle, an invasive species of the United States and Canada, is …

Molecular Systematics Of Isoëtes (Isoëtaceae) In Eastern North America, Peter William Schafran

Biological Sciences Theses & Dissertations

Isoëtes (Isoëtaceae, Isoetales, Lycopodiophyta) is a cosmopolitan genus of aquatic lycophytes, occurring on every continent except Antarctica. Of approximately 200 total taxa, about half are in a clade of species mostly occurring in North and South America. Eastern North America accounts for 22% of global taxonomic diversity, containing 32 fertile taxa and 16 named hybrids. This taxonomic diversity is built upon relatively little morphological difference, and even combined with phylogenetic analysis using several nuclear and chloroplast DNA markers, no well-resolved systematic treatment within this clade exists.

This study aims to clarify the relationships between all species and subspecies of Isoëtes …

Pollinator Visitation Frequency Associated With Native And Non-Native Plants In A Mid-Atlantic Piedmont (Usa) Urban Garden, Nicholas J. Ruppel, Saunders M. Riley, Ellis D. Mumford, Barbara L. Swedo

Virginia Journal of Science

The recent focus on the importance of native plants and their pollinators has highlighted the critical role of local species in their natural environment. As urban encroachment, climate change, and invasive species continues to threaten native habitats, it is increasingly important to promote the use of local green spaces as refugia for native plants and their pollinators. The aim of this project, therefore, was to identify and assess the visitation frequency of insect pollinators associated with an urban setting within the Piedmont region of Virginia, and compare their association with native versus closely-related but non-native summer-flowering plants. Several modes of …

Low- Copy Nuclear Markers In Isoëtes (Isoëtaceae) Identified With Transcriptomes, Peter W. Schafran, Gabriel Johnson, W. Carl Taylor, Elizabeth A. Zimmer, Lytton J. Musselman

Biological Sciences Faculty Publications

PREMISE OF THE STUDY: Few genetic markers provide phylogenetic information in closely related species of Isoëtes (Isoëtaceae). We describe the development of primers for several putative low- copy nuclear markers to resolve the phylogeny of Isoëtes, particularly in the southeastern United States.

METHODS AND RESULTS: We identified regions of interest in Isoëtes transcriptomes based on low- copy genes in other plants. Primers were designed for these regions and tested with 16 taxa of Isoëtes and one species of Lycopodium. Parts of the pgiC, gapC, and IBR3 gene regions show phylogenetic signal within the North American and …

Does Channel Island Acmispon (Fabaceae) Form Cohesive Evolutionary Groups?, Mitchell E. Mcglaughlin, Lynn Riley, Kaius Helenurm, Lisa A. Wallace

Biological Sciences Faculty Publications

The California Channel Islands are unique relative to other island chains due to their close proximity to the California mainland and the fact that individual islands, or groups of islands, vary in their distance to the mainland and other islands. This orientation raises questions about whether island taxa with widespread distributions form cohesive evolutionary units, or if they are actually composed of several distinct evolutionary entities, either derived from independent mainland-to-island colonization events or divergence due to prolonged allopatric isolation. The 4 northern islands are clustered in a line (6-8 km separation among islands), while the 4 southern islands are …

Interesting, Provocative, And Enigmatic: Morphological Observations On Southeastern Quillworts (Isoetes Isoetaceae, Lycopodiophyta, Rebecca D. Bray, Peter W. Schafran, Lytton J. Musselman

Biological Sciences Faculty Publications

The unique morphology of quillworts has received limited attention, and such studies have been limited to only a few species. Our extensive field work during the past two decades has revealed variation in the structures of the plant, including the rhizomorph, scales, phyllopodia, and abscission caps. Polarity of the axes of southeastern quillwort rhizomorphs varies from discoid (most species), to elongate, to upright with axis branching in several species. In species of intermittent streams, these branched rhizomorphs produce plantlets that break off in running water. Scales are tiny brown or black structures in alternating whorls with sporophylls (leaves). They are …

Population-Level Coordination Of Pigment Response In Individual Cyanobacterial Cells Under Altered Nitrogen Levels, Jaclyn Murton, Aparna Nagarajan, Amelia Y. Nguyen, Michelle Liberton, Harmony A. Hancock, Himadri B. Pakrasi, Jerilyn A. Timlin

