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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Taxonomic studies in Cyperaceae

Oteng-Yeboah, Alfred Apau January 1972 (has links)
Part I deals with the supra-specific classification of the subfamily Cyperoideae (excluding the tribe Rhynchosporeae) on a world-wide basis. It involves a broad survey of comparative exomorphic and endomorphic characters, with an analysis and synthesis of all available information from the literature. Many microscopic features of the leaf, culm, glume; hypogynous perianth bristle, stamen, style, stigma and fruit have been examined, many of them for the first time. Most of these features, together with the already known characters commonly used in the classification of genera in the subfamily Cyperoideae, have been employed to form the basis of the supra-specific classification presented here. The two large Linnaean genera, viz: Scirpus and Cyperus, have been split into a number of small, natural genera. Four distinct taxa, previously included in Scirpus a.l., are for the first time accorded generic status, though formal generic names have not been given to 3 of these. These 3 unnamed genera have been temporarily called Genera A, B and C. Cyperus, in the restricted sense used here, is found still to be partly unnatural, but further studies are needed before attempting to change its circumscription. Of the 47 genera adopted in this work, 25 are monotypic and/or geographically restricted; the rest being widely distributed. The maximum concentration of species and genera is found to occur in the tropics. Formal taxonomic treatments have been given to all the 47 genera in the conclusion, except for those genera which were not personally investigated; for the latter only keys for their identification and appropriate literature references have been given. An informal tribal and subtribal grouping has been proposed to accommodate the narrower, more natural genera adopted, since the limits of the traditional tribes Cypereae and Scirpeae no longer stand. New nomenclatural combinations, as well as the list of species and citation of voucher specimens studied anatomically, have been given in Appendices. Part II deals with the revision of the entire subfamily Cyperoideae as it is represented in the area covered by the Flora of Turkey (Davis 1965-). 47 species representing 21 genera are found in this area. This number includes taxa either seen by me or accepted from reliable records in the literature. Descriptions, synonymy, habitats, specimen citations on a grid basis, notes on the variability of Turkish species, and a key for their identification have been included in this account. Two new taxa have been discovered, for which English diagnoses have been given. Finally, an attempt has been made to explain some of the apparent disjunctions in the distribution of certain species in Turkey.
2

Experimentální studium ekologie kriticky ohroženého druhu rozchodníku huňatého / Ecology of critically endangered \kur{Sedum villosum}-experimental study

DILLINGEROVÁ, Hana January 2019 (has links)
The aim of this diploma thesis was to elaborate a literature survey and especially to conduct an experimental study of ecological demands of the critically endangered species Sedum villosum. The localities, on which S. villosum formely occurred, disappeared largely because of habitat destruction by draining and plowing of wet meadows, or by the abandonment followed by development of high vegetation and biomass accumulation. Therefore, this work could contribute to the knowledge of shadow influence and surrounding vegetation concurency on seed germination and flowering of this species. Retrieved knowledge can be later used for rescue program realization (repatriation options, strengthening populations, habitat requirements). The experiments showed a significant negative effect of the shading and the presence of surrounding vegetation (sedges, brown mosses and peat mosses) on germination and flowering of S. villosum. Furthermore, it was found that S. villosum is able to germinate directly on water surface, with seed germination even higher than on wet soil. The experimental sowing, planting and subsequent monitoring of germination, growth and survival of S. villosum at the rehabilitated area of Knížecí Pláně (NP Šumava) showed that it is possible to strengthen S. villosum population by sowing and planting autochthonous material on prepared areas with a torn down turf. As an acceptable tools seems to be using mulch from mown in the area of the original population. Similar process can be used in the future for restoring historical localities of this species.
3

Строение корней осок из местообитаний с разной степенью увлажнения : магистерская диссертация / Structure of sedge roots from hab-its with different degrees of humidification

