Search Results (2)

Rhizomatous growth and associated physiological integration can allow a clonal dune species to potentially compensate for the selective removal of leaves associated with herbivory. Hydrocotyle bonariensis is a rhizomatous clonal plant species that is abundant in the coastal dune environments of the southeastern United States that are inhabited by large feral horse populations. H. bonariensis has been shown to integrate resources among ramets within extensive clones as an adaptation to resource heterogeneity in sandy soils. In this study, we hypothesized that clonal integration is a mechanism that promotes H. bonariensis persistence in these communities, despite high levels of herbivory by feral horses. In a field experiment, we used exclosures to test for herbivory in H. bonariensis over a four-month period. We found that feral horses utilized H. bonariensis as a food species, and that while grazing will suppress clonal biomass, H. bonariensis is able to maintain populations in a high grazing regime with and without competition present. We then conducted an experiment in which portions of H. bonariensis clones were clipped to simulate different levels of grazing. Half of the clones were severed to eliminate the possibility of integration. We found that after 12 weeks, the mean number of leaves and ramets increased as the grazing level increased, for integrated clones. Integrated clones had significantly increased biomass production compared to the severed equivalents. Our research suggests that rhizomatous growth and physiological integration are traits that allow clonal plant species to maintain populations and to tolerate grazing in coastal dune environments. Full article

Sulfated polysaccharides (SP) are found mainly in seaweeds and animals. To date, they have only been found in six plants and all inhabit saline environments. Furthermore, there are no reports of SP in freshwater or terrestrial plants. As such, this study investigated the presence of SP in freshwaters Eichhornia crassipes, Egeria densa, Egeria naja, Cabomba caroliniana, Hydrocotyle bonariensis and Nymphaea ampla. Chemical analysis identified sulfate in N. ampla, H. bonariensis and, more specifically, E. crassipes. In addition, chemical analysis, FT-IR spectroscopy, histological analysis, scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDXA), as well as agarose gel electrophoresis detected SP in all parts of E. crassipes, primarily in the root (epidermis and vascular bundle). Galactose, glucose and arabinose are the main monosaccharides found in the sulfated polysaccharides from E. crassipes. In activated partial thromboplastin time (APTT) test, to evaluate the intrinsic coagulation pathway, SP from the root and rhizome prolonged the coagulation time to double the baseline value, with 0.1 mg/mL and 0.15 mg/mL, respectively. However, SP from the leaf and petiole showed no anticoagulant activity. Eichornia SP demonstrated promising anticoagulant potential and have been selected for further studies on bioguided fractionation; isolation and characterization of pure polysaccharides from this species. Additionally in vivo experiments are needed and are already underway. Full article