Biological Sciences Faculty Publications

Cyanobacterial phycobilisome (PBS) pigment-protein complexes harvest light and transfer the energy to reaction centers. Previous ensemble studies have shown that cyanobacteria respond to changes in nutrient availability by modifying the structure of PBS complexes, but this process has not been visualized for individual pigments at the single-cell level due to spectral overlap. We characterized the response of four key photosynthetic pigments to nitrogen depletion and repletion at the subcellular level in individual, live Synechocystis sp. PCC 6803 cells using hyperspectral confocal fluorescence microscopy and multivariate image analysis. Our results revealed that PBS degradation and re-synthesis comprise a rapid response to …

Isoetes Mississippiensis: A New Quillwort From Mississippi, Usa, Peter W. Schafran, Steven W. Leonard, Rebecca D. Bray, W. Carl Taylor, Lytton John Musselman

Biological Sciences Faculty Publications

Isoetes mississippiensis S.W. Leonard, W.C. Taylor, L.J. Musselman and R.D. Bray (Isoetaceae, Lycopodiophyta) is a new species known from two sites along tributaries of the Pearl River in southern Mississippi. This species is distinguished from other species in the southeastern United States by a combination of character states including a basic diploid (2n=22) chromosome count, laevigate megaspores, and a narrow velum covering less than one-third of the adaxial sporangium wall.

Molecular Phylogenetics And Historical Biogeography Of The Tribe Chiococceae (Rubiaceae), Sushil Kumar Paudyal

Biological Sciences Theses & Dissertations

Chiococceae are a monophyletic assemblage of morphologically very diverse groups of plants ranging in habit from subshrubs to shrubs to tall trees exhibiting an astonishing variation in shapes and sizes of corolla, and kinds of fruits and seeds. They are primarily distributed in the Neotropics but also occur in the West Pacific islands; thus exhibiting amphi-Pacific tropical disjunction. This study addresses the phylogenetic relationships and biogeography of the Chiococceae using molecular DNA sequence data, and presents novel data on the tribal and generic delimitations, intergeneric relationships, and the origin and dispersal of this group.

In the most recent tribal delimitations …

Predicting Carbon Isotope Discrimination In Eelgrass (Zostera Marina L.) From The Environmental Parameters- Light, Flow, And [Dic], Meredith L. Mcpherson, Richard C. Zimmerman, Victoria J. Hill

OES Faculty Publications

Isotopic discrimination against ¹³C during photosynthesis is determined by a combination of environmental conditions and physiological mechanisms that control delivery of CO₂ to RUBISCO. This study investigated the effects of light, flow, dissolved inorganic carbon (DIC) concentration, and its speciation, on photosynthetic carbon assimilation of Zostera marinaL. (eelgrass) using a combination of laboratory experiments and theoretical calculations leading to a mechanistic understanding of environmental conditions that influence leaf carbon uptake and determine leaf stable carbon isotope signatures δ¹³C. Photosynthesis was saturated with respect to flow at low velocity ~ 3 cm s^-1, but …

Characterization Of Terrestrial Dissolved Organic Matter Fractionated By Ph And Polarity And Their Biological Effects On Plant Growth, Rachel L. Sleighter, Paolo Caricasole, Kristen M. Richards, Terry Hanson, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

Background: Humic substances are ubiquitous in the environment, complex mixtures, and known to be beneficial to plant growth. To better understand and identify components responsible for plant growth stimulation, a terrestrial aquatic DOM sample was fractionated according to pH and polarity, obtaining acid-soluble and acid-insoluble portions, as well as acid-soluble hydrophobic and hydrophilic fractions using C18. The various fractions were characterized then evaluated for their biological effects on plant growth using bioassays with corn at two carbon rates.

Results: Approximately 43% and 57% of the carbon, and 31% and 69% of the iron, was found in the acid-insoluble and acid-soluble …

A Molecular Framework Phylogeny For Ptilotus (Amaranthaceae), Timothy A. Hammer

Biological Sciences Theses & Dissertations

Ptilotus (Amaranthaceae) is an Australian genus with over 100 species, most of which occur in arid Western Australia. Ptilotus has been a taxonomically difficult genus; despite rigorous morphological studies into the genus over many years, previous workers have found it difficult to delimit infrageneric groups due to inconsistent morphological variation. With the goal to establish a phylogenetic framework for the genus, 100 taxa were sampled, including 87 Ptilotus spp., and the ITS nrDNA and matK cpDNA were sequenced. The phylogeny was reconstructed using Bayesian, maximum likelihood and maximum parsimony analyses on separate and concatenated datasets. Morphological characters were assessed and …

