No description available.

No description available.

The taxonomic affinities of the plants formerly-referred to Oncidium section Oncidium, (Orchidaceae) in the Caribbean Islands have been studied with respect to morphological, cytogenetical, biochemical and geographic data. The data was-examined employing numerical taxonomic methods. The study involved 57 taxa (28 taxa of the plants belonging to the orchid group studied and 29 related-species)-and a total of 63 attributes. The literature and all available herbarium specimens-concerning the plants studied were viewed critically. This resulted in the clarification of some problems of identification and taxonomy. The plants studied were reclassified into, the*genera Braasiella, Hispaniella, Olgasis and Tolumnia. For all but one species formerly referred to Oncidium section Oncidium, living material was obtained through purchase, donation or through personal collecting in the Caribbean Islands. Living plants were examined in respect to morphological and ultrastructural characters. For all but three taxa, the chromosome number (2n) was determined. The data obtained was compared with the data formerly reported. For nine taxa, the diploid chromosome numbers are reported for the first time. Field studies were performed in selected areas of Jamaica, Haiti and the Dominican Republic to determine some aspects of the pollination ecology, ecology and distribution of some of the taxa. -3- Leaf flavonoid fingerprinting was performed on material obtained from all 57 taxa studied, using two dimensional paper chromatography. All data obtained was collated using numerical taxonomic methods. It became apparent during this study that a number of previously described taxa needed clarification as far as their identity is concerned. Furthermore, it became apparent that the species formerly referred to, oncidium sect. Oncidium, differ from all other groups of the genus Oncidium sensu Garay and stacy, as well as from all genera within the Oncidiinae, in such a way as to warrant their separation as autonomous genera. These have been published by Rafinesque (1837), Braem (1980) and Braem et al. (1984). This work also shows the difficulty of gaining total objectivity in a systematic study. The main problems arise from the selection of attributes, and the difficulties experienced in the coding of the data.

Interaction between orchids and fungi belongs to little understood aspects of orchid biology. This thesis investigated an identity of mycorrhizal and other fungal symbionts of several European orchid species and also an influence of these fungal symbionts on ecology, distribution, and evolution of the studied orchid species. Diverse methodological approaches were used including in situ seed germination, culture-dependent and -independent techniques for fungal isolation and identification, molecular phylogenetics, stable isotope analyses, and transmission electron microscopy.

Relationship and interfertility of Habenaria dilatata (lursh) Hook.,H. hyperborea (L.) R.Br, and H. saccata Greene was studied. Intraspecific and interspecific crosses were made. Chromosome counts of the three species showed 21 pairs of chromosomes in the cells, except for a small green-flowered population from Manning Park with n = 42 which was considered tetraploid and possibly of hybrid origin. These counts agree with earlier ones for the three species. Since creation of the genus Habenaria Willd» these species have been included under tribe Ophrydeae, which now has been changed to Orchideae, subtribe Orchidinae to conform with the rulings of the International Code of Botanical Nomenclature (1959)* In spite of apparently close relationships the species maintain their distinctness, even when growing sym-patrically, indicating barriers to outcrossing, or for plants growing in northerly regions, a lack of pollinators. Autogamous tendencies have therefore developed and H. dilatata and H. hyperborea are outcrossing or autogamous when the need arises. H. saccata seems to be self-sterile. Microsporogenesis in the species studied follows that of other orchids. The archesporial cell directly becomes the spore mother cell. All descendants of this cell stay together and divide together, forming a massula or pollen packet. Pollen mitosis results in the 2-nucleate pollen grain which is shed as such. The generative nucleus divides in the pollen tube, producing the 2 sperm nuclei, as the tube enters the ovary. Only the chalazal megaspore is functional. Three simultaneous divisions produce the monosporic, 8-nucleate Polygonum-type embryo sac. Fusion of the polar nuclei is the rule and takes place before fertilization. Triple fusion follows, hut the primary endosperm nucleus begins to degenerate usually before the r-ypote starts to divide. An haustorial susy ensor develops, which does not take part in the construction of the embryo proper. The mature embryo is an un differentiated body of 50-60 cells, suspended in the air-filled cavity of the reticulate testa. It takes from 3-4 weeks from pollination to saturation of the embryo. Intraspecific crosses were all successful. Interspecific crosses produced a higher percentage of seed with well developed embryos in IT. hyperborea x H. saccata crosses than in crosses between H. riil tata and either of the 2 other species. The tetraploid plants were successful both as seed and pollen parents. Regular meiosis would indicate allopolyploid origin. Artificial pollinations showed that gene flow is possible and that artificial crosses are easy to make. In nature isolating mec'r an isms must rrevent the species from losing their identity although hybridization may take place under favourable conditions. Control plants of H. dilatata and H, hyperhorea not emasculated and not protected showed a full seed set, indicating autocamy, whereas unpollinated H. sancata yielded only empty seed. / Science, Faculty of / Botany, Department of / Graduate

