995 resultados para Gentiana Sect Stenogyne


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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As Eriocaulaceae brasileiras encontram-se distribuídas principalmente nos campos rupestres que se estendem de Minas Gerais à Bahia, na Cadeia do Espinhaço. Paepalanthus Mart. é o maior gênero da família e apresenta cerca de 450 espécies, sendo que Paepalanthus sect. Diphyomene Ruhl. possui cerca de 20 espécies que já pertenceram a diversas categorias taxonômicas. Com o objetivo de correlacionar a anatomia e a taxonomia desta seção, além de levantar caracteres diagnósticos para suas espécies, foi estudada a anatomia de folhas, brácteas e escapos. Folhas e brácteas de Paepalanthus sect. Diphyomene apresentam diferenças na forma e no espessamento das células epidérmicas; no espessamento do mesofilo; na disposição dos feixes vasculares; presença ou ausência de hipoderme; diferente forma e composição de parede das células da extensão de bainha do feixe vascular; forma e constituição da margem e presença ou ausência de parênquima aqüífero na face adaxial. No escapo, foram observadas diferenças quanto ao número e contorno de costelas e extensão da medula. Assim, a proposta de divisão de P. sect. Diphyomene em duas categorias é corroborada. São caracteres diagnósticos para as espécies: presença de parênquima aquífero na face adaxial e ausência de extensão de bainha do feixe vascular em folhas de Paepalanthus urbanianus; presença de feixes vasculares distribuídos em ordem decrescente de tamanho em direção à margem em folhas e brácteas e contorno triangular do escapo em P. flaccidus, presença de nove costelas em escapos de P. acanthophyllus e dez em P. macer. Foi elaborada uma chave de identificação das espécies de Paepalanthus sect. Diphyomene com base nas características anatômicas levantadas

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Bulbophyllum, which comprises 1876 species, is considered the second largest genus of angiosperms, with a pantropical distribution. The morphological and anatomical floral studies in the genus are incipient, with data restricted to the gynostemium and lip of some species. Based on molecular data, six sections were recognized within Bulbophyllum at the Neotropics, amongst them Bulbophyllum sect. Micranthae, which comprises 12 species distributed in central South America. We aimed to study the floral anatomy of six species of Bulbophyllum sect. Micranthae, in order to determine useful characters to differentiate them and contribute to the anatomical characterization of the section as a whole. Floral anatomy was assessed through usual techniques of light microscopy. The data found here for B. adiamantinum, B. chloroglossum, B. epiphytum, B. mentosum, B. micranthum and B. rupicolum allowed to identificate the presence of glandular trichomes and the possible presence of a secretory region on the lip, which might produce substances used as a reward to pollinators. The most significant anatomical characters to the species characterization were the shape and ornamentation of the outer periclinal walls of the epidermal cells, as well as the number of vascular bundles in dorsal and lateral sepals and at the lip. The data also allowed the differentiation between B. epiphytum and B. rupicolum, species very similar in morphology and phylogenetically related. Besides that, the data also allowed the discussion regarding the maintenance of B. mentosum within the section: although its inclusion is supported by molecular studies, the anatomical data here presented shows greater differences compared to the other species, not supporting its maintenance in Bulbophyllum sect. Micranthae

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The new species, Matayba obovata (Sapindaceae), from southern and southeastern Brazil is described, illustrated, and contrasted to its putatively closest relatives. Palynological characters are also described. The new species belongs to sect. Matayba. A key to identify M. obovata and related species in the Atlantic Forest is included.

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Baccharis napaea, a new species belonging to subgen. Tarchonanthoides sect. Coridifoliae is described and illustrated. The new species is compared to and distinguished from the sympatric species B. coridifolia, B. erigeroides, and B. scabrifolia, and from the allopatric B. bicolor. Baccharis napaea occurs in open subtropical highland grasslands and the edges and open glades of subtropical mixed forests on the south Brazilian plateau. Additionally, a distribution map and description of habitat and conservation status of the new species are presented.

