Academic literature on the topic 'Clematis'

The object of the investigation was to determine factors influencing the distribution of C. vitalba in New Zealand, and to distinguish areas which may be susceptible to infestation. Seed of C. vitalba required exposure to light for germination. Exposure 5 min/day to light resulted in significantly higher total germination than long exposure (16 hr photoperiod). Transplantation of C. vitalba seedlings into different forest types showed a strong correlation between survival and percentage of total photosynthetically active photon flux density (PPFD) received. Gas exchange measurements demonstrated a high PPFD saturation level for stomatal conductance and assimilation. Stomatal opening took 20 minutes to complete after transfer from shade to high PPFD. Shading of plants grown in a glasshouse experiment resulted in significantly less growth at light intensities of less than 14% of full sunlight. C. vitalba grew significantly faster on soil from a podocarp forest than on soil from a beech forest. Addition of phosphorus to the beech forest soil significantly increased growth but there was no response to added calcium. Seedlings of C. vitalba grew best in well drained soil. Waterlogged soil significantly reduced growth. The major factor influencing distribution of C. vitalba is soil drainage rather than a calcium requirement. Therefore C. vitalba is a light demanding plant which can establish only in relatively open sites. Podocarp forests south of Auckland on free-draining sites are extremely susceptible to invasion due to the high fertility of the soils under this forest type. Herbicide-soaked wooden plugs, inserted into mature sterns, proved to be a safe and effective control method.

Clematis vitalba, introduced to New Zealand from Europe in the early 1900s, is an invasive weed which poses a high risk to native forest remnants, particularly in the central North Island and upper and central South Island. Its dispersal techniques and rate of spread make it a particular challenge for managers attempting to control its range expansion. Is the population abundance and distribution of C. vitalba on Banks Peninsula seed or microsite limited? I tested the presence of seed limitation in three populations of C. vitalba at two sites by measuring seed dispersal and checking for the presence of a soil seed bank. At a location where C. vitalba is absent due to control efforts, I investigated the presence of a long-term seed bank and long-distance dispersal. I also tested the degree of microsite limitation in C. vitalba at the two sites by surveying the natural distribution of seedlings, monitoring seedling emergence after seed addition and measuring the survival and growth of planted seedlings. Soil samples taken from the Port Hills and Akaroa sites contained low amounts of previous-season C. vitalba seed (an average of 0.0125 seeds per m² in the forest and 0.0025 per m² in the open) and cofirmed the presence of a small short-term soil seed bank. Seed rain was greater at Akaroa (3912 seeds caught) than on the Port Hills (1507 seeds caught), which is also reflected in a larger seed bank at Akaroa. The distribution of natural seedlings and growth of planted seedlings suggests that the optimum habitat for this species varies among different life stages. At the site cleared of C. vitalba more than eight years ago, there were no seeds in the seed bank but new seeds arrived by long-distance dispersal. Overall, these results suggest that microsite limitation has a greater role near the parent plant and seed limitation becomes more pronounced at increasing distance from the seed source. Clematis vitalba populations continue to spread from ongoing long-distance dispersal and short-distance dispersal with lateral expansion of established populations; established populations are more likely to be limited by the availability of microsites while expanding populations will be seed limited at the edge of the population where plant density is low.

Clematis spp. L. is a twining vine covered in showy blooms. Typical growth of hybrids is from the main leader, producing a thin, unbranched plant with one cyme. Apical dominance is released by cutting back the vine during production. Cutting back, or pinching, of a plant is labor intensive and compromises bloom for vegetative growth at time of sales. The purpose of this project was to eliminate manual pinching by treating young plants with chemical plant growth regulators (PGRs) that enhance branching without removal of the apical meristem. The first project evaluated the use of Atrimmec (dikegulac sodium), Fascination (BA+GA4+7), Florel (ethephon), and Dropp 50 (thidiazuron) on Clematis cultivars Ernest Markham, and Hagley Hybrid, and Clematis viticella 'Polish Spirit.' Plants treated with 800 mg·L-1 Atrimmec, or 800 or 1200 mg·L-1 Fascination experienced an increase in branch numbers. The second experiment manipulated the ratio of the components of Fascination, 6-BA and GA4+7, to reduce phytotoxicity experienced in the first experiment. The optimal ratio to enhance branching was 1:1, which is the stock solution for Fascination. All ratios produced phytotoxic symptoms. A third experiment tested lower rates of thidiazuron and added CPPU (forchlorfenuron) to the list of PGRs to test. The last experiment took the most effective PGR treatments, Atrimmec at 800 mg·L-1, and Fascination at 800 or 1200 mg·L-1, and compared them to the current production practices of pinching. Large flowering cultivars of clematis were used, including 'Comotesse de Bouchard,' 'Ernest Markham,' and 'Hagley Hybrid.' Atrimmec increased branch numbers and suppressed leader lengths without a mechanical pinch. Results from Fascination varied by cultivar.<br>Master of Science

