Hygrophila polysperma is a plant native to Asia that has been introduced into the Comal River, TX and is thriving while Ludwigia repens, a species native to the river appears to be declining. Both plants have similar morphologies and occupy similar habitats in the river. Two plant competition experiments were conducted to examine the competitive interactions between the two species. First, an experimental design was developed in which established Ludwigia plants were 'invaded' by sprigs of Hygrophila to determine if established Ludwigia populations would be negatively impacted by invasion. The second experiment focused on establishment and growth of sprigs of each species under three competition scenarios. Results show that the continued growth of well-established Ludwigia plants was significantly depressed by the invasion of Hygrophila in comparison with those that had not been invaded. Furthermore, the growth of Hygrophila sprigs was uninhibited by the presence of Ludwigia, but the presence of Hygrophila negatively impacted the growth of Ludwigia sprigs. There was no difference in the growth of Hygrophila sprigs whether planted alone, with Ludwigia sprigs or even if planted into stands of established Ludwigia.

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A study of hypersensitivity of high school students to the oleoresins of fifty common North Texas plants.

The nature of this problem divides itself into two parts, that is, a study of the old sewage plants in operation through the summer of 1947 and a study of the new plant put in operation during the fall of the same year.

Call number: LD2668 .T4 1959 F53

Assessment of aquatic plant selection by waterfowl has been conducted during the winters of 1997-2000 on 49 0.2-0.79 ha research ponds in north central Texas. Ponds were categorized by dominant plant species into eight habitat types. Census with waterfowl species identification were performed to investigate impacts of aquatic vegetation and water depth on waterfowl. Eighteen waterfowl species were observed. Peak migration occurred in late December/early January. Mixed native ponds and mixed native/hydrilla ponds were the most frequently selected habitat types. The study included correlation analysis between pond water levels and waterfowl use. Full ponds received greatest use followed by half full ponds, while almost empty ponds received minimal use. Time activity budgets were conducted on waterfowl utilizing mixed native and hydrilla ponds to compare waterfowl time partitioning on native aquatic vegetation versus hydrilla. Although only minor differences were found in time budgets, social status appears to be strongly related to habitat selection. Ducks on native ponds were paired (86%), conversely no ducks on hydrilla ponds were paired. Hydrilla pond although frequently utilized, were populated by lower status birds mostly single hens.

This research represents the first systematic collection of the woody plants throughout the Cross Timbers. It provides the first keys to these plants in their vegetative condition, plant descriptions, distribution maps, and some quantitative measurements used for descriptive purposes. Descriptions of the woody plants were constructed as an aid in verification after a specimen has been identified by use of the keys. The measurements given pertain only to the woody plants as they occur in the Cross Timbers. Distributional maps are provided for all the taxa considered in this research. With the exception of those species which have the ecological amplitude to grow throughout the Cross Timbers, the distribution of the majority of the remaining species seems to be most strongly influenced by average annual precipitation. In a few instances, conditions associated with latitude appear to govern the distribution of species or varieties within the Cross Timbers. Throughout the Cross Timbers, post oak (Quercus stelta), blackjack oak (Quercus marilandica), and hickory (Caraa texan) dominate the upland forests. The streamside forests are dominated by willow (alix nigra), cottonwood (Populus deltoides), and hackberry (Celtis laevi ata). The variation in the vegetation of the Cross Timbers is not due to any change in dominant species, but rather to the distribution of the associated species which occur in the two prominent community types.

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This study documents that external and internal forces were causes of change at VCWTP. External forces caused. Fort Worth to reorganize and introduce new management at VCWTP after 1982. These improvements led to VCWTP being selected best managed wastewater treatment plant in the nation by EPA in 1988. This study first analyzes external and internal forces responsible for changes at VCWTP. A history of plant operations also is reviewed. Personnel interviews were conducted of perceptions of employees. Finally, statistics obtained of the plant operation from 1969 to 1988 are compared with personal interviews. Five forces effect change at VCWTP; population, regulatory requirements, political conflicts, an organizational and managerial factors. Turnaround occurred as external and internal corrections were made.

The problem of investigating the adaptability of plant fibers for basketry was two-fold. The first part was the selection and preparation of the plants. Suitable collection time, drying methods, and processing and soaking procedures were determined through a series of experiments, performed during each season of the year. In the second part experimental samples were woven by using the basic basketry techniques to illustrate the usability and versatility of each plant fiber. The survey of forty plants proved that there are readily available plants suitable for basketry. The simplicity of the process, the ready availability of plants, the nominal cost of supplies, and the variety of visual elements obtainable were advantages realized from this investigation.