No description available.

Spiranthes Parksii Correll is an endangered orchid of Texas. Populations of S. parksii are threatened by habitat loss and degradation resulting from human population growth and attendant development and resource extraction. Conservation easements have been established for the protection of the species, but little is known about the population dynamics of S. parksii and the biotic and abiotic factors which drive them. A baseline of ecological information is necessary to the creation of effective management plans for the conservation of this species. The work presented here is an experimental investigation of the affects of large herbivores on S. parksii population dynamics. We explored direct impacts of herbivore browsing as well as indirect impacts resulting from removal of neighboring vegetation on S. parksii population fluctuations and the demographic parameters underlying them. To determine direct herbivore affects on demographic characteristics and their implications for S. parksii population dynamics, we established 32, 1.5mx1.5m plots in areas of high S. parksii abundance. Each of the plots was randomly assigned one of two treatments: herbivore exclusion and control. Demographic parameters were recorded for each individual located within the plots. The data suggest that large and small herbivore browsing affects different lifecycle transitions through removal of photosynthetic and reproductive tissue. These transition alterations have the potential to affect S. parksii population growth. To investigate the indirect impacts of herbivory on S. parksii population dynamics, we established 32 5mx5m plots. Each plot was randomly assigned one of four fertilizer treatments: control, nitrogen addition, phosphorus addition, and nitrogen and phosphorus additions. One half of each plot was randomly assigned one of two biomass removal treatments: unaltered control and biomass removal during orchid dormancy. Demographic data was collected for individuals within the plots. Plots with phosphorus and nitrogen phosphorus additions generally differed regarding orchid demographic variables from nitrogen addition plots and unfertilized controls. Also, available light tended to be greater during orchid flowering in plots with biomass removed than in unclipped controls. A complete understanding of both direct and indirect herbivore impacts on S. parksii population dynamics is necessary for effective conservation of this endangered orchid.

The Neotropical cloud forest inhabiting orchid Dracula felix has long been postulated to be a fungal mimic due to the form of its lower labellum and attraction to it by drosophilid flies that are often found feeding on fungal fruiting bodies in the surrounding area. The low number of co-occurring flowers in the area combined with the high number of fruiting fungi appears to have driven the evolution of the orchid genus Dracula to mimic these co-occurring fungi so that pollinators may be recruited. Over several years of working with these orchids we have noticed a particular lapping behavior by the pollinating flies on the labella and sepals of the Dracula flowers. In this study we have first surveyed floral yeasts and molds associated with Dracula flowers and then investigated the role of these fungi in attracting pollinators and offering a food reward to retain them for pollination purposes. In addition to the floral yeasts, leaf endophytes and root associated fungi were cultured and identified, and their frequencies were determined.