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Vorbesitzer: Johann Maximilian Zum Jungen

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Plant species distributions are expected to shift and diversity is expected to decline as a result of global climate change, particularly in the Arctic where climate warming is amplified. We have recorded the changes in richness and abundance of vascular plants at Abisko, sub-Arctic Sweden, by re-sampling five studies consisting of seven datasets; one in the mountain birch forest and six at open sites. The oldest study was initiated in 1977-1979 and the latest in 1992. Total species number increased at all sites except for the birch forest site where richness decreased. We found no general pattern in how composition of vascular plants has changed over time. Three species, Calamagrostis lapponica, Carex vaginata and Salix reticulata, showed an overall increase in cover/frequency, while two Equisetum taxa decreased. Instead, we showed that the magnitude and direction of changes in species richness and composition differ among sites.

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Palynological investigation of a 410 cm long core section from Tso Kar (33°10'N, 78°E, 4527 m a.s.l.), an alpine lake situated in the arid Ladakh area of NW India at the limit of the present-day Indian summer monsoon, was performed in order to reconstruct post-glacial regional vegetation and climate dynamics. The area was covered with alpine desert vegetation from ca. 15.2 to 14 kyr BP (1 kyr=1000 cal. years), reflecting dry and cold conditions. High influx values of long-distance transported Pinus sylvestris type pollen suggest prevailing air flow from the west and northwest. The spread of alpine meadow communities and local aquatic vegetation is a weak sign of climate amelioration after ca. 14 kyr BP. Pollen data (e.g. influx values of Pinus roxburghii type and Quercus) suggest that this was due to a strengthening of the summer monsoon and the reduced activity of westerly winds. The further spread of Artemisia and species-rich meadows occurred in response to improved moisture conditions between ca. 12.9 and 12.5 kyr BP. The subsequent change towards drier desert-steppe vegetation likely indicates more frequent westerly disturbances and associated snowfalls, which favoured the persistence of alpine meadows on edaphically moist sites. The spread of Chenopodiaceae-dominated vegetation associated with an extremely weak monsoon occurred at ca. 12.2-11.8 kyr BP during the Younger Dryas interstadial. A major increase in humidity is inferred from the development of Artemisia-dominated steppe and wet alpine meadows with Gentianaceae after the late glacial/early Holocene transition in response to the strengthening of the summer monsoon. Monsoonal influence reached maximum activity in the Tso Kar region between ca. 10.9 and 9.2 kyr BP. The subsequent development of the alpine meadow, steppe and desert-steppe vegetation points to a moderate reduction in the moisture supply, which can be linked to the weaker summer monsoon and the accompanying enhancement of the winter westerly flow from ca. 9.2 to 4.8 kyr BP. The highest water levels of Tso Kar around 8 kyr BP probably reflect combined effect of both monsoonal and westerly influence in the region. An abrupt shift towards aridity in the Tso Kar region occurred after ca. 4.8 kyr BP, as evidenced by an expansion of Chenopodiaceae-dominated desert-steppe. Low pollen influx values registered ca. 2.8-1.3 kyr BP suggest scarce vegetation cover and unfavourable growing conditions likely associated with a further weakening of the Indian Monsoon.

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1. Late glacial and postglacial sediments from three former lakes in the Lake Garda area (Southern Alps) were investigated. 2. The pollen diagram from Bondone (1550 m) shows an older phase rich in NAP. A younger one corresponds with the Younger Dryas time according to two radiocarbon determinations. In the Preboreal no climatic deterioration could be found. 3. At first plants, which are nowadays typical for snow-ground, pioneer and dwarf shrub associations, immigrated into the surroundings of Bondone. In Alleröd times larch and pine appeared as the first trees. At the beginning of the Preboreal dense forest existed in that region. During the Alleröd timber line was at about 1500 m. 4. In the pollen diagrams from Saltarino (194 m) and Fiavè (654 m) an oldest period rich in NAP is followed by two stadial and two interstadial phases. Tree birches and larches immigrated during the oldest interstadial phase. 5. In the case of Saltarino and Fiavè only a preliminary dating could be made. A correlation seems to be possible with diagrams published by Zoller as well as with the diagram of Bondone. Discrepances in dating, which arise then, are discussed. According to the two possibilities of dating the youngest stadial is synchronous either with the so-called Piottino stadial or the Younger Dryas time. Consequently the oldest interstadial phase of Saltarino corresponds either with the Bölling or with a pre-Bölling interstadial. The last possibility seems to be more probable. 6. In the southern part of the Lake Garda area reforestation was preceded by a long shrub phase mainly with Juniperus. At about 650 m there was a period with Pinus mugo and only with a small amount of Juniperus before reforestation. A phase with Betula nana well known from areas north of the Alps could nowhere be found. 7. In the area under study larch appeared as the first tree. Lateron it has been the most important constituent of the forests near timber line. Birch, which plays an important role as a pioneer tree in Denmark - for instance at the transition of the pollen zones III/IV - as well as in Southern Germany during Bölling time, was of less importance at the southern border of the Alps. In that area the spreading of Pinus occurred very early causing dense forests. 8. During the last stadial phase (probably Younger Dryas time) dense forests with Pinus and Larix existed at 650 m. In the lower part of the Lake Garda area, however, both thermophilous trees as Quercus and herbs frequently occurred. This leads to the conclusion that during this time tree growth was limited by dryness in lower altitudes of the border of the Southern Alps. Pinus and Juniperus, however, do not show higher values in this period, a fact which cannot yet be explained. 9. A list of plants, which were found in the sediments, is compiled. Helodium lanatum, Dictamnus albus, Mercurialis cf. ovata, Buxus, Cerinthe cf. minor, Onosma, Anthericum and Asphodelus albus are findings, which are of special interest for the history of the flora of that region.