The Ethnobotany Of Pistacia Eurycarpa Yalt. In Iraqi-Kurdistan: Its Uses, Chemical Composition, And Anti-Biotic Activity Of Its Resin, Peter W. Schafran

Biological Sciences Theses & Dissertations

Pistacia eurycarpa Yalt. is a wild relative of pistachio (P. vera L.} that grows in the Zagros Mountains. For the Kurds who inhabit these mountains the tree has practical and cultural applications. All parts of this tree have a use, for structural materials, food, and medicine. While weII known in this region, the ethnobotany of P. eurycarpa is unknown in the outside world. I spent May and June of 2011 - 2013 in Sulaimani, Kurdistan, Iraq, collecting information on this tree. In this time period I was able to witness the harvest of unripe fruits. Information about the tree …

Environmental And Physiological Influences On Productivity And Carbon Isotope Discrimination In Eelgrass (Zostera Marina L.), Meredith Leigh Mcpherson

OES Theses and Dissertations

A short-term longitudinal study was used to examine the relations of achievement motivation, general motivation, interest, and self-regulatory predictors to cognitive strategy use and academic performance. A total of 102 college undergraduates enrolled in their first college-level introductory psychology course completed an Achieving Tendency Scale of achievement motivation, the Motivated Strategies For Learning Questionnaire, and an Interest Profile in psychology during the first two weeks of the semester. At midterm they completed the Study Activity Survey of cognitive strategy use. At the end of the semester exam grades, total points earned in the course, and grade point average were obtained. …

Cumulative Response Of Ecosystem Carbon And Nitrogen Stocks To Chronic Co2 Exposure In A Subtropical Oak Woodland, Bruce A. Hungate, Paul Dijkstra, Zhuoting Wu, Benjamin D. Duval, Frank P. Day, Alisha L.P. Brown

Biological Sciences Faculty Publications

·Rising atmospheric carbon dioxide (CO₂) could alter the carbon (C) and nitrogen (N) content of ecosystems, yet the magnitude of these effects are not well known. We examined C and N budgets of a subtropical woodland after 11 yr of exposure to elevated CO₂.

·We used open-top chambers to manipulate CO₂ during regrowth after fire, and measured C, N and tracer ¹⁵N in ecosystem components throughout the experiment.

·Elevated CO₂ increased plant C and tended to increase plant N but did not significantly increase whole-system C or N. Elevated CO₂ increased soil …

Evolution On The Hawaiian Hotspot: Biogeography And Divergence Time Estimation Of Kadua (Rubiaceae), Kenneth L. Parker

Biological Sciences Theses & Dissertations

Recent studies on the colonization time of Hawaiian plant and animal lineages have suggested certain lineages arrived to the archipelago before the formation of the extant islands. Kadua, a recently resurrected genus, is mostly endemic to the Hawaiian Archipelago, with many member taxa autochthonous to individual islands. This work investigates the colonization time of Kadua to the Hawaiian Islands. Sequence analyses of the quickly evolving nuclear regions ITS, ETS and 5s-NTS regions for 20 Hawaiian and 7 French Polynesian species of Kadua were used to create dated phylogeny calibrated with island ages. The phylogeny suggests a single colonization of Hawaii …

A New Species Of Diploid Quillwort (Isoetes, Isoetaceae, Lycophyta) From Lebanon, Jay F. Bolin, Rebecca D. Bray, Lytton John Musselman

Biological Sciences Faculty Publications

A new species, Isoetes libanotica Musselman, Bolin & B. D. Bray (Isoetaceae, Lycophyta), is described from Akkar District of northern Lebanon. It is a seasonal terrestrial species of basaltic soils, diploid (2n = 22), with complete velum coverage. Megaspore diameter ranges from 338 to 477 mu m with remote, low tuberculate ornamentation and a low to obsolete equatorial girdle; microspore length ranges from 25 to 30 mu m, with echinate ornamentation. At the type locality of I. libanotica, two other Isoetes L. species occur sympatrically. These superficially similar Isoetes species can be differentiated from I. libanotica using megaspore …

Distributions And Abundances Of Microstegium Vimineum Along Forest Roadsides At The Grassy Hill Natural Area, Franklin County, Virginia, Gregory D. Turner

