Life Sciences Commons^™

Status Of Plants In Virginia, Michael H. Renfroe

Virginia Journal of Science

OVERVIEW OF BOTANICAL DIVERSITY

Virginia possesses a unique and varied assemblage of plant life. There are 3,164 species, subspecies and varieties of plants in Virginia (Weakley et al. 2012). As classified by the Virginia Department of Conservation and Recreation’s Division of Natural Heritage (DCR-DNH), they form some 94 ecological groups and 317 community types across five distinct physiographic provinces: Coastal Plain, Piedmont, Blue Ridge, Ridge and Valley, and Appalachian Plateau. The state extends 469 miles from east to west and 201 miles north to south at the widest points, enclosing 42,326 square miles of territory. This diverse range of environmental …

Groundwater Thresholds For Root Decomposition And The Relation To Barrier Island Ecological State Changes, Matthew Lee Smith

Biological Sciences Theses & Dissertations

Barrier islands off the eastern shore of Virginia exhibit distinct habitats that abruptly transition between periodically brackish/freshwater marshes, wooded swales, and sparsely vegetated dunes. There is strong evidence that the plant communities and ecosystem processes occurring in each habitat are primarily influenced by nutrient availability and the distance between two of the three free surfaces: land and freshwater. At the Virginia Coast Reserve-Long Term Ecological Research Site in Virginia, USA, thresholds to belowground decomposition rates were identified by measuring decay of native roots and rhizomes at 32 elevations in relation to mean annual groundwater levels (-0.356 – 1.937 m). Negative …

Molecular Phylogeny Of The Genus Houstonia And Allies In Rubiaceae, Hunter Lee Shanks

Biological Sciences Theses & Dissertations

Houstonia (Rubiaceae) is a strictly North American genus of 24 species distributed from Mexico, throughout the United States, up to Canada. Houstonia has proven to be a taxonomically difficult genus since the Linnaean description of Houstonia and the related genera: Hedyotis and Oldenlandia in 1753. For over 250 years botanists have lumped and separated Houstonia from Hedyotis and Oldenlandia based on various morphological characters. The most recent circumscription of Houstonia (Terrell 1996) separated the genus into two subgenera with each subgenus containing two sections. Nuclear (ITS) and plastid (trnL-F, rps16) DNA sequences were used to build a molecular phylogeny depicting …

Section Abstracts: Botany

Virginia Journal of Science

Abstracts of the Botany Section for the 93rd Annual Meeting of the Virginia Academy of Science, May 21-23, 2015, James Madison University, Richmond, Virginia

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 …

Plant Species Rather Than Climate Greatly Alters The Temporal Pattern Of Litter Chemical Composition During Long-Term Decomposition, Yongfu Li, Na Chen, Mark E. Harmon, Yuan Li, Xiaoyan Cao, Mark A. Chappell, Jingdong Mao

Chemistry & Biochemistry Faculty Publications

A feedback between decomposition and litter chemical composition occurs with decomposition altering composition that in turn influences the decomposition rate. Elucidating the temporal pattern of chemical composition is vital to understand this feedback, but the effects of plant species and climate on chemical changes remain poorly understood, especially over multiple years. In a 10-year decomposition experiment with litter of four species (Acer saccharum, Drypetes glauca, Pinus resinosa, and Thuja plicata) from four sites that range from the arctic to tropics, we determined the abundance of 11 litter chemical constituents that were grouped into waxes, carbohydrates, …