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The high-altitude lake Tso Moriri (32°55'46'' N, 78°19'24'' E; 4522 m a.s.l.) is situated at the margin of the ISM and westerly influences in the Trans-Himalayan region of Ladakh. Human settlements are rare and domestic and wild animals are concentrating at the alpine meadows. A set of modern surface samples and fossil pollen from deep-water TMD core was evaluated with a focus on indicator types revealing human impact, grazing activities and lake system development during the last ca. 12 cal ka BP. Furthermore, the non-pollen palynomorph (NPP) record, comprising remains of limnic algae and invertebrates as well as fungal spores and charred plant tissue fragments, were examined in order to attest palaeolimnic phases and human impact, respectively. Changes in the early and middle Holocene limnic environment are mainly influenced by regional climatic conditions and glacier-fed meltwater flow in the catchment area. The NPP record indicates low lake productivity with high influx of freshwater between ca. 11.5 and 4.5 cal ka BP which is in agreement with the regional monsoon dynamics and published climate reconstructions. Geomorphologic observations suggest that during this period of enhanced precipitation the lake had a regular outflow and contributed large amounts of water to the Sutlej River, the lower reaches of which were integral part of the Indus Civilization area. The inferred minimum fresh water input and maximum lake productivity between ca. 4.5-1.8 cal ka BP coincides with the reconstruction of greatest aridity and glaciation in the Korzong valley resulting in significantly reduced or even ceased outflow. We suggest that lowered lake levels and river discharge on a larger regional scale may have caused irrigation problems and harvest losses in the Indus valley and lowlands occupied by sedentary agricultural communities. This scenario, in turn, supports the theory that, Mature Harappan urbanism (ca. 4.5-3.9 cal ka BP) emerged in order to facilitate storage, protection, administration, and redistribution of crop yields and secondly, the eventual collapse of the Harappan Culture (ca. 3.5-3 cal ka BP) was promoted by prolonged aridity. There is no clear evidence for human impact around Tso Moriri prior to ca. 3.7 cal ka BP, with a more distinct record since ca. 2.7 cal ka BP. This suggests that the sedimentary record from Tso Moriri primarily archives the regional climate history.

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Studies of the annual pollen and spore deposition in different areas of the Lena Delta were undertaken for the first time in the Asian sector of the Arctic during the Russian-German ''LENA 98'' and ''LENA 99'' expeditions in the framework of the International ''Laptev Sea System-2000'' Project. To achieve this objective, three spore-pollen traps were set up along the meridional delta profile in accordance with the European Pollen Monitoring Programme for the period July 1998 to August 1999. A comparison between the results of spore-pollen analysis of the contents of traps and the surrounding vegetation was performed. The results confirmed the current spore-pollen spectra are comprised both of pollen and spores of the local plants and of long-distance pollen and spores. The dependence of the long-distance pollen deposition on the character of the wind regime of the region was established. The prevailing southerly and southeasterly wind direction determines the main pollen influx of tree species from the areas of their growth south of the delta. The features of the morphological structure and fossilization of pollen and the features of the productive capability and plant growing conditions are of large significance in the pollen transfer and deposition.

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