Virginia Journal of Science

In summer 2005, plots were surveyed along roads passing through forest habitats at the Grassy Hill Natural Area Preserve in Franklin County, Virginia to assess the distributions and abundances of Microstegium vimineum in transects located at increasing distances away from roadsides into forest interiors. Across plots, Microstegium was encountered almost exclusively in roadside transects, where abundances were relatively high. While forest composition and topographic features were similar across plots, percent canopy cover and leaf litter depth were greater in interior compared to roadside transects due to undisturbed tree canopies and ground cover located in interior plot areas. Results imply that …

The Loss Of Species: Mangrove Extinction Risk And Geographic Areas Of Global Concern, Beth A. Polidoro, Kent E. Carpenter, Lorna Collins, Norman C. Duke, Aaron M. Ellison, Joanna C. Ellison, Elizabeth J. Farnsworth, Edwino S. Fernando, Kandasamy Kathiresan, Nico E. Koedam, Suzanne R. Livingstone, Toyohiko Miyagi, Gregg E. Moore, Vien Ngoc Nam, Jin Eong Ong, Jurgenne H. Primavera, Serverino G. Salmo, Jonnell C. Sanciango, Sukristijono Sukardjo, Yamin Wang, Jean Wan Hong Yong

Biological Sciences Faculty Publications

Mangrove species are uniquely adapted to tropical and subtropical coasts, and although relatively low in number of species, mangrove forests provide at least US $1.6 billion each year in ecosystem services and support coastal livelihoods worldwide. Globally, mangrove areas are declining rapidly as they are cleared for coastal development and aquaculture and logged for timber and fuel production. Little is known about the effects of mangrove area loss on individual mangrove species and local or regional populations. To address this gap, species-specific information on global distribution, population status, life history traits, and major threats were compiled for each of the …

Interisland Variability Of Dune Plant Community Structure On Virginia's Barrier Islands, Justin K. Shafer

Biological Sciences Theses & Dissertations

The barrier islands of the Virginia Coast Reserve LTER site provide an opportunity to study interisland variability of dune plant communities. My research focused on the variation in biomass and diversity of communities among islands and dune positions. Grassy dunes of young, intermediate and old age were sampled on Smith, Hog, and Parramore Islands. Aboveground biomass was obtained from harvest plots, and roots were extracted from cores. Data were collected on depth to groundwater and total soil nitrogen. Variation in mean aboveground biomass was evident among the islands with the highest values on Hog Island, followed by Smith, then Parramore …

Ecological And Genetic Status Of The Purple Pitcher Plant, Sarracenia Purpurea L., In Maryland And Virginia, Philip M. Sheridan

Biological Sciences Theses & Dissertations

Sarracenia purpurea is a rare wetland plant in Virginia and a threatened species in Maryland, with two potential subspecies in the region. I utilized restriction fragments from the intron of the chalcone synthase gene to compare S. purpurea populations and determine whether the subspecies concept was supported. I performed a census of existing populations, compiled all known historical data on the species, and investigated the reasons for the species demise and predicted dates of extinction. Bloom phenology was examined to see if climate change may have influenced bloom period. Soil, vegetation, and climatic information was obtained to determine if taxonomic …

Ecology And Molecular Phylogenetics Of Hydnora (Hydnoraceae) In Southern Africa, Jay Francis Bolin

Biological Sciences Theses & Dissertations

The Hydnoraceae are a clade of root holoparasitic angiosperms that contain two small genera, Hydnora and Prosopanche. This study, focused on Hydnora, presents novel data regarding the pollination biology, germination ecology, parasite-host nutritional relationships, and the molecular systematics of this group. Experimental addition of the primary pollinator, Dermestes maculatus to Hydnora africana chamber flowers demonstrated beetle imprisonment during the carpellate stage. Changes in the inner surfaces of the androecial chamber allowed beetle escape after pollen release. Most beetles escaped, dusted with viable pollen, three days after pollen release. To investigate germination ecology, aqueous root extracts of host and …

Microspore Wall Morphogenesis And Orbicule Ultrastructure Of Isoetes, Khalid Alarid

Biological Sciences Theses & Dissertations

The microspore wall morphogenesis and orbicule ultrastructure of Isoetes were studied using electron microscopy. Microspore wall morphogenesis in five species of Isoetes (I. appalachiana, I. engelmannii, I. hyemalis, I. piedmontana, and an undescribed species from York Co., VA, USA) was studied using scanning and transmission electron microscopy. Results show that they generally have the same developmental stages in terms of microspore wall morphogenesis. The mature microspore wall consisted of four layers: perispore, paraexospore, exospore and endospore. Paraexospore formation began during the tetrad stage. The exospore was then formed between the paraexospore and the plasma membrane. During the free spore …