Understanding why some introduced alien plant species become invasive whilst others fail is a fundamental question in ecology, not least because of the considerable ecological and economic damage caused by invasive plants globally. Identifying factors that drive alien plant invasions can inform efforts to predict the nsk of invasion by an introduced plant species. This would allow prevention of introduction of high risk aliens, as well as targeted management of species already introduced that pose the latest threats to the ecolocal integrity of host ecosystems. However, generalisations among the findings of comparative plant invasion studies have been limited by a lack of control of confounding variables such as propagule pressure, time since introduction and phylogeny, a lack of knowledge of introduced species that failed to establish, and inconsistent use of terminology defining the invasion process. This thesis used Amani Botanical Garden (ABG) in the East Usambara Mountains of Tanzania, as a comparative case study system to assess the relative ability of multiple factors to explain invasion success of species introduced to a tropical forest ecosystem.

Thesis (MTech (Horticulture))--Cape Peninsula University of Technology, 2016. / This study focused on optimising four types of in-vitro conservation methods, namely: 1), micropropagation, 2) in-vitro slow growth, 3) seed germination and 4) cryopreservation for selected endangered plant species indigenous to the Cape Floristic Region. It is one of the targets set by United Nations millennium development goals, to integrate different conservation measures in order to preserve plant diversity and mitigate losses of genetic diversity. Therefore this study uses Phalaenopsis hybrids as a trial species that can be studied for the conservation of endangered Disa and Eulophia species through micropropagation and in vitro slow growth. Also conservation attempts on Leucadendron and Mimetes species that occur in the Cape Floristic Region were attemted to increase population densities by increasing germination percentages using smoke. Furthermore, the study attempted to store seeds by assessing different cooling rates for optimising cryopreservation measures for effective conservation. The use of tissue culture to increase propagules especially critically endangered species in South African has proven to be feasible. For the trial hybrids, shoot and protocorm explants of Phalaenopsis Psychosis Pink X P. No. 1; P. Large white X P. Large pink; P. No. 1 X P. Large pink; P. Mini pink X Brighton belle; and the P. aphrodite formed clusters of protocorms and shoots when cultured on ½ strength MS media supplemented with 10, 20 and 30gL-1 banana extract or ½ strength Murashige and Skoog, (1962) (MS) media supplemented with peptone. Continuous protocorms formation could therefore be obtained by culturing endangered Disa and Eulophia shoots and protocorms on banana containing media. Plantlet conversion from somatic embryos produced on 10gL-1 banana extract enriched media was successfully achieved on ½ strength MS supplemented with 20gL-1 sucrose and no plant growth regulators in the medium. However, optimum rooting was achieved on ½ strength MS supplemented with 30gL-1 of banana extract and this medium yielded the highest survival percentages for plantlet acclimatisation. Furthermore, ½ strength MS supplemented with 1gL-1 of peptone served as a stimulant for shoot development and protocorm formation. When coupled with banana extract at all stages of development, regeneration and rooting were enhanced.

The Mimulus washingtonensis complex is a group of morphologically similar species centered in the Pacific Northwest. All are rare, and most are under consideration for listing as endangered. Morphometric and pollination data were used in developing a revised taxonomy for the group. Five species and two varieties are recognized. Mimulus pulsiferae Gray is the most widespread, occurring from southern Washington to northern California. Mimulus hymenophyllus Meinke and M. jungermannioides Suksd. are cliff species endemic to river drainages in northern Oregon. Mimulus washingtonensis Gand. occurs in east-central Oregon and western Idaho, represented by the var. washingtonensis and var. ampliatus (Grant) Meinke comb. et stat. nov., respectively. Mimulus patulus Pennell is resurrected from synonymy and differentiated from M. washingtonensis on the basis of morphology, distribution, and pollination biology. This autogamous species includes var. patulus, occurring in the Snake River drainage, and var. montanus Meinke var. nov., primarily from the northern Rocky Mountains. Mimulus evanescens Meinke sp. nov. is described from an extant population in Lassen County, California, and historic collections from widely scattered stations in Oregon and Idaho. The new species is morphologically intermediate between M. breviflorus Piper and M. latidens (Gray) Greene. Calyx and leaf morphology also suggest an affinity to M. grayi Grant, M. inconspicuus Gray, and M. acutidens Greene, of cismontane California. Mimulus evanescens should be considered critically endangered, because of its limited numbers and habitat degradation. Mimulus washingtonensis is pollinated by small native bees, primarily two species of Dialictus (Halictidae). These bees were specific to Mimulus flowers but did not distinguish between flowers of M. washingtonensis and M. guttatus DC., a related species that increases with habitat disturbance. Experiments showed that mixed pollen loads diminish seed set in M. washingtonensis, since the thigmotropic stigma of that species closes permanently after any amount of conspecific pollen is applied. Although M. washingtonensis has a low pollen/ovule ratio (29.9), it is considered facultatively xenogamous based on floral morphology, stigma sensitivity, and autogamous seed set levels. Populations occurred in small, edaphically restricted patches, and they exhibited seed set reductions related to outcrossing distance. Substrate disturbance may limit reproduction in M. washingtonensis by changing population structure, threatening pollinators, and increasing competition for pollination by promoting growth and flowering of M. guttatus. / Graduation date: 1992

Thesis (M.Sc.)--Memorial University of Newfoundland, 2002. / Restricted until October 2003. Includes bibliographical references.

published_or_final_version / Zoology / Master / Master of Philosophy

Thesis (M. Env. St.)--University of Adelaide, Mawson Graduate Centre for Environmental Studies, 1993. / Includes bibliographical references (leaves 63-71).

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographic references (leaves [114]-129).

Thesis (M.S.)--Missouri State University, 2009. / "May 2009." Includes bibliographical references (leaves 12, 28-29, 39). Also available online.

Thesis (Ph.D.)--Aberdeen University, 2009. / Title from web page (viewed on July 23, 2009). Includes bibliographical references.

Thesis (M.Sc. (Environmental Science)) - Rhodes University, 2007.