Тукова, Д. Е., Tukova, D. E. January 2021 (has links)
Магистерская диссертация на тему «СТРОЕНИЕ КОРНЕЙ ОСОК ИЗ МЕСТООБИТАНИЙ С РАЗНОЙ СТЕПЕНЬЮ УВЛАЖНЕНИЯ» состоит из 52 страниц машинописного текста, включая 19 рисунков, 2 таблицы и 113 литературных источников. Работа посвящена изучению морфологического и анатомического строения корней осок из местообитаний с разной степенью увлажнения и разных экоморф, или экологических групп по отношению к увлажнению. В исследованный материал входят собственные сборы и зафиксированные растительные образцы научных руководителей. Цель – изучение строения корней осок из местообитаний с разной степенью увлажнения и разных экоморф по отношению к увлажнению. Задачи: Изучить внешние признаки корневых систем и строение поглощаю-щих корней у осок разных экоморф и местообитаний; Установить, какие признаки и в какой степени связаны с экоморфой видов, а какие изменяются под действием режима увлажнения местообитаний независимо от принадлежности к экоморфе. Растения собраны в начале июня в период цветения большинства исследован-ных видов 2019-2021 гг. в местообитаниях, образующих градиент по увлажнению: водоем-луг-лес-сухой склон. Экологические группы по степени увлажнения среды (гигрофиты, мезофиты, ксеромезофиты) выделены по литературному источнику [Овеснов и др., 2007]. С помощью стандартных методик структурной ботаники изучены внешние признаки корневых систем и строение поглощающих корней 23 вида осок. Регистрировали параметры: число порядков ветвления корней, тип волосков, длина типичных волосков, диаметр корня; диаметр стелы; толщину паренхимы; число слоев клеток в паренхиме; число слоев клеток в экзодерме, толщину коры. Расчетные показатели – парциальный объем коры и стелы, %. В работе представлены 2 способа формирования учетных единиц. При анализе экологических групп, учетной единицей считается вид. Исследуя группы осок из местообитаний с разной степенью увлажнения, учетной единицей считается особь. Статистический анализ проводился с помощью программы STATISTICA 10. Использовали однофакторный дисперсионный анализ (F) (ANOVA) Непараметриче-ские критерии Краскела –Уоллиса (H) и Критерий (χ2) Пирсона. Результаты магистерской диссертации показали, что признаками тонких корней изученных осок, наиболее чувствительными к режиму увлажнения, являются: число порядков ветвления корней; встречаемость выпуклых корневых волосков; длина типичных корневых волосков; диаметр среза, толщина коры; выраженность экзодермы; У изученных осок от переувлажненных местообитаний к засушливым: а) увеличивается число порядков ветвления корней; б) уменьшаются: встречаемость выпуклых корневых волосков, длина корневых волосков, диаметр среза, толщина первичной коры за счет уменьшения слоев экзодермы. Несмотря на таксоноспецифичное строения корней осок, существует явно выраженная экологическая пластичность ряда признаков внутри обширного рода Carex. Полученные результаты согласуются с опубликованными данными. Результаты были представлены в устном докладе на Всероссийской конференции молодых ученых «Экология: факты, гипотезы, модели», проходившей в апреле 2021 года. Планируется публикация данных в сборнике конференции в виде тезисов. / The master's thesis on the topic "STRUCTURE OF SEDGE ROOTS FROM HAB-ITS WITH DIFFERENT DEGREES OF HUMIDIFICATION" consists of 52 pages of typewritten text, including 19 figures, 2 tables and 113 literature sources. The work is devoted to the study of the morphological and anatomical structure of sedge roots from habitats with varying degrees of moisture and different ecological groups. The analysis of the work consists of materials from our collection and recorded plant material [Konoplenko et al., 2017]. The goal is to study the structure of sedge roots from habitats with varying degrees of moisture and different ecomorphs in relation to moisture. Tasks: 1) To study the external signs of root systems and the structure of absorbing roots in sedges of different ecomorphs and habitats; 2) Establish which features and to what extent are associated with the ecomorph of the species, and which ones change under the influence of the habitat moistening regime, regardless of belonging to the ecomorph. To tackle these problems, the plants were collected in habitats forming a moisture gradient: reservoir-meadow-forest-dry slope. The ecological groups of sedge species were identified according to the literature [Ovesnov et al., 2007] according to the degree of en-vironmental moisture: hygrophytes, mesophytes, Xeromesophytes. Using the methods of structural botany, the external signs of root systems and the structure of absorbing roots of 23 species of sedges were studied. The following parameters were recorded: the number of orders of root branching, hair type, length of typical hairs, root diameter; stele diameter; parenchyma thickness; the number of cell layers in the parenchyma; the number of cell layers in the exoderm, the thickness of the cortex. Integral indicators - the partial volume of the cortex and ste-le,%. Statistical analysis was carried out using the STATISTICA 10 program. One-way analysis of variance (F) (ANOVA) was used. Nonparametric Kruskal-Wallis tests (H) and Pearson's test (χ2). The results of the master's thesis showed that the features of the thin roots of the studied sedges, the most sensitive to the moisture regime, are:the number of orders of root branching; the occurrence of convex root hairs; length of typical root hairs; cut diameter, bark thickness; the severity of exoderm; In the studied sedges, from waterlogged to arid habitats: a) the number of orders of branching of roots increases; b) decrease: the occurrence of convex root hairs, length of root hairs, cut diameter, thickness of the primary cortex due to a decrease in exoderm layers. Despite the taxon-specific structure of sedge roots, there is a pronounced ecological plasticity of a number of characters within the vast genus Carex. The results obtained are consistent with published data. These results were presented in an oral report at the All-Russian Conference of Young Scientists "Ecology: Facts, Hypotheses, Models", held in April 2021. It is planned to publish data in the conference collection in the form of abstracts.

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