Germination ecology of four Epipactis species (E. albensis, E. atrorubens, E. helleborine, E. purpurata) was studied. Habitat preferences of adult plants were analyzed using phytosociological relevés from the Czech Phytosociological Database. A field experiment was carried out to determine course of germination of Epipactis seeds sown in different habitat types. Relationship between ecological preferences and germination ecology, and spatial aspects of seed dispersal and seedling recruitment are discussed.

Submitted by Jorge Cativo (jcativo@gmail.com) on 2018-05-23T22:12:32Z No. of bitstreams: 2 VariedadesdeespeciesdeorquideasencontradasnaAmazoniaClaudiaLimaCabral.pdf: 87962 bytes, checksum: 67b14c047c6db4395f97de1f2c5a1203 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-05-23T22:12:32Z (GMT). No. of bitstreams: 2 VariedadesdeespeciesdeorquideasencontradasnaAmazoniaClaudiaLimaCabral.pdf: 87962 bytes, checksum: 67b14c047c6db4395f97de1f2c5a1203 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-03-02 / Dichaea bragae is a pendulous plant, small, reaching five centimeters in length, the flower reaches five centimeters and has a structure called the lip, which is a modified petal. It is a landing structure of insect pollinators. The flower of Anathalis manausesis, according to the researcher, is only 3 millimeters (mm) and its leaf is less than 1 centimeter (cm). It is considered the smallest of the species already described. Brazil registers more than three thousand types of orchids. In Amazonas, there are about 300. According to the biologist, Amazonian orchids have characteristics similar to those of other regions. They can be found mainly in the so-called Amazonian campinaranas, areas with sandy soils, and also in the canopy of trees. Orchids have a preference, a need for light, a diffuse light. And the treetops are an ideal environment for them. In a dense ombrophilous forest, which is a tall forest, with trees up to 25 or 30 meters, you can hardly see orchids. / La Dichaea bragae es una planta péndula, pequeña, llegando a cinco centímetros de longitud, la flor llega a cinco centímetros y presenta una estructura llamada labelo, que es un pétalo modificado. Es una estructura de aterrizaje de insectos polinizadores. La flor de la Anathalis manausesis, de acuerdo con el investigador, tiene sólo 3 milímetros (mm) y su hoja mide menos de 1 centímetro (cm). Se considera la menor de las especies ya descritas. Brasil registra más de tres mil tipos de orquídeas. En el Amazonas, son cerca de 300. De acuerdo con el biólogo, las orquídeas de la amazonia tienen características similares a las de otras regiones. Se pueden encontrar, principalmente, en las llamadas campinaranas amazónicas, áreas con suelos arenosos, y también en la copa de árboles. Las orquídeas tienen preferencia, una necesidad de luz, una luz difusa. Y la copa de los árboles es un ambiente ideal para ellas. En un bosque de ombrófilo denso, que es un bosque alto, con árboles de hasta 25 o 30 metros, difícilmente usted puede ver orquídeas. / A Dichaea bragae é uma planta pêndula, pequena, chegando a cinco centímetros de comprimento, a flor chega a cinco centímetros e apresenta uma estrutura chamada labelo, que é uma pétala modificada. É uma estrutura de pouso de insetos polinizadores. Já a flor da Anathalis manausesis, de acordo com o pesquisador, tem apenas 3 milímetros (mm) e sua folha mede menos de 1 centímetro (cm). Ela é considerada a menor das espécies já descritas. o Brasil registra mais de três mil tipos de orquídeas. No Amazonas, são cerca de 300. De acordo com o biólogo, as orquídeas da amazônia têm características semelhantes às de outras regiões. Elas podem ser encontradas, principalmente, nas chamadas campinaranas amazônicas, áreas com solos arenosos, e também na copa de árvores. Orquídeas têm preferência, uma necessidade de luz, uma luz difusa. E a copa das árvores é um ambiente ideal para elas. Em uma floresta de ombrófila densa, que é uma floresta alta, com árvores de até 25 ou 30 metros, dificilmente você consegue enxergar orquídeas