Phoma clematidina (Thum.) Boerema is identified as the causal agent of leaf spot and wilt of large flowered Clematis hybrids in New Zealand. Three distinct strains of the pathogen can be distinguished. Phoma clematidina is a wound pathogen normally forming leafspots on both wilt susceptible and resistant cultivars. The final wilt symptom is usually the result of nodal rotting or "stem girdling" following hyphal extension into the node from the infected leaf, as P. clematidina is not a true vascular pathogen. Resistance to wilt was shown to be manifest by abscission or senescence of infected leaves. Pathogenicity is associated with production of a toxin, ascochitine (C15H1605), which could be isolated from leaf lesions and culture filtrate. A reverse phase High Performance Liquid Chromatography system was developed to confirm purity of the ascochitine preparation before identification by 1H Nuclear Magnetic Resonance (NMR) spectroscopy. Identification was confirmed by 13C NMR spectroscopy and mass spectroscopy. Ascochitine induced endogenous electrolyte leakage from sensitive leaf cells and caused blackening of leaf tissue similar to that observed in leaf lesions. The main organelles affected appear to be chloroplasts and mitochondria although extensive cellular damage is evident. Laboratory trials showed chlorothalonil and fenpropimorph to be the most effective fungicides in inhibiting P. clematidina spore germination and mycelial growth, and a mixture of these fungicides was used to effect control in the glasshouse. Cultural practices will however, remain an important factor in disease prevention and control.

The genus Clematis L. (Ranunculaceae) was used as a new model group to assess the role of the Himalayan orogeny on generation of biodiversity through investigations of its phylogeny, phylogeography and taxonomy. Although existing checklists include 28 species of Clematis from Nepal, a comprehensive taxonomic revision of available material in herbaria and additional sampling from fieldwork during this study has led to the recognition of 21 species of Clematis in Nepal, including one species (C. kilungensis) not previously recorded from Nepal. Exisiting phylogenetic and taxonomic concepts were tested with the addition of new samples from Nepal. The results highlight the shortcomings of the previous studies which were poorly resolved and indicate the need for a thorough revision of the sectional classification. Despite the increased sampling the results are still equivocal due to poor statistical support along the backbone of the phylogeny. Groups of species in well supported terminal clades are broadly comparable with results from previous studies although there are fewer clearly recognisable and well supported clades. The published dates for the evolution of Clematis were tested and the methodology of the previous study critically reappraised. The results indicate that the genus Clematis is approximately twice as old as previously reported and evolved in the middle Miocene. The phylogeny also demonstrates that, even allowing for poor support for the relationships between groups of species within Clematis, the extant Nepalese species must have multiple independent origins from at least 6 different colonisations. With their occurrence in the Pliocene and Pleistocene, these events are relatively recent in relation to the Himalayan orogeny, and may be linked more to the dispersal ability of Clematis than to the direct effects of the orogeny. Additional Nepalese samples of Koenigia and Meconopsis were added to exisiting datasets and these were reanalysed. The result from Clematis, Koenigia and Meconopsis were appraised in light of the the geocientific literature and previously published phylogeographic studies to create an overview of the drivers behind speciation in the Himalaya.

The phylogeny of Clematis, section Viorna, was characterized in this study using molecular data. Two nuclear introns were sequenced for a variety of taxa: actin and nitrate reductase. Actin intron sequence data yielded very little phylogenetic information. Some basal clades were resolved, but there were very few well supported relationships between species of the Viorna section in both the neighbor joining and maximum parsimony analyses. Nitrate reductase intron sequence data was slightly more variable. The number of well supported relationships in both the neighbor joining and maximum parsimony analyses for nitrate reductase was greater, but still not sufficient to yield an informative tree. Two possible explanations for the lack of variation are that these species have not evolved many differences in these intron sequences or that common alleles are flowing between the species. Hybrid analysis using the actin intron was inconclusive because the experimentally generated hybrid possessed an allele that neither parents tested had. More sampling from multiple individuals from both parent and multiple hybrid individuals is necessary to answer this question. The hybrid specimen tested was homozygous for the nitrate reductase intron marker, and both parents also possessed the allele. This did not directly support or refute the use of these markers for tracking the hybridization